2022/01/19 更新

写真a

オオサカ テツヤ
逢坂 哲彌
所属
研究院(研究機関) ナノ・ライフ創新研究機構
職名
特任研究教授

学内研究所等

  • 2020年
    -
    2022年

    理工学術院総合研究所   兼任研究員

  • 2006年
    -
     

    理工学術院総合研究所(各務記念材料技術研究所)   流動研究員

学歴

  •  
    -
    1974年

    早稲田大学   理工学研究科   応用化学  

  •  
    -
    1974年

    早稲田大学   理工学研究科   応用化学  

  •  
    -
    1969年

    早稲田大学   理工学部   応用化学  

学位

  • 早稲田大学   工学博士

  • Dr.Eng.

経歴

  • 2016年
    -
     

    早稲田大学 理工学術院 名誉教授

  • 2016年
    -
     

    早稲田大学 ナノ・ライフ創新研究機構 名誉機構長

  • 2016年
    -
     

    早稲田大学 ナノ・ライフ創新研究機構 名誉機構長

  • 2015年
    -
    2016年

    早稲田大学ナノ・ライフ創新研究機構 機構長

  • 2014年
    -
    2016年

    早稲田大学 理工学術院 副学術院長

  • 2014年
    -
    2016年

    早稲田大学 総長室参与

  • 2014年
    -
    2016年

    早稲田大学 総長室参与

  • 2014年
    -
    2016年

    早稲田大学 総長室参与

  • 2014年
    -
    2016年

    早稲田大学 総長室参与 学長代理(研究推進)

  • 2015年
    -
     

    早稲田大学 スマートエナジーシステム・イノベーションセンター長

  • 2010年
    -
    2014年

    早稲田大学ナノ理工学研究機構 機構長

  • 2010年
    -
    2013年

    早稲田大学 先端科学・健康医療融合研究機構 副機構長

  • 2011年
    -
     

    早稲田応用化学会 副会長

  • 2007年
    -
    2011年

    早稲田大学 総合研究機構評価委員会 委員 現在に至る

  • 2008年
    -
    2010年

    Deputy Dean, Faculty of Science and Engineering, Waseda University

  • 2008年
    -
    2010年

    Director of Waseda Research Institute for Science and Engineering

  • 2008年
    -
    2010年

    早稲田大学 理工学術院総合研究所 所長 (理工学術院 副学術院長 兼任)

  • 2004年
    -
    2010年

    早稲田大学 先端科学・健康医療融合研究機構 事務局長

  • 2007年
    -
     

    早稲田大学 理工学術院 教授 現在に至る(再編により名称変更)

  • 2002年
    -
    2006年

    早稲田大学 研究推進部 部長

  • 2001年
    -
    2004年

    宮城学院大学 評議員

  • 2003年
    -
     

    早稲田大学大学院 理工学研究科ナノ理工学専攻 教授(兼任) 現在に至る

  • 1998年
    -
    2002年

    早稲田大学大学院 理工学研究科 委員長, 早稲田大学 評議員

  • 1996年
    -
    1998年

    早稲田大学 応用化学科主任

  • 1989年
    -
    1990年

    米国ミネソタ大学客員教授

  • 1986年
    -
     

    早稲田大学 教授 現在に至る(再編により2007年より理工学術院先進理工学部)

  • 1986年
    -
     

    早稲田大学 教授 現在に至る(再編により2007年より理工学術院先進理工学部)

  • 1986年
    -
     

    早稲田大学 教授 現在に至る(再編により2007年より理工学術院先進理工学部)

  • 1981年
    -
    1985年

    早稲田大学 助教授

  • 1979年
    -
    1980年

    早稲田大学 専任講師

  • 1976年
    -
    1978年

    米国ジョージタウン大学 博士研究員

  • 1975年
    -
    1978年

    早稲田大学 助手

  •  
     
     

    現在に至る

▼全件表示

所属学協会

  •  
     
     

    米国電気化学会

  •  
     
     

    アメリカ科学振興協会

  •  
     
     

    米国化学会

  •  
     
     

    国際純正・応用化学連合

  •  
     
     

    米国電子情報通信学会

  •  
     
     

    (社)電気学会

  •  
     
     

    日本表面科学会

  •  
     
     

    (社)腐食防食協会

  •  
     
     

    (社)高分子学会

  •  
     
     

    (社)応用物理学会

  •  
     
     

    (社)日本金属学会

  •  
     
     

    (社)電子情報通信学会

  •  
     
     

    公益社団法人 日本工学アカデミー

  •  
     
     

    (社)日本磁気学会 (旧日本応用磁気学会)

  •  
     
     

    (社)エレクトロニクス実装学会 (旧プリント回路学会)

  •  
     
     

    (社)表面技術協会 (旧金属表面技術協会)

  •  
     
     

    (社)日本化学会

  •  
     
     

    (社)電気化学会

  •  
     
     

    国際電気化学会

▼全件表示

 

研究分野

  • 電気電子材料工学

  • ナノバイオサイエンス

  • 電子デバイス、電子機器

研究キーワード

  • 応用電気化学

論文

  • Detection of Over-Discharged Nickel Cobalt Aluminum Oxide Lithium Ion Cells Using Electrochemical Impedance Spectroscopy and Differential Voltage Analysis

    Norihiro Togasaki, Tokihiko Yokoshima, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   168 ( 7 )  2021年07月

     概要を見る

    Addressing the reuse of lithium ion batteries (LIBs) extracted from used battery packs is an option for addressing environmental concerns. To guarantee their safety, the development of non-destructive analysis to identify LIBs exposed to over-discharge is mandatory. In this study, over-discharge-induced degradation in graphite/nickel cobalt aluminum oxide (NCA) lithium ion cells was investigated using differential voltage analysis (DVA) and electrochemical impedance spectroscopy (EIS). Two-stage cell capacity decay was solely observed in the deep over-discharge cycling at a lower cutoff voltage (LCV) of 1.00 V; in the first stage, the capacity gradually decreased similar to that at LCV >= 2.50 V, and then decreased steeply. In the over-discharge cycling, the DVA results confirmed that the electrode balancing between the anode and cathode contribute to increasing the cell capacity, whereas the cathode capacity decreased as cycling progressed, suggesting that electrode degradation induced by over-discharge is difficult to assess using the cell capacities. EIS analysis revealed that the charge-transfer resistance and interfacial capacitance of the NCA cathode changed markedly in the first stage under over-discharge. This study reports a meticulous characterization of over-discharge of LIBs using non-destructive electrochemical analysis and introduces a critical aspect for their detection before serious cell deterioration.

    DOI

  • High-rate and high sulfur-loaded lithium-sulfur batteries with a polypyrrole-coated sulfur cathode on a 3D aluminum foam current collector

    Natsuki Nakamura, Tokihiko Yokoshima, Hiroki Nara, Hitoshi Mikuriya, Ayahito Shiosaki, Seongki Ahn, Toshiyuki Momma, Tetsuya Osaka

    MATERIALS LETTERS   285  2021年02月

     概要を見る

    In this study, the high-rate performance of high sulfur-loaded cathodes have been demonstrated using a novel battery that comprises of a 3 dimensional aluminum foam (current collector), sulfur (active material), acetylene black (conductive additive), and polypyrrole (PPy) coating. Consequently, a stacked laminated cell was prepared, which comprised of two 70 x 70 mm(2) PPy-sulfur/ketjen black sheets (sulfur loading = 4.3 mg/cm(2)), 1 M lithium bis-(trifluoromethylsulfonyl)imide (LiTFSI) with dimethoxyethane (DME) and 1,3-dioxolane (DOL), (DME/DOL = 1/1 vol%), and three Li foils as the cathodes, electrolyte, and anodes, respectively. The 1 M LiTFSI DME/DOL electrolyte, which is suitable for high rate, is applicable because the PPy coating suppresses dissolution of polysulfide into the electrolyte. The discharge capacities were 462 mAh (1075 mAh/g sulfur) at 0.4C (267 mA) and 251 mAh (583 mAh/g-sulfur) at 3.8C (2670 mA). An enhanced conductive path was formed in the cathode by the 3D Al foam and AB, which considerably improved the high-rate performance. This demonstration is particularly significant from the viewpoint of commercializing the high-power output and high-energy-density Li-S batteries for industrial applications such as small mobile device and drone power source. (c) 2020 Elsevier B.V. All rights reserved.

    DOI

  • Potassium-Regulated Immobilization of Cortisol Aptamer for Field-Effect Transistor Biosensor to Detect Changes in Charge Distribution with Aptamer Transformation

    Shigeki Kuroiwa, Hiroki Hayashi, Ryo Toyama, Naoto Kaneko, Katsunori Horii, Keishi Ohashi, Toshiyuki Momma, Tetsuya Osaka

    Chemistry Letters    2021年01月

    DOI

  • Effect of fluoroethylene carbonate and vinylene carbonate additives on full-cell optimization of Li-ion capacitors

    Seongki Ahn, Minori Fukushima, Hiroki Nara, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Osaka

    ELECTROCHEMISTRY COMMUNICATIONS   122  2021年01月

     概要を見る

    Lithium-ion capacitors (LICs) operate by two mechanisms, namely a double-layer mechanism based on a capacitor-like positive electrode and the intercalation mechanism of a battery-like negative electrode. Hence, well-designed reaction kinetics between the positive electrode and negative electrode are essential for optimizing LIC full-cell configurations. In this study, we investigated the influences of fluoroethylene carbonate (FEC) or vinylene carbonate (VC) as electrolyte additives on full-cell performance of LICs. We confirmed that the internal resistance of graphite increased with the use of FEC, which degraded the cyclability of the LIC full-cell. Conversely, LICs consisting of the VC additive had good cyclability over 4000 cycles owing to the solid electrolyte interphase (SEI) containing polymeric species. This detailed investigation into the function of SEI compounds derived from VC additives and their effect on cyclability will provide new insights into optimization of LIC full-cell configurations with appropriate electrolyte additives.

    DOI

  • Immobilization of Target-Bound Aptamer on Field Effect Transistor Biosensor to Improve Sensitivity for Detection of Uncharged Cortisol

    Hiroki Hayashi, Ryo Toyama, Ryota Takibuchi, Sho Hideshima, Shigeki Kuroiwa, Naoto Kaneko, Katsunori Horii, Keishi Ohashi, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHEMISTRY   89 ( 2 ) 134 - 137  2021年

     概要を見る

    Field effect transistor (FET) biosensors are capable of detecting various biomolecules, although challenges remain in the detection of uncharged molecules. In this study, the detection of uncharged cortisol was demonstrated by interfacial design using a technique to immobilize target-bound aptamers. The target-bound aptamers, which formed a higher-order structure than target-unbound aptamers, expanded the distance between adjacent aptamers and reduced the steric hindrance to the conformational change. The density-controlled aptamers efficiently induced their conformational changes with the cortisol binding, which resulted in the improvement of the sensitivity of FET biosensors. (C) The Author(s) 2020. Published by ECSJ.

    DOI

  • Excess heat production in the redox couple reaction of ferricyanide and ferrocyanide.

    Atsushi Sugiyama, Makoto Miura, Yoshinobu Oshikiri, Yena Kim, Ryoichi Morimoto, Miki Miura, Tetsuya Osaka, Iwao Mogi, Yusuke Yamauchi, Ryoichi Aogaki

    Scientific reports   10 ( 1 ) 20072 - 20072  2020年11月  [国際誌]

     概要を見る

    In order to establish the universality of the excess heat production in electrochemical reaction, under a high magnetic field, as one of the most fundamental electrochemical reactions, the case of ferricyanide-ferrocyanide redox reaction was examined, where ionic vacancies with ± 1 unit charge were collided by means of magnetohydrodynamic (MHD) flow. As a result, from the pair annihilation of the vacancies with opposite signs, beyond 7 T, excess heat production up to 25 kJ·mol-1 in average at 15 T was observed, which was attributed to the liberation of the solvation energy stored in a pair of the vacancy cores with a 0.32 nm radius, i.e., 112 kJ·mol-1. Difference between the observed and expected energies comes from the small collision efficiency of 0.22 due to small radius of the vacancy core. Ionic vacancy initially created as a by-product of electrode reaction is unstable in solution phase, stabilized by releasing solvation energy. Ionic vacancy utilizes the energy to enlarge the core and stores the energy in it. As a result, solvated ionic vacancy consists of a polarized free space of the enlarged core surrounded by oppositely charged ionic cloud. The accuracy and precision of the measured values were ascertained by in situ standard additive method.

    DOI PubMed

  • Tetrameric jacalin as a receptor for field effect transistor biosensor to detect secretory IgA in human sweat

    Hiroki Hayashi, Naoki Sakamoto, Sho Hideshima, Yoshitaka Harada, Mika Tsuna, Shigeki Kuroiwa, Keishi Ohashi, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   873  2020年09月

     概要を見る

    Secretory immunoglobulin A (s-IgA), found in biological fluids, is useful for monitoring condition on mental health to prevent depression. In this study, the non-invasive detection of s-IgA in human sweat was demonstrated using field effect transistor (FFT) bioscnsors modified with a plant lectin, jacalin, as a receptor. The s-IgA molecules were detected with greater sensitivity using the jacalin-immobilized FET biosensors as compared to the sensitivity shown by Fabimmobilized FET bioscnsors. Jacalin, which is a small lectin tetramcr, has four glycan-binding sites and can capture a large number of s-IgA molecules within the charge-detectable region in terms of Dcbye length. Moreover, the jacalin-immobilized FET bioscnsor could detect s-IgA at concentrations ranging from 0.1 mu g/ml. to 100 mu g/mL Additionally, by using a filtration process to eliminate the interference of other components found in human sweat, our FET sensing system could specifically and quantitatively detect s-IgA. Therefore, our results show the utility of this device in monitoring mental stress.

    DOI

  • Understanding and applying coulombic efficiency in lithium metal batteries

    Jie Xiao, Qiuyan Li, Yujing Bi, Mei Cai, Bruce Dunn, Tobias Glossmann, Jun Liu, Tetsuya Osaka, Ryuta Sugiura, Bingbin Wu, Jihui Yang, Ji-Guang Zhang, M. Stanley Whittingham

    NATURE ENERGY   5 ( 8 ) 561 - 568  2020年08月

     概要を見る

    Coulombic efficiency (CE) has been widely used in battery research as a quantifiable indicator for the reversibility of batteries. While CE helps to predict the lifespan of a lithium-ion battery, the prediction is not necessarily accurate in a rechargeable lithium metal battery. Here, we discuss the fundamental definition of CE and unravel its true meaning in lithium-ion batteries and a few representative configurations of lithium metal batteries. Through examining the similarities and differences of CE in lithium-ion batteries and lithium metal batteries, we establish a CE measuring protocol with the aim of developing high-energy long-lasting practical lithium metal batteries. The understanding of CE and the CE protocol are broadly applicable in other rechargeable metal batteries including Zn, Mg and Na batteries.

    DOI

  • Facile fabrication of sulfur/Ketjenblack-PEDOT:PSS composite as a cathode with improved cycling performance for lithium sulfur batteries

    Seongki Ahn, Takayuki Noguchi, Toshiyuki Momma, Hiroki Nara, Tokihiko Yokoshima, Norihiro Togasaki, Tetsuya Osaka

    CHEMICAL PHYSICS LETTERS   749  2020年06月

     概要を見る

    Lithium sulfur batteries (LSBs) are regarded as promising electrochemical energy storage devices owing to their higher theoretical capacity than commercial cathode materials. Herein, we report a simple method for preparing a modified sulfur/Ketjenblack (S/KB) cathode using polymer composite poly(3,4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT:PSS), which displays ionic and electron conductivity and can suppress polysulfide dissolution during the charge-discharge process. The S/KB + PEDOT:PSS cathode displayed higher electrochemical performance than the S/KB cathode. The effectiveness of suppressing polysulfide dissolution was determined visually and by UV-visible spectroscopy. The findings demonstrate the multi-functionality of PEDOT:PSS as an efficient electron conductive additive for S/KB cathode in high-performance LSBs.

    DOI

  • Prediction of overcharge-induced serious capacity fading in nickel cobalt aluminum oxide lithium-ion batteries using electrochemical impedance spectroscopy

    Norihiro Togasaki, Tokihiko Yokoshima, Yasumasa Oguma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   461  2020年06月

     概要を見る

    Prediction of degradation in lithium-ion batteries is critical to ensure battery safety. In this study, we report for the first time that electrochemical impedance spectroscopy (EIS) predicts serious capacity fade in lithium-ion batteries, which results from charge-discharge cycling under overcharge conditions. A nickel cobalt aluminum oxide (NCA) lithium-ion cell shows a two-stage capacity fade in the overcharge condition with an upper cutoff voltage (UCV) of 4.4 V. The capacity gradually decreases as cycling progresses (first stage), and then decreases steeply in the later cycles (second stage). Such a two-stage capacity fade is not observed when cell cycling in the appropriate voltage range (UCV <= 4.2 V). In the first stage, the cell capacities cycled at UCVs of 4.2 V and 4.4 V are approximately identical, with an inductively coupled plasma atomic emission spectrometry analysis confirming overcharge-induced deposition of Ni and Co on the anode surface. EIS analysis is used to model these deposited metals as enhanced impedance signals that represent the charge transfer resistance and interfacial capacitance of the anode in the first stage. This allows the advance prediction of overcharge-induced serious capacity decay in lithium-ion batteries to prevent cell destruction.

    DOI

  • Technology of electrochemical impedance spectroscopy for an energy-sustainable society

    Hiroki Nara, Tokihiko Yokoshima, Tetsuya Osaka

    CURRENT OPINION IN ELECTROCHEMISTRY   20   66 - 77  2020年04月

     概要を見る

    Electrochemical impedance spectroscopy has been widely used to understand the chemistry and physics of battery systems. This review covers electrochemical impedance spectroscopy used for the interpretation of impedance data of lithium-ion batteries (LIBs) from advanced equivalent circuit models to the mathematical model, which is developed by John Newman. In addition, as a method to realize an energy-sustainable society using diagnostics based on the combination of LIBs and electrochemical impedance spectroscopy, on-board diagnostics of battery packs are achieved based on an input signal generated by a power controller in a battery management system instead of the conventionally used frequency response analyzer. The diagnostic system is applicable to energy management systems which are installed in homes, buildings, and communities, accumulating the impedance data on state of health of LIBs. Finally, a future possibility regarding the diagnostics of battery packs coupled with the machine learning of impedance data is introduced.

    DOI

  • Synthesis of Stacked Graphene-Sn Composite as a High-Performance Anode for Lithium-Ion Capacitors

    Seongki Ahn, Yamato Haniu, Hiroki Nara, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   167 ( 4 )  2020年02月

     概要を見る

    A Lithium-ion capacitor (LIC) is composed of an electrochemical capacitor-like cathode and battery-like anode which store charge based on non-faradaic and faradaic processes, respectively. As an anode material for LIC, graphite is widely used because of its physical and electrochemical advantages. In the LIC system, stable cyclability at the high rate conditions is essential for bridging the gap between lithium-ion batteries and supercapacitors. However, there have been reported that the low working potential of graphite (close to 0.05 V vs Li/Li+) causes Li plating on the graphite surface and non-unity coulombic efficiency at high current charge/discharge results in degradation of cycle performance. To overcome this issue, stacked reduced graphene oxide-tin (SrGO-Sn) composite by co-reduction of graphene oxide and Sn2+ are studied in this work. The LIC consisting of SrGO-Sn anode shows good long-term cyclability with a remarkable capacity retention of 85, 77, and 60% at 10,000, 50,000, and 100,000th cycle and coulombic efficiency of 98% after 120,000 cycles. We believe that this study presents a new approach to the design of the high-performance LIC using an alternative to conventional graphite-based anode materials. (c) 2020 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.

    DOI

  • Effect of Mass Balancing on Cell Performance and Electrochemical Investigation of Sn-Ni Alloy as Anode for Li-Ion Capacitors

    Seongki Ahn, Yusuke Nakamura, Hiroki Nara, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   167 ( 13 )  2020年01月

     概要を見る

    Lithium-ion capacitors (LICs) have been attracting research interest over the past years as promising electrochemical energy devices because they show higher energy densities than supercapacitors and higher power densities than batteries. In this study, we synthesized an Sn-Ni alloy by electrodeposition and applied it as an anode for LICs. To optimize the full-cell configuration, we controlled the mass balancing between the loading amounts of active materials in the cathode and anode with different mass ratios of 16:1, 8:1, and 4:1. In addition, the Sn-Ni alloy was investigated using electrochemical impedance spectroscopy under different depth of discharge (DOD) levels. The LICs assembled with a mass ratio of 4:1 between the cathode and anode exhibited good cyclability, rate performance, energy, and power density. This study not only improved the cycle performance of LICs full cell by mass balancing, but also revealed the relationship between the electrochemical characteristics of LICs and DOD levels of the Sn-Ni anode.

    DOI

  • Influence of Li-salts on Cycle Durability of Sn-Ni Alloy Anode for Lithium-ion Capacitor

    Yusuke Nakamura, Hiroki Nara, Seongki Ahn, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Osaka

    ELECTROCHEMISTRY   88 ( 2 ) 74 - 78  2020年

     概要を見る

    Tin-nickel (Sn-Ni) alloy is a promising candidate as an anode for the lithium-ion capacitor (LIC) because it is superior in volumetric energy density compared with that of the graphite anode. However, its cycle durability requires improvement, even with a higher utilization ratio of the anode. The effect of lithium salts, LiPF6 and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is investigated for usage in the LIC in severe conditions (utilization ratio of the anode: 20%). The LIC with LiTFSI delivered its initial capacity up to similar to 400 cycles, which is 4 times longer than the LIC with LiPF6. The reason for the capacity decay in the LiPF6 system is attributed to the narrowing of the potential range of the activated carbon cathode due to a widening potential range of the Sn-Ni alloy anode during operation. This widening is attributed to the loss of the active material due to peeling-off from the substrate. However, when LiTFSI is used, no such decay is observed. It is suggested that a polymer-like solid electrolyte interphase derived from TFSI- may suppress the loss of the active material. This finding can encourage the development of an Sn-based anode for LICs in combination with a mild operating condition and electrolyte additives. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

  • Synthesis of Lithium Sulfide (Li2S) Wrapped Carbon Nano Composite for Binder-Free Li2S Cathode

    Yunwen Wu, Toshiyuki Momma, Hiroki Nara, Tao Hang, Ming Li, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   167 ( 2 )  2020年01月

     概要を見る

    Lithium sulfide (Li2S) is considered to be a promising cathode material for safer energy storage cells due to its compatibility with Li metal-free anodes. However, challenges remain regarding the insulating nature of Li2S, which leads to poor electrochemical performance, currently making Li2S electrodes far from practical in real-world applications. Herein we present a chemical method to synthesize Li2S nanoflake wrapped carbon material, Ketjenblack (LS@KB) composite, which can be coated on different current collectors without the addition of a binder. The high contact area between KB nanoparticles and Li2S nanoflakes effectively improves the cathode's conductivity, which contributes to a high Li2S weight ratio (83%). In addition, we prove that the well wrapped LS@KB structure enhances the physical confinement of polysulfides, leading to improved cyclability. As a result, the synthesized LS@KB cathode delivers stable cyclability (1000 cycles) with a fading rate of 0.03% per cycle at 0.5 C-rate. This room temperature fabrication strategy conquers the major drawbacks existing in Li2S fabrication, such as high temperature, hazardous gas release, complex and high-cost production process, making it a promising cathode material for light and safe portable electronic devices. (C) 2020 The Electrochemical Society ("ECS"). Published on behalf of ECS by IOP Publishing Limited.

    DOI

  • Communication-Solvate Ionic Liquid Incorporating Lithium Nitrate as a Redox Mediator for Lithium-Oxygen Batteries

    Norihiro Togasaki, Takuya Naruse, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   166 ( 14 ) A3391 - A3393  2019年10月

     概要を見る

    A solvate ionic liquid (SIL) of highly concentrated 4.0 M lithium nitrate (LiNO3) in a dimethylsulfoxide solution is introduced for lithium-oxygen batteries. As a redox mediator (RM), highly concentrated LiNO3 in the SIL works more effectively than the lower concentrated one to decompose lithium peroxide (Li2O2) on the cathode with an extremely low charging voltage of 3.6 V. In addition, X-ray photoelectron spectroscopy analysis confirms that side products during discharging and charging are markedly restricted in the SIL. The low solubility of Li2O2 intermediate (LiO2) in the SIL may be an important reason for the restriction of side products. (C) The Author(s) 2019. Published by ECS.

    DOI

  • Application of Sn-Ni Alloy as an Anode for Lithium-Ion Capacitors with Improved Volumetric Energy and Power Density

    Seongki Ahn, Yusuke Nakamura, Hiroki Nara, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   166 ( 15 ) A3615 - A3619  2019年10月  [査読有り]

     概要を見る

    Lithium-ion capacitors (LIC) constructed by combining a supercapacitor-like cathode and battery-like anode are expected to bridge a gap between low power density from lithium-ion batteries (LIB) and low energy density from the supercapacitors. In this study, we synthesize the Sn-Ni alloy by electrodeposition in the aqueous solution as an anode for LIC. The lower volume expansion rate of Sn-86 than pure Sn anode can be confirmed by in-operando investigation using an optically transparent cell during the 1st charging process. This is attribute to the co-deposited Ni can act as a buffer matrix to restrain volume expansion. For the full-cell test, the pre-lithiation condition of Sn-Ni was investigated with different depth of discharge levels. As a result, a LIC consisting of activated carbon (AC) cathode and Sn-86 exhibits a good cyclability for 3000 cycles with a capacity retention of 80% and coulombic efficiency of 98% at 3000th cycle. The Sn-Ni//AC LIC shows improved volumetric energy and power density than graphite//AC LIC. This study presents a new possibility of Sn-Ni alloy as an anode for the improved electrochemical performance of LIC. (C) 2019 The Electrochemical Society.

    DOI

  • Tin addition for mechanical and electronic improvement of electrodeposited Si–O–C composite anode for lithium-ion battery

    Seongki Ahn, Takahiro Kadoya, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    Journal of Power Sources   437   226858  2019年10月  [査読有り]

    DOI

  • Fabrication of powdered Si-O-C composite by electrodeposition harvesting method as a long-cycle-life anode material for lithium-ion batteries

    Seongki Ahn, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    MATERIALS LETTERS   251   184 - 187  2019年09月  [査読有り]

     概要を見る

    In this work, we present a powdered Si-O-C composite, namely pSi-O-C composite, synthesized by electrodeposition harvesting method. This new type of the Si-O-C composite shows impressive results, such as outstanding cyclability with a good discharge capacity of 616 mAh g(-1) which reached 10,000 cycles, and a remarkable coulombic efficiency of 99% at the 10,000th cycle. Furthermore, the pSi-O-C composite demonstrates the highest amounts of loaded silicon compared to different types of Si-O-C composite deposited on a Cu and CNTs/Cu substrate. (C) 2019 Elsevier B.V. All rights reserved.

    DOI

  • Glycan-immobilized dual-channel field effect transistor biosensor for the rapid identification of pandemic influenza viral particles.

    Sho Hideshima, Hiroki Hayashi, Hiroshi Hinou, Shunsuke Nambuya, Shigeki Kuroiwa, Takuya Nakanishi, Toshiyuki Momma, Shin-Ichiro Nishimura, Yoshihiro Sakoda, Tetsuya Osaka

    Scientific reports   9 ( 1 ) 11616 - 11616  2019年08月  [査読有り]  [国際誌]

     概要を見る

    Pandemic influenza, triggered by the mutation of a highly pathogenic avian influenza virus (IFV), has caused considerable damage to public health. In order to identify such pandemic IFVs, antibodies that specifically recognize viral surface proteins have been widely used. However, since the analysis of a newly discovered virus is time consuming, this delays the availability of suitable detection antibodies, making this approach unsuitable for the early identification of pandemic IFVs. Here we propose a label-free semiconductor-based biosensor functionalized with sialic-acid-containing glycans for the rapid identification of the pandemic IFVs present in biological fluids. Specific glycans are able to recognize wild-type human and avian IFVs, suggesting that they are useful in discovering pandemic IFVs at the early stages of an outbreak. We successfully demonstrated that a dual-channel integrated FET biosensing system, which were modified with 6'-sialyllactose and 3'-sialyllactose for each gate area, can directly and specifically detect human H1N1 and avian H5N1 IFV particles, respectively, present in nasal mucus. Furthermore, to examine the possibility of identifying pandemic IFVs, the signal attributed to the detection of Newcastle disease virus (NDV) particles, which was selected as a prime model of a pandemic IFV, was clearly observed from both sensing gates. Our findings suggest that the proposed glycan-immobilized sensing system could be useful in identifying new pandemic IFVs at the source of an outbreak.

    DOI PubMed

  • In-situ lithiation through an ‘injection’ strategy in the pouch type sulfur-graphite battery system

    Toshiyuki Momma, Yunwen Wu, Hitoshi Mikuriya, Hiroki Nara, Tetsuya Osaka

    Journal of Power Sources   430   228 - 232  2019年08月  [査読有り]

    DOI

  • Electrodeposited Si-O-C as a High-Rate Performance Anode for Li-ion Capacitor

    Seongki Ahn, Toshiyuki Momma, Wataru Sugimoto, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   166 ( 12 ) A2683 - A2688  2019年08月  [査読有り]

     概要を見る

    Li-ion capacitors (LIC) which bridge the advantages of supercapacitors and Li-ion batteries have attracted a great deal of attention as a promising energy storage device. In this study, we synthesize the Si-O-C by electrodeposition at low levels of electricity below 2.0 C cm(-2) as an anode for LIC. The deposited Si amounts are controlled by charge density during electrodeposition from 0.3 to 1.0 C cm(-2). The material and electrochemical characteristics of Si-O-C fabricated at a charge density of 1.0 C cm(-2) are studied. The LIC consisting of Si-O-C anode shows an encouraging 95% retention of the initial capacity after 1000 cycles. In addition, the LIC shows a capacity retention ratio of 94% at 140 C-rate. This study reveals the potential prospect to use Si-O-C fabricated by electrodeposition as an anode for a high-rate capability for LIC. (C) The Author(s) 2019. Published by ECS.

    DOI

  • Effect of enhanced structural stability of Si-O-C anode by carbon nanotubes for lithium-ion battery

    Seongki Ahn, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    MATERIALS LETTERS   245   200 - 203  2019年06月  [査読有り]

     概要を見る

    Herein, we synthesized the structural stabilized Si-O-C composite using carbon nanotubes (CNTs). The SiO-C/CNTs is employed and tested as an anode for lithium-ion batteries (LIBs) assembled with the LiCoO2 cathode. Through the usage of CNTs, it is possible to improve the cyclability and capacity retention ratio by enhanced structural stability. The enhanced electrochemical performance of LiCoO2//Si-O-C full-cell with CNTs indicates the high potential as a way to produce the high-performance LIBs. (C) 2019 Elsevier B.V. All rights reserved.

    DOI

  • Effect of Heating and Cooling Rates in Annealing for Preparation of L1(0)-FePt Nanoparticles on Si Substrate

    Yoshiki Fujihira, Toru Asahi, Toshiyuki Momma, Tetsuya Osaka

    ECS JOURNAL OF SOLID STATE SCIENCE AND TECHNOLOGY   8 ( 4 ) P217 - P222  2019年04月

     概要を見る

    In order to obtain highly ordered L1(0)-FePt nanoparticles for hard disk drive applications, the L1(0)-phase transformation of chemically synthesized FePt nanoparticles deposited on a naturally oxidized Si substrate was investigated using rapid thermal annealing. The heating and cooling rates during annealing were changed logarithmically with a constant annealing temperature (800 degrees C) and holding time (10 min). Almost completely ordered L1(0)-FePt nanoparticles were confirmed by grazing incidence X-ray diffraction measurements, irrespective of the heating and cooling rates, and the amount of the silicide changed in response to both. Nearly pure L1(0)-FePt was obtained when rapid heating (more than 780 K/min) and rapid cooling (more than 290 K/min) were applied. L1(0)-FePt degraded into Fe3Si and PtSi when the cooling rate was lower than 7.8 K/min. Rapid heating as well as rapid cooling of FePt nanoparticles can provide a facile route for the high-throughput production of L1(0)-FePt-based high-density magnetic recording media. (c) 2019 The Electrochemical Society.

    DOI

  • Operando Analysis of Thermal Runaway in Lithium Ion Battery during Nail-Penetration Test Using an X-ray Inspection System

    Tokihiko Yokoshima, Daikichi Mukoyama, Fujio Maeda, Tetsuya Osaka, Koji Takazawa, Shun Egusa

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   166 ( 6 ) A1243 - A1250  2019年04月

     概要を見る

    The thermal runaway of a lithium ion battery (LIB) during a nail-penetration test was investigated using an LIB internal short circuit observation system equipped with an X-ray scanner (LiSC scanner). Using high-speed moving images and high-precision voltage measurements, the layer-by-layer internal short circuit caused by the nail was clearly observed during nail motion. Following this motion, gas generation outside the cell, which is well-known in thermal runaway, was observed. The main causes of smoke are speculated to be the boiling of the electrolyte and/or decomposition of the active materials owing to heating by the short circuit current. The initial behavior of the short circuit before gas generation was clearly observed. Therefore, gas generation, which is well-known to indicate an internal short circuit of the cell, and the electrical behavior of the short circuit during the nail-penetration test were observed separately. This LiSC scanner allowed us to analyze the details of the internal short circuit of the cell, and it is expected to lead to significant advancements in the safety of LIBs. (c) The Author(s) 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited.

    DOI

  • Metal phosphide nanoparticles embedded in carbon as efficient electrocatalyst for oxygen evolution reaction

    Sangaraju Shanmugam, Arumugam Sivanantham, Mariko Matsunaga, Ulrich Simon, Tetsuya Osaka

    ELECTROCHIMICA ACTA   297   749 - 754  2019年02月

     概要を見る

    We describe a facile and simple solid-state thermolysis route for the preparation of Co, Ni, and Fe phosphide nanoparticles embedded in amorphous carbon using an organometallic complex. This was achieved by using a suitable organometallic complex in a single step synthetic route without using any solvent or catalyst. The advantage of using such precursor was to offer a source for metal, phosphorus and carbon without using any additional sources. The morphology of products was characterized by transmission electron microscopy, scanning electron microscopy and nature of carbon was analyzed using the Raman microscope and X-ray diffraction. The electrocatalytic oxygen evolution reaction (OER) activity and stability of the metal phosphide nanostructure was evaluated using the rotating disk electrode technique. The CoP, NiP and FeP exhibit the OER overpotential of 370, 380 and 550 mV at 10 mA cm(-2), respectively in 0.1 M KOH electrolyte. Among prepared phosphide catalysts, cobalt phosphide shows a lowest Tafel slope indicate favorable kinetics for the OER activity than nickel and iron phosphide catalysts. (C) 2018 Elsevier Ltd. All rights reserved.

    DOI

  • Systematic analysis of interfacial resistance between the cathode layer and the current collector in lithium-ion batteries by electrochemical impedance spectroscopy

    Hiroki Nara, Daikichi Mukoyama, Ryo Shimizu, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   409   139 - 147  2019年01月  [査読有り]

     概要を見る

    Lithium-ion batteries are required to have high-power density, that is to reduce impedance, for use in electric vehicles. This paper focuses on interfacial resistance between the cathode layer (CL) and the current collector (CC) observed at high frequencies, which is generally attributed to a resistance of surface film like SEI. To investigate the interfacial resistance systematically, different interfaces between the CL and the CC were prepared by controlling the press rate for the cathode preparation, or by introducing a carbon under-coating layer (CUL), followed by electrochemical impedance spectroscopy (EIS). The interfacial resistance between the CL and the CC prepared with an insufficient press rate or without a CUL was extremely high for the entire cathode. From the cathode cross-sectional observation, it was observed that this high interfacial resistance was caused by low contact rate at the interface. Using a pouch-type symmetric cell, EIS revealed that the interfacial resistance is attributed to electric resistance, that is, contact resistance at the interface. Also, the other resistances were attributed to be the ionic resistance of the electrolyte and pores in the cathode, and the charge transfer resistance of the cathode. Furthermore, the effectiveness of the CUL was shown to decrease the cathode impedance.

    DOI

  • Direct observation of internal state of thermal runaway in lithium ion battery during nail-penetration test

    Tokihiko Yokoshima, Daikichi Mukoyama, Fujio Maeda, Tetsuya Osaka, Koji Takazawa, Shun Egusa, Satomi Naoi, Satoru Ishikura, Koichi Yamamoto

    JOURNAL OF POWER SOURCES   393   67 - 74  2018年07月

     概要を見る

    A system using a high-speed and high-precision X-ray inspection system for testing internal short circuits in lithium-ion batteries (LIBs) was firstly developed for the safety test on LIBs. X-ray transmission moving images of the anode and cathode were obtained in the layered LIB structure. The nail-penetration test was chosen to test for the presence of an internal short circuit. This system would allow direct observation of smoke generation inside outside the battery, ballooning of the pouch, as well as changing layered structures of electrodes in real time. Since the results of a conventional nail-penetration test are indicated only by smoke generation, fire, or explosion, this new system allows electrode changes in the pouch to be observed for the first time. This system is expected to lead to great developments in the safety of LIBs.

    DOI

  • Preface for "Lithium ion batteries and beyond"

    Min-Sik Park, Yusuke Yamauchi, Hua-Kun Liu, Tetsuya Osaka

    APL MATERIALS   6 ( 4 )  2018年04月

    DOI

  • Prevention of redox shuttle using electropolymerized polypyrrole film in a lithium–oxygen battery

    N. Togasaki, R. Shibamura, T. Naruse, T. Momma, T. Osaka

    APL Materials   6 ( 4 ) 047704-1 - 047704-8  2018年04月

    DOI

  • Effect of human serum on the electrical detection of amyloid-β fibrils in biological environments using azo-dye immobilized field effect transistor (FET) biosensor

    S. Hideshima, S. Wustoni, M. Kobayashi, H. Hayashi, S. Kuroiwa, T. Nakanishi, T.Osaka

    Sens. Bio-Sens. Res.   17   25 - 29  2018年02月

    DOI

  • Multianalyte Detection of Cancer Biomarkers in Human Serum Using Label-free Field Effect Transistor Biosensor

    Ke Si, Shanshan Cheng, Sho Hideshima, Shigeki Kuroiwa, Takuya Nakanishi, Tetsuya Osaka

    SENSORS AND MATERIALS   30 ( 5 ) 991 - 999  2018年

     概要を見る

    Recent statistics show that the incidence and mortality of cancer are on the rise. Among all types of cancer, lung cancer and liver cancer arc the most prevalent. We have many biomarkers for these two cancers, among which the cytokeratin fragment 21-1 (CYFRA 21-1) and a-fetoprotein (AFP) are the most common and widely used. Among the various detection methods, the field effect transistor (FET) biosensor is one of the most attractive approaches, providing a label-free, fast, and low-cost electrical detection of biomarkers with high specificity and sensitivity. In previous work, we applied biomarkers for a single cancer type. With the detection of CYFRA 21-1 and neuron-specific enolase (NSE), lung cancer was differentiated in the early stages. Compared with the early work, the biomarkers for the two cancer types, CYFRA 21-1 for lung cancer and AFP for liver cancer, were prepared in this work. The detection of CYFRA 21 1 and AFP in human serum was achieved at the same time with the limits of detection of 1 and 10 ng mL(-1), while the cut-off values were 4 and 10 ng mL(-1). The method featured short analytical time, small sample volume, and low cost. With its good selectivity and appropriate sensitivity, clinical application will become popular in the future.

    DOI

  • Label-free detection of allergens in food via surfactant-induced signal amplification using a field effect transistor-based biosensor

    Sho Hideshima, Mai Saito, Keisuke Fujita, Yoshitaka Harada, Mika Tsuna, Satoshi Sekiguchi, Shigeki Kuroiwa, Takuya Nakanishi, Tetsuya Osaka

    SENSORS AND ACTUATORS B-CHEMICAL   254   1011 - 1016  2018年01月  [査読有り]

     概要を見る

    In recent years, food safety concerning food allergy has received increasing attention globally. A simple and sensitive detection method should be developed to measure trace amounts of allergens in foods. Here, we propose a label-free field effect transistor (FET)-based biosensing system for the detection of a buckwheat allergenic protein, BWp16, by surfactant-induced signal amplification. BWp16 could be detected by coupling with an anionic surfactant, sodium dodecyl sulfate (SDS), as this coupling enhanced the net charge of the protein, enough to be detected by FET biosensors. A significant response was observed when the allergen was coupled with SDS, while the responses were decreased or unchanged when it was coupled with a cationic or non-ionic surfactant, suggesting that the SDS coupling maintains the antibody recognition ability of the target allergen, and it would be useful to enhance the sensor responses. The fluorescence spectroscopic measurement revealed that the SDS molecules were successfully coupled with target allergenic protein BWp16, resulting in an increase in its net charge. Furthermore, we demonstrated that the FET biosensor enables specific detection of the allergen in food at the desired concentration levels for food safety analysis, suggesting that it could be used as an alternative food allergen analyzer, both industrially and domestically. (C) 2017 The Authors. Published by Elsevier B.V.

    DOI

  • Effective induction of death in mesothelioma cells with magnetite nanoparticles under an alternating magnetic field.

    Shofu Matsuda, Eri Nakajima, Takuya Nakanishi, Airi Hitsuji, Hong Zhang, Akane Tanaka, Hiroshi Matsuda, Toshiyuki Momma, Tetsuya Osaka

    Materials science & engineering. C, Materials for biological applications   81   90 - 96  2017年12月  [査読有り]  [国際誌]

     概要を見る

    With the objective of finding an avenue for development of magnetic hyperthermia as an effective mesothelioma treatment, the influence of heating by magnetite nanoparticles (MNPs) with a diameter of ~40nm, which were incorporated into cells and then subjected to AC magnetic field, on induction of cell death was investigated in all three histological subtypes of human mesothelioma cells (i.e., epithelioid NCI-H28, sarcomatoid NCI-H2052, and biphasic MSTO-211H cells). Cellular uptake of MNPs was observed in all cell types, but the amount of MNPs incorporated per cell into MSTO-211H cells was smaller than in NCI-H28 and NCI-H2052 cells. On the other hand, cell death induced by cellular uptake of MNPs was observed specifically in MSTO-211H cells. Hence, when cells are heated by intracellular MNPs under AC magnetic field, a high degree of cell mortality in NCI-H28 and NCI-H2052 cells is induced by the temperature increase derived from the high amount of intracellular MNPs, but the combination of intracellular heating and cell-type-specific toxicity of MNPs induced high rates of cell death in MSTO-211H cells even at a lower temperature. Almost all of the heated cells were dead after 24-h incubation at 37°C in all histological subtypes. Additionally, higher mortalities were observed in all three types of mesothelioma cells after MNPs-heating, as compared to the heating with a thermostatic bath. Herein, the significance of cellular uptake of MNPs for effectively inducing cell death in mesothelioma has been demonstrated in vitro.

    DOI PubMed

  • Fabrication of photo-electrochemical biosensors for ultrasensitive screening of mono-bioactive molecules: the effect of geometrical structures and crystal surfaces.

    Naeem Akhtar, Mohammed Y Emran, Mohamed A Shenashen, Hesham Khalifa, Tetsuya Osaka, Ahmed Faheem, Takayuki Homma, Hiroshi Kawarada, Sherif A El-Safty

    Journal of materials chemistry. B   5 ( 39 ) 7985 - 7996  2017年10月  [国際誌]

     概要を見る

    The controlled design of biosensors based on the photo-electrochemical technique with high selectivity, sensitivity, and rapid response for monitoring of mono-bioactive molecules, particularly dopamine (DA) levels in neuronal cells is highly necessary for clinical diagnosis. Hierarchical carbon-, nitrogen-doped (CN) nickel oxide spear thistle (ST) flowers associated in single-heads (S), and symmetric and asymmetric-double heads (D and A, respectively) that are tightly connected through a micrometric dipole-like rod or trunk were fabricated by using a simple synthetic protocol. The CN-ST flower heads were decorated with dense nano-tubular like hedgehog needle skins in vertical alignments. These designated architectures are key features for creating biosensor surface electrodes for photo-electrochemical, ultrasensitive screening of mono-bioactive molecules. The exceptional electrode designs produced numerous catalytically active sites, large surface area, and high electron-transfer mobility. The active coating of carbon-nitrogen nanospheres significantly enhanced the photo-electrocatalytic activity of the prepared biosensor electrodes and prevented leakage of photocatalytic activity under long-term exposure to irradiation. Among all photo-electrochemical assays, the biosensors showed significant sensitivity and selectivity for DA in the presence of interfering molecules such as ascorbic acid (AA), uric acid (UA), adrenaline (A), and noradrenaline (NA). The photo-electrochemical property of the CN-SST-{110} crystal surface electrode showed significant sensing performance for DA in terms of unimpeded diffusion pathways, a wide concentration-detection range, and a low detection limit, even in the presence of potentially interfering molecules compared with other electrode-modified CN-DST-{111} and CN-AST-{101} crystal surfaces. Furthermore, the CN-SST photo-biosensor electrode shows potential in the selective and sensitive determination of DA in real samples, such as human serum and secreted DA from living cells. This finding indicates that the hierarchical ST biosensor may enable analytical discrimination and monitoring of DA and can be employed for clinical diagnosis application.

    DOI PubMed

  • On-site chemical pre-lithiation of S cathode at room temperature on a 3D nano-structured current collector

    Yunwen Wu, Toshiyuki Momma, Seongki Ahn, Tokihiko Yokoshima, Hiroki Nara, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   366   65 - 71  2017年10月  [査読有り]

     概要を見る

    This work reports a new chemical pre-lithiation method to fabricate lithium sulfide (Li2S) cathode. This pre-lithiation process is taken place simply by dropping the organolithium reagent lithium naphthalenide (Li(+)Naph(-)) on the prepared sulfur cathode. It is the first time realizing the room temperature chemical pre-lithaition reaction attributed by the 3D nanostructured carbon nanotube (CNT) current collector. It is confirmed that the Li2S cathode fabricated at room temperature showing higher capacity and lower hysteresis than the Li2S cathode fabricated at high temperature pre-lithiation. The prelithiated Li2S cathode at room temperature shows stable cycling performance with a 600 mAh g(-1), capacity after 100 cycles at 0.1 C-rate and high capacity of 500 mAh g(-1) at 2 C-rate. This simple on -site prelithiation method at room temperature is demonstrated to be applicable for the in-situ pre-lithiation in a Li metal free battery. (C) 2017 The Authors. Published by Elsevier B.V.

    DOI

  • Review of Physiological Balance Sensing in an Unobtrusive Manner

    Keishi Ohashi, Shigeki Kuroiwa, Sho Hideshima, Takuya Nakanishi, Tetsuya Osaka

    ELECTRONICS AND COMMUNICATIONS IN JAPAN   100 ( 9 ) 50 - 55  2017年09月  [査読有り]

     概要を見る

    The concept of unobtrusive physiological balance sensing system implementing biosensors is discussed. Biosensors connected with a data system are expected to play a significant role when we extend the sensing objects from body to mind and spirit. Here, we describe the unobtrusive monitoring system using field effect transistor-type sensors and wireless communication devices. Substances subject to the survey of our research will include small ions, immunoglobulins, and hormones. (C) 2017 Wiley Periodicals, Inc.

    DOI

  • Impedance Measurements of Kilowatt-Class Lithium Ion Battery Modules/Cubicles in Energy Storage Systems by Square-Current Electrochemical Impedance Spectroscopy

    Tokihiko Yokoshima, Daikichi Mukoyama, Hiroki Nara, Suguru Maeda, Kazuhiro Nakazawa, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   246   800 - 811  2017年08月  [査読有り]

     概要を見る

    Electrochemical impedance measurements of lithium ion batteries (LIBs) in energy storage systems (ESS) were performed. Square-current electrochemical impedance spectroscopy (SC-EIS), which is a simple and cost-effective approach to measure impedance, was chosen to investigate a large-scale LIB system. Harmonics calculated by Fourier transform from a square waveform were used to determine the impedance. On the basis of a simple electrochemical reaction involving the ferri/ferro-cyanide redox couple and the LIB, the accuracy of the impedance measurement was found to depend on both the signal-to-noise ratio of the power spectra of the harmonics as well as the attenuation rate of the "measured value of impedance" and the "theoretical spectra value" from Fourier series. The accuracy was improved by adjusting the input waveform to be close to an ideal square waveform from Fourier series. The accuracy was further improved by the combined use of a simple moving average and an overall average. The impedance from a degraded square waveform generated by a cost-effective power controller was able to be determined by increasing the measurement time, which aided averaging. By designing the input signal to be close to an ideal square waveform from Fourier series, kilowatt-class LIB modules/cubicles in an ESS was able to be measured. Moreover, a degraded LIB module in an ESS was able to be detected using EIS, which highlights the utility of this technique for in situ impedance measurements of large-scale LIB systems. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

  • Carbonate-based additive for improvement of cycle durability of electrodeposited Si-O-C composite anode in glyme-based ionic liquid electrolyte for use in lithium secondary batteries

    Shohei Seko, Hiroki Nara, Moongook Jeong, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   243   65 - 71  2017年07月  [査読有り]

     概要を見る

    The cycle durability of electrodeposited Si-O-C composite anodes in glyme-based ionic liquid electrolytes, known as Li(G3)TESI or Li(G4)TFSI (triglyme: G3 and tetraglyme: G4), which is one of the most promising electrolytes for sulfur cathode, was improved for use in lithium secondary batteries by using additives, fluoroethylene carbonate (FEC) or vinylene carbonate (VC). We revealed an importance of the activation process and the effects of additives in the Si-O-C composite anode. The capacity of the Si-O-C composite anode decreased with charge-discharge cycles in electrolytes without additives. Meanwhile, although the capacity retention in electrolytes with additives was improved by 10-20%, their initial capacity was smaller than those without additives. To solve the contradiction, an activation process, in which the Si-O-C composite anode was charged and discharged in electrolytes without additives, was introduced before charge-discharge cycles in electrolytes with additives. Owing to the optimized activation process, the initial capacity in electrolytes with additives showed as high as 1100-1300 mAh(-1) as those without additives with better capacity retention. Therefore, the necessity to adequately generate an activation reaction and to form SEI derived from additives for the Si-O-C composite anode to have better charge-discharge performance was demonstrated. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

  • Impedance Analysis of LiNi1/3Mn1/3Co1/3O2 Cathodes with Different Secondary-particle Size Distribution in Lithium-ion Battery

    Hiroki Nara, Keisuke Morita, Daikichi Mukoyama, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   241   323 - 330  2017年07月  [査読有り]

     概要を見る

    Mid to low frequency impedance for a cathode in a lithium ion battery (LIB), which is affected by lithiumion diffusion into active materials, was investigated. We had earlier suggested that charge-transfer and diffusion impedances are attributed to a particle size distribution for a commercially available LIB, and we designed an equivalent circuit in which two series circuits of charge-transfer resistance and Warburg impedance were connected in parallel. Here, to validate the design of the equivalent circuit, the secondary-particle size distribution of the LiNi1/3Mn1/3Co1/3O2 cathode in a lab-made LIB, in which the secondary-particles were controlled into wide and narrow distribution by sieving, was investigated by electrochemical impedance spectroscopy. The equivalent circuit was designed in which series circuits of charge-transfer resistance and Warburg impedance were connected in parallel. Dependency of impedance response on the number of parallels of the series circuits was evaluated for the cathodes using different secondary-particle size distributions of the active material. Additionally, the tendency of change in the charge-transfer resistance and the limiting capacitance was discussed from the standpoint of secondary-particle size distribution. The results confirm the effectiveness of the designed equivalent circuit which reflects the secondary-particle size distribution of cathode active materials. (C) 2017 Elsevier Ltd. All rights reserved.

    DOI

  • Generating Synthetic Profiles of Onshore Wind Power for Power Flow Simulation on Power System

    Yu Fujimoto, Seigo Furuya, Yasuhiro Hayashi, Tetsuya Osaka

    JOURNAL OF ENERGY ENGINEERING   143 ( 3 ) 1 - 8  2017年06月

     概要を見る

    An increased penetration of wind energy into the power system will lead to instability of local voltage and global frequency in Japan. Power flow simulation is a powerful tool for understanding the electrical behavior in the power system caused by wind energy; however, plausible and various wind power profiles are required to perform a meaningful simulation to evaluate the effect of wind generators. This paper proposes a procedure of generating synthetic wind power profiles that involve the plausible short-term fluctuation for a power flow simulation based on the spatial kriging method and the bootstrap method. (C) 2016 American Society of Civil Engineers.

    DOI

  • A pre-lithiation method for sulfur cathode used for future lithium metal free full battery

    Yunwen Wu, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   342   537 - 545  2017年02月  [査読有り]

     概要を見る

    Lithium metal free sulfur battery paired by lithium sulfide (Li2S) is a hot point in recent years because of its potential for relatively high capacity and its safety advantage. Due to the insulating nature and high sensitivity to moisture of Li2S, it calls for new way to introduce Li ion into S cathode besides the method of directly using the Li2S powder for the battery pre-lithiation. Herein, we proposed a pre-lithiation method to lithiate the polypyrrole (PPy)/S/Ketjenblack (KB) electrode into PPy/Li2S/KB cathode at room temperature. By this process, the fully lithiated PPy/Li2S/KB cathode showed facilitated charge transfer than the original PPy/S/KB cathode, leading to better cycling performance at high C-rates and disappearance of over potential phenomenon. In this work, the ion-selective PPy layer has been introduced on the cathode surface by an electrodeposition method, which can suppress the polysulfide dissolution from the cathode source. The lithium metal free full battery coupled by the prepared Li2S/KB cathode and graphite anode exhibited excellent cycling performance. Hence, we believe this comprehensive fabrication approach of Li2S cathode will pave a way for the application of new type lithium metal free secondary battery. (C) 2016 Elsevier B.V. All rights reserved.

    DOI

  • 液体クロマトグラフィー-四重極飛行時間型質量分析法(LC-QToF/MS)を用いたLiイオン二次電池の保存劣化解析

    栃原美佐子, 栃原美佐子, 奈良洋希, 横島時彦, 門間聰之, 門間聰之, 逢坂哲彌, 逢坂哲彌

    電気化学および工業物理化学   85 ( 11 ) 721 - 727  2017年  [査読有り]

    DOI J-GLOBAL

  • The Potential for the Creation of a High Areal Capacity Lithium-Sulfur Battery Using a Metal Foam Current Collector

    Hiroki Nara, Tokihiko Yokoshima, Hitoshi Mikuriya, Shingo Tsuda, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   164 ( 1 ) A5026 - A5030  2017年  [査読有り]

     概要を見る

    A high areal capacity lithium-sulfur battery making use of mass produced aluminum metal foam as a current collector was investigated. A sulfur/Ketjenblack (KB) composite was filled and deposited into the aluminum foam current collector via a predetermined filling procedure, resulting in high sulfur loading. The value for this loading was found to be 17.7 mg sulfur/cm(2) by using carboxymethyl cellulose and styrene butadiene rubber (CMC + SBR) as a binder. An operating single-layer pouch-type cell with an S/KB+CMC+SBR on Al foam cathode was created as a result of this synthesis and found to possess an unprecedentedly high areal capacity of 21.9 mAh/cm(2). On the basis of the achieved areal capacity, the energy density of a theoretical lithium-sulfur battery was estimated with the assumption of an electrolyte/sulfur ratio of 2.7 mu L/mg. This was calculated upon 100% of the pore volume in the S/KB-CMC + SBR on Al foam cathodes and polyolefin separator, along with the inclusion of the weights of the tabs for the current lead and pouch film packaging in the case of a seven-layer pouch-type battery. With this calculation, it was determined that the creation of a lithium-sulfur battery with an energy density of greater than 200 Wh/kg is plausible. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.

    DOI

  • Development of Areal Capacity of Si-O-C Composites as Anode for Lithium Secondary Batteries Using 3D-Structured Carbon Paper as a Current Collector

    Seongki Ahn, Moongook Jeong, Koki Miyamoto, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   164 ( 2 ) A355 - A359  2017年  [査読有り]

     概要を見る

    To enlarge the areal capacity of Si-O-C composites as an anode for high energy Li secondary batteries, 3D-structured carbon paper is used as a current collector for electrodeposition of Si-O-C composites. For higher surface affinity between organic solvents with carbon paper, surface treatment of carbon paper is carried out using a sulfuric acid-hydrogen peroxide mixture (SPM) solution. The higher deposited Si amounts and areal capacity are obtained by SPM treatment of carbon paper due to its enhanced surface affinity between carbon paper and electrolytes during Si-O-C electrodeposition. In addition, two kinds of organic solvents, propylene carbonate (PC) and ethylene carbonate/diethyl carbonate (EC/DEC), are employed to investigate their suitability for the electrodeposition of Si-O-C composites. As a result, it is confirmed that the Si-O-C composites synthesized by EC/DEC solvents show more stable cycle abilities than in the case of using PC solvents at a high charge current density of 1.0 mA cm(-2). This is due to the exfoliation of carbon paper by PC, resulting in fast capacity fading during charge/discharge cycle. Nevertheless, it is confirmed that the use of carbon paper as a substrate for Si-O-C electrodeposition is an effective way to increase deposited Si amounts and discharge areal capacity. (C) 2017 The Electrochemical Society. All rights reserved.

    DOI

  • 液体クロマトグラフィー - 四重極飛行時間型質量分析法を用いたLiイオン二次電池の保存劣化過程の解析

    栃原美佐子, 奈良洋希, 横島時彦, 門間聰之, 逢坂哲彌

    Electrochem.   85   721 - 727  2017年

  • A Comparative Study of LiNO3 and LiTFSI for the Cycling Performance of δ-MnO2 Cathode in Lithiym-Oxygen Batteries

    N. Togasaki, T. Gobara, T. Momma, T. Osaka

    J. Electrochem. Soc.   164 ( 9 ) A2225 - A2230  2017年  [査読有り]

    DOI

  • Techniques for realizing practical application of sulfur cathodes in future Li-ion batteries

    H. Nara, S. Tsuda, T. Osaka

    J. Solid State Electrochem.   100   1 - 13  2017年

  • Electrophoretically deposited carbon nanotube anchor layer to improve areal capacity of Si-O-C composite anode for lithium secondary batteries

    Seongki Ahn, Moongook Jeong, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   336   203 - 211  2016年12月  [査読有り]

     概要を見る

    In this study, we report the preparation of carbon nanotubes (CNTs) anchor layer on a Cu substrate (CNTs/Cu) by using electrophoretic deposition technique. The CNTs anchor layer increases adhesion strength between Si-O-C composites and Cu substrate, as a result, it is possible to improve deposited Si amounts and areal capacity. The electrodeposited Si-O-C composites on CNTs/Cu (Si-O-C/CNTs/Cu) show homogenously coated surface morphology without cracks even large passing charge for electrodeposition of 15 C cm(-2), resulting in 0.21 mg cm(-2) of deposited Si amounts. On the other hand, Si-O-C composites deposited on as-received Cu substrate (Si-O-C/Cu) begin to peel off from substrate at 8 C cm(-2) of passing charge, resulting in 0.13 mg cm(-2) of deposited Si amounts, and decrease down to 0.10 mg cm(-2) at 15 C cm(-2) of passing charge. As a results, the improved Si amounts deposited on CNTs/Cu substrate achieve higher areal capacity, delivering 0.24 mA h cm(-2), which attains increase in 84.6% in comparison to Si-O-C/Cu, which has areal capacity of 0.13 mA g cm(-2) at 8 C cm(-2) of passing charge. Moreover, the Si-O-C/CNTs/Cu shows improved anode performances including discharge capacity and C-rate performance of the Si-O-C composites than Si-O-C/Cu without CNTs anchor layer. (C) 2016 Elsevier B.V. All rights reserved.

    DOI

  • In Vitro Investigation of the Effect of Intracellular and Extracellular Magnetite Nanoparticles Subjected to Alternating Magnetic Field on MCF-7 Human Breast Cancer Cells

    Takuya Nakanishi, Shofu Matsuda, Kisako Kaneko, Hong Zhang, Tetsuya Osaka

    CHEMISTRYSELECT   1 ( 19 ) 6092 - 6102  2016年11月  [査読有り]

     概要を見る

    To evaluate the efficiency with which intra-and extracellular magnetite nanoparticles (MNPs) induce cell death under an alternating magnetic field (AMF), we comparatively investigated two systems consisting of MCF-7 human breast cancer cells and MNPs: one is a "simply-added" system, which is essentially a simple mixture of cells and extracellular MNPs, and the other is a "pre-cultivated" system that contains both intra-and extracellular MNPs. We also evaluated the effect of heating by thermostatic water bath (WB) on cell death in both systems. The degree of cell death was greater under heating with MNPs subjected to AMF than in the WB-heating in both systems. At higher doses of MNPs, the degree of cell death was greater in the "pre-cultivated" system than in the "simply-added" system using both heating methods. The cellular uptake of MNPs induced slight cell damage and caused a high degree of cell death at higher temperatures. A significant decrease in cell viability was observed in the presence of internalized MNPs under the AMF and was suggested to be a result of the combined effect of intracellular heating and cellular damage by MNPs.

    DOI

  • New approach for enhancing electrical conductivity of electrodeposited Si-based anode material for Li secondary batteries: Self-incorporation of nano Cu metal in Si–O–C composite

    M. Jeong, S. Ahn, T. Yokoshima, H. Nara, T. Momma, T. Osaka

    Nano Energy   28   51 - 62  2016年10月  [査読有り]

    DOI

  • Correction: Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy.

    Kyoung Sub Kim, Jiyoung Kim, Joo Young Lee, Shofu Matsuda, Sho Hideshima, Yasurou Mori, Tetsuya Osaka, Kun Na

    Nanoscale   8 ( 25 ) 12843 - 12843  2016年07月  [査読有り]  [国際誌]

     概要を見る

    Correction for 'Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy' by Kyoung Sub Kim, et al., Nanoscale, 2016, DOI: 10.1039/c6nr02273a.

    DOI PubMed

  • Conversion of protein net charge via chemical modification for highly sensitive prion detection using field effect transistor (FET) biosensor

    Shofarul Wustoni, Sho Hideshima, Shigeki Kuroiwa, Takuya Nakanishi, Yasuro Mori, Tetsuya Osaka

    SENSORS AND ACTUATORS B-CHEMICAL   230   374 - 379  2016年07月  [査読有り]

     概要を見る

    A robust and applicable strategy of signal amplification for field effect transistor (FET) biosensor is of scientifically and technologically importance to detect wide range of target molecules, particularly for the molecules of low charge density, and to configure highly sensitive analysis. In this communication, we demonstrate a simple technique to modify the net charge of target protein based on the concept of protein conjugation for the detection of prion, which is infectious and transmissible protein in neurodegenerative disorders. The increases of prion net charge after chemical modification generate signal amplification and have remarkably enhanced the sensitivity of FET biosensor below than femtomolar (fM) level. Thus, we suggest that such strategy is promising technique for achieving a highly sensitive detection at very low concentration that is useful for early determination of protein biomarkers. (C) 2016 Elsevier B.V. All rights reserved.

    DOI

  • Stimuli-responsive magnetic nanoparticles for tumor-targeted bimodal imaging and photodynamic/hyperthermia combination therapy.

    Kyoung Sub Kim, Jiyoung Kim, Joo Young Lee, Shofu Matsuda, Sho Hideshima, Yasurou Mori, Tetsuya Osaka, Kun Na

    Nanoscale   8 ( 22 ) 11625 - 34  2016年06月  [国際誌]

     概要を見る

    Despite magnetic nanoparticles having shown great potential in cancer treatment, tremendous challenges related to diagnostic sensitivity and treatment efficacy for clinical application remain. Herein, we designed optimized multifunctional magnetite nanoparticles (AHP@MNPs), composed of Fe3O4 nanoparticles and photosensitizer conjugated hyaluronic acid (AHP), to achieve enhanced tumor diagnosis and therapy. Fe3O4 nanoparticles (MNPs) were synthesized by a facile hydrolysis method. MNPs have higher biocompatibility, controllable particle sizes, and desirable magnetic properties. The fabricated AHP@MNPs have enhanced water solubility (average size: 108.13 ± 1.08 nm), heat generation properties, and singlet oxygen generation properties upon magnetic and laser irradiation. The AHP@MNPs can target tumors via CD44 receptor-mediated endocytosis, which have enhanced tumor therapeutic effects through photodynamic/hyperthermia-combined treatment without any drugs. We successfully detected tumors implanted in mice via magnetic resonance imaging and optical imaging. Furthermore, we demonstrated the photodynamic/hyperthermia-combined therapeutic efficacy of AHP@MNPs with synergistically enhanced efficacy against cancer.

    DOI PubMed

  • Preparation of anatase phase titanium dioxide film by non-aqueous electrodeposition

    Takuma Hachisu, Kazuaki Shi, Tokihiko Yokoshima, Atsushi Sugiyama, Shigeki Kuroiwa, Tetsuya Osaka, Noriko Nakajima, Masahiro Yoshino

    ELECTROCHEMISTRY COMMUNICATIONS   65   5 - 8  2016年04月  [査読有り]

     概要を見る

    The electrodeposition-annealing route to fabricating thin film of the promising photocatalyst material anatase-titanium dioxide (anatase-TiO2) has been studied. The sample was deposited with a solution of N,N-dimethylformamide containing titanium compound by controlled-potential technique. SEM image showed the annealed sample at 600 degrees C for 1 h under air provided a continuous film with a thickness of ca. 350 nm. In this sample, X-ray photoelectron spectrumcorresponding to the Ti 2p peak assigned to a chemical bond of TiO2 and X-ray diffraction peaks assigned to the anatase phase were observed, respectively. Electrochemical oxidation in sodium sulfate solution on this annealed film was enhanced in the presence of UV light radiation. These results confirm the successful synthesis of photocatalytic anatase-TiO2 film by the electrodeposition and annealing process. (C) 2016 Elsevier B.V. All rights reserved.

    DOI

  • Enhanced cycling performance of a Li metal anode in a dimethylsulfoxide-based electrolyte using highly concentrated lithium salt for a lithium-oxygen battery

    Norihiro Togasaki, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   307   98 - 104  2016年03月  [査読有り]

     概要を見る

    Stable charge-discharge cycling behavior for a lithium metal anode in a dimethylsulfoxide (DMSO)-based electrolyte is strongly desired of lithium-oxygen batteries, because the Li anode is rapidly exhausted as a result of side reactions during cycling in the DMSO solution. Herein, we report a novel electrolyte design for enhancing the cycling performance of Li anodes by using a highly concentrated DMSO-based electrolyte with a specific Li salt. Lithium nitrate (LiNO3), which forms an inorganic compound (Li2O) instead of a soluble product (Li2S) on a lithium surface, exhibits a >20% higher coulombic efficiency than lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium perchlorate, regardless of the loading current density. Moreover, the stable cycling of Li anodes in DMSO-based electrolytes depends critically on the salt concentration. The highly concentrated electrolyte 4.0 M LiNO3/DMSO displays enhanced and stable cycling performance comparable to that of carbonate -based electrolytes, which had not previously been achieved. We suppose this enhancement is due to the absence of free DMSO solvent in the electrolyte and the promotion of the desolvation of Li ions on the solid electrolyte interphase surface, both being consequences of the unique structure of the electrolyte. (C) 2015 Elsevier B.V. All rights reserved.

    DOI

  • Lifetime of Ionic Vacancy Created in Redox Electrode Reaction Measured by Cyclotron MHD Electrode.

    Atsushi Sugiyama, Ryoichi Morimoto, Tetsuya Osaka, Iwao Mogi, Miki Asanuma, Makoto Miura, Yoshinobu Oshikiri, Yusuke Yamauchi, Ryoichi Aogaki

    Scientific reports   6   19795 - 19795  2016年01月  [査読有り]  [国際誌]

     概要を見る

    The lifetimes of ionic vacancies created in ferricyanide-ferrocyanide redox reaction have been first measured by means of cyclotron magnetohydrodynamic electrode, which is composed of coaxial cylinders partly exposed as electrodes and placed vertically in an electrolytic solution under a vertical magnetic field, so that induced Lorentz force makes ionic vacancies circulate together with the solution along the circumferences. At low magnetic fields, due to low velocities, ionic vacancies once created become extinct on the way of returning, whereas at high magnetic fields, in enhanced velocities, they can come back to their initial birthplaces. Detecting the difference between these two states, we can measure the lifetime of ionic vacancy. As a result, the lifetimes of ionic vacancies created in the oxidation and reduction are the same, and the intrinsic lifetime is 1.25 s, and the formation time of nanobubble from the collision of ionic vacancies is 6.5 ms.

    DOI PubMed

  • Impedance Analysis with Transmission Line Model for Reaction Distribution in a Pouch Type Lithium-Ion Battery by Using Micro Reference Electrode

    Hiroki Nara, Daikichi Mukoyama, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   163 ( 3 ) A434 - A441  2016年  [査読有り]

     概要を見る

    Electrochemical impedance spectroscopy (EIS) using an equivalent circuit is a powerful tool in the diagnosis of lithium-ion batteries (LIBs). However, LIBs have been increasingly used in applications requiring power higher than that used for conventional LIBs for portable electric devices. Considering this demand for LIBs, the ionic resistances in the electrodes, which raise a reaction distribution under high-power operation, are important. This consequently means EIS analysis should include ionic resistances in the electrodes in equivalent circuits. Additionally, the impedance response of LIBs are too complicated to be analyzed in detail because the impedance response consists of overlapping elemental processes such as chemical reactions and ion migration. This paper therefore presents an analysis of impedance responses, which are independently obtained by a micro reference electrode, by using a transmission line model (TLM) that possesses the ability to count the ionic resistances in the electrodes. Similar to the conventional Randles equivalent circuit, the equivalent circuit with TLM could fit the impedance responses simulated by the equivalent circuit with measured responses. This paper discusses the potential of EIS using an equivalent circuit coupled with a TLM for diagnosis of LIBs in power applications. (C) The Author(s) 2015 Published by ECS. All rights reserved.

    DOI

  • Promotion of Self-Assembly Patterning of FePt Nanoparticles by Tuning the Concentration of Oleylamine/Oleic Acid Surfactants in a Coating Solution

    Yoshiki Fujihira, Takuma Hachisu, Suguru Shitanda, Kenichiro Aikawa, Atsushi Sugiyama, Jun Mizuno, Shuichi Shoji, Toru Asahi, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   163 ( 5 ) D171 - D174  2016年  [査読有り]

     概要を見る

    To provide a bit-patterned perpendicular magnetic recording medium consisting of an array of FePt magnetic nanoparticles, the effect of the total dispersant concentrations of oleylamine and oleic acid in a FePt-nanoparticle/toluene coating solution on a self-assembled nanoparticle array with a long-range periodicity on a flat SiO2/Si substrate and two patterned substrates, respectively, was examined. At a surfactant concentration greater than 0.8 vol%, FePt nanoparticles with an average size of 4.4 nm were arrayed in a two-dimensional and hexagonal-close-packed ordered array with 8.3-nm pitches on the flat surface. Self-assembled nanoparticles were arrayed on the bottom surface of the patterned trench, the array exhibited a hexagonal-close-packed structure. Furthermore the line defects in the arrays are caused by the waviness of the trench walls, and the surface roughness. (C) 2016 The Electrochemical Society. All rights reserved.

    DOI

  • Film Properties of Electropolymerized Polypyrrole for a Sulfur/Ketjenblack Cathode in Lithium Secondary Batteries

    Natsuki Nakamura, Yunwen Wu, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   163 ( 5 ) A683 - A689  2016年  [査読有り]

     概要を見る

    A novel polypyrrole (PPy) film was investigated to determine the optimal conditions for operation in a Li/S battery. The PPy film was prepared by oxidative electropolymerization to improve the Li/S battery performance, as reported in our previous paper. In such a system, the PPy film was coated directly on the S/Ketjenblack cathode to solve the problem of polysulfide dissolution. The optimum PPy film preparation conditions to prevent polysulfide dissolution and to promote Li+ permeability were determined by varying the PPy polymerization bath composition and polymerization potential. As a result, the inclusion of 1.0 M lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) in the polymerization bath (0.1 M pyrrole in 1-methyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl) imide) was found to be the most important factor for producing a PPy film with a high Li+ transport number (t(Li+) approximate to 1). A polymerization potential of 4.5 V versus Li/Li+ was shown to be optimum for the promotion of Li+ permeability. The mechanism by which the PPy film prevents polysulfide dissolution and increases Li+ permeability is discussed by analyzing the SEM, CV, XPS, and C-13 solid-state NMR data. (C) The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/),which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. All rights reserved.

    DOI

  • Signal amplification in electrochemical detection of buckwheat allergenic protein using field effect transistor biosensor by introduction of anionic surfactant

    S. Hideshima, K. Fujita, Y. Harada, M. Tsuna, Y. Seto, S. Sekiguchi, S. Kuroiwa, T. Nakanishi, T. Osaka

    Sens. Bio-Sens. Res.   7   90 - 94  2016年

  • 生体バランス物質のさりげないセンシングに関するレビュー

    大橋啓之, 黒岩繁樹, 秀島翔, 中西卓也, 逢坂哲彌

    電気学会論文誌 E   136 ( 8 ) 357 - 361  2016年

    J-GLOBAL

  • Electrochemical impedance spectroscopy analysis with a symmetric cell for LiCoO2 cathode degradation correlated with Co dissolution

    Hiroki Nara, Keisuke Morita, Tokihiko Yokoshima, Daikichi Mukoyama, Toshiyuki Momma, Tetsuya Osaka

    AIMS MATERIALS SCIENCE   3 ( 2 ) 448 - 459  2016年

     概要を見る

    Static degradation of LiCoO2 cathodes is a problem that hinders accurate analysis using our developed separable symmetric cell. Therefore, in this study we investigate the static degradation of LiCoO2 cathodes in separable symmetric cells by electrochemical impedance spectroscopy (EIS) and inductively coupled plasma analyses. EIS measurements of LiCoO2 cathodes are conducted in various electrolytes, with different anions and with or without HF and/or H2O. This allows us to determine the static degradation of LiCoO2 cathodes relative to their increase of charge transfer resistance. The increase of the charge transfer resistance of the LiCoO2 cathodes is attributed to cobalt dissolution from the active material of LiCoO2. Cobalt dissolution from LiCoO2 is revealed to occur even at low potential in the presence of HF, which is generated from LiPF6 and H2O. The results indicate that avoidance of HF generation is important for the analysis of lithium-ion battery electrodes by using the separable cell. These findings reveal the condition to achieve accurate analysis by EIS using the separable cell.

    DOI

  • 電気化学インピーダンス法による電極/電解液界面分析の最新動向-蓄電・発電デバイスの評価解析-1.リチウムイオン二次電池の電気化学インピーダンス解析

    逢坂哲彌, 門間聰之, 横島時彦, 向山大吉, 奈良洋希

    電気化学および工業物理化学   84 ( 12 ) 919 - 984  2016年

    J-GLOBAL

  • Industrialization trial of a biosensor technology

    K. Ohashi, T. Osaka

    ECS Transactions   75 ( 39 ) 1 - 9  2016年

     概要を見る

    A biosensing system is commercialized based on a concept of physiological balance for healthcare. The addition of low-cost biochemical sensors to the sensing system would help with scientific prescriptions based on contemporary medicine. As a candidate for a low-cost and robust chemical sensor platform, the ion-sensitive field-effect transistor (ISFET) has long been examined. After reviewing past ISFET research, our two approaches for new business trials are discussed. One approach is based on the progressiveness of technology that relies on a public finance with existing big companies. Another approach is a lean startup based on a customer development model for entrepreneurs.

    DOI

  • One-Step Hydrothermal Synthesis of SnS2/SnO2/C Hierarchical Heterostructures for Li-ion Batteries Anode with Superior Rate Capabilities

    Chun-Yi Chen, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   183   78 - 84  2015年11月  [査読有り]

     概要を見る

    Novel three-dimensional hierarchical heterostructures composed of two-dimensional SnS2 nanoflakes and zero-dimensional SnO2 nanoparticles were fabricated via a one-step hydrothermal method. Size of the heterostructures was ca. 2 mu m in diameter, and individual SnS2 nanoflakes with thickness of ca. 150 nm were connected to central core of the heterostructures. The SnO2 nanoparticles in a diameter of ca. 5 nm uniformly covered entire surface of the SnS2 nanoflakes. Moreover, both of these structures were highly crystalline. Meanwhile, amorphous carbon was formed within the heterostructures. The SnS2/SnO2/C hierarchical heterostructures had a high initial specific reversible capacity of 1065.7 mAh g(-1), stable cycling stability of 638 mAh g(-1) after 30 cycles, and superior rate capability of 550.8 mAh g(-1) at 1C rate. These SnS2/SnO2/C hierarchical heterostructures showed better performance than individual SnS2 and SnO2 nanomaterials, and the performance was even higher than the graphene-SnS2 and graphene-SnO2 nanohybrid materials. This is attributed to a synergistic effect of high surface area, which is provided by the unique SnS2 internal nanoflake layered structures decorated with ultra-fine SnO2 nanoparticles, and an effective beneficial buffer matrix to accommodate the large volume change upon cycling, which is caused by the side-products such as Li2S or Li2O. The SnS2 nanoflake was deduced to play a similar role as graphene material, since both possess 2D conducting layer structures. The uniform carbon dispersion within the structures also stabilizes the structures and improves electrical conductivity of the hierarchical heterostructures. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

  • Synthesis of cobalt ferrite nanoparticles using spermine and their effect on death in human breast cancer cells under an alternating magnetic field

    Shofu Matsuda, Takuya Nakanishi, Kisako Kaneko, Tetsuya Osaka

    ELECTROCHIMICA ACTA   183   153 - 159  2015年11月  [査読有り]

     概要を見る

    To compare heat generation under an AC magnetic field for inducing cancer cell death, CoFe2O4 and Fe3O4 nanoparticles with a diameter of similar to 10 nm were synthesized by hydrolysis in an aqueous solution containing the metal chlorides iron(III) chloride and cobalt(II) or iron(II) chloride, with spermine or N,N'-bis(3-aminopropyl)butane-1,4-diamine, as a base and a protective reagent. Both CoFe2O4 and Fe3O4 nanoparticles were incorporated into human breast cancer MCF-7 cells; the nanoparticles exhibited little toxicity on the cells. When the cells containing nanoparticles were subjected to an AC magnetic field, MCF-7 cell death was induced by heat generated from similar to 10-nm CoFe2O4 nanoparticles but not from similar to 10-nm Fe3O4 nanoparticles. An increase in coercivity derived from the substitution of Fe2+ with Co2+ facilitated the ability of the nanoparticles to induce cell death in human breast cancer cells under an AC magnetic field. (C) 2015 Elsevier Ltd. All rights reserved.

    DOI

  • Micro-scale Li2S–C composite preparation from Li2SO4 for cathode of lithium ion battery

    J. Liu, H. Nara, T. Yokoshima, T. Momma, T. Osaka

    Electrochim. Acta   183   70 - 77  2015年11月  [査読有り]

    DOI

  • Label-free detection of Cu(II) in a human serum sample by using a prion protein-immobilized FET sensor.

    Shofarul Wustoni, Sho Hideshima, Shigeki Kuroiwa, Takuya Nakanishi, Yasuro Mori, Tetsuya Osaka

    The Analyst   140 ( 19 ) 6485 - 8  2015年10月  [査読有り]  [国際誌]

     概要を見る

    We have developed a field effect transistor (FET) sensor to sensitively detect copper ions (Cu(2+)) in a human serum (HS) sample for promising health-care diagnosis. By utilizing a Cu(2+)-binding prion protein that was immobilized on the FET gate surface, such an FET sensor can provide a simple, label free and highly selective performance, even in HS samples. We demonstrated the sensitivity of the sensor at the nanomolar level, 0-100 nM, which is very useful for the detection range of Cu(2+) deficiency in practical applications.

    DOI PubMed

  • Role of the solid electrolyte interphase on a Li metal anode in a dimethylsulfoxide-based electrolyte for a lithium-oxygen battery

    Norihiro Togasaki, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   294   588 - 592  2015年10月  [査読有り]

     概要を見る

    The effect of the solid electrolyte interphase (SEI) on a Li anode on the charge-discharge cycling performance in 1 M LiTFSI/dimethylsulfoxide electrolyte solution is examined by using charge-discharge cycling. The chemical structure of the surface and interior of the SEI strongly affects the cycling performance of the anode. The observed coulombic efficiency is low (<45%) when organic compounds such as lithium alkyl carbonates and polycarbonate form predominantly on the surface and interior. However, when inorganic compounds such as Li2CO3, Li2O, and LiF form instead, the coulombic efficiency increases to >85%. This enhanced efficiency remains constant regardless of the O-2 content and despite <1000 ppm concentration of the contaminant H2O in the electrolyte. Thus, the lithium surface should be protected by inorganic compounds prior to cycling to prevent it from undergoing side reactions with the electrolyte during cycling in the electrolyte. (C) 2015 Elsevier B.V. All rights reserved.

    DOI

  • Application of Electrochemical Impedance Spectroscopy to Ferri/Ferrocyanide Redox Couple and Lithium Ion Battery Systems Using a Square Wave as Signal Input

    Tokihiko Yokoshima, Daikichi Mukoyama, Kazuhiro Nakazawa, Yuhei Gima, Hidehiko Isawa, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   180   922 - 928  2015年10月  [査読有り]

     概要を見る

    To realize electrochemical impedance spectroscopy (EIS) using a simple measurement system, application of a square potential/current waveform to the input signals of EIS was investigated. The impedance of a simple redox reaction of [Fe(CN)(6)](4-)/[Fe(CN)(6)](3-) solution was measured by the potentio-EIS using a square waveform as the input signal, which was generated by a potentiostat system without a frequency response analyzer (FRA). A steady impedance response in the frequency range of 40 Hz-3.5 kHz was obtained, and the impedance was obtained by the potentiostat system with an FRA. The errors-the differences between the impedance measured by EIS with a square potential waveform and that of conventional EIS-were sufficiently low to allow impedance analysis. The impedance of a lithium-ion battery (LIB) was measured by galvano-EIS using a square waveform input signal generated by a power controller. A steady impedance response in the frequency range of 5 Hz-2.5 kHz was obtained, and the errors were sufficiently low to allow impedance analysis. It was demonstrated that both square potential-EIS (SP-EIS) and square current-EIS (SC-EIS) have great potential as simple systems for measuring impedance. Moreover, it was demonstrated that SC-EIS has potential as a simple measurement system for analyzing the state of an LIB. Thus, the potential of the SP/SC-EIS methodology was confirmed for electrochemical systems. (C) 2015 Published by Elsevier Ltd.

    DOI

  • Induction of Cell Death in Mesothelioma Cells by Magnetite Nanoparticles.

    Shofu Matsuda, Airi Hitsuji, Takuya Nakanishi, Hong Zhang, Akane Tanaka, Hiroshi Matsuda, Tetsuya Osaka

    ACS biomaterials science & engineering   1 ( 8 ) 632 - 638  2015年08月  [査読有り]  [国際誌]

     概要を見る

    Nanoparticle uptake and cell death following addition of magnetite nanoparticles (MNPs) with a diameter of ∼10 nm were evaluated in three histological types of human mesothelioma cells, NCI-H28 (epithelioid), NCI-H2052 (sarcomatoid), and MSTO-211H (biphasic) cells, and human breast cancer MCF-7 cells. Dose-dependent cell death was observed in MSTO-211H cells but not in MCF-7 cells, although cellular uptake of MNPs was observed in both cell types. Mesothelioma NCI-H28 and NCI-H2052 cells showed behavior more similar to that of breast cancer MCF-7 cells than that of mesothelioma MSTO-211H cells. DNA fragmentation and microarray analyses suggested that MNPs induced transforming growth factor β2 related apoptosis in MSTO-211H cells. On the other hand, the viability of human mesothelioma cells containing MNPs with a diameter of ∼40 nm was investigated after exposure to an alternating magnetic field. Temperature increase under the alternating magnetic field and high rates of cell death were observed in all three histological types of human mesothelioma.

    DOI PubMed

  • One-minute deposition of micrometre-thick porous Si-Cu anodes with compositional gradients on Cu current collectors for lithium secondary batteries

    Jungho Lee, Kei Hasegawa, Toshiyuki Momma, Tetsuya Osaka, Suguru Noda

    JOURNAL OF POWER SOURCES   286   540 - 550  2015年07月  [査読有り]

     概要を見る

    We report micrometre-thick porous Si-Cu anodes that are rapidly co-deposited on Cu current collectors in 1 mm. This rapid deposition is realized by heating Si and Cu powders to similar to 2000 degrees C and elevating their vapour pressures, while the porous and amorphous anode structure is realized by keeping the substrates at 100 degrees C. The films spontaneously form a 2-4.5-mu m-thick composition gradient that changes from a Cu-rich region at the bottom to a Si-rich region at the top of the film, because of the higher vapour pressure for Cu than Si. A small addition of 5 wt% Cu to the Si source enhances the cycle performance of the film remarkably in a half-cell test, yielding a gravimetric capacity of 1250 mAh g(film)(-1), a volumetric capacity of 1956 mAh cm(film)(-3), and an areal capacity of 0.96 mAh cm(anode)(-2) at the 100th cycle. However, excess addition of Cu causes partial Si crystallization in the films, which results in poorer cycle performance. While further improvement is needed, this rapid vapour deposition method yields Si-Cu films with compositional gradients on Cu current collectors in 1 min using inexpensive and safe Si and Cu powder sources, and is attractive for practical Si-based anode fabrication. (C) 2015 Elsevier B.V. All rights reserved.

    DOI

  • Label-free detection of tumor markers using field effect transistor (FET)-based biosensors for lung cancer diagnosis

    Shanshan Cheng, Sho Hideshima, Shigeki Kuroiwa, Takuya Nakanishi, Tetsuya Osaka

    SENSORS AND ACTUATORS B-CHEMICAL   212   329 - 334  2015年06月  [査読有り]

     概要を見る

    Detection of tumor markers is important for cancer diagnosis. Field effect transistor (FET) has been recognized as a powerful technique for label-free, sensitive, real-time, and multifunctional biosensing. Here, we developed FET biosensors that allow the label-free detection of cytokeratin fragment 21-1 (CYFRA 21-1) and neuron-specific enolase (NSE), useful tumor markers for lung cancer type differentiation. It was found that the FET biosensor was capable of quantitatively detecting these tumor markers in both phosphate-buffered saline and human serum. Additionally, we developed a multianalyte FET biosensor for the selective multiplexed detection of CYFRA 21-1 and NSE at the same time, by integrating two antibody types on the same chip, providing a step towards the realization of sensor arrays. The multianalyte FET biosensor, as described herein, will help for lung cancer differential diagnosis with advantages of simple and rapid detection procedures, low sample consumption, and low cost. (C) 2015 Elsevier B.V. All rights reserved.

    DOI

  • Sensitive electrical detection of human prion proteins using field effect transistor biosensor with dual-ligand binding amplification.

    Shofarul Wustoni, Sho Hideshima, Shigeki Kuroiwa, Takuya Nakanishi, Masahiro Hashimoto, Yasuro Mori, Tetsuya Osaka

    Biosensors & bioelectronics   67   256 - 62  2015年05月  [国際誌]

     概要を見る

    Simple and accurate detection of prion proteins in biological samples is of utmost importance in recent years. In this study, we developed a label-free electrical detection-based field effect transistor (FET) biosensor using thiamine as a probe molecule for a non-invasive and specific test of human prion protein detection. We found that thiamine-immobilized FETs can be used to observe the prion protein oligomer, and might be a significant test for the early diagnosis of prion-related diseases. The thiamine-immobilized FET was also demonstrated for the detection of prion proteins in blood serum without any complex pre-treatments. Furthermore, we designed a dual-ligand binding approach by the addition of metal ions as a second ligand to bind with the adsorbed prion protein on the thiamine-immobilized surface. When the prion attached to metal ions, the additional positive charge was induced on the gate surface of the FET. This approach was capable of amplifying the magnitude of the FET response and of enhancing the sensitivity of the FET biosensor. Detection of prion proteins has achieved the required concentration for clinical diagnosis in blood serum, which is less than 2 nM. In summary, this FET biosensor was successfully applied to prion detection and proved useful as a simple, fast, sensitive and low-cost method towards a mass-scale and routine blood screening-based test.

    DOI PubMed

  • Effect of electrolyte on cycle performances of the electrodeposited Sn-O-C composite anode of lithium secondary batteries

    Moongook Jeong, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   275   525 - 530  2015年02月  [査読有り]

     概要を見る

    The electrodeposited Sn-O-C composite anode cycling with LiClO4 delivered stable cycle performances showing discharge capacity of 473 mA h g Risri with 95% of coulombic efficiency at 100th cycle. However, the anode showed poor cycle performances with LiPF6 delivering discharge capacity of 69 mA h g(-1) of sn at 100th cycle with 70% of coulombic efficiency. Electrochemical investigation performed by cyclic voltammetry and differential capacity plots revealed that the Sn-O-C composite cycling with LiPF86 suffered from retarded phase transition reaction between Li and Sn during charge/discharge process. X-ray photoelectron spectroscopy declared the existence of fluorinated-Sn and LiF. Moreover, energy dispersive X-ray spectroscopy found increase in their amount with repeated cycles. The morphologies of the Sn-O-C composite cycled with LiPF6 showed aggregated particles containing the chemical state of fluorinated-Sn and LiF on its surface. Furthermore, the significant pulverization and aggregation of the active material were observed from the Sn-O-C composite cycled by LiPF6 rather than that of LiClO4, which was probably promoted by the generated HF strongly corroding metallic component. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

  • Li-rich Li-Si alloy as a lithium-containing negative electrode material towards high energy lithium-ion batteries.

    Shinichiroh Iwamura, Hirotomo Nishihara, Yoshitaka Ono, Haruhiko Morito, Hisanori Yamane, Hiroki Nara, Tetsuya Osaka, Takashi Kyotani

    Scientific reports   5   8085 - 8085  2015年01月  [査読有り]  [国際誌]

     概要を見る

    Lithium-ion batteries (LIBs) are generally constructed by lithium-including positive electrode materials, such as LiCoO2, and lithium-free negative electrode materials, such as graphite. Recently, lithium-free positive electrode materials, such as sulfur, are gathering great attention from their very high capacities, thereby significantly increasing the energy density of LIBs. Though the lithium-free materials need to be combined with lithium-containing negative electrode materials, the latter has not been well developed yet. In this work, the feasibility of Li-rich Li-Si alloy is examined as a lithium-containing negative electrode material. Li-rich Li-Si alloy is prepared by the melt-solidification of Li and Si metals with the composition of Li21Si5. By repeating delithiation/lithiation cycles, Li-Si particles turn into porous structure, whereas the original particle size remains unchanged. Since Li-Si is free from severe constriction/expansion upon delithiation/lithiation, it shows much better cyclability than Si. The feasibility of the Li-Si alloy is further examined by constructing a full-cell together with a lithium-free positive electrode. Though Li-Si alloy is too active to be mixed with binder polymers, the coating with carbon-black powder by physical mixing is found to prevent the undesirable reactions of Li-Si alloy with binder polymers, and thus enables the construction of a more practical electrochemical cell.

    DOI PubMed

  • Suppression of polysulfide dissolution by polypyrrole modification of sulfur-based cathodes in lithium secondary batteries

    Natsuki Nakamura, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   274   1263 - 1266  2015年01月

     概要を見る

    In order to solve the problem of polysulfide dissolution into the electrolyte on sulfur-based cathodes, we propose a novel method of modifying the S cathode by coating it with a polypyrrole (PPy) film, which is prepared by oxidative electropolymerization using a solution consisting of, 1-methyl-1-butylpyrrolidinium bis(trifluoromethanesulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and pyrrole. The PPy film demonstrates a high Li+ transport number. The film also exhibits a superior ability to inhibit polysulfide dissolution into the electrolyte during the charge discharge cycles. Furthermore, the charge discharge properties of the coated cathode is evaluated using an electrolyte consisting of 1.0 M LiTFSI in a mixture of 1,2-dimethoxyethane (DME) and 1,3-dioxolane (DOL), which is known to easily dissolve polysulfides. Because of the surface modification with the PPy film, the cathode exhibits excellent specific capacities of 823 and 354 mAh g(-1) at C-rates of 0.1 and 1.0 C, respectively, with high coulombic efficiency. Thus, the strategy of coating the S cathode with PPy is successful in inhibiting the polysulfides dissolution even in electrolytes known to easily dissolve polysulfides, besides allowing high C-rate operation. Further, the modification of the S cathode allows the selection of a suitable electrolyte based on the anode, rather than being limited by the cathode. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

  • 30 years of electroless plating for semiconductor and polymer micro-systems

    Y. Shacham-Diamand, T. Osaka, Y. Okinaka, A. Sugiyama, V. Dubin

    MICROELECTRONIC ENGINEERING   132   35 - 45  2015年01月  [査読有り]

     概要を見る

    Electroless deposition (ELD) is a well-known method for preparing thin films of metals and their alloys. It is a highly selective method allowing additive patterning of isolated and embedded structures on insulating substrates, e.g. glass, plastic or ceramic. It is a relatively low temperature (less than the boiling point of the electrolyte) and low cost process compared to other physical and chemical vapor deposition methods. ELD features uniform and normally conformal deposition (additives may affect its conformality) with low defect density and some unique material properties. In the last 30 years electroless plating of metals (e.g. copper, gold, nickel, cobalt, palladium, iron, silver, etc.) and their alloys, was demonstrated for micro system applications: microelectronics, micro electro mechanics, micro electro optics and microfluidics, micro fuel cells, micro batteries etc. Electroless plating was also demonstrated on nano structures, both artificial and natural. In this paper we present a short tribute to the recent advances in electroless plating in the last 30 years. Those advances and innovations are due to the work of many scientists and engineers on a time span started in the 19th century. The progress in electroless plating followed the need and the trend for better metallization technologies for complex structures with critical dimensions that had been shrinking continuously in the last few decades. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

  • Liquid Chromatography-Quadruple Time of Flight Mass Spectrometry Analysis of Products in Degraded Lithium-Ion Batteries

    Misako Tochihara, Hiroki Nara, Daikichi Mukoyama, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   162 ( 10 ) A2008 - A2015  2015年  [査読有り]

     概要を見る

    The electrode surfaces of degraded lithium-ion batteries (LIB) were analyzed by liquid chromatography-quadrupole time of flight mass spectrometry (LC-QTOF/MS). The solid-electrolyte interphase (SET) layer influences the performance of LIBs. Therefore, we conducted a study aimed at clarifying the deterioration mechanism of LIBs by examining the components in the SET before and after degradation due to cycling. We believe that the change in the mass transfer characteristics at the electrode interface influenced by SET deterioration can be clarified via Lc-QTOF/MS, which would allow elucidation of the deterioration mechanism. The analysis results showed that the degradation products contain multiple components, including polymers of carbonate compounds and phosphate esters, which are formed via electrochemical and chemical reactions, resulting in remarkably reduced capacity. The results suggest that LC-QTOF/MS is a valuable technique for the degradation analysis of LIBs. (C) The Author(s) 2015. Published by ECS. All rights reserved.

    DOI

  • 健康医療分野での応用を目指す半導体バイオセンシング

    秀島翔, 逢坂哲彌, 逢坂哲彌

    Chemical Sensors   31 ( 3 ) 98 - 103  2015年

    J-GLOBAL

  • ドライルーム省エネ除湿システムの研究(第2報)微量水分領域対応型システムの開発

    長澤雅俊, 逢坂哲彌, 横島時彦, 三上秀人, 佐原亮

    空気調和・衛生工学会学術講演会講演論文集   2015 ( 3 (Web) ) 149 - 152  2015年

    J-GLOBAL

  • Review—Development of Diagnostic Process for Commercially Available Batteries, Especially Lithium Ion Battery, by Electrochemical Impedance Spectroscopy

    T. Osaka, D. Mukoyama, H. Nara

    J. Electrochem. Soc.   162 ( 14 ) A2529 - A2537  2015年  [査読有り]

    DOI

  • Electrodeposited three-dimensional porous Si-O-C/Ni thick film as high performance anode for lithium-ion batteries

    Xin Qian, Tao Hang, Hiroki Nara, Tokihiko Yokoshima, Ming Li, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   272   794 - 799  2014年12月  [査読有り]

     概要を見る

    A novel 3D porous Si-O-C/Ni thick film anode is successfully prepared by electrodeposition of porous Ni on Cu substrate and galvanostatical electrodeposition of Si-O-C composite on porous Ni substrate. The 3D porous Si-O-C/Ni thick film is electrochemically activated at a current density of 50 mu A cm(-2) for the first cycle and 200 mu A cm(-2) (0.5 C) for the subsequent cycles, it displays superior electrochemical performance with discharge capacity of 706.3 mAh g(-1) of Si after 100 cycles. The properties of this thick film is analyzed by field emission scanning electron microscopy (FESEM) and scanning transmission electron microscopy with energy dispersive X-ray analyzer (STEM-EDX). The results show that Si-O-C composite not only covers the surface area of porous Ni but also attaches to the highly porous dendritic walls, along with the porous structure of Ni which provides proper accommodation for the volume change of silicon during the lithiation/delithiation processes, are believed to result in the high capacity and excellent cyclability. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

  • Zinc-air battery: understanding the structure and morphology changes of graphene-supported CoMn(2)O(4) bifunctional catalysts under practical rechargeable conditions.

    Moni Prabu, Prakash Ramakrishnan, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka, Sangaraju Shanmugam

    ACS applied materials & interfaces   6 ( 19 ) 16545 - 55  2014年10月  [査読有り]  [国際誌]

     概要を見る

    Nitrogen-doped/undoped thermally reduced graphene oxide (N-rGO) decorated with CoMn2O4 (CMO) nanoparticles were synthesized using a simple one-step hydrothermal method. The activity and stability of this hybrid catalyst were evaluated by preparing air electrodes with both primary and rechargeable zinc-air batteries that consume ambient air. Further, we investigated the relationship between the physical properties and the electrochemical results for hybrid electrodes at various cycles using X-ray diffraction, scanning electron microscopy, galvanodynamic charge-discharging and electrochemical impedance spectroscopy. The structural, morphological and electrocatalytic performances confirm that CMO/N-rGO is a promising material for safe, reliable, and long-lasting air cathodes for both primary and rechargeable zinc-air batteries that consume air under ambient condition.

    DOI PubMed

  • Enhancement effect of trace H2O on the charge discharge cycling performance of a Li metal anode

    Norihiro Togasaki, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   261   23 - 27  2014年09月  [査読有り]

     概要を見る

    The effects of a small amount of H2O with and without CO2 in an electrolyte of I M LiPF6/ethylene carbonate and diethyl carbonate on the cycling life of a Li metal anode is investigated in this paper using charge discharge cycling. A low cycling performance, which is less than 55%, is observed with the electrolyte with trace H2O but without CO2; however, when the trace H2O is accompanied by CO2, performance drastically improves and coulombic efficiency reaches a maximum of 88.9%. In the presence of CO2, the cycling performance is found to be strongly affected by the H2O content in the electrolyte, and increases with an increase in H2O content of up to 35 ppm. From an X-ray photoelectron spectroscopy analysis, trace H2O is found to affect the compounds of the solid electrolyte interphase (SEI) on the lithium surface and produces an Li2CO3 and LW layer on the upper part of the SEI, both known to be good passivation layers for preventing side reactions during charge discharge cycling. (c) 2014 Elsevier B.V. All rights reserved.

    DOI

  • Microbubble Formation from Ionic Vacancies in Copper Electrodeposition under a High Magnetic Field

    Makoto Miura, Ryoichi Aogaki, Yoshinobu Oshikiri, Atsushi Sugiyama, Ryoichi Morimoto, Miki Miura, Iwao Mogi, Yusuke Yamauchi

    ELECTROCHEMISTRY   82 ( 8 ) 654 - 657  2014年08月  [査読有り]

     概要を見る

    Ionic vacancies created in copper electrodeposition have been first observed by converting to microbubbles via. nanobubbles. Since the copper deposition potential was much more positive than hydrogen evolution one, the microbubbles were ascribed not to hydrogen bubbles but to the ionic vacancies. Then, the evolution times of the microbubbles at an overpotential of -300 mV were examined under various magnetic flux densities. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

  • Enhanced Oxygen Reduction Activities of Pt Supported on Nitrogen-Doped Carbon Nanocapsules

    Sangaraju Shanmugam, Jakkid Sanetuntikul, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   137   41 - 48  2014年08月  [査読有り]

     概要を見る

    The nitrogen-doped carbon nanocapsules (NCNCs) were explored as catalyst support for oxygen reduction reaction (ORR) in acid electrolyte. The deposition of Pt particles on NCNCs support was characterized using various physico-chemical techniques, such as scanning electron microscope, transmission electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy. The high resolution transmission electron microscopy reveals that Pt particles are uniformly dispersed onto the NCNCs and particles size of about 2.2 nm was observed. The electrochemical ORR activities of the Pt supported on NCNCs catalysts were studied and compared with a commercial catalyst. Pt/NCNC showed enhanced ORR activity and better stability than a commercial Pt/C catalyst. The enhanced performance of Pt supported NCNCs can be attributed to the better dispersion and utilization of Pt nanoparticles. (C) 2014 Elsevier Ltd. All rights reserved.

    DOI

  • A lithium-ion sulfur battery based on a carbon-coated lithium-sulfide cathode and an electrodeposited silicon-based anode.

    Marco Agostini, Jusef Hassoun, Jun Liu, Moongook Jeong, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka, Yang-Kook Sun, Bruno Scrosati

    ACS applied materials & interfaces   6 ( 14 ) 10924 - 8  2014年07月  [査読有り]  [国際誌]

     概要を見る

    In this paper, we report a lithium-ion battery employing a lithium sulfide cathode and a silicon-based anode. The high capacity of the silicon anode and the high efficiency and cycling rate of the lithium sulfide cathode allowed optimal full cell balance. We show in fact that the battery operates with a very stable capacity of about 280 mAh g(-1) at an average voltage of 1.4 V. To the best of our knowledge, this battery is one of the rare examples of lithium-metal-free sulfur battery. Considering the high theoretical capacity of the employed electrodes, we believe that the battery here reported may be of potential interest as high-energy, safe, and low-cost power source for electric vehicles.

    DOI PubMed

  • Electrochemical impedance analysis of electrodeposited Si-O-C composite thick film on Cu microcones-arrayed current collector for lithium ion battery anode

    Tao Hang, Daikichi Mukoyama, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Ming Li, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   256   226 - 232  2014年06月  [査読有り]

     概要を見る

    The impedance behaviors of Si-O-C composite film electrodeposited on Cu microcones-arrayed current collector have been investigated to understand the electrochemical process kinetics that influences the cycling performance when used as a highly-durable anode in a lithium battery. The impedance was measured by using impedance spectroscopy in equilibrium conditions at various depths of discharge and during several hundred charge-discharge cycles. The measured impedance was interpreted with an equivalent circuit composed of solid electrolyte interphase (SEI) film, charge transfer and solid state diffusion. The impedance analysis shows that the change of charge transfer resistance is the main contribution to the total resistance Change during discharge, but an abrupt augmentation of diffusive resistance at high depth of discharge is also observed which cannot be explained very well by the presented model. The impedance evolution of this electrode during charge-discharge cycles suggests that the slow growth of the SEI film as well as the increase of the electrode density are responsible for the capacity fading after long term cycling. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

  • Distinction of impedance responses of Li-ion batteries for individual electrodes using symmetric cells

    Toshiyuki Momma, Tokihiko Yokoshima, Hiroki Nara, Yuhei Gima, Tetsuya Osaka

    ELECTROCHIMICA ACTA   131   195 - 201  2014年06月  [査読有り]

     概要を見る

    Symmetric cells were prepared with a newly designed separable cell module, which enabled ca. 70 mm by 70 mm electrode sheets to be used for a pouch type 5 Ah class Li-ion battery (LIB). Impedance analysis of the LIB as a full cell state was successfully performed with electrochemical parameters obtained by an impedance analysis of symmetric cells of anodes and cathodes obtained from the operated Li-ion batteries. While the charge transfer resistance of the cathode was found to increase after reassembling the cells symmetrically, other electrochemical parameters were found not to change when comparing the values obtained for full cells with symmetric cells. Eelectrodes degraded by charge/discharge cycling of the battery were also investigated, and the parameter change caused by the degradation was confirmed. (C) 2014 Elsevier Ltd. All rights reserved.

    DOI

  • Carbon-coated Li2S Synthesized by Poly(vinylpyrrolidone) and Acetylene Black for Lithium Ion Battery Cathodes

    Jun Liu, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    CHEMISTRY LETTERS   43 ( 6 ) 901 - 903  2014年06月  [査読有り]

     概要を見る

    A carbon-coated Li2S was prepared through an adsorption and successive annealing process by using poly(vinylpyrrolidone) (PVP) and acetylene black (AB) as carbon source with Li2S powder. The coating layer was composed of amorphous carbon and embedded AB particles. The carbon coating was found to effectively alleviate the dissolution of polysulfide and the discharge capacity at the first 15 cycles was 800 mA h g(-1) with gradual fading afterward.

    DOI

  • Label-Free Electrical Assay of Fibrous Amyloid β Based on Semiconductor Biosensing

    S. Hideshima, M. Kobayashi, T. Wada, S. Kuroiwa, T. Nakanishi, N. Sawamura, T. Asahi, T. Osaka

    Chem. Commun.   50 ( 26 ) 3476 - 9  2014年04月  [査読有り]  [国際誌]

    DOI PubMed

  • Effects of chemical treatment of indium tin oxide electrode on its surface roughness and work function

    Md. Zaved Hossain Khan, Takuya Nakanishi, Tetsuya Osaka

    SURFACE & COATINGS TECHNOLOGY   244   189 - 193  2014年04月  [査読有り]

     概要を見る

    In this paper, we report the effects of chemical treatment of indium tin oxide (ITO) surface on its surface chemistry such as chemical composition and surface roughness and on its usage as an electrode with monolayer modification. Atomic force microscopy, angel-resolved X-ray photoelectron spectroscopy, and Kelvin probe force microscopy have been used to investigate the morphology and the chemical properties of commercial thin ITO films after several treatments commonly used prior to the formation of organic layer on the surface. The amount of spike present on the surface of as-received ITO substrates was significantly reduced by etching with KOH whereas the roughness of ITO increased with HCI etching. We demonstrated that the successive treatment of ITO electrode with HCI and KOH affects the surface characteristics such as roughness and work function, contributing to the potentiometric detection of tiyptophan. (C) 2014 Elsevier B.V. All rights reserved.

    DOI

  • Field Effect Transistor Biosensor Using Antigen Binding Fragment for Detecting Tumor Marker in Human Serum.

    Shanshan Cheng, Kaori Hotani, Sho Hideshima, Shigeki Kuroiwa, Takuya Nakanishi, Masahiro Hashimoto, Yasuro Mori, Tetsuya Osaka

    Materials (Basel, Switzerland)   7 ( 4 ) 2490 - 2500  2014年03月  [査読有り]  [国際誌]

     概要を見る

    Detection of tumor markers is important for cancer diagnosis. Field-effect transistors (FETs) are a promising method for the label-free detection of trace amounts of biomolecules. However, detection of electrically charged proteins using antibody-immobilized FETs is limited by ionic screening by the large probe molecules adsorbed to the transistor gate surface, reducing sensor responsiveness. Here, we investigated the effect of probe molecule size on the detection of a tumor marker, α-fetoprotein (AFP) using a FET biosensor. We demonstrated that the small receptor antigen binding fragment (Fab), immobilized on a sensing surface as small as 2-3 nm, offers a higher degree of sensitivity and a wider concentration range (100 pg/mL-1 μg/mL) for the FET detection of AFP in buffer solution, compared to the whole antibody. Therefore, the use of a small Fab probe molecule instead of a whole antibody is shown to be effective for improving the sensitivity of AFP detection in FET biosensors. Furthermore, we also demonstrated that a Fab-immobilized FET subjected to a blocking treatment, to avoid non-specific interactions, could sensitively and selectively detect AFP in human serum.

    DOI PubMed

  • Effect of Synthetic Quartz Nanoparticle-Supported Counter Electrode on Dye-Sensitized Solar Cell

    Shigeki Kuroiwa, Atsushi Kyan, Tomoko Ito, Nobuaki Komatsu, Takuya Nakanishi, Tetsuya Osaka

    ELECTROCHEMISTRY   82 ( 3 ) 165 - 167  2014年03月  [査読有り]

     概要を見る

    We fabricated dye-sensitized solar cells (DSSCs) with synthetic quartz nanoparticle (SQNP)-supported Pt/fluorine doped tin oxide counter electrodes to utilize an adsorptive capacity of synthetic quartz. The amperage of I-3(-) reduction was 1.6 times higher with SQNP than that without SQNP. SQNP also improved the photocurrent density-voltage characteristics and the incident photon to current conversion efficiency spectra in the visible region. These suggest that SQNP enhances the I-3(-) reduction activity on the counter electrode and the electron transfer to the photoanode. The SQNP-supported counter electrode is expected to be useful to raise the efficiency of a DSSC. (C) The Electrochemical Society of Japan, All rights reserved.

    DOI

  • Preface

    Tetsuya Osaka

    ELECTROCHEMISTRY   82 ( 1 ) 1 - 1  2014年01月

  • New Si-O-C composite film anode materials for LIB by electrodeposition

    Tetsuya Osaka, Hiroki Nara, Toshiyuki Momma, Tokihiko Yokoshima

    JOURNAL OF MATERIALS CHEMISTRY A   2 ( 4 ) 883 - 896  2014年  [査読有り]

     概要を見る

    Silicon is one of the most promising materials for lithium secondary battery anodes. However, silicon anodes have a critical drawback to their practical application, which is capacity degradation due to pulverization of the active material by the large volume change of silicon during charge-discharge cycles. This paper reviews recent studies on silicon-based anodes that have attempted to overcome this poor cycle durability through structural control such as through thin films, porous structures, core-shell structures, and by alloying with other metals, and by application of proper binders. Among them, binder-free Si-O-C composite films prepared by electrodeposition exhibit outstanding cycle durability. The origin of this excellent durability is discussed in depth from the standpoint of chemical and morphological changes. Consequently, the combination of active materials such as Si and Li2Si2O5 and inactive materials such as L(i)2O, Li2CO3, and organic compounds is suggested to result in outstanding properties as a lithium secondary battery anode.

    DOI

  • Monitoring Amyloid Sup35NM Growth with Label-Free Electrical Detection Using a Field-Effect Transistor Biosensor

    Sho Hideshima, Shofarul Wustoni, Shigeki Kuroiwa, Takuya Nakanishi, Ayumi Koike-Takeshita, Tetsuya Osaka

    CHEMELECTROCHEM   1 ( 1 ) 51 - 54  2014年01月  [査読有り]

    DOI

  • 誘導ナノ構造科学 化学的界面制御による金属ナノ粒子の単層配列形成とその高機能デバイス応用-ウエハースケールでのテラナノドット/平方インチ級配列膜形成を目指して-

    蜂巣琢磨, 水野潤, 庄子習一, 逢坂哲彌, 蜂巣琢磨, 水野潤, 庄子習一, 逢坂哲彌, 逢坂哲彌

    機能材料   34 ( 3 )  2014年

    J-GLOBAL

  • Analysis of an Electrodeposition Mechanism of Sn-O-C Composite from an Organic Electrolyte

    Moongook Jeong, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   161 ( 7 ) D3025 - D3031  2014年  [査読有り]

     概要を見る

    Sn-O-C composites were electrodeposited using organic carbonate solvents and their electrochemical mechanism was thoroughly investigated to achieve desired anode performances, such as high capacity and cycle durability for lithium secondary batteries. Cyclic voltammetry study clarified the multiple stages of electrochemical mechanism during the Sn-O-C composite deposition process. It was revealed that Sn deposition, decomposition of organic electrolytes, and reaction between Li+ and deposited Sn were consecutively carried out. X-ray photoelectron spectroscopy and field emission scanning electron microscopy were performed to characterize how each stage contributes to the formation of the Sn-O-C composite. The results showed increase in metallic Sn composition and dense coating with fine particle sizes with a higher overpotential stage. Afterward, different Sn-O-C composite anodes were prepared by varying charge quantities passing through each deposition stage and their electrochemical performances as anode materials were investigated. Discharge capacities were obtained from the lowest value of 33 mAh g of Sn-1 to the highest value of 429 mAh g of Sn-1 at the 100th cycle by varying deposition conditions. Consequently, it was suggested that anode performance was significantly influenced by an electrodeposition process consisting of three consecutive stages with different overpotential regions and reactions of Li ion with deposited Sn. (C) 2014 The Electrochemical Society. All rights reserved.

    DOI

  • Influence of the diffusion-layer thickness during electrodeposition on the synthesis of nano core/shell Sn-O-C composite as an anode of lithium secondary batteries

    Moongook Jeong, Tokihiko Yokoshima, Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    RSC ADVANCES   4 ( 51 ) 26872 - 26880  2014年  [査読有り]

     概要を見る

    Electrodeposition was conducted from an organic carbonate solvent via the potentiostatic technique through three consecutive steps in order to synthesise Sn-O-C composite, which delivered a discharge capacity of 596 mA h g of Sn-1 after 50 cycles. However, the composite anode suffered from a significantly low initial discharge capacity, delivering a discharge capacity of 79 mA h g of Sn-1 until the 5th cycle. It was deduced that the improbably low initial capacity was induced by the deposition of Li-rich compounds, which were formed by electrolyte decomposition accompanied by the reduction product of supporting electrolyte salts during the electrodeposition process, on the surface layer. In order to improve the poor initial capacity, we modified the chemical composition of the surface layer by means of implementing the agitation of the electrolyte during the deposition process. This gave rise to varying the diffusion-layer thickness during the deposition process due to the enhancement of convection by movement of the electrolyte itself. As a result, we achieved improvement of the initial discharge capacity, delivering 572 mA h g of Sn-1 at the 1st cycle and 586 mA h g of Sn-1 at the 50th cycle. It was revealed that the surface layer was composed of a decomposition product of the organic carbonate solvent. Furthermore, a smaller particle size of the Sn-O-C composite was obtained via electrolyte agitation, giving rise to homogeneous shell formation on the Sn compound core. Herein, we thoroughly examined the influence of varying diffusion-layer thickness during the deposition process on the properties of the Sn-O-C composites from an electrochemical standpoint.

    DOI

  • 急速加熱処理による合成鉄白金ナノ粒子配列膜の規則化過程

    相川健一郎, 藤平誉樹, 蜂巣琢磨, 杉山敦史, 逢坂哲彌, 逢坂哲彌, 山根明, 坂脇彰, 茂智雄

    電子情報通信学会技術研究報告   114 ( 327(MR2014 23-27) ) 23 - 28  2014年

    J-GLOBAL

  • Li2S cathode modified with polyvinylpyrrolidone and mechanical milling with carbon

    J. Liu, H. Nara, T. Yokoshima, T. Momma, T. Osaka

    J. Power Sources   273   1136 - 1141  2014年

  • Impedance analysis of the effect of flooding in the cathode catalyst layer of the polymer electrolyte fuel cell

    Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   113   720 - 729  2013年12月  [査読有り]

     概要を見る

    A common understanding of polymer electrolyte fuel cells (PEFCs) is important to promote the development of PEFCs. This understanding is crucial because complicated phenomena such as chemical reactions, ion transport, and gas diffusion occur during the operation of PEFCs. Electrochemical impedance spectroscopy (EIS), which can separate reactions into elementary processes, is a powerful tool for the analysis of PEFCs without requiring disassembly of the cell. In this study, the effect of flooding in the cathode catalyst layer of PEFCs was analyzed by EIS using the transmission line model (TLM) to determine the distribution of catalytic reactions in the primary and secondary pores. The analysis was conducted by varying experimental conditions such as the relative humidity of the gases supplied into the anode and cathode, the flow rate, and the partial pressure of oxygen in the gas mixture supplied to the cathode channel. The EIS analysis suggests that the resistance to the catalytic reaction in the primary pores drastically increased with the current density. The results suggest that the flooding preferentially occurred in the primary pores, resulting in the reduction of active sites by generated water. The EIS method is a powerful tool for developing membrane electrode assemblies (MEAs) with effective porosity and tortuosity for gas diffusion and ionic transportation, and furthermore, it is a useful tool for judging the process of MEA preparation. (C) 2013 Elsevier Ltd. All rights reserved.

    DOI

  • New Analysis of Electrochemical Impedance Spectroscopy for Lithium-ion Batteries

    Tetsuya Osaka, Hiroki Nara, Daikichi Mukoyama, Tokihiko Yokoshima

    JOURNAL OF ELECTROCHEMICAL SCIENCE AND TECHNOLOGY   4 ( 4 ) 157 - 162  2013年12月  [査読有り]

     概要を見る

    First of all, we express our deepest sympathies for the passing of Professor Su-Moon Park. In the present paper, an electrochemical impedance spectroscopy (EIS), which Professor Su-Moon Park also used frequently for the investigation of electroconducting polymer, is introduced as a recent evaluation tool for a commercially available lithium-ion battery (LIB). The paper surveys how to design equivalent circuits while explaining physical and chemical phenomena in the LIB and how to get more accurate impedance spectra with varying the measuring temperatures. Additionally, a square current EIS (SC-EIS) technique, which we have suggested, is introduced for the larger LIB system as a promising technique for the future.

    DOI

  • Structural analysis of highly-durable Si-O-C composite anode prepared by electrodeposition for lithium secondary batteries

    Hiroki Nara, Tokihiko Yokoshima, Mitsutoshi Otaki, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   110   403 - 410  2013年11月  [査読有り]

     概要を見る

    The structure of the highly durable silicon-based anode prepared by electrodeposition was investigated for volume change and chemical structure. With repeated charge-discharge cycles, the volume change resulting from the anode film thickness decreased, and, after 100 cycles, essentially no difference was observed between the charged and discharged states. The buffering effect of the volume change was considered to be achieved by the formation of Li2O, Li2CO3, and lithium silicates such as Li4SiO4, whose existence were supported by STEM, EELS, and XPS analyses. From the structural analyses, the main reactions related to the capacity of the silicon-based anode were considered to be the formation of LixSi and Li2Si2O5. LixSi and Li2Si2O5 can be delithiated into Si and SiO2, respectively. (C) 2013 Elsevier Ltd. All rights reserved.

    DOI

  • Structural analysis of highly durable Si-O-C composite anode prepared by electrodeposition for lithium secondary batteries (vol 107, pg 1, 2013)

    Hiroki Nara, Tokihiko Yokoshima, Mitsutoshi Otaki, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   110   402 - 402  2013年11月  [査読有り]

    DOI

  • Sn-O-C composite anode for Li secondary battery synthesized by an electrodeposition technique using organic carbonate electrolyte

    Toshiyuki Momma, Moongook Jeong, Tokihiko Yokoshima, Hiroki Nara, Ayano Toyoda, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   242   527 - 532  2013年11月  [査読有り]

     概要を見る

    The Sn-O-C composite anode for the Li secondary battery was synthesized by electrodeposition using an organic carbonate solvent. The composite of Sn with organic/inorganic compounds was prepared by the simultaneous reaction of the reduction of Sn2+ ions and electrolysis of the mixture of ethylene carbonate and propylene carbonate. The galvanostatic potential transients for the electrodeposition of the Sn-O-C composite indicate that multiple steps of reactions corresponding to the electrochemical reduction of the tin precursor and the decomposition of organic solvents are involved. The morphology, crystalline structure and chemical composition of the as-deposited Sn-O-C composite anode were characterized to elucidate the mechanism of the synthesis of the buffering matrix enduring volume expansion.The electrochemical behavior of the Sn-O-C composite anode was investigated by cyclic voltammetry and galvanostatical charge/discharged tests. The discharge capacity of 465 mAh (g of Sn)(-1) was obtained at the 100th cycle showing 80% of the capacity retention after the 100th cycle. The discharge capacity was stable after the 50th cycle, where the phase transformation of the Sn element from Sn to Li0.4Sn at the discharged state was found. (C) 2013 Elsevier B.V. All rights reserved.

    DOI

  • Effect of the size of receptor in allergy detection using field effect transistor biosensor

    Sho Hideshima, Shigeki Kuroiwa, Marika Kimura, Shanshan Cheng, Tetsuya Osaka

    ELECTROCHIMICA ACTA   110   146 - 151  2013年11月

     概要を見る

    Allergy diagnosis, conducted to determine whether a specific syndrome is attributable to allergy, plays a significant role in the overall health examination. In this paper we report that the detection of allergy-associated protein, immunoglobulin E (IgE), was achieved by using field effect transistors (FETs) immobilized with an antigen as a receptor, which is smaller in size than the conventional receptor (antibody). The antigen-immobilized FETs exhibit a higher response to IgE than the antibody-immobilized FETs, suggesting that the smaller receptor not only makes the more effective use of the charge-detectable region for the PET-based detection in terms of Debye length, but also provides more recognition sites for target molecules and greater ability to block nonspecific adsorption of non-related proteins because of the closely-packed immobilized receptors. In addition, the application of the antigen to FET biosensor gives an advantage in the identification of the specific allergen. These results show that the small receptor of antigen is more effective than the antibody in the allergy detection using PET biosensors. (C) 2013 Elsevier Ltd. All rights reserved.

    DOI

  • Attomolar detection of influenza A virus hemagglutinin human H1 and avian H5 using glycan-blotted field effect transistor biosensor.

    Sho Hideshima, Hiroshi Hinou, Daisuke Ebihara, Ryosuke Sato, Shigeki Kuroiwa, Takuya Nakanishi, Shin-Ichiro Nishimura, Tetsuya Osaka

    Analytical chemistry   85 ( 12 ) 5641 - 4  2013年06月  [査読有り]  [国際誌]

     概要を見る

    Influenza virus, through cell invasion and propagation with the interaction between hemagglutinin (HA) present on its surface and glycans on the host cell, causes a rapidly spreading infection throughout the world. In the present investigation, we succeeded for the first time in the attomolar-level sensing and discrimination of influenza A viral HA molecules H1 and H5 by using a glycan-immobilized field effect transistor (FET) biosensor. The small ligand glycans immobilized on the FET device, which make effective use of the charge-detectable region for FET-based detection in terms of Debye length, gave an advantage in the highly sensitive detection of the proteins. Two kinds of trisaccharides receptors terminating in sialic acid-α2,6-galactose (6'-sialyllactose) and in sialic acid-α2,3-galactose (3'-sialyllactose) were conjugated directly with the SiO2 surface of FET devices by a simple glycoblotting method using the self-assembled monolayer (SAM) of aminooxy terminated silane-coupling reagent, 3-aminooxypropyltriethoxysilane. Furthermore, it was demonstrated that the FETs with densely immobilized glycans, which possess the high capture ability by achieving the glycoside cluster effect, clearly distinguish HA molecules between their subtypes H1 (human) and H5 (avian) at the attomolar level, while the conventional method based on HA antibodies achieves only picomolar-level detection. Our findings indicate that the glycan-immobilized FET is a promising device to detect various pathogenic bacteria and viruses through glycan-protein interaction found ubiquitously in many infectious diseases.

    DOI PubMed

  • Preparation of LiClO4-doped Titanium Organodiphosphonates Possessing Oligomeric Ethylene Oxide Chains and Their Ionic Conductivity

    Hitomi Saito, Masataka Dobashi, Hiroki Naka, Toshiyuki Momma, Tetsuya Osaka, Yoshiyuki Sugahara

    CHEMISTRY LETTERS   42 ( 3 ) 318 - 320  2013年03月  [査読有り]

     概要を見る

    Hybrids possessing both oligomeric ethylene oxide chains and Ti-O-P networks were prepared from TiCl4 and organodiphosphonic acid [(HO)(2)OP(C2H4O)(3)C2H4PO(OH)(2)] via a nonhydrolytic sol gel process and subsequently treated with a LiClO4 solution. The P/Ti ratio was fixed at 2 and the ethylene oxide unit/Li+ ratio was changed from 5 to 20. Li+ ions are likely to be solvated by ether oxygen atoms. Li+ ion transport in the hybrids with ionic conductivity values in the 10(-5) S cm(-1) range was observed at ambient temperatures.

    DOI

  • Electrochemical impedance spectroscopy analysis for lithium-ion battery using Li4Ti5O12 anode

    Tao Hang, Daikichi Mukoyama, Hiroki Nara, Norio Takami, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   222   442 - 447  2013年01月  [査読有り]

     概要を見る

    The impedance of Li-ion battery using a Li4Ti5O12 (LTO) anode for high-power applications was measured at various depths of discharge and temperatures during charge discharge cycles. The measured impedance was interpreted with an equivalent circuit made up of anode and cathode, in which the cathode component was composed of two particle size factors. The values obtained for equivalent circuit elements by modeling were in good agreement with the results measured by other techniques, and indicated that the capacity fade of this Li-ion battery due to cycling is mainly caused by the increase of interfacial resistance and a decrease in the capacity of the LiCoO2 cathode. These results suggest that the cyclability of this LIB was improved by using an LTO anode, and show the validity of the equivalent circuit for interpreting the causes of capacity fade. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

  • Silicon composite thick film electrodeposited on a nickel micro-nanocones hierarchical structured current collector for lithium batteries

    Tao Hang, Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   222   503 - 509  2013年01月  [査読有り]

     概要を見る

    Electrodeposition methods were developed for the fabrication of Si composite anodes with nickel micro-nanocones hierarchical structure (MHS) current collectors for Li secondary batteries. This unique structured nickel current collector is electrodeposited in a simple process to create a complex high surface area conductive substrate, as well as to enhance the interfacial strength between active materials and substrate during cyclic lithiation/delithiation. The MHS supported Si composite anode demonstrated outstanding Li+ storage properties with reversible capacity over 800 mAh g(-1) (600 mu Ah cm(-2)) after 100th cycle with superior retention of 99.6% per cycle. The improved performance of nickel MHS supported Si thick films indicate the potential for their application as electrode materials for high performance energy storage. 2012 Elsevier B.V. All rights reserved.

    DOI

  • Structural analysis of highly-durable Si-O-C composite anode prepared by electrodeposition for lithium secondary batteries

    H. Nara, T. Yokoshima, M. Otaki, T. Momma, T. Osaka

    Electrochim. Acta   107   1 - 8  2013年

  • 鉄白金ナノ粒子の単層規則配列形成に向けた塗布成膜条件の最適化

    蜂巣琢磨, 四反田卓, 相川健一郎, 藤平誉樹, 杉山敦史, 水野潤, 水野潤, 庄子習一, 庄子習一, 逢坂哲彌, 逢坂哲彌, 山根明, 坂脇彰, 茂智雄

    電子情報通信学会技術研究報告   113 ( 297(MR2013 19-25) ) 1 - 6  2013年

    J-GLOBAL

  • ウェットプロセスによる高機能磁性薄膜の創製

    逢坂哲彌, 蜂巣琢磨, 杉山敦史, 横島時彦

    日本磁気学会研究会資料   192nd   19 - 25  2013年

    CiNii J-GLOBAL

  • 最近の武井記念講演から 湿式表面処理による機能性材料の開発と今後の展開-磁気記録,半導体,そして医療分野への応用を目指して

    逢坂哲彌

    表面技術   64 ( 4 ) 216 - 221  2013年

    J-GLOBAL

  • Non-electrochemical Nanobubble Formation in Ferricyanide/Ferrocyanide Redox Reaction by the Cyclotron Effect under a High Magnetic Field

    Atsushi Sugiyama, Tetsuya Osaka, Ryoichi Aogaki, Ryoichi Aogaki, Yusuke Yamauchi, Ryoichi Morimoto, Makoto Miura, Iwao Mogi, Yoshinobu Oshikiri, Miki Miura, Tetsuya Osaka

    Electrochemistry   81 ( 11 ) 890 - 892  2013年  [査読有り]

     概要を見る

    From the observation of coalesced microbubbles arising from supersaturated nanobubbles in ferricyanide/ferrocyanide redox reaction, the first evidence of the conversion from ionic vacancies to nanobubbles has been obtained. Since ionic vacancies are created without any electron transfer, the microbubbles are evolved in a different way from ordinal electrochemical gas reactions. © 2013, The Electrochemical Society of Japan. All rights reserved.

    DOI

  • Mechanical and Electrical Properties of Au-Ni-C Alloy Films Produced by Pulsed Current Electrodeposition

    Tokihiko Yokoshima, Areji Takanaka, Takuma Hachisu, Atsushi Sugiyama, Yutaka Okinaka, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   160 ( 11 ) D513 - D518  2013年  [査読有り]

     概要を見る

    Au-Ni-C alloys films electrodeposited by a pulsed current method were investigated to assess the crystalline structure, sheet resistance, and wear resistance, for use as an electronic contact material. In particular, we have analyzed the effects of citric acid concentration and pulse off-time on the mechanical and electrical properties of the electrodeposited Au-Ni-C alloy films. The electrodeposition bath used in this study was composed of K[Au(CN)(2)] and NiSO4 center dot 6H(2)O as precursors, and citric acid as the complexing agent. The film microstructure and composition were controlled by adjusting the interval of pulse off-time and the concentration of citric acid. With the prolongation of the pulse off-time interval, XRD results indicated that the amorphous structure with high Ni and C contents was transformed into a nanocrystalline structure, followed by the formation of crystals with small Ni and C contents. The amorphous and nanocrystalline films showed a high Knoop hardness of ca. 500 kg mm(-2), while that of the crystalline films was found to be 300 kg mm(-2). The wear resistance of the film electrodeposited by the pulsed current method was remarkably good compared to that of the direct-current electrodeposition films, even though both films exhibited essentially identical microstructure and composition. The wear property was considered to be relevant to the restoration of the surface flatness of the film by the galvanic displacement deposition of Au during the pulse off time. (C) 2013 The Electrochemical Society. All rights reserved.

    DOI

  • Special Issue ELECTROCHEMICAL FRONTIERS IN GLOBAL ENVIRONMENT AND ENERGY Selection of papers from the 62nd Annual Meeting of the International Society of Electrochemistry 12-16 September 2011, Niigata, Japan Foreword

    Tetsuya Osaka, Toshiyuki Momma

    ELECTROCHIMICA ACTA   82   1 - 2  2012年11月

    DOI

  • Ac impedance analysis of lithium ion battery under temperature control

    Toshiyuki Momma, Mariko Matsunaga, Daikichi Mukoyama, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   216   304 - 307  2012年10月  [査読有り]

     概要を見る

    Ac impedance spectra of electrochemical systems are analyzed by considering adequate equivalent circuits, while the differentiation of responses for each elemental step is sometimes difficult. In this study, enlarged impedances were measured by lowering the temperature of a lithium ion battery (LIB) to make the separation of confusing responses easier. The impedance spectra obtained at the temperatures between -20 degrees C and 20 degrees C showed drastic change in sizes with shifting of the characteristic frequency. The analysis of impedance spectra using an equivalent circuit revealed changes in resistance of each component and shifting of the time constant for each elemental step. The frequency domain of impedance response of solid electrolyte interphase (SEI) was found to overlap with that of the inductive component of the outer electric lead at 20 degrees C in our study. The impedance measurement at the low temperatures is considered to be useful for the detection of the SEI and the accurate evaluation of LIB. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

  • Cytotoxicity evaluation of magnetite (Fe3O4) nanoparticles in mouse embryonic stem cells.

    Chigusa Shundo, Hong Zhang, Takuya Nakanishi, Tetsuya Osaka

    Colloids and surfaces. B, Biointerfaces   97   221 - 5  2012年09月  [査読有り]  [国際誌]

     概要を見る

    Magnetite nanoparticles are expected to be applied in the medical field because of their biocompatibility and high saturated magnetization. In this paper, magnetite nanoparticles with a diameter of approximately 40 nm were evaluated for their safety by using mouse embryonic stem (mES) cells. First, various doses of magnetite nanoparticles were added to mES cells to find an optimal dose and to evaluate viability and keeping undifferentiated states of mES. The uptake of nanoparticles by mES cells was confirmed by using cytospin and transmission electron microscopy. Next, mES cells containing magnetite nanoparticles were collected by a magnet column 24h after the addition of magnetite nanoparticles, and the change in the ratio of those mES cells to the total mES cells was assayed by FACS 0, 4, 8, 12, 16, 24, 48 and 72 h after incubation. The result showed that the ratio decreased with time, indicating that the mES cells excreted the nanoparticles, for there was no change in the total number of cells. Based on these results, it was concluded that magnetite nanoparticles were safe to mES cells.

    DOI PubMed

  • Detection of Matrix Metalloproteinase-2 by Field Effect Transistor with a Fibronectin-immobilized Gate

    Daisuke Yamamoto, Sho Hideshima, Shigeki Kuroiwa, Takuya Nakanishi, Tetsuya Osaka

    CHEMISTRY LETTERS   41 ( 8 ) 825 - 827  2012年08月  [査読有り]

     概要を見る

    Matrix metalloproteinase (MMP) is known to be involved in chronic inflammation, tumor invasion, and carcinogenesis. To detect MMP-2, we examined the use of field effect transistors (FETs). After the addition of MMP-2 to a fibronectin (FN)-immobilized gate, negative value of FET response was observed, which indicates MMP-2 decreased the amount of negative charges arising from FN molecules. This FET device successfully detected MMP-2 by utilizing degradation of FN on the gate.

    DOI

  • Effect of magnetite nanoparticles on living rate of MCF-7 human breast cancer cells.

    Daisuke Baba, Yasuhiro Seiko, Takuya Nakanishi, Hong Zhang, Atsushi Arakaki, Tadashi Matsunaga, Tetsuya Osaka

    Colloids and surfaces. B, Biointerfaces   95   254 - 7  2012年06月  [査読有り]  [国際誌]

     概要を見る

    Superparamagnetic and ferromagnetic magnetite nanoparticles, with diameters of approximately 13 and 44 nm, respectively, were synthesized and their uptake amount and heating efficiency were evaluated for application to magnetic hyperthermia. Both nanoparticles had almost the same zeta-potential (+10.2 mV) and hydrodynamic size (∼1 μm) and there was no significant difference in their uptake amount 18 h after they were added to the medium. After internalization, the ferromagnetic nanoparticles incorporated in human breast cancer cells (MCF-7) showed a higher heating efficiency than the superparamagnetic nanoparticles when an external magnetic field (4 kW, 250 kHz) high enough to produce heat by hysteresis loss was applied, followed by cellular death of MCF-7 with high ferromagnetic nanoparticle content.

    DOI PubMed

  • Proposal of novel equivalent circuit for electrochemical impedance analysis of commercially available lithium ion battery

    Tetsuya Osaka, Toshiyuki Momma, Daikichi Mukoyama, Hiroki Nara

    JOURNAL OF POWER SOURCES   205   483 - 486  2012年05月  [査読有り]

     概要を見る

    To analyze impedance response of an electrochemical system, it is important to model the system with an adequate equivalent circuit. In the present work, an equivalent circuit was designed for the analysis of lithium ion batteries with the contributions of a variety of diffusion parameters resulting from the various particle sizes for the cathode and the solid-electrolyte interphase formed on the anode particles, as well as electrochemical reactions and inductive components. Residual errors resulting from the data fitting was investigated for a variety of equivalent circuits used. The electrochemical impedance of the electrodes in commercial lithium ion batteries at various states of charge was analyzed to evaluate the proposed circuit. (C) 2012 Elsevier B.V. All rights reserved.

    DOI

  • Electrochemical Impedance Analysis on Degradation of Commercially Available Lithium Ion Battery during Charge-Discharge Cycling

    Daikichi Mukoyama, Toshiyuki Momma, Hiroki Nara, Tetsuya Osaka

    CHEMISTRY LETTERS   41 ( 4 ) 444 - 446  2012年04月  [査読有り]

     概要を見る

    The degradation of the commercial Li ion battery was analyzed by electrochemical impedance spectroscopy, where our previous proposed equivalent circuit was applied. The degradation with the cycling was clearly explained by the main parameters of capacitive and resistive components, i.e., it responded until 300 cycles to the decrease in capacitive component, while after 300 to 550 cycles to the increase in resistive component.

    DOI

  • Highly durable SiOC composite anode prepared by electrodeposition for lithium secondary batteries

    Hiroki Nara, Tokihiko Yokoshima, Toshiyuki Momma, Tetsuya Osaka

    ENERGY & ENVIRONMENTAL SCIENCE   5 ( 4 ) 6500 - 6505  2012年04月  [査読有り]

     概要を見る

    A highly durable SiOC composite anode was prepared for use in lithium secondary batteries. The SiOC composite was synthesized by electrodeposition of SiCl4. The composite anode delivered a discharge capacity of 1045 mA h per gram of Si at the 2000th cycle and 842 mA h per gram of Si even at the 7200th cycle. The reason for the excellent cyclability was investigated by methods including field emission scanning electron microscopy (FESEM), scanning transmission electron microscopy with an energy dispersive X-ray analyser (STEM-EDX), and X-ray photoelectron spectroscopy (XPS). The results revealed that the excellent cyclability was achieved by the homogeneous dispersion of SiOx and organic/inorganic compounds at the nanometre scale. The structural uniformity of the SiOC composite is believed to have suppressed the crack formation attributable to the stress resulting from the reaction of silicon with lithium during charge-discharge cycles.

    DOI

  • Injection of synthesized FePt nanoparticles in hole-patterns for bit patterned media

    Takuma Hachisu, Wataru Sato, Shugo Ishizuka, Atsushi Sugiyama, Jun Mizuno, Tetsuya Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   324 ( 3 ) 303 - 308  2012年02月

     概要を見る

    FePt nanoparticles of uniform sizes, compositions, and crystal structures can be obtained by chemical synthesis. Additionally, the nanoparticles can be well dispersed by the adsorption of a surfactant on the nanoparticle surface. Previously, the immobilization of FePt nanoparticles on a thermal oxide Si substrate was carried out by chemical synthesis, utilizing the Pt-S bonding between the -SH functional group in (3-mercaptopropyl)trimethoxysilane, MPTMS and Pt in FePt nanoparticles. However, controlling FePt nanoparticle arrays by this synthesis method was very difficult. In the present study, we attempted to control the distortion of the arrangement of FePt nanoparticles using an MPTMS layer modified with a silane coupling reaction and a geometrical structure prepared by ultraviolet nanoimprint lithography (UV-NIL). In this study, the hole-patterns used for the geometrical structure on Si(1 0 0) were 200 nm wide, 40 nm deep, and had a 500 nm pitch. The 5.6 nm FePt nanoparticles were used to coat the hole-patterns by using a picoliter pipette. An XHR-SEM image clearly revealed that the FePt nanoparticles were successfully arranged as a single layer with an average pitch of 10.0 nm by PL-S bonding in the hole-patterns on Si(1 0 0). (C) 2010 Elsevier B.V. All rights reserved.

    DOI

  • Foreword

    T. Osaka, T. Momma

    Electrochim. Acta   82   1 - 2  2012年

  • Foreword

    T. Osaka, T. Momma

    EXPERT OPINION ON DRUG SAFETY   11 ( 1 ) I - I  2012年01月  [査読有り]

    DOI

  • 電界効果トランジスタを用いたマイクロセンサ-pHセンサからバイオセンサまで-

    逢坂哲彌, 黒岩繁樹, 秀島翔, 中西卓也

    Chemical Sensors   28 ( 1 ) 8 - 15  2012年

    CiNii J-GLOBAL

  • 磁性薄膜研究の最前線 I-合金薄膜形成技術-湿式法を用いた磁性薄膜の形成

    逢坂哲彌, 横島時彦, 杉山敦史

    まぐね   7 ( 1 ) 12 - 19  2012年

    J-GLOBAL

  • 電気化学デバイス工学の確立と深化

    逢坂哲彌

    未来材料   12 ( 7 ) 48 - 53  2012年

    CiNii J-GLOBAL

  • Detection of tumor marker in blood serum using antibody-modified field effect transistor with optimized BSA blocking

    Sho Hideshima, Ryosuke Sato, Sayaka Inoue, Shigeki Kuroiwa, Tetsuya Osaka

    SENSORS AND ACTUATORS B-CHEMICAL   161 ( 1 ) 146 - 150  2012年01月  [査読有り]

     概要を見る

    This paper demonstrates that antibody-modified field effect transistors (FETs), which were treated with bovine serum albumin (BSA) blocking, had quantitative capability for tumor marker detection in blood serum. Antibody-modified surface covered with 0.1% BSA effectively minimized nonspecific adsorption of blood proteins. Tumor markers with their isoelectric points of around 5 generated strong signals in body environmental pH (pH 7.4) in proteins with isoelectric points ranging from 3 to 10. Detection of a tumor marker alpha-fetoprotein in blood serum at required level for clinical diagnosis (10 ng/mL) was achieved. The obtained results suggest that the fabricated FETs be expected to practical application in medical fields for direct detection of multi-tumor markers from blood. (C) 2011 Elsevier B.V. All rights reserved.

    DOI

  • Chiral sensing system based on the formation of diastereomeric metal complex on a homocysteine monolayer using field effect transistor

    Daisuke Yamamoto, Takuya Nakanishi, Tetsuya Osaka

    ELECTROCHIMICA ACTA   56 ( 26 ) 9652 - 9655  2011年11月  [査読有り]

     概要を見る

    A self-assembled monolayer (SAM) of L-homocysteine (L-Hcy) formed on the surface of a gold-deposited gate of a field effect transistor (FET) was used to differentiate between enantiomers of amino acids, for which the formation of diastereomeric metal complexes is fundamental for chiral discrimination. Here, we focus our attention on the dependence of the FET response on the analyte amino acids, the central metal ions involved in complex formation, and the solution pH. Using the L-Hcy SAM-modified gate with added Cu(II), notable negative FET responses were enantioselectively observed for the L-enantiomers of alanine (Ala), phenylalanine, and tryptophan, whereas differences in the FET responses between enantiomers were negligible for asparagine and aspartic acid. Regarding the enantioselectivity for Ala, the addition of Cu(II) was demonstrated to show higher selectivity as compared to other metal ions such as Co(II) and Ni(II). Moreover, for the addition of L-Ala and Cu(II), a particularly strong negative FET response was observed at pH 5.5. (C) 2011 Elsevier Ltd. All rights reserved.

    DOI

  • Potentiometric Detection of Serotonin, Melatonin, and Their Precursors/Metabolites with Monolayer-Modified Indium Tin Oxide Electrode and Their Concentration Dependency

    Md. Zaved Hossain Khan, Takuya Nakanishi, Tetsuya Osaka

    SENSOR LETTERS   9 ( 5 ) 1849 - 1852  2011年10月  [査読有り]

     概要を見る

    A novel potentiometric method using an indium tin oxide (ITO) electrode, surface-treated with aminopropylsilane and disuccinimidyl suberate successively, has been developed for measuring serotonin (5-HT), 5-hydroxy-L-tryptophan (5-HTP), 5-hydroxy-indole-acetic acid (5-HIAA), and melatonin (MT) (N-acetyl-5-methoxytryptamine) in phosphate buffered saline (PBS) solution (pH 7.4). A linear concentration range of 1 nM to 100 mu M was obtained with a correlation coefficient of 0.995 for all target analytes. The minimum detectable concentration obtained was 0.1 nM for 5-HT and 1.0 nM for other analytes. The relationship between the molecular structure of the indole derivatives and the enhanced potential shift behaviour was also discussed. This simple and efficient method can be used to measure other neurotransmitters, as well.

    DOI

  • Effect of surface roughness and surface modification of indium tin oxide electrode on its potential response to tryptophan

    Md Zaved Hossain Khan, Takuya Nakanishi, Shigeki Kuroiwa, Yoichi Hoshi, Tetsuya Osaka

    ELECTROCHIMICA ACTA   56 ( 24 ) 8657 - 8661  2011年10月  [査読有り]

     概要を見る

    The effect of surface modification of indium tin oxide (ITO) electrode on its potential response to tryptophan was investigated for ITO substrates with different surface roughness. It was found that a small difference in surface roughness, between similar to 1 and similar to 2 nm of R(a) evaluated by atomic force microscopy, affects the rest potential of ITO electrode in the electrolyte. A slight difference in In:Sn ratio at the near surface of the ITO substrates, measured by angle-resolved X-ray photoelectron spectrometry and Auger electron spectroscopy is remarkable, and considered to relate with surface roughness. Interestingly, successive modification of the ITO surface with aminopropylsilane and disuccinimidyl suberate, of which essentiality to the potential response to indole compounds we previously reported, improved the stability of the rest potential and enabled the electrodes to respond to tryptophan in case of specimens with R(a) values ranging between similar to 2 and similar to 3 nm but not for those with R(a) of similar to 1 nm. It was suggested that there are optimum values of effective work function of ITO for specific potential response to tryptophan, which can be obtained by the successive modification of ITO surface. (C) 2011 Elsevier Ltd. All rights reserved.

    DOI

  • Electrodeposited novel highly durable SiOC composite anode for Li battery above several thousands of cycles

    Toshiyuki Momma, Seiichi Aoki, Hiroki Nara, Tokihiko Yokoshima, Tetsuya Osaka

    ELECTROCHEMISTRY COMMUNICATIONS   13 ( 9 ) 969 - 972  2011年09月  [査読有り]

     概要を見る

    A novel SiOC composite anode material for a Li battery was realized by electrochemical co-deposition of Si, C. and O elements. The composite was deposited by reduction of SiCl(4) in a propylene carbonate based solution. After the initiation process by reduction of the composite in a Li(+) containing electrolyte solution, the SiOC composite was found to be about 3.3 mu m in average thickness and the composite performed as a Li battery anode with over 1000 mAh g(-1) of Si for more than 2000 cycles, and moreover have continued for 7000 cycles with gradual degradation. (C) 2011 Elsevier B.V. All rights reserved.

    DOI

  • Effect of the atmosphere on chemical composition and electrochemical properties of solid electrolyte interface on electrodeposited Li metal

    Toshiyuki Momma, Hiroki Nara, Shinpei Yamagami, Chika Tatsumi, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   196 ( 15 ) 6483 - 6487  2011年08月  [査読有り]

     概要を見る

    Many efforts have been paid to realize the superior anodes for future Li batteries in either the dry Ar atmosphere or the dry air atmosphere. In this work, in order to clarify the effects of such atmospheres, the most reactive anodes of Li were freshly electrodeposited under the dry Ar or under the dry air condition. The Solid Electrolyte Interface (SEI) formed during the electrodeposition of Li anodes is revealed to have a different chemical composition and protective feature. The Li deposited under the dry air was revealed to have longer cycle life in the electrolyte than that deposited in Ar, even in the electrolyte containing ionic liquid. From the XPS results, the SEI formed in dry air is proved to be different from that formed in Ar gas atmospheres. that is, the SEI formed in dry air consists of Li(2)CO(3) and Li nitride. In order to improve the performance of the anodes, the atmosphere for the initial preparation of the anode/electrolyte interface should be tuned. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.

    DOI

  • Efficient electrocatalytic oxygen reduction over metal free-nitrogen doped carbon nanocapsules.

    Sangaraju Shanmugam, Tetsuya Osaka

    Chemical communications (Cambridge, England)   47 ( 15 ) 4463 - 5  2011年04月  [査読有り]  [国際誌]

     概要を見る

    Nitrogen doped carbon nanocapsules (NCNCs) were synthesized as a non-noble electrocatalyst for the ORR using a simple and efficient route. The NCNCs exhibited higher activity than the commercial Pt/C catalyst, excellent stability, and resistance to methanol oxidation in the oxygen reduction reaction.

    DOI PubMed

  • Preface

    Tetsuya Osaka

    ELECTROCHEMISTRY   79 ( 2 ) 79 - 79  2011年02月

    DOI

  • Fabrication of stable antibody-modified field effect transistors using electrical activation of Schiff base cross-linkages for tumor marker detection.

    Sho Hideshima, Ryosuke Sato, Shigeki Kuroiwa, Tetsuya Osaka

    Biosensors & bioelectronics   26 ( 5 ) 2419 - 25  2011年01月  [査読有り]  [国際誌]

     概要を見る

    In this paper, we present a method of fabricating a rigid antibody-immobilized surface using electric activation of a glutaraldehyde (GA)-modified aminopropylsilyl surface for stable antibody-modified field effect transistors (FETs). Electric activation of the GA-modified gate surface of the FET reduces Schiff bases, which are easily hydrolyzed and collapsed, formed between GA and 3-aminopropyltriethoxysilane, resulting in preventing the immobilized antibodies from desorbing from the surface. The lack of Raman peaks that could be assigned to a Schiff base after the electrical activation of the GA-modified surface indicated that the electric activation had reduced the Schiff base. The use of the antibody-modified FETs has three advantages for the detection of antigens: increased sensitivity, distinct recognition ability, and improved reproducibility. A tumor marker, alpha-fetoprotein (AFP), was quantitatively detected up to a concentration of 10 ng/mL using the antibody-modified FET. The detection ability of the FET accomplished a cutoff value of hepatic cancer. The quantitative detection of AFP in a solution with contaminating proteins was also demonstrated. This electric activation method is applicable to other antibody-modified FETs.

    DOI PubMed

  • Prospects of on-chip fuel cell performance: improvement based on numerical simulation

    Satoshi Tominaka, Sousuke Ohta, Tetsuya Osaka, Richard Alkire

    ENERGY & ENVIRONMENTAL SCIENCE   4 ( 1 ) 162 - 171  2011年01月

     概要を見る

    On-chip fuel cells are promising power sources for future electronics and microdevice applications including on-chip sensors and micro-air-vehicles. Previously, we reported a small scale (0.4 mm wide and 6 mm long) on-chip fuel cell of an air-breathing, membrane-less and monolithic design, which exhibited the highest power for an on-chip fuel cell, 1.4 mu W (J. Am. Chem. Soc., 2008, 130, 10456). In order to improve the performance, precise understanding of the phenomena occurring in the cells is of primary importance. Thus, this paper focuses on understanding cell operation by using numerical simulation, and on implementing cell improvements based on the simulation results. The initial quantitative study concluded that the performance of the on-chip fuel cell was limited owing to oxygen-supply caused by cathode flooding. Thus, we experimentally added the hydrophobic ionomer (Nafion) onto the cell to reduce the influence of the flooding, and successfully increased the maximum power from 2.0 to 2.8 mu W. This power is considered sufficient for microsensor application. On the basis of additional simulation results, we show that performance may potentially be improved to over 100 mu W by increasing the effective surface areas of catalysts to a level comparable with methanol fuel cells. If successful, such performance enhancements would position the on-chip fuel cell as a viable candidate for future micro-devices, and point to promising directions for fuel cell development efforts.

    DOI

  • 電気化学会のさらなる発展に向けて

    T. Osaka

    Electrochemistry   79   79 - 79  2011年

  • Development on Self-assembly Technique for Arrangement of Chemically Synthesized FePt Nanoparticles

    Takuma Hachisu, Atsushi Sugiyama, Tetsuya Osaka

    MAGNETIC MATERIALS PROCESSES AND DEVICES 11   33 ( 34 ) 107 - 113  2011年

     概要を見る

    This paper reviews our study of bit patterned media (BPM) using L1(0) (face centered tetragonal)-FePt nanoparticles. For the practical use of L1(0)-FePt nanoparticles to BPM, some breakthroughs are required: a highly ordered two-dimensional array of nanoparticles on a substrate, a controlled orientation of the axis of easy magnetization in vertical direction on a substrate. Previously, we reported about the achievement for uniformity FePt nanoparticles by controlling chemical synthesis conditions. Moreover, we confirmed the selective chemical interaction Pt in the surface of FePt nanoparticles and SH group with (3-mercaptopropyl)tri-methoxysilane (MPTMS). This study presented a new hybrid technique combining the selective chemical bonding and a substrate with a geometrical grid in order to control the array of FePt nanoparticles with uniform direction of their magnetization. We succeed in preparing uniform array of nanoparticles on geometrical grid with size of 200 nm square prepared using ultraviolet nanoimprint lithography (UV-NIL).

    DOI

  • Relation between Effective Charge Numbers and Signals Caused by Protein Adsorption on Field Effect Transistor Detection

    S. Hideshima, T. Nakamura, S. Kuroiwa, T. Osaka

    BIOELECTRONICS, BIOINTERFACES, AND BIOMEDICAL APPLICATIONS 4   35 ( 7 ) 121 - 124  2011年  [査読有り]

     概要を見る

    This paper describes a practical method for predicting signals of an adsorbed protein detected by field effect transistors (FETs). The FETs detect the change of the surface charge caused by protein adsorption. The sensing signals strongly depend on an ionic strength of the buffer solution. The prediction of signals is useful for optimizing the strength. A calculation method using three-dimensional conformation structure of proteins was proposed for the prediction tool in the latest paper citing biotin-avidin interaction as an example. To verify availability of the method for alternative adsorbed protein, an adsorption model of streptavidin, which also has a binding ability to biotin, was investigated. Streptavidin has little charge in a buffer solution at pH 7.4 calculated from the method. The results suggest that the signals caused by adsorption of streptavidin were barely detectable using a biotinylated FET.

    DOI

  • 微細結晶-非晶質混在金・ニッケル合金めっき膜の析出条件と物性

    千田一敬, 岩井良太, 徳久智明, 加藤勝, 山近紀行, 沖中裕, 逢坂哲彌, 逢坂哲彌, 逢坂哲彌

    表面技術   62 ( 8 ) 397 - 402  2011年

    J-GLOBAL

  • Gold nanoparticles enhance efficiency of in vitro gene transcription-translation system

    Daxiang Cui, Hong Zhang, Kan Wang, Feng Gao, Xueqing Zhang, Toru Asahi, Rong He, Tetsuya Osaka

    Nano Biomedicine and Engineering   3 ( 2 ) 120 - 125  2011年

     概要を見る

    Herein we report that the in vitro gene transcription-translation efficiency can be dramatically enhanced by gold nanoparticles of 5nm in diameter. The addition of less than or equal to 1.2 nM of gold nanoparticles of 5 nm in diameter into rapid-translation-system (RTS) reagents increased the transcription-translation efficiency up to 30% and shortened the reaction time to 4 h, with the same or higher translation yields. Gold nanoparticles did not decrease the yields' bioactivity. The results show that gold nanoparticles of 5 nm may act as a bio-catalyst in the RTS reaction. This innovation has great potential in applications such as large-scale protein fabrication, gene transcription-translation regulation, and studies of structure and function of toxic protein. © 2011 DX. C, et al.

    DOI

  • Impedance Analysis Counting Reaction Distribution on Degradation of Cathode Catalyst Layer in PEFCs

    Hiroki Nara, Satoshi Tominaka, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   158 ( 9 ) B1184 - B1191  2011年  [査読有り]

     概要を見る

    A novel transmission line (TML) model is proposed for the impedance analysis, which is nondestructive measurement, on degraded cathode catalyst layers in polymer electrolyte fuel cells (PEFCs). The test PEFC consisted of 1.0 mg/cm(2) of Pt-Ru as an anode catalyst, 1.0 mg/cm(2) of Pt as a cathode catalyst, and Nafion 212 as an electrolyte. The model counts the distribution of the oxygen reduction reaction (ORR) at the inside and outside of agglomerates of the carbon supported catalysts. We demonstrated the importance of the distribution of the ORR for achieving excellent agreement between the calculated and experimental data. The change in parameters obtained by impedance analysis with the TML model was verified by destructive tests, such as transmission electron microscopy, field emission scanning electron microscopy, cyclic voltammetry, micro-Fourier transform infrared spectroscopy and nitrogen adsorption-desorption measurements. Variations of the parameters such as the charge transfer resistance, the double layer capacitance, and the ionic resistance inside and outside the agglomerates of the carbon supported catalysts could be explained by multiple considerations of these destructive test results. Impedance analysis with the TML model offers the possibility understanding the state of degraded cathode catalyst layers in membrane electrode assemblies without the need for disassembling PEFCs. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3610988] All rights reserved.

    DOI

  • Effect of palladium nuclei insertion by electroless deposition on magnetic intergranular isolation and read/write characteristics in SmCo5 perpendicular magnetic recording media

    Atsushi Sugiyama, Yuko Egawa, Isao Koizumi, Masahiro Yoshino, Jiro Hokkyo, Toru Asahi, Takanori Kiya, Jun Ariake, Kazuhiro Ouchi, Tetsuya Osaka

    SPECIAL ISSUE ON THE 9TH PERPENDICULAR MAGNETIC RECORDING CONFERENCE   16   68 - 74  2011年  [査読有り]

     概要を見る

    In order to improve the magnetic intergranular isolation between the magnetic grains in the SmCo5 perpendicular magnetic recording media, the palladium nuclei deposited by an electrochemical process were introduced into a sputter deposition process of the SmCo5 film. A few nanometer size Pd nuclei were electrochemically deposited on the sputtered Cu underlayer by a displacement deposition (chemical plating). The sizes of Pd nuclei were controlled by adjusting the Pd ion concentration in electrolyte solutions. The magnetic domain size in Sm-Co layer deposited on Pd nuclei / Cu / Ti underlayer became smaller and the magnetization reversal process was changed from the wall motion to the coherent rotation. Moreover, the read/write characteristics were improved at higher linear recording densities. (C) 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of the Organising Committee of the 9th Perpendicular Magnetic Recording Conference

    DOI

  • ビットパターンメディアへの適用に向けたFePtナノ粒子の規則配列化

    佐藤亘, 蜂巣琢磨, 杉山敦史, 水野潤, 庄子習一, 逢坂哲彌

    電子情報通信学会技術研究報告   111 ( 307(MR2011 19-24) ) 31 - 34  2011年

    J-GLOBAL

  • シクロオレフィンポリマー上への電析-脱合金法によるPtCu触媒の形成

    三須義竜, 西世古弘, 横島時彦, 門間聰之, 門間聰之, 逢坂哲彌, 逢坂哲彌

    表面技術   62 ( 12 ) 720 - 722  2011年

    J-GLOBAL

  • Effect of Carbon Inclusion on Microstructure of Electrodeposited Au-Ni Alloy Films

    Takahiro Inoue, Kazuo Sato, Tokihiko Yokoshima, Atsushi Sugiyama, Yutaka Okinaka, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   158 ( 6 ) D403 - D407  2011年  [査読有り]

     概要を見る

    The microstructure of electrodeposited nano-crystalline Au-Ni film was investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM). Carbon was found to be included in the deposit, and the state of bonding and dispersion of the carbon and its effect on the microstructure of Au-Ni film were studied. Nano-crystalline films were found to be composed of Au-rich crystalline phase and Ni-rich phase, and the latter consisted of crystalline and amorphous phases. The amorphous phase contained a large number of carbon particles measuring 5-20 nm. TEM and STEM examinations showed that the large carbon particles possess a graphite-like structure with some of the particles being arranged in arrays. Mechanism of the carbon inclusion was discussed based on the results of XRD and the composition analysis of Au-free Ni film electrodeposited from a cyanide-containing bath. These results showed that carbon is co-deposited with Ni as nickel carbide and also as carbon particles. It is concluded that the inclusion of carbon and the coexistence of Au and Ni are the conditions necessary for the formation of amorphous structure of the electrodeposited Au-Ni alloy film. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3579417] All rights reserved.

    DOI

  • 二次電池

    逢坂哲彌, 奈良洋希

    エネルギーと動力   ( 特集号 ) 25 - 32  2011年

    J-GLOBAL

  • Nanoporous PdCo catalyst for microfuel cells: Electrodeposition and dealloying

    Satoshi Tominaka, Tetsuya Osaka

    Advances in Physical Chemistry   2011   2011  2011年

     概要を見る

    PdCo alloy is a promising catalyst for oxygen reduction reaction of direct methanol fuel cells because of its high activity and the tolerance to methanol. We have applied this catalyst in order to realize on-chip fuel cell which is a membraneless design. The novel design made the fuel cells to be flexible and integratable with other microdevices. Here, we summarize our recent research on the synthesis of nanostructured PdCo catalyst by electrochemical methods, which enable us to deposit the alloy onto microelectrodes of the on-chip fuel cells. First, the electrodeposition of PdCo is discussed in detail, and then, dealloying for introducing nanopores into the electrodeposits is described. Finally, electrochemical response and activities are fully discussed. Copyright © 2011 Satoshi Tominaka and Tetsuya Osaka.

    DOI

  • 学から産への技術発信

    逢坂哲彌

    電気化学秋季大会講演要旨集   2011   578 - 581  2011年

    J-GLOBAL

  • 将来のめっき技術 電子部品の金めっき膜

    杉山敦史, 横島時彦, 蜂巣琢磨, 沖中裕, 逢坂哲彌

    表面技術   62 ( 12 ) 635 - 641  2011年

    J-GLOBAL

  • Microstructure of Electrodeposited Nano-Crystalline Au-Ni Alloy Films

    Takahiro Inoue, Kazuo Sato, Tokihiko Yokoshima, Takahiro Sawaguchi, Atsushi Sugiyama, Yutaka Okinaka, Tetsuya Osaka

    MOLECULAR STRUCTURE OF THE SOLID-LIQUID INTERFACE AND ITS RELATIONSHIP TO ELECTRODEPOSITION 7   33 ( 37 ) 27 - 34  2011年  [査読有り]

     概要を見る

    The microstructure of electrodeposited Au-Ni films was investigated by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning transmission electron microscopy (STEM). Nano-crystalline films were found to be composed of three different phases: Au-rich crystalline phase, Ni-rich crystalline phase, and Ni-rich amorphous phase. Particles of carbon measuring 5 to 20 nm were also found in the deposit. It is assumed that the inclusion of a large amount of carbon particles causes the formation of the amorphous phase. The microstructure and the state of dispersion of the carbon particles were also investigated. The results of TEM and STEM observations showed that the carbon particles possess either the graphite structure or the amorphous structure with some of the particles being arranged in arrays. Scanning tunneling microscopy (STM) was performed to study the relationship between the structure of species adsorbed on the electrode surface and the process of carbon inclusion.

    DOI

  • Synthesis of mesoporous PtCu film modified with Ru submonolayer as catalyst for methanol electrooxidation.

    Satoshi Tominaka, Mayumi Shigeto, Hiroshi Nishizeko, Tetsuya Osaka

    Chemical communications (Cambridge, England)   46 ( 47 ) 8989 - 91  2010年12月  [査読有り]  [国際誌]

     概要を見る

    A mesoporous PtCu catalyst modified with a Ru submonolayer is successfully synthesized by a facile electrochemical process of electrodeposition, dealloying and Ru underpotential deposition. The material has a large specific surface area comparable to nanoparticles (11 m(2) g(-1)) and exhibits a promising catalyst activity for the methanol oxidation reaction.

    DOI PubMed

  • Sialylglycan-modified Field Effect Transistor for Detection of Charged Lectin under Physiological Conditions

    Takahiro Nakamura, Yoshihiro Sakurai, Sho Hideshima, Shigeki Kuroiwa, Tetsuya Osaka

    CHEMISTRY LETTERS   39 ( 12 ) 1245 - 1247  2010年12月  [査読有り]

     概要を見る

    Determination of protein charges under physiological conditions by field effect transistors (FETs) is challenging because of the screening effect by solution counter ions We showed that sugar-chain-modified FETs can detect proteins under physiological conditions Protein charges are detectable on the gate interface by applying sugar chains as receptors these sugar chains are short and highly flexible Threshold voltage shifts caused by adsorption of SSA lectin from Sambucus sieboldiana onto sialylglycan-modified FET showed a linear relationship with SSA concentrations under physiological conditions

    DOI

  • Improvement of magnetic intergranular isolation and evaluation of read/write characteristics on SmCo5 perpendicular magnetic thin films

    Toru Asahi, Isao Koizumi, Yuko Egawa, Masahiro Yoshino, Atsushi Sugiyama, Jiro Hokkyo, Takanori Kiya, Jun Ariake, Kazuhiro Ouchi, Tetsuya Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   322 ( 23 ) 3784 - 3788  2010年12月  [査読有り]

     概要を見る

    SmCo5 alloy is a promising candidate for ultra-high-density perpendicular magnetic recording (PMR) media because of its high uniaxial magnetocrystalline anisotropy K-u of more than 1.1 x 10(8) erg/cm(3). Previously, we successfully achieved high K-u in a sputter-deposited SmCo5 thin film by introducing a Cu/Ti dual underlayer. However, in order to apply the SmCo5 films to practical PMR media, it is necessary to decrease medium noise. A granulated magnetic film comprising of small and magnetically decoupled grains is effective in reducing the medium noise. In this paper, we have proposed a new granular film that is fabricated by partial thermodiffusion of Cu between the Sm-Co continuous layer and the Cu underlayer, which is granulated using compositional segregation caused by the addition of Ta2O5. We have analyzed the magnetic properties, magnetic domain size, and magnetization reversal process of the proposed SmCo5 film. The magnetic domain size decreased and the magnetization reversal process changed from the magnetic-wall-motion mode to a coherent rotation mode to some extent on isolation of magnetic grains. The read/write characteristics of granulated SmCo5 double-layered media were also evaluated. The medium noise decreased and the signal-to-noise ratio increased for the granulated double-layered (PMR) medium. (C) 2010 Elsevier B.V. All rights reserved.

    DOI

  • Sulfated zirconia as a proton conductor for fuel cells: Stability to hydrolysis and influence on catalysts

    Satoshi Tominaka, Toshiyuki Momma, Bruno Scrosati, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   195 ( 13 ) 4065 - 4071  2010年07月  [査読有り]

     概要を見る

    Sulfated zirconia is an inorganic solid superacid having sulfate groups covalently bonded to its surface. In this work, sulfated zirconia is synthesized by a solvent-free method to obtain it in the nanoparticle form. This nanostructured sulfated zirconia has been evaluated in terms of (i) chemical stability to hydrolysis and to hydrogen peroxide by thermogravimetric analysis, and (ii) influences on Pt catalyst activity by cyclic voltammetry using sulfated-zirconia dispersion as a supporting electrolyte solution. The results demonstrate that our sulfated zirconia is stable almost perfectly to hydrolysis but partly decomposed by a Fenton reagent containing hydrogen peroxide and Fe2+. In addition, we show that oxygen reduction activity of Pt catalyst in a sulfated-zirconia dispersion is comparatively high (specific activity at 0.9 V vs. RHE, i(0.9): ca. 17 mu A cm(-2)) compared to that in a 0.5 M sulfuric acid solution (i(0.9): ca. 15 mu A cm(-2)). Finally, we demonstrate that sulfated zirconia does not influence hydrogen oxidation reaction. These results lead us to conclude that sulfated zirconia is a promising proton conductor for fuel cells. (C) 2010 Published by Elsevier B.V.

    DOI

  • Chiral discrimination between alanine enantiomers by field effect transistor with a homocysteine monolayer-modified gate

    Mariko Matsunaga, Daisuke Yamamoto, Takuya Nakanishi, Tetsuya Osaka

    ELECTROCHIMICA ACTA   55 ( 15 ) 4501 - 4505  2010年06月  [査読有り]

     概要を見る

    The application of field effect transistor (FET) to chiral discrimination was investigated. An Au film vapor-deposited on a self-assembled monolayer (SAM) of (3-mercaptopropyl)trimethoxysilane, which was formed on the SiO2 gate of FET as an adhesive and insulating layer, stabilizes the drain current-gate voltage (I-d-V-g) property of FET. The modification by homocysteine(Hcy)SAM on the surface of Au-coated gate makes it possible for the FET to distinguish between the enantiomers of alanine (Ala). Namely, after the sequential addition of Ala and Cu(II) to a K2SO4 solution in this system, it was confirmed that the lateral shift of I-d-V-g curves for the FET corresponded to the chirality of Ala. With the L-Hcy SAM-modified gate, a notable negative shift was observed for L-Ala, whereas the shift observed with D-Ala was much smaller. In contrast, opposite results were obtained with D-Hcy SAM. Results of quartz crystal microbalance measurement suggested that such an FET response was originated from the enantioselective formation of diastereomeric Cu complexes with Ala molecules on the Hey SAM. This system was demonstrated to respond quantitatively to one enantiomeric form of Ala in mixed solutions of two enantiomers as well as in pure enantiomeric solutions (C) 2010 Elsevier Ltd. All rights reserved.

    DOI

  • Fabrication of SmCo5-CrTa Granular Films

    A. Sugiyama, I. Koizumi, Y. Egawa, M. Yoshino, J. Hokkyo, T. Asahi, T. Osaka

    IEEE TRANSACTIONS ON MAGNETICS   46 ( 6 ) 1699 - 1701  2010年06月  [査読有り]

     概要を見る

    A Sm-Co-CrTa granular layer between a Sm-Co continuous layer and a Cu underlayer was prepared in order to improve magnetic properties and magnetic reversal process of Sm-Co perpendicular film. A phase of CrTa alloy in Sm-Co-CrTa layer has a role in control of Cu partial interlayer diffusion between the Sm-Co continuous layer and the Cu underlayer. The Cu diffusion provides the partial crystallization of SmCo5 in the continuous layer. Although the perpendicular coercivity of films decreased slightly by introducing the CrTa alloy into Sm-Co layer, the magnetic intergranular exchange interaction in the films was drastically improved. Size of average magnetic cluster became smaller and magnetization reversal process was changed from a wall-motion to a coherent rotation for increasing the thickness ratio of Sm-Co-CrTa/Sm-Co layers. We confirmed that an addition of Sm-Co-CrTa layer is effective to reduce the intergranular exchange interaction in Sm-Co perpendicular films without deterioration of perpendicular magnetic anisotropy.

    DOI

  • Electrochemical analysis of perpendicular mesoporous Pt electrode filled with pure water for clarifying the active region in fuel cell catalyst layers

    Satoshi Tominaka, Chia-Wen Wu, Kazuyuki Kuroda, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   195 ( 8 ) 2236 - 2240  2010年04月  [査読有り]

     概要を見る

    A perpendicular mesoporous platinum film is used as a model electrode to clarify the effectiveness of catalysts inside agglomerates of fuel cell catalyst layers on the basis of experimental facts. The analysis clarifies that: (i) Pt surface even apart from Nafion ionomer phase can be electrochemically active: (ii) its response is different from that of the surface covered with ionomer; and (iii) ionic resistance in pores filled with pure water is too high (ca. 0.18 M Omega cm) for fuel cell reactions to smoothly occur. We conclude that such catalysts in pores filled with pure water are ineffective for fuel cell reactions due to the high ionic resistance, though their catalytic activity is possibly higher than that of the catalysts covered with Nafion. (C) 2009 Published by Elsevier B.V.

    DOI

  • 参照用電界効果トランジスタのイオン応答への表面モルフォロジーの効果(E)

    黒岩 繁樹, 柴崎 友美, 逢坂 哲彌

    電気化学および工業物理化学 : denki kagaku   78 ( 2 ) 143 - 145  2010年02月  [査読有り]

    DOI CiNii

  • Nanostructured catalyst with hierarchical porosity and large surface area for on-chip fuel cells

    Satoshi Tominaka, Yusuke Nakamura, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   195 ( 4 ) 1054 - 1058  2010年02月

     概要を見る

    This communication reports the synthesis of mesoporous Pd-Co dendrites with both a unique hierarchical porosity and a large surface area by the combination of electrodeposition and dealloying. The resultant mesoporous dendrites consist of microparticles with a diameter of a few hundred nanometers, and the particles have mesopores with around 10 nm width. The mesoporous dendrites are found to be Pd8Co2, to be composed of pure Pd crystalline phases and amorphous Pd-Co phases, and to be covered with Pd-skin layers. This catalyst exhibits a high activity in the oxygen reduction reaction. Thus, this novel catalyst is attractive as a catalyst for on-chip fuel cells. which require catalysts to be deposited precisely onto tiny current collectors. (C) 2009 Published by Elsevier B.V.

    DOI

  • Potential Response of Monolayer-Modified Indium Tin Oxide Electrodes to Indole Compounds

    Takuya Nakanishi, Tsubasa Ueno, Mariko Matsunaga, Md. Zaved Hossain Khan, Tetsuya Osaka

    ELECTROANALYSIS   22 ( 4 ) 393 - 398  2010年02月  [査読有り]

     概要を見る

    Potential response of indium tin oxide (ITO) electrode modified by treatment with disuccinimidyl suberate (DSS) was investigated to various target molecules. Distinctively, the DSS-modified ITO electrode exhibited a potential shift to the molecules possessing an indole group such as tryptophan, tryptamine and indole propionic acid, while little response to benzoic acid, phenylalanine, proline, proline amide, and arginine was observed. In addition, the combination of this specificity to indoles and enantioselective affinity of human serum albumin (HSA), which was additionally immobilized on the DSS-modified ITO electrode, brought about enantioselective potential response to tryptophan.

    DOI

  • Analysis of Electrodeposited Au-Ni Alloy Films for Carbon Inclusion and Crystallinity

    Takahiro Inoue, Kazuo Sato, Masahiro Yoshino, Kazutaka Senda, Masahiro Yanagisawa, Yutaka Okinaka, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   157 ( 5 ) D274 - D277  2010年  [査読有り]

     概要を見る

    Carbon inclusion and its effect on the crystallinity of electrodeposited Au-Ni alloy films are discussed based on the results of X-ray diffraction (XRD) spectroscopy, chemical composition analysis, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Under an optimum set of conditions, both citrate bath and pyrophosphate bath yield Au-Ni alloy deposits, which are amorphous to the XRD measurement. The carbon content of the amorphous deposit is higher than that of the crystalline deposit, and this trend is observed for deposits from both citrate and pyrophosphate baths. Experimental results are presented, showing that the amorphous deposits from both citrate and pyrophosphate baths contained a comparable amount of carbon, which indicates that CN from KAu(CN)(2) is the major source of carbon inclusion in the deposits from both baths. The results of XPS and, more clearly, Raman spectroscopy show that the amorphous Au-Ni deposit contains a large amount of carbon in the amorphous state, which apparently forms as a result of the decomposition of CN, whereas only the crystalline deposit contains carbon in the form of CN. It is concluded that carbon inclusion and the state of included carbon play a significant role in the process of creating the amorphous structure of Au-Ni alloy electrodeposits.

    DOI

  • Evaluation of stability difference between asymmetric homochiral dimer in (S)-thalidomide crystal and symmetric heterochiral dimer in (RS)-thalidomide crystal

    Toshiya Suzuki, Masahito Tanaka, Motoo Shiro, Norio Shibata, Tetsuya Osaka, Toru Asahi

    PHASE TRANSITIONS   83 ( 3 ) 223 - 234  2010年  [査読有り]

     概要を見る

    This article discusses differences in physicochemical properties such as solubility and melting point between (S)-thalidomide and (RS)-thalidomide based on crystal structures determined by X-ray diffraction experiments. Investigation of such differences is of great importance because thalidomide has attracted considerable attention again due to its wide-range bioactivity for intractable diseases. In this article, structures of hydrogen-bonded rings were compared between asymmetric homochiral dimers in (S)-thalidomide crystal and symmetric heterochiral dimers in (RS)-thalidomide crystal. The heterochiral dimer was evaluated to be more stable than the homochiral dimer by the energy calculations for hydrogen-bonded rings in those dimers. These results indicate that differences in physicochemical properties between enantiomeric and racemic thalidomides originate from the difference of structural stability between homochiral and heterochiral dimers.

    DOI

  • Real time PCR based on fluorescent quenching of mercaptoacetic acid-modified CdTe quantum dots for ultrasensitive specific detection of nucleic acids

    D. Cui, Q. Li, P. Huang, K. Wang, Y. Kong, H. Zhang, X. You, R. He, H. Song, J. Wang, C. Bao, T. Asahi, F. Gao, T. Osaka

    Nano Biomedicine and Engineering   2   45 - 55  2010年

  • Effects of CdSe/ZnS quantum dots covered multi-walled carbon nanotubes on murine embryonicstem cells

    Daxiang Cui, Hong Zhang, Jie Sheng, Zheng Wang, Asahi Toru, Rong He, Osaka Tetsuya, Feng Gao, Hoon Sung Cho, Chris Huth, Hengyao Hu, Giovanni M. Pauletti, Donglu Shi

    Nano Biomedicine and Engineering   2 ( 4 ) 236 - 244  2010年

     概要を見る

    Stem cells nanotechnology has emerged as a new exciting area, and holds great potential for research and development of stem cells as novel therapeutic platforms for genetic, traumatic, and degenerative medicine. Vital to the success of this technology are approaches that reproducibly facilitate in vivo cell tracking, expansion, differentiation, and transplantation. Herein we reported the effects of CdSe/ZnS quantum dots covered multi-walled carbon nanotubes (FMNTs) on mice embryonic stem cell line CCE cells. The FMNTs were prepared by plasma surface treatment and characterized by high resolution transmission electron microscopy (HR-TEM), and incubated with murine ES CCE cells for 1 to 28 day.These ES cells were observed by confocal laser scanning microscopy, and were analyzed by real time reverse transcription-polymerase chain reaction (RTPCR), flow cytometry (FCM) and MTT method. Results showed that prepared FMNTs exhibited green fluorescent signal, could enter into ES cells in time-dependent means, more than 20 μg ml-1 FMNTs induced ES cells become smaller and smaller as the incubation time increased, and inhibited cell growth in dose-and time-dependent means, induced apoptosis of ES cells
    conversely, 5 μg ml-1 FMNTs could markedly stimulate the expression of Sox1 and Hsp27, and inhibit expression of OCT4 in ES cells, FCM analysis showed that differentiation marker Flk-1 exhibited higher expression compared with control ES cells. In conclusion, high dose of FMNTs can inhibit proliferation of ES cells, low dose of FMNTs can improve the differentiation of ES cells, FMNTs can have potential applications in in vivo tracking, imaging and regulation of the proliferation and differentiation of ES cells. © 2010 D. Cui, et al.

    DOI

  • Mesoporous PdCo sponge-like nanostructure synthesized by electrodeposition and dealloying for oxygen reduction reaction

    Satoshi Tominaka, Tomoya Hayashi, Yusuke Nakamura, Tetsuya Osaka

    JOURNAL OF MATERIALS CHEMISTRY   20 ( 34 ) 7175 - 7182  2010年  [査読有り]

     概要を見る

    A mesoporous PdCo sponge-like nanostructure was successfully synthesized by the combination of electrodeposition and dealloying, and was evaluated as a catalyst for the oxygen reduction reaction of fuel cells. The synthesized film had a sponge-like mesoporosity consisting of 5-30 nm thick ligaments with pores of tens of nanometers. Its porosity was estimated to be ca. 62%, suggesting that the oxygen transport in the film was smooth. The resultant composition was Pd93Co7, whose crystalline phase was determined to be a solid solution of Pd92Co8 by X-ray diffractometry. This degree of alloying is known to induce the most desirable lattice contraction into a Pd catalyst for the oxygen reduction reaction. Actually, the mesoporous PdCo catalyst had a higher specific activity than the Pt catalyst in the potential range of <0.85 V vs. SHE, i.e., the potential range of interest for fuel cell operation. This fascinatingly higher catalytic activity was attributable to the preferable reaction mechanism, because the PdCo electrode had a lower Tafel slope (43 mV decade (1)) than a typical Pt electrode (71 mV decade(-1)).

    DOI

  • 化学的手法によるFePtナノ粒子の均一配列と結晶構造の単一配向化

    蜂巣琢磨, 杉山敦史, 逢坂哲彌

    電子情報通信学会技術研究報告   110 ( 310(MR2010 34-41) ) 39 - 45  2010年

    J-GLOBAL

  • ウエットプロセスを用いた古くて新しい磁性膜の形成 磁性めっき膜の動向

    杉山敦史, 蜂巣琢磨, 横島時彦, 逢坂哲彌

    表面技術   61 ( 6 ) 396 - 401  2010年

    J-GLOBAL

  • ウエットプロセスを用いた古くて新しい磁性膜の形成 高飽和磁束密度を有する軟磁性めっき膜

    逢坂哲彌, 横島時彦

    表面技術   61 ( 6 ) 402 - 408  2010年

    J-GLOBAL

  • New Proposal for the Interfacial Design toward the Establishment of Electrochemical Device Engineering

    Tetsuya Osaka, Takuya Nakanishi

    ELECTROCHEMICAL ENGINEERING FOR THE 21ST CENTURY (DEDICATED TO RICHARD C. ALKIRE)   28 ( 29 ) 17 - 24  2010年  [査読有り]

     概要を見る

    This paper describes an overview of our research with the title of Establishment of Electrochemical Device Engineering. The goal of this work is to develop systematic methodologies for the creation of advanced materials and devices based on the design of the interface, which is derived from our study of the practical application of Electrochemical Nanotechnology. We introduce three-, two-, and zero-dimensional viewpoints to the design of the interface between electrode and electrolyte based on electrochemical nanotechnology. In this manuscript, two-dimensional design is explained first and then three- and zero-dimensional topics are mentioned.

    DOI

  • CONDUCTIVE POLYMERS: Electroplating of Organic Films

    T. Osaka, S. Komaba, T. Momma

    Modern Electroplating 5th Ed     421 - 432  2010年

  • 知的財産シンポジウム 文と理,対峙から協働へ─文理融合型知的財産の活用方法を探る─

    高林龍, 朝日透, 中村修二, 逢坂哲彌, 熊倉禎男, 小泉直樹

    企業と法創造   7   246 - 262  2010年

  • 粒径を制御したマグネタイトナノ粒子の合成とそのバイオ・医療応用に向けた検討

    中西卓也, ZHANG Hong, 逢坂哲彌

    電子情報通信学会技術研究報告   110 ( 310(MR2010 34-41) ) 13 - 15  2010年

    J-GLOBAL

  • Theoretical Optimization Method of Buffer Ionic Concentration for Protein Detection Using Field Effect Transistors

    Sho Hideshima, Hila Einati, Takahiro Nakamura, Shigeki Kuroiwa, Yosi Shacham-Diamand, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   157 ( 12 ) J410 - J414  2010年  [査読有り]

     概要を見る

    Field effect transistors (FETs) may respond to charge variations occurring when proteins are adsorbed to the gate surface. The electrolyte electrostatic screening allows a practical detection of charges that are only within a distance of approximately the double layer thickness, which is related to the Debye length in the electrolyte. Hence, operating the FET biomolecular sensors at the highest possible ionic concentration improves reproducibility; however, it may reduce the signal if the concentration is too high. Here, we propose an optimization method of the buffer ionic concentration using a figure of merit "charge number," Z(d), which is defined as the ratio between the effective number of the surface charges and the number of immobilized molecules. The theoretical Z(d) was calculated using a three-dimensional conformation data taken from the Protein Data Bank. The Z(d) was obtained from the total number of four charged amino acids of avidin, arginine (positive), lysine (positive), aspartic acid (negative), and glutamic acid (negative), which are within the double layer length from the surface. To verify this model, we chose avidin-biotin interaction. The experimental Z(d), which was obtained for three buffer concentrations, matched the theoretical Z(d). This method shortens the solution calibration time and reduces the analyte amount. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3491764] All rights reserved.

    DOI

  • Arrangement of FePt Nanocubes Utilizing Chemical Binding Selectivity

    Takuma Hachisu, Wataru Sato, Atsushi Sugiyama, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   157 ( 9 ) D514 - D518  2010年

     概要を見る

    This study on future ultrahigh density magnetic recording devices aims to develop a technique for arranging FePt nanocubes on a substrate by using organosilane as an interlayer. An array of FePt nanocubes was formed by chemical synthesis, utilizing the Pt-S binding between the SH functional group in (3-mercaptopropyl)trimethoxysilane and Pt in the FePt nanocubes. The morphology of the FePt nanocube array on the substrate was characterized using atomic force microscopy and plan-view scanning electron microscopy, which revealed that the array was a monolayer. After SiO(2) was coated by chemical vapor deposition as a protective layer for sintering prevention, annealing was carried out at 900 degrees C for 3 h in a reducing atmosphere to transform the crystal structure of the FePt nanocubes to the L1(0) phase. X-ray diffraction results revealed that the annealed FePt nanocube array had a FePt(110) orientation and L1(0) phases such as (001) and (110). The Pt-S binding did not obstruct the L1(0) ordering of FePt. Consequently, a method for arranging nanoparticles by using the organic molecules with functional groups that can interact with nanoparticle selectivity as an interlayer can be applied as a formation technique for arranging a wide range of nanoparticles. (C) 2010 The Electrochemical Society. [DOI:10.1149/1.3465631] All rights reserved.

    DOI

  • Magnet microarray for single cell entrapment and culture

    Marie Asami, Tomoko Yoshino, Naonobu Shimamoto, Masahiro Yoshino, Toru Asahi, Tetsuya Osaka, Tadashi Matsunaga

    JOURNAL OF BIOSCIENCE AND BIOENGINEERING   108   S163 - S163  2009年11月

    DOI

  • Effect of surface charge of magnetite nanoparticles on their internalization into breast cancer and umbilical vein endothelial cells.

    Tetsuya Osaka, Takuya Nakanishi, Sangaraju Shanmugam, Shintaro Takahama, Hong Zhang

    Colloids and surfaces. B, Biointerfaces   71 ( 2 ) 325 - 30  2009年07月  [査読有り]  [国際誌]

     概要を見る

    Internalization of magnetite nanoparticles with diameter of approximately 40 nm into normal and cancer cells was examined by microscopic observation and flow cytometry. Magnetite nanoparticles were synthesized by hydrolysis in an aqueous solution containing ferrous chloride with organic amines as a base. It was demonstrated that the difference in surface charge of magnetite nanoparticles brought about the difference in uptake efficiency. The nanoparticles with positive charge showed higher internalization into human breast cancer cells than the nanoparticles with negative charge, while the degree of internalization of the positively- and negatively-charged nanoparticles into human umbilical vein endothelial cells (HUVEC) was almost the same.

    DOI PubMed

  • Biosensing by optical waveguide spectroscopy based on localized surface plasmon resonance of gold nanoparticles used as a probe or as a label.

    Mayuki Kajiura, Takuya Nakanishi, Hironori Iida, Harumi Takada, Tetsuya Osaka

    Journal of colloid and interface science   335 ( 1 ) 140 - 5  2009年07月  [査読有り]  [国際誌]

     概要を見る

    The application of localized surface plasmon resonance (LSPR) of gold nanoparticles for the detection of biotin-streptavidin binding, as a typical biological reaction, was investigated by using optical waveguide spectroscopy, and two different modes for the use of gold nanoparticles, one as a probe and the other as a label were compared with each other. The combination with optical waveguide spectroscopy was found to bring about a high sensitivity for the biomolecular detection system using LSPR of gold nanoparticles in both modes. In particular, the mode using gold nanoparticles as a label was demonstrated to be of advantage to devising proper procedures for using nanoparticles and evaluating actual response relevant to the phenomenon concerned, and thus to sensitive detection.

    DOI PubMed

  • Ionic conductivity improvement in primary pores of fuel cell catalyst layers: Electropolymerization of m-aminobenzenesulfonic acid and its effect on the performance

    Satoshi Tominaka, Kazuya Goto, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   192 ( 2 ) 316 - 323  2009年07月  [査読有り]

     概要を見る

    Catalyst layers of direct methanol fuel cells (DMFCs) are modified by in situ electropolymerization of m-aminobenzenesulfonic acid. By using electrochemical impedance spectroscopy and porosimetry, this modification is found to add polymer electrolyte into primary pores (<10 nm), where ionic resistance is high for lack of polymer electrolyte (i.e., Nafion), and the additional electrolyte successfully decreases the ionic resistance by 10-15% compared to the plain carbon surface with a slight ion-conductivity (>40 k Omega cm). In view of methanol oxidation characteristics, this modification decreases the resistance by ca. 25% (from 5.1 Omega cm(2) to 3.7 Omega cm(2)) at 0.6V vs. DHE, resulting in the increase in the cell voltage of DMFC test by ca. 20 mV. The clear relation between the performance and the microstructures is concluded to be helpful to understand the performance of fuel cell electrodes in detail. (C) 2009 Elsevier B.V. All rights reserved.

    DOI

  • Sonochemical Synthesis of Non-platinum Nanoparticles and Their Electrocatalytic Activity for Oxygen Reduction

    Toshiyuki Momma, Jong-Eun Park, Jandee Kim, Yohtaro Yamazaki, Tetsuya Osaka

    ELECTROCHEMISTRY   77 ( 6 ) 465 - 467  2009年06月  [査読有り]

     概要を見る

    Non-platinum nanoparticles (Pd, Au, PdAu) have been prepared by sonochemical synthesis. The nanoparticle-modified electrodes showed improved catalytic activity for oxygen reduction compared with Pt nanoparticles in alkaline solution even in the presence of methanol.

    DOI

  • Fabrication of free-standing albumin-nanosheets having heterosurfaces.

    Yosuke Okamura, Takahiro Goto, Daisuke Niwa, Yoshihito Fukui, Masanobu Otsuka, Norikazu Motohashi, Tetsuya Osaka, Shinji Takeoka

    Journal of biomedical materials research. Part A   89 ( 1 ) 233 - 41  2009年04月  [査読有り]  [国際誌]

     概要を見る

    Sheet-shaped carriers, having both obverse and reverse surfaces and thus a large contact area for targeting a site, have several advantages over spherical-shaped carriers, which have an extremely small contact area for targeting sites. Here, we proposed a novel method to prepare a free-standing ultrathin and biocompatible nanosheet having heterosurfaces, by a combination of four processes: (1) specific adsorption of recombinant human serum albumin (rHSA) molecules onto a patterned octadecyltrimethoxysilane self-assembled monolayer region (ODS-SAM), (2) preparation of nanosheets of rHSA molecules bearing thiol groups (SH-rHSA) via two-dimensionally disulfide crosslinking, (3) surface modification of the resulting nanosheet, and (4) preparation of the free-standing nanosheet by detachment from the ODS-SAM. The SH-rHSA molecules at pH 5.0 and a concentration of 1 microg/mL were specifically adsorbed on the patterned ODS-SAM regions by hydrophobic interaction, and were two-dimensionally crosslinked in the presence of copper ion as an oxidant. The rHSA-nanosheets were then simply detached from the ODS-SAM by treatment with surfactant. We succeeded in the preparation of rectangular (10 microm x 30 microm) and ultrathin (4.5 +/- 1.0 nm) rHSA-nanosheets on a patterned ODS-SAM, and could also obtain free-standing rHSA-nanosheets having heterosurfaces by surface modification with fluorescent latex beads. Thus, the rHSA-nanosheets having heterosurfaces could be regarded as a new biomaterial for drug carriers, hemostatic reagents, wound dressing for burn injury, and so forth.

    DOI PubMed

  • Synthesis of carbon-supported Pd-Sn catalyst by ultrasonic irradiation for oxygen reduction reaction

    Jandee Kim, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   189 ( 2 ) 909 - 915  2009年04月  [査読有り]

     概要を見る

    Carbon-supported Pd-Sn (Pd-Sn/C) catalyst was prepared under ultrasonic irradiation, and its electrocatalytic activity for oxygen reduction reaction (ORR) was evaluated in 0.5M KOH. TEM images showed that the prepared Pd-Sn/C catalyst particles are smaller in average size than carbon-supported Pd (Pd/C) catalyst particles. XRD and XPS results indicated the small particle size and the electronic interaction between Pd and Sn for the Pd-Sn/C catalyst. The Pd-Sn/C catalyst has a higher ORR activity than the Pd/C catalyst in alkaline media. In addition, the Pd-Sn/C catalyst showed a lower Tafel slope and a larger number of electrons transferred for ORR, compared with those of the Pd/C catalyst. These results indicate that Sn influences both the kinetics and the mechanism of ORR. Based on these results, the Pd-Sn/C catalyst prepared by using ultrasonic irradiation can be expected as a promising ORR catalyst in alkaline media. (C) 2009 Elsevier B.V. All rights reserved.

    DOI

  • Cell performance of Pd-Sn catalyst in passive direct methanol alkaline fuel cell using anion exchange membrane

    Jandee Kim, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   189 ( 2 ) 999 - 1002  2009年04月  [査読有り]

     概要を見る

    Direct methanol alkaline fuel cell (DMAFC) using anion exchange membrane (AEM) was operated in passive condition. Cell with AEM exhibits a higher open circuit voltage (OCV) and superior cell performance than those in cell using Nafion. From the concentration dependences of methanol, KOH in fuel and ionomer in anode catalyst layer, it is found that the key factors are to improve the ionic conductivity at the anode and to form a favorable ion conductive path in catalyst layer in order to enhance the cell performance. In addition, by using home-made Pd-Sn/C catalyst as a cathode catalyst on DMAFC, the membrane electrode assembly (MEA) using Pd-Sn/C catalyst as cathode exhibits the higher performance than the usual commercially available Pt/C catalyst in high methanol concentration. Therefore, the Pd-Sn/C catalyst with high tolerance for methanol is expected as the promising oxygen reduction reaction (ORR) catalyst in DMAFC. (C) 2009 Elsevier B.V. All rights reserved.

    DOI

  • Synthesis of Pd-Sn nanoparticles by ultrasonic irradiation and their electrocatalytic activity for oxygen reduction

    Jandee Kim, Jong-Eun Park, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   54 ( 12 ) 3412 - 3418  2009年04月  [査読有り]

     概要を見る

    Nanoparticles of Pd-Sn were prepared under various conditions by applying ultrasonic irradiation, and their electrocatalytic activity for oxygen reduction was evaluated in 0.5 M KOH. The average size of Pd-Sn nanoparticles thus prepared was about 3-5 nm. The Pd in Pd-Sn nanoparticles was found to be mostly in the metallic state. The electrocatalytic activity of the Pd-Sn nanoparticles for the oxygen reduction reaction (ORR) is greater than Pt or Pd nanoparticles in alkaline media. The molar ratio of Pd to Sn metal ions in the synthesizing solution, their initial concentrations, the concentration of ethanol, which increases primary hydrogen radicals during sonolysis, and the concentration of citric acid were found to affect the size distribution of the Pd-Sn nanoparticles, and therefore, those factors controlled the electrocatalytic activity for ORR. Particularly, the concentration of citric acid was found to be important for controlling the surface property on Pd-Sn particles to adjust the electrocatalytic activity for ORR. (C) 2009 Elsevier Ltd. All rights reserved.

    DOI

  • Tb3+-enhanced Potentiometric Detection of Single Nucleotide Polymorphism by Field Effect Transistors

    Jinping Wang, Kenya Ito, Takuya Nakanishi, Shigeki Kuroiwa, Tetsuya Osaka

    CHEMISTRY LETTERS   38 ( 4 ) 376 - 377  2009年04月  [査読有り]

     概要を見る

    The use of Tb3+ as a center ion and media to introduce more exogenously negative charges onto double-stranded DNA (dsDNA), can greatly enhance potentiometric signals produced by the shift of gate voltage of field effect transisitor (FET). Furthermore, different affinities of Tb3+ to normal and mismatched dsDNAs amplified the signal difference between their detections, which can improve the discrimination of single nucleotide polymorphism.

    DOI

  • 磁性ナノ粒子とRaman散乱分光法を使った抗原抗体反応の定量検出

    秀島翔, 柳沢雅広, 新垣篤史, 松永是, 逢坂哲彌

    表面科学学術講演会講演要旨集   29th   142 - 146  2009年

    DOI J-GLOBAL

  • 大型研究プロジェクトASMeW構築と電気化学ナノテクノロジーの展開

    T. Osaka

    早稲田大学応用化学会会報   79   9 - 14  2009年

  • 早稲田大学先進理工学研究科応用化学専攻/ナノ理工学専攻応用物理化学研究室

    T. Osaka

    表面技術   60   398 - 401  2009年

  • Effect of Carbon Content on the Electrical Resistivity of Electrodeposited Copper

    Tetsuya Osaka, Noriyuki Yamachika, Masahiro Yoshino, Madoka Hasegawa, Yoshinori Negishi, Yutaka Okinaka

    ELECTROCHEMICAL AND SOLID STATE LETTERS   12 ( 3 ) D15 - D17  2009年  [査読有り]

     概要を見る

    Copper films electrodeposited from acid sulfate baths containing conventional additives used in the damascene process for the fabrication of ultralarge-scale integration interconnects were analyzed quantitatively to investigate the relation between carbon content and electrical resistivity of the deposit. In the as-deposited state, the resistivity of deposits that did not exhibit self-annealing effects in scanning ion microscope examination increased almost linearly with carbon content in the range of 0.002-0.045 wt %. The deposits that exhibited self-annealing effects showed higher resistivity values at identical carbon contents. After self-annealing, resistivity values of all deposits varied almost linearly with carbon content. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3054273] All rights reserved.

    DOI

  • Morphology and Magnetic Properties of Iron Oxide Nanostructures Synthesized with Biogenic Polyamines

    Sangaraju Shanmugam, Takuya Nakanishi, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   156 ( 7 ) K121 - K127  2009年  [査読有り]

     概要を見る

    A facile and simple approach for the synthesis of nanosized iron oxide and oxyhydroxide using biogenic polyamines is described. At room temperature, the highly crystalline nanoparticles of magnetite (Fe3O4) with average sizes of 44 +/- 2 and 37 +/- 1 nm were synthesized with spermine and spermidine, respectively. The magnetite nanoparticles formed by the biogenic polyamines exhibited a ferrimagnetic behavior at room temperature. When the same reaction was carried out at low temperature, crystalline nanorods of lepidocrocite (gamma-FeOOH) with a high aspect ratio were formed. It was revealed that the lepidocrocite nanorods with an aspect ratio of 70 formed bundles, each of which consisted of several nanorods stacked together by the side on fashion. It was suggested that the nanorods are of single-crystalline nature and exhibit a superparamagnetic behavior at room temperature. As the reaction temperature increased from 40 to 70 degrees C, the formation of magnetite nanotetrapods, nanorods, and nanoparticles was observed depending on the reaction temperatures. Magnetic properties of products were demonstrated to depend on the morphology, the degree of crystallinity, and the presence of amorphous oxyhydroxide. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3125767] All rights reserved.

    DOI

  • Effect of electrochemically structured titanium alloys on cell morphology

    S. Roy, Qi-Bai Wu, S. Nouraei, S. Ngalim, M. Birch, A. McCaskie, H. Zhang, T. Osaka

    ECS Transactions   16 ( 38 ) 17 - 25  2009年

     概要を見る

    Ti alloys are commonly used as dental and orthopaedic implants. It has been shown that surface topography can influence cell genesis, behaviour and growth. In this work we have electropolished and micro-patterned Ti-6Al-4V alloy to study the effect of surface topography on cell morphology. Electroetching was carried out in a flat cell under galvanostatic polarisation of 5.0 V and 9.0 V vs. SCE, using a 3.0 M H2SO4 - methanol electrolyte. Electropolishing conditions were achieved when the overpotential was 9.0 V. Micropatterning of Ti alloy substrates was carried out at the same potentials by etching through mask
    a methanol stable SU-8 photoresist was used for this purpose. Human mesenchymal stem cells were seeded and grown on these substrates. It was found that surface nano and micro scale topography influenced cell numbers and morphology, respectively. ©The Electrochemical Society.

    DOI

  • Controlled synthesis and magnetic properties of iron oxide nanostructures using biogenic polyamines

    Sangaraju Shanmugam, Takuya Nakanishi, Tetsuya Osaka

    ECS Transactions   16 ( 45 ) 189 - 197  2009年

     概要を見る

    A facile and simple approach has been described for the synthesis of magnetite nanoparticles and iron oxyhydroxide nanorods using biogenic polyamines. At room temperature, highly crystalline magnetite particles with average size of 44 ± 2 and 37 ± 1 nm were synthesized with spermine and spermidine, respectively. The formation of nanoparticles was characterized with TEM, HRTEM, XPS and SQUID. The magnetite nanoparticles formed by the biogenic polyamines exhibits ferrimagnetic behavior at 300 K. When the reaction was carried out at low temperature, high aspect ratio, well crystalline nanorods were observed. X-ray diffraction and Infrared spectroscopy suggests that the nanorods correspond to lepidocrocite (γ-FeOOH). TEM analysis shows each bundle consisting of several nanorods stacked together by side on fashion. γ-FeOOH nanorods with high aspect ratio of 70 were observed. The SQUID analysis reveals that the lepidocrocite nanorods exhibit superparamagnetic behavior at room temperature. ©The Electrochemical Society.

    DOI

  • Surface Modification of Chemically Synthesized FePt nanoparticles

    T. Hachisu, T. Yotsumoto, A. Sugiyama, T. Osaka

    ECS Trans.   16   199 - 206  2009年

  • On-chip direct methanol fuel cells of a monolithic design: consideration of validity of an active-type system

    Satoshi Tominaka, Hiroyuki Obata, Tetsuya Osaka

    ENERGY & ENVIRONMENTAL SCIENCE   2 ( 8 ) 845 - 848  2009年  [査読有り]

     概要を見る

    The performance of an on-chip direct methanol fuel cell of monolithic design with an active-type system was improved more than 6-fold up to > 100 mu W by using hydrogen peroxide as an oxidant solution instead of dissolved oxygen, but the energy-loss caused by strong capillary forces required a redesign of both microchannel size and the system.

    DOI

  • On-chip fuel cells for safe and high-power operation: investigation of alcohol fuel solutions

    Satoshi Tominaka, Hiroshi Nishizeko, Sousuke Ohta, Tetsuya Osaka

    ENERGY & ENVIRONMENTAL SCIENCE   2 ( 8 ) 849 - 852  2009年  [査読有り]

     概要を見る

    An on-chip fuel cell, of membraneless, air-breathing and monolithic design, was proven to operate on a different fuel (methanol, ethanol or 2-propanol) solution containing an acidic ion-conductor (sulfuric acid) or a neutral one (phosphate buffer).

    DOI

  • Future technology proposal for Damascene process using all wet electrochemical technique

    Tetsuya Osaka, Masahiro Yoshino, Yosi Shacham-Diamand

    ECS Transactions   19 ( 24 ) 67 - 73  2009年

     概要を見る

    All-wet process was developed for fabricating diffusion barrier layer and Copper wiring for ultra large scale integration (ULSI) by means of a combination technique of electroless deposition and surface modification of Pd-activated ligand-bearing organic layer. In this paper, we performed detailed analysis of the Pd-activated ligand-bearing organic layer. Moreover, we successfully deposited thin electroless NiB layer on the Pd-activated molecular layer of 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (TAS) in a small reactor at a low temperature in a few minutes. ©The Electrochemical Society.

    DOI

  • Fabrication of On-Chip Fuel Cells on Polymer Substrates

    Satoshi Tominaka, Hiroshi Nishizeko, Hidetoshi Shinohara, Jun Mizuno, Tetsuya Osaka

    PROTON EXCHANGE MEMBRANE FUEL CELLS 9   25 ( 1 ) 1961 - 1969  2009年

     概要を見る

    Here we report fabrication of tiny on-chip fuel cells on polymer films. Since on-chip cells which we have so far fabricated on silicon substrates through a series of microfabrication procedures are of a simple microchannel-based design, their fabrication on a polymer substrate by molding is attractive in terms of the rapid fabrication and of the inexpensive fabrication procedures and materials. To do so, a nickel mold was first prepared by electroplating from the conventional silicon-based cell, i.e., a master, and then the cell was replicated on cycloolefin polymer films by hot embossing. The microchannel thus replicated on the polymer film was confirmed to be almost identical to the silicon master by observation with a confocal microscope. Finally, Au current collectors sufficiently adhesive to the polymer were successfully deposited after the surface modification by an oxygen plasma treatment.

    DOI

  • 記録媒体の化学 記録材料を考える

    逢坂哲彌

    化学と教育   57 ( 1 ) 4 - 5  2009年

    J-GLOBAL

  • 電気化学ナノテクノロジーの研究展開

    逢坂哲彌

    電気化学および工業物理化学   77 ( 1 ) 90 - 94  2009年

    J-GLOBAL

  • Effect of Surface Morphology of Reference Field Effect Transistor Modified by Octadecyltrimethoxysilane on Ionic Responses

    Shigeki Kuroiwa, Jinping Wang, Daisuke Satake, Satoshi Nomura, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   156 ( 4 ) J67 - J72  2009年  [査読有り]

     概要を見る

    For completion of on-chip field effect transistor (FET) biosensors, it is essential to produce a reference FET instead of a reference electrode that uses an inner electrolyte. In this study, a light-addressable potentiometric sensor (LAPS) modified by a self-assembled monolayer (SAM) of octadecylsilane (ODS) was pH-insensitive (-1.5 mV/pH), but it was sensitive to ionic strength as was reported in polymer-gate FETs. Our purpose was to make clear the problems of the evaluation methods of ODS-SAM FETs concerning pH and ionic responses and the effect of the surface morphology to improve a reference SAM-FET. An ODS-SAM LAPS and FET were deposited under different conditions. pH and ionic responses, roughness measured by atomic force microscope, and contact angle (CA) were greatly changed by the difference in morphology of the ODS-SAM. ODS coagulation raised the CA. It is difficult to distinguish the ODS-SAM with and without ODS coagulation only by CA, but CA is utilizable for observing the state of hydroxyl groups on the surface without ODS coagulation. ODS coagulation caused the pH response with the ODS-SAM but decreased the ionic response of the LAPS. Controlling the surface morphology of the ODS-SAM is important to suppress the pH and ionic sensitivities for an in vivo applicable reference FET.

    DOI

  • Bendable fuel cells: on-chip fuel cell on a flexible polymer substrate

    Satoshi Tominaka, Hiroshi Nishizeko, Jun Mizuno, Tetsuya Osaka

    ENERGY & ENVIRONMENTAL SCIENCE   2 ( 10 ) 1074 - 1077  2009年  [査読有り]

     概要を見る

    A novel concept of fuel cells, i.e., bendable fuel cells, is proposed and demonstrated by the fabrication of on-chip fuel cells on cycloolefin polymer films. This approach overcomes the brittleness and cost problems, i.e., a troubling aspect of miniaturized devices, of on-chip fuel cells.

    DOI

  • Fabrication of Electroless CoWP/NiB Diffusion Barrier Layer on SiO2 for ULSI Devices

    Tetsuya Osaka, Hitoshi Aramaki, Masahiro Yoshino, Kazuyoshi Ueno, Itsuaki Matsuda, Yosi Shacham-Diamand

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   156 ( 9 ) H707 - H710  2009年  [査読有り]

     概要を見る

    We investigated the electroless CoWP/NiB diffusion barrier layer for ultralarge-scale integration (ULSI) interconnection by forming the immobilizing Pd catalyst on an organosilane layer. When the electroless CoWP film was formed directly on a Pd-activated organosilane layer, it became islandlike and did not form a continuous layer. When it was formed on an electroless NiB deposited on a Pd-activated organosilane layer, the electroless CoWP film was uniform and formed a continuous layer 10 nm thick. The transmission electron microscopy images of the interfaces of Cu/CoWP/NiB/SiO2 showed that, at an annealing temperature up to 400 degrees C for 30 min, the interfaces remained unchanged and clear, showing no trace of Cu diffusion into the SiO2 substrate. In-plane X-ray diffraction patterns indicated that the CoWP/NiB film had an amorphous structure and was stable against heat-treatment up to 500 degrees C for 30 min. An evaluation of sheet resistance measurements suggested that the CoWP/NiB film shows appropriate barrier properties for Cu diffusion up to 400 degrees C. The CoWP/NiB film was used as a seed for electroless Cu plating. Trenches 100 nm wide were coated with a 10 nm CoWP/NiB barrier followed by successful trench filling by electroless Cu plating.

    DOI

  • Effect of Organosilane Underlayers on the Effectiveness of NiB Barrier Layers in ULSI Metallization

    Masahiro Yoshino, Hitoshi Aramaki, Itsuaki Matsuda, Yutaka Okinaka, Tetsuya Osaka

    ELECTROCHEMICAL AND SOLID STATE LETTERS   12 ( 4 ) D19 - D21  2009年  [査読有り]

     概要を見る

    A process was developed for producing a barrier layer of NiB by means of electroless deposition on an underlayer of Pd-activated organosilane monolayer formed on the insulator. An attempt was made to decrease the thickness of the NiB layer without adversely affecting its barrier property to make it compatible with further miniaturized ultralarge-scale integration (ULSI) devices of the future. This aim was achieved by using 3-[2-(2-aminoethylamino)ethylamino]propyltrimethoxysilane (TAS) as the underlayer between the NiB layer and the substrate. By using TAS instead of 3-aminopropyltriethoxysilane (APTES) which was used in our previous study, the minimum acceptable thickness of the NiB barrier layer was successfully reduced to 6 nm. The copper deposit formed on the barrier layer in trenches was free of defects, and it was stable even after annealing at 400 degrees C for 30 min.

    DOI

  • Preparation of human immune effector T cells containing iron-oxide nanoparticles.

    Hironori Iida, Kosuke Takayanagi, Takuya Nakanishi, Akiko Kume, Kouji Muramatsu, Yoshio Kiyohara, Yasuto Akiyama, Tetsuya Osaka

    Biotechnology and bioengineering   101 ( 6 ) 1123 - 8  2008年12月  [査読有り]  [国際誌]

     概要を見る

    Preparation of human immune T cells containing iron-oxide nanoparticles was carried out for the development of magnetically mediated immunotherapy. Peripheral blood lymphocytes (PBLs) after the incubation with magnetite nanoparticles were found to contain measurable ferric ions, which suggested the incorporation of magnetite nanoparticles. Transmission electron microscopic (TEM) study indicated that the incorporation of magnetite nanoparticles was mediated by endocytosis of PBLs. Furthermore, the effects of dosages and diameter of magnetite nanoparticles on the magnetite incorporation were investigated, and it was demonstrated that the increase in dosage promoted the incorporation of nanoparticles and the uptake into PBLs was more effective for magnetite nanoparticles, which formed smaller aggregations in medium. Finally, the demonstration of magnetite incorporation into enriched T cells and tumor antigen-specific cytotoxic T lymphocyte (CTL) line promises the achievement of magnetically mediated immunotherapy with tumor-specific CTLs containing magnetic nanoparticles.

    DOI PubMed

  • Sulfated zirconia nanoparticles as a proton conductor for fuel cell electrodes

    Satoshi Tominaka, Naohisa Akiyama, Fausto Croce, Toshiyuki Momma, Bruno Scrosati, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   185 ( 2 ) 656 - 663  2008年12月  [査読有り]

     概要を見る

    Sulfated zirconia nanoparticles are evaluated as a possible alternative for a solid proton conductor in a fuel-cell catalyst layer. Two methods are applied for the synthesis of the nanoparticles, i.e.: (i) a conventional method treating ZrO2 particles in sulfuric acid, and (ii) a solvent-free method directly synthesizing sulfated zirconia nanoparticles through the thermal decomposition of a mixture of ZrOCl2 and (NH4)(2)SO4. The nanoparticles synthesized by the solvent-free method have a size of 5-10 nm and an amorphous structure, and moreover their properties are promising in view of the application. In particular, the proton conductivity of the nanoparticles is high enough, i.e. of the 10(-2) S cm(-1) order, to be comparable to that of Nafion. Even though they possibly reduce the activity of Pt catalyst, layers containing sulfated zirconia as a proton conductor prove to be active as catalyst in fuel cell prototypes. Compared with conventional, Nafion-based cells, the maximum power density of the cells using sulfated zirconia is about one third. We believe that improvement in the preparation procedures for catalyst layers and membrane electrode assemblies will improve the cell performance. Therefore sulfated zirconia can be a valid proton conductor for fuel cell application. (C) 2008 Elsevier B.V. All rights reserved.

    DOI

  • Enantioselective potential response of a human serum albumin-modified ITO electrode for tryptophan

    Mariko Matsunaga, Tsubasa Ueno, Takuya Nakanishi, Tetsuya Osaka

    ELECTROCHEMISTRY COMMUNICATIONS   10 ( 12 ) 1844 - 1846  2008年12月

     概要を見る

    The present study aims at extending the possibility of utilizing bulky molecules such as proteins for fabricating electrochemical chiral sensors using an indium tin oxide (ITO) electrode. Enantioselective potential response of the human serum albumin (HSA)-modified ITO electrode was observed for tryptophan (Trp) when HSA was immobilized on an ITO electrode surface modified with disuccinimidyl suberate (DSS). In this sensing system. the enantioselective interaction between HSA and Trp is detected through the chemically reactive DSS group immobilized on the ITO electrode. (C) 2008 Elsevier B.V. All rights reserved.

    DOI

  • Magnetic circular dichroism of [Co/Pd] and [CoB/Pd] multilayered films

    A. Agui, A. Asahi, J. Sayama, M. Mizumaki, M. Tanaka, T. Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   320 ( 22 ) 3015 - 3018  2008年11月  [査読有り]

     概要を見る

    Magnetic circular dichroism (MCD) and X-ray absorption spectra (XAS) at the Co L(2,3)-edge of [Co/Pd](20) and [CoB/Pd](20) multilayered films, which were fabricated at 260 degrees C with different magnetic layer thicknesses (delta), have been measured. The lineshapes of XAS-MCD show that the electronic state of Co 3d of the films hardly changes even when sputtered at higher temperatures. The expectation values of orbital and spin angular momentum (&lt; L(z)&gt; and &lt; S(z)&gt;) are estimated using the sum rule, and it is found that &lt; L(z)&gt;/&lt; S(z)&gt; in delta&lt;0.5 nm is larger than that in delta&gt;0.5 nm. (C) 2008 Elsevier B. V. All rights reserved.

    DOI

  • Improvement of magnetic properties and read/write characteristics in SmCo(5) perpendicular thin films

    Toru Asahi, Isao Koizumi, Yuta Kikuchi, Masahiro Yoshino, Atsushi Sugiyama, Jiro Hokkyo, Tetsuya Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   320 ( 22 ) 3075 - 3078  2008年11月  [査読有り]

     概要を見る

    An SmCo(5) alloy is a promising candidate for ultra-high density magnetic recording media because of its strong uniaxial magnetocrystalline anisotropy, whose constant, K(u), is more than 1.1 x 10(8) erg/cm(3). Recently, we successfully obtained high perpendicular magnetic anisotropy for a sputter-deposited SmCo(5) thin film by introducing a Cu/Ti dual underlayer. However, it is necessary to improve magnetic properties and read/write (R/W) characteristics for applying SmCo(5) thin films to perpendicular magnetic recording media. In this study, we focused on reduction of magnetic domain size and change of a magnetization reversal process of SmCo(5) perpendicular magnetic thin. films by introducing carbon (C) atoms into the constituent Cu underlayer. The magnetic domain size became small and the ratio of coercivity (H(c)) against magnetic anisotropy (H(k)) which is an index of the magnetization reversal process was increased by adding C atoms. We also evaluated the R/W characteristics of SmCo(5) double-layered media including C atoms. The medium noise was decreased and signal-to-noise ratio increased by introducing the C. The addition of C into the Cu underlayer is effective for changing the magnetization reversal process, reducing medium noise and increasing SNR. (C) 2008 Published by Elsevier B. V.

    DOI

  • Preparation of FePt Nanoparticles with a Narrow Size Distribution in Ionic Liquids

    Tetsuya Osaka, Takuma Hachisu, Atsushi Sugiyama, Izumi Kawakita, Takuya Nakanishi, Hironori Iida

    CHEMISTRY LETTERS   37 ( 10 ) 1034 - 1035  2008年10月

     概要を見る

    Nanoparticles of FePt were prepared in two different ionic liquids (ILs). Because IL serves not only as a solvent but also as a surfactant, the particles prepared could be dispersed stably in hexane without adding other surfactants. The size distribution of the particles was found to be narrow without depending oil a size-selection process such as centrifugation. In addition, the particle sizes and composition were found to depend on the kind of IL employed.

    DOI

  • 日本磁気学会の財務状況について : 学会のさらなる発展のために

    逢坂 哲彌, 鈴木 義茂, 吉沢 克仁

    まぐね = Magnetics Japan   3 ( 9 ) 397 - 401  2008年09月

    CiNii

  • Stereospecificity in redox reactions of catechins at gold electrodes modified with self-assembled monolayers of homocysteine

    Takuya Nakanishi, Mariko Matsunaga, Makoto Nagasaka, Tsubasa Ueno, Tetsuya Osaka

    ELECTROCHIMICA ACTA   53 ( 21 ) 6209 - 6214  2008年09月  [査読有り]

     概要を見る

    The stereospecificity of a self-assembled monolayer (SAM) of homocysteine formed on the (111)-oriented gold surface toward the molecules with two chiral centers was investigated. Redox behaviors of catechins, which are electrochemically active molecules with two chiral centers, were analyzed with cyclic voltammetry by using a gold electrode modified with one enantiomeric form of homocysteine. The homocysteine SAM of one enantiomeric form was demonstrated to block the redox reaction of one enantiomer of catechin or epicatechin greater than that of the other, with cross inversion for the other enantiomer, in acidic solution. In addition, the homocysteine SAM on the gold electrode was suggested to recognize the chirality of one of the two chiral centers in catechin and epicatechin. (C) 2008 Elsevier Ltd. All rights reserved.

    DOI

  • On-Chip Fuel Cell: Micro Direct Methanol Fuel Cell of an Air-breathing,Membraneless,and Monolithic Design

    S. Tominaka, S. Ohta, H. Obata, T. Momma, T. Osaka

    J. Am. Chem. Soc. (Highlighted in NPG Asia Materials)   130 ( 32 ) 10456 - 7  2008年08月  [査読有り]  [国際誌]

    DOI PubMed

  • Effect of growth temperature on the shape and crystallinity of chemically produced FePt nanoparticles

    Takuma Hachisu, Takahiro Yotsumoto, Atsushi Sugiyama, Hironori Iida, Takuya Nakanishi, Toru Asahi, Tetsuya Osaka

    CHEMISTRY LETTERS   37 ( 8 ) 840 - 841  2008年08月

     概要を見る

    The process of preparation of FePt nanoparticles was investigated with emphasis on the effect of "growth temperature," at which the atomic diffusion between Pt-rich and Fe-rich phases leads to the formation of uniform nanoparticles. Consequently, it was demonstrated that by controlling, the growth temperature, the shape and crystallinity of FePt nanoparticles can be controlled. Oil the other hand, the size and composition were almost invariable at 5.6 +/- 0.5 nm and Fe53Pt47. respectively.

    DOI

  • Perpendicular mesoporous Pt thin films: electrodeposition from titania nanopillars and their electrochemical properties.

    Satoshi Tominaka, Chia-Wen Wu, Toshiyuki Momma, Kazuyuki Kuroda, Tetsuya Osaka

    Chemical communications (Cambridge, England)   25 ( 25 ) 2888 - 90  2008年07月  [国際誌]

     概要を見る

    A perpendicular mesoporous platinum electrode with a flat surface is successfully synthesized by electrodeposition using titania nanopillars as template, and the electrochemical studies indicate that this material is a promising catalytic electrode for fuel cells because of its high surface area and perpendicular nanopores.

    DOI PubMed

  • Electrodeposition of amorphous Au-Ni alloy film

    Noriyuki Yamachika, Yuta Musha, Junji Sasano, Kazutaka Senda, Masaru Kato, Yutaka Okinaka, Tetsuya Osaka

    ELECTROCHIMICA ACTA   53 ( 13 ) 4520 - 4527  2008年05月

     概要を見る

    It was found that, by choosing an optimum bath composition, amorphous Au-Ni alloy containing up to 40 at.% of Au with respect to the sum of Au and Ni can be electrodeposited from a bath prepared by excluding tungsten from the Au-Ni-W bath that we developed previously. Elemental analysis showed that the deposit contains 15-20 at.% of carbon and 2 at.% of nitrogen. Hardness of this deposit is almost three times as high as that of the conventional hard gold. The electrical contact resistance measured against a pure gold wire is comparable to that of the hard gold. The amorphous structure of the Au-Ni deposit is stable at temperatures up to 300 degrees C for at least 1 h. The amorphous tungsten-free Au-Ni deposit is worthy of consideration for applications in the fabrication of micro- and nano-scale electrical contacts. (c) 2008 Elsevier Ltd. All rights reserved.

    DOI

  • Electrodeposited Pd-Co catalyst for direct methanol fuel cell electrodes: Preparation and characterization

    Satoshi Tominaka, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   53 ( 14 ) 4679 - 4686  2008年05月

     概要を見る

    Pd-Co alloy has been recently proposed as a catalyst for the cathode of direct methanol fuel cells with both excellent oxygen reduction activity and methanol tolerance, hence electrodeposition of this alloy is an attractive approach for synthesizing porous metal electrodes with high methanol tolerance in direct methanol fuel cells. In this Study, we electrodeposited two types of Pd-Co films onto Au substrates by applying different Current density (-10 or -200 mA cm(-2)); and then characterized them in terms of morphology, composition, crystal structure, and catalytic activity. Pd-Co deposited at -10 mA cm(-2) was smooth and possessed smaller particles (ca. 10 nm), while that at -200 mA cm-2 was dendritic (or rough) and possessed larger particles (ca. 50 nm). Both the Pd-Co alloys were found to be almost the same Structure, i.e. a solid solution of ca. Pd7Co3 With Pd-skin, and also confirmed to possess comparable activity in oxygoen reduction to Pt (potential difference at 1.0 mu A cm(-2) was 0.05 V). As for methanol tolerance, cell-voltage was not influenced by addition of I mol dm(-3) methanol to the oxidant solution. Our approach provides fundamental technique for synthesizing Pd-Co porous metal electrodes by electrodeposition. (C) 2008 Elsevier Ltd. All rights reserved.

    DOI

  • Effect of pH on the Enantiospecificity of Homocysteine Monolayer on Au (111) for the Redox Reaction of 3,4-Dihydroxyphenylalanine

    M. Matsunaga, M. Nagasaka, T. Nakanishi, T. Sawaguchi, T. Osaka

    Electroanal.   20 ( 9 ) 955 - 962  2008年05月  [査読有り]

    DOI

  • Feasibility of an interpenetrated polymer network system made of di-block copolymer composed of polyethylene oxide and polystyrene as the gel electrolyte for lithium secondary batteries

    Hiroki Nara, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHEMISTRY   76 ( 4 ) 276 - 281  2008年04月

     概要を見る

    The feasibility of a di-block copolymer, composed of a polyethylene oxide (PEO) chain and a polystyrene (PS) chain covalently bonded, as the gel electrolyte for lithium secondary batteries was investigated. The PEO-PS di-block copolymer gel electrolyte showed a high ionic conductivity of similar to 1 mS/cm at room temperature. Moreover, it retained good mechanical strength within a co-continuous phase separated structure, and it suppressed the dendritic deposition of Li. Indications were that the interface between the electrolyte and the Li metal was chemically stable, as a result of the PEO phase fixed to PS by covalent bonding. In addition, it was indicated that the Li/PEOPS di-block copolymer gel electrolyte/LiFePO4 cell had a high charge-discharge efficiency of similar to 99% during 30 cycles, while maintaining a discharge capacity of 124 mAh/g.

    DOI

  • Fabrication of free-standing nanoparticle-fused nanosheets and their hetero-modification using sacrificial film

    Yosuke Okamura, Saori Utsunomiya, Hidenori Suzuki, Daisuke Niwa, Tetsuya Osaka, Shinji Takeoka

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   318 ( 1-3 ) 184 - 190  2008年04月

     概要を見る

    Sheet-shaped carriers, having obverse and reverse surfaces and thus a large contact area as a targeting site, have several advantages over spherical-shaped carriers, which have an extremely small contact area. Herein is proposed a novel method for the preparation of free-standing nanoparticle-fused nanosheets having uniform micrometer shape, nanometer thickness and heterogenous surfaces, using a water-soluble sacrificial film. This was achieved by combination of four processes: (1) specific adsorption of latex beads at pH 5.0 and a concentration of 1.0 x 10(11) mL(-1) onto a patterned dodecyltrimethoxysilane self-assembled monolayer (DTS-SAM) region by a conventional dry patterning process, (2) fabrication of the latex bead-sheet via thermal-fusion at 110 degrees C for 60s, (3) preparation of the free-standing nanosheet by detachment from the DTS-SAM, and (4) hetero-modification of the resulting nanosheet using a water-soluble poly(acrylic acid) as a sacrificial supporting film. Thus, this sheet-shaped carrier having hetero-surfaces can be regarded as a new material for delivery of drugs, hemostatic reagents and as wound dressings for bum injury, etc. (C) 2007 Elsevier B.V. All rights reserved.

    DOI

  • Numerical simulation of DMFC-capacitor hybrid power supply system for small electronic devices

    Toshiyuki Momma, Hiroki Nara, Tetsuya Osaka

    ELECTROCHEMISTRY   76 ( 4 ) 270 - 275  2008年04月

     概要を見る

    A simple numerical simulation of current flowing through electronic devices was examined for a hybrid power supply system composed of a DMFC and a capacitor connected in parallel. The simulation was investigated by representing a combination of ohmic resistance, charge transfer reaction resistance, mass transfer resistance and double layer capacitance of a DMFC as a simple ideal resistor, based on measured data when DMFC was generating electricity. The simulation result was found to agree with experimental measured current flowing through the DMFC and the capacitor, although a slight disagreement was observed because of the presence of ohmic resistance between circuit components. The simulation of DMFC-capacitor hybrid power supply system indicated the importance of the inner resistance of the capacitor. The hybrid simulation was also applied to a system assumed to consist of mu DMFC and micro electrochemical capacitor (MECC) system. The effect of applying a DC-DC converter to the system was indicated. The simulation allows to predict the degree of improvement required without performing actual fabrication of mu DMFC and MECC.

    DOI

  • A wet process for forming an adhesive copper layer on polyimide film

    Tetsuya Osaka, Satoshi Wakatsuki, Toyoto Masuda, Masahiro Yoshino, Noriyuki Yamachika, Junji Sasano, Itsuaki Matsuda, Yutaka Okinaka

    ELECTROCHEMISTRY   76 ( 3 ) 191 - 196  2008年03月  [査読有り]

     概要を見る

    A wet process for forming an adhesive Cu layer on polyimide (PI) film was developed. In this process, the surface of the PI film is pretreated in plasma, followed by the formation of a ligand-bearing organic layer of 3-aminopropyl-triethoxy silane (APTES) molecules. After catalyzation with a solution containing Pd ions, thin layers of NiB as the underlayer and that of Cu as the conductive layer are deposited by electroless depositions, and then a 10 pm thick Cu layer is electrodeposited. The peel strength of the specimen prepared by this method was found to depend on the morphology of the NiB underlayer. A continuous NiB layer functions as a barrier layer that prevents Cu from contacting the PI film. In the presence of this efficient barrier layer, the peel strength was found to improve after annealing at 150 degrees C.

    DOI

  • Existence and origin of compensation layer thickness in Tb20Co80/Pd multilayered films

    Masahito Tanaka, Toru Asahi, Akane Agui, Masaichiro Mizumaki, Junichi Sayama, Tetsuya Osaka

    JOURNAL OF PHYSICS D-APPLIED PHYSICS   41 ( 5 ) 55003  2008年03月  [査読有り]

     概要を見る

    Magnetic properties of [ Tb20Co80/Pd(0.8 nm)](20) multilayered films with a TbCo layer of thickness 0.2-8.0 nm were studied using spectroscopic techniques of soft x-ray absorption (XAS) and magnetic circular dichroism ( MCD) at the Co L-2,L-3 and Tb M-4,M-5 edges. The compensation layer thickness of TbCo, where magnetization becomes zero, was observed to be 5-6 nm. XAS and MCD analyses using the sum rule revealed that the existence of the compensation layer thickness was primarily because the projected Tb 4f magnetic moment was enhanced with the increase in the layer thickness, while the Co 3d moment was independent of the layer thickness. Below the compensation layer thickness, Co sublattice magnetization was dominant.

    DOI

  • Cycle and rate properties of mesoporous tin anode for lithium ion secondary batteries

    Hiroki Nara, Yoshiki Fukuhara, Azusa Takai, Masaki Komatsu, Hitomi Mukaibo, Yusuke Yamauchi, Toshiyuki Momma, Kazuyuki Kuroda, Tetsuya Osaka

    CHEMISTRY LETTERS   37 ( 2 ) 142 - 143  2008年02月

     概要を見る

    A mesoporous Sn anode was electrodeposited in the presence of lyotropic liquid crystals made of nonionic surfactants. The introduction of mesoporous structure was effective for the accommodation of volume change of Sn during charge and discharge cycling of Li ions. The discharge capacity of the mesoporous Sn anode at 1 C rate was as high as 425 mA h g(-1) at the 100th cycle, and that was as high as 320 mA It g(-1) at the 100th cycle even though at 5 degrees C rate.

    DOI

  • Immobilization of gold nanoparticles on optical waveguides with organosilane monolayer

    Takuya Nakanishi, Harumi Takada, Hironori Iida, Mayuki Kajiura, Tetsuya Osaka

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   313   234 - 238  2008年02月  [査読有り]

     概要を見る

    Synthesis of An nanoparticles (NPs) and their immobilization on optical waveguide (OWG) made of quartz plate were carried out aiming at application to sensing. Au NPs with diameters of similar to 5 nm and similar to 20 nm were synthesized by reduction of tetrachloroaurate ions with borohydride and immobilized on quartz OWG coated with monolayer of organosilane. With the OWG spectroscopy, the surface plasmon absorption of the An NPs immobilized on OWG was suggested to be influenced by the particle size and the interparticle distance and to response to the refractive index of nanoparticle proximity sensitively. (C) 2007 Elsevier B.V. All rights reserved.

    DOI

  • エレクトロニクス実装学会の発展に向けて

    逢坂哲彌

    エレクトロニクス実装学会誌   11   475 - 476  2008年

  • SmCo5垂直磁気記録媒体の開発

    小泉公, 朝日透, 朝日透, 吉野正洋, 杉山敦史, 法橋滋郎, 逢坂哲彌, 逢坂哲彌

    電子情報通信学会技術研究報告   108 ( 313(MR2008 30-37) ) 43 - 48  2008年

    J-GLOBAL

  • Mechanical analysis and in situ structural and morphological evaluation of Ni-Sn alloy anodes for Li ion batteries

    J. Chen, S. J. Bull, S. Roy, H. Mukaibo, H. Nara, T. Momma, T. Osaka, Y. Shacham-Diamand

    JOURNAL OF PHYSICS D-APPLIED PHYSICS   41 ( 2 ) 25302  2008年01月

     概要を見る

    In lithium ion batteries, it has previously been shown that Ni-Sn thin film anodes containing 62 at.% Sn show outstanding electrochemical characteristics, e. g. good capacity and endurance, during charge-discharge cycling. However, their mechanical response, which is likely related to their lifetime in service, has so far received relatively little attention. To address this, nanoindentation and nanowear techniques have been used to characterize the mechanical properties of thin Ni-Sn films electrodeposited on a copper substrate. In situ morphology analysis together with in situ stress measurement has been performed to assess the properties of Ni-Sn thin film anodes during electrochemical cycling. The change in mechanical properties, residual stress and fracture behaviour of the anodes is related to the phase changes which occur during charge-discharge cycling. The correlation between the mechanical properties of the films and their charge-discharge characteristics serves as a useful indicator for optimized design of a Sn-based intermetallic anode film for lithium ion secondary batteries.

    DOI

  • Synthesis of Pd-Sn nanoparticles by using ultrasonic irradiation and their electrocatalytic activity for oxygen reduction

    J. Kim, J. Park, T. Momma, T. Osaka

    ECS Transactions   11 ( 31 ) 51 - 60  2008年

     概要を見る

    Nanoparticles of Pd-Sn were prepared under various conditions by applying ultrasonic irradiation. The Pd-Sn nanoparticles thus prepared were about 3-5 nm in diameter. The Pd in Pd-Sn nanoparticles was found to be mostly in the metallic state. The PdSn nanoparticles have a better oxygen reduction reaction (ORR) activity than Pt and Pd nanoparticles in alkaline media. The mole ratio of Pd to Sn metal ions, their initial concentrations, the amount of ethanol, which served as the reducing agent for metal ions, and the amount of citric acid in the synthesizing solution were found to affect the size and distribution of obtained Pd-Sn nanoparticles. Therefore, the electrocatalytic activity for oxygen reduction was controlled by the above factors. Particularly, the amount of citric acid is important to control the surface modification on Pd-Sn particles to adjust the electrocatalytic activity for oxygen reduction. ©The Electrochemical Society.

    DOI

  • Effects of dendrimer-functionalized multi-walled carbon nanotubes on murine embryonic stem cells

    D. Cui, H. Zhang, Z. Wang, A. Toru, O. Tetsuya

    ECS Transactions   13 ( 14 ) 111 - 116  2008年

     概要を見る

    Herein we firstly reported the effects of generation 5 polyamidoamine dendrimerfunctionalized fluorescent multi-walled carbon nanotubes(dMNTs) on mice embryonic stem cell line CCE. The dMNTs were prepared and characterized, and incubated with murine ES CCE cells for 1 to 5day. These ES cells were observed by fluorescent microscopy, and were analyzed by flow cytometer and MTT. Results showed that the dendrimer-functionalized fluorescent multi-walled carbon nanotubes were successfully synthesized, could enter into ES cells quickly, more than 20μg/ml dose caused ES cells become smaller and smaller as the incubation time increased, and inhibited cell growth in dose- and time-dependent means, less than 5 μg/ml dose improves ES differentiation. These results demonstrate that dMNTs are toxic to ES cells at large dose, can induce ES cells' differentiation at small dose. The prepared dMNTs may be a highly efficient gene delivery system for ES cells, have potential applications in ES research. © The Electrochemical Society.

    DOI

  • Organic Derivatives of the Layered Perovskite HLaNb2O7・xH2O with Polyether Chains on the Interlayer Surface: Characterization, Intercalation of LiClO4, and Ionic Conductivity

    Y. Takeda, T. Momma, T. Osaka, K. Kuroda, Y. Sugahara

    J. Mater. Chem.   18 ( 30 ) 3581 - 3587  2008年  [査読有り]

    DOI

  • Organic molecular sensor with plasmon antenna

    M. Yanagisawa, N. Shimamoto, T. Nakanishi, M. Saito, T. Osaka

    ECS Transactions   16 ( 11 ) 397 - 409  2008年

     概要を見る

    An organic molecular sensor with a plasmon antenna was developed. A coaxial Ag grating antenna was designed by a finite differential time domain (FDTD) calculation and fabricated by a lift-off process. When pumping light was irradiated onto the sensor, a surface plasmon wave was generated and focused at the center of the antenna
    this wave produced a strong electric field. By coating a cystamine self-assembled monolayer (SAM) onto the sensor, strong Raman scattering light produced by a surface-enhanced Raman scattering (SERS) effect was observed at the center of the device. The Raman spectrum showed good agreement with that of cystamine on a Ag surface. The Raman intensity at the center of the device increased significantly and was more than 2,000 times that outside the device. Our optical sensor can detect an unknown single molecule and can be incorporated into other sensors such as gas sensors and biosensors. © The Electrochemical Society.

    DOI

  • Effect of surface morphology of a SiO2/Si reference electrode modified by ODMS on the responses to pH and ionic strength

    Jinping Wang, Junji Sasano, Tetsuya Osaka

    ECS Transactions   16 ( 11 ) 507 - 515  2008年

     概要を見る

    The purpose of this work was to study the effect of surface morphology on the responses to pH and ionic strength of a SiO2/Si reference electrode (RE) modified by octadecyltrimethoxysilane (ODMS). Representative REs with contact angles (CA) of 60°, 80° and 106° were studied in various solutions: those with combined effects of pH and ionic strength, those with ionic strength variation and constant pH, and those with pH variation and constant ionic strength. REs with the flat surface show response to ionic strength, while REs with the rough surface show response to pH. The reason may be that total ionic strength determines the charge and potential distribution in the electrolyte-insulator-semiconductor structure for REs with flat surfaces, but that the combined effects of uncovered binding sites, penetration of H + into pinholes, and the special adsorption of H+ dictate the charge and potential distribution for REs with rough surfaces. © The Electrochemical Society.

    DOI

  • Nanoindentation and Nanowear Study of Sn and Ni-Sn Coatings

    J. Chen, S. J. Bull, S. Roy, A. Kapoor, H. Mukaibo, H. Nara, T. Momma, T. Osaka, Y. Shacham-Diamand

    Tribol. Int.   41   25302 - 25314  2008年

  • New Trends in Nanoparticles: Syntheses and Their Applications to Fuel Cells,Health Care,and Magnetic Storage

    T. Osaka, H. Iida, S. Tominaka, T. Hachisu

    Isr. J. Chem.   48 ( 3-4 ) 333 - 347  2008年  [査読有り]

    DOI

  • 高飽和磁束密度軟磁性薄膜の開発とその波及的応用

    逢坂哲彌

    電子情報通信学会技術研究報告   108 ( 313(MR2008 30-37) ) 19 - 24  2008年

    J-GLOBAL

  • 電気化学ナノテクノロジーのバイオ・医療分野への展開(Application of Electrochemical Nanotechnology to Bio and Medical Fields)

    T. Osaka, J. Sasano, M. Matsunaga, H. Iida

    J. Surf. Finish. Soc. Jpn.   59   355 - 362  2008年

  • Synthesis of Pd-Sn nanoparticles by using ultrasonic irradiation and their electrocatalytic activity for oxygen reduction

    J. Kim, J. Park, T. Momma, T. Osaka

    ECS Transactions   11 ( 31 ) 51 - 60  2008年

     概要を見る

    Nanoparticles of Pd-Sn were prepared under various conditions by applying ultrasonic irradiation. The Pd-Sn nanoparticles thus prepared were about 3-5 nm in diameter. The Pd in Pd-Sn nanoparticles was found to be mostly in the metallic state. The PdSn nanoparticles have a better oxygen reduction reaction (ORR) activity than Pt and Pd nanoparticles in alkaline media. The mole ratio of Pd to Sn metal ions, their initial concentrations, the amount of ethanol, which served as the reducing agent for metal ions, and the amount of citric acid in the synthesizing solution were found to affect the size and distribution of obtained Pd-Sn nanoparticles. Therefore, the electrocatalytic activity for oxygen reduction was controlled by the above factors. Particularly, the amount of citric acid is important to control the surface modification on Pd-Sn particles to adjust the electrocatalytic activity for oxygen reduction. ©The Electrochemical Society.

    DOI

  • Magnetically induced orientation of mesochannels in mesoporous silica films at 30 tesla.

    Yusuke Yamauchi, Makoto Sawada, Masaki Komatsu, Atsushi Sugiyama, Tetsuya Osaka, Noriyuki Hirota, Yoshio Sakka, Kazuyuki Kuroda

    Chemistry, an Asian journal   2 ( 12 ) 1505 - 12  2007年12月  [査読有り]  [国際誌]

     概要を見る

    We demonstrate the magnetically induced orientation of mesochannels in mesoporous silica films prepared with low-molecular-weight surfactants under an extremely high magnetic field of 30 T. This process is principally applicable to any type of surfactant that has magnetic anisotropy because such a high magnetic field provides sufficient magnetic energy for smooth magnetic orientation. Hexadecyltrimethylammonium bromide (CTAB) and polyoxyethylene-10-cetyl ether (Brij 56) were used as cationic and nonionic surfactants, respectively. According to XRD and cross-sectional TEM, mesochannels aligned perpendicular to the substrates were observed in films prepared with low-molecular-weight surfactants, although the effect was incomplete. The evolution of these types of films should lead to future applications such as highly sensitive chemical sensors and selective separation.

    DOI PubMed

  • Direct deposition of nanostructured Pt particles onto a Ni foam from lyotropic liquid crystalline phase by displacement plating

    Yusuke Yamauchi, Masaki Komatsu, Azusa Takai, Ryusuke Sebata, Makoto Sawada, Toshiyuki Momma, Minekazu Fuziwara, Tetsuya Osaka, Kazuyuki Kuroda

    ELECTROCHIMICA ACTA   53 ( 2 ) 604 - 609  2007年12月  [査読有り]

     概要を見る

    Nanostructured Pt particles are directly deposited onto a Ni foam by utilizing displacement plating after a lyotropic liquid crystalline phase including Pt species was prepared within macropores of the Ni foam. The EDS mapping of Pt after deposition corresponds to the macroscopic framework of the Ni foam, indicating the uniform displacement plating of Pt on the surface of the Ni foam. The Pt particles of 150-250 nm in size are formed over the entire area of the surface of the Ni foam. The TEM images prove that the nanoscale rods (width: about 3 nm) are aggregated with each other to form nanoscale porosity. The active area of Pt can be estimated to be ca. 12 m(2)/g by using the cyclic voltammogram in sulfuric acid. Our method realizes one-step production of hierarchical macro-meso type porous electrodes. (c) 2007 Elsevier Ltd. All rights reserved.

    DOI

  • Preparation of high magnetic flux density CoNiFeB film by electroless deposition for application to magnetic recording devices

    M. Yoshino, Y. Kikuchi, A. Sugiyama, T. Osaka

    ELECTROCHIMICA ACTA   53 ( 2 ) 285 - 289  2007年12月  [査読有り]

     概要を見る

    A CoNiFeB soft magnetic thin film with high saturation magnetic flux density (B-s) for use as a magnetic recording head core material or as a soft magnetic underlayer of a double perpendicular magnetic recording medium was prepared by electroless deposition. When the CoNiFeB alloy thin film was deposited on a evaporated Cu (100 nm thick)/glass substrate, the saturated magnetic flux density was found to increase up to 2.0 T by increasing the concentration of FeSO4, The coercivity (H-c) was found to decrease to 6 Oe while the saturated magnetic flux density was maintained higher than 1.8 T by optimizing the concentrations of tartaric acid and citric acid in the electroless plating solution. An X-ray diffraction (XRD) study showed that the intensity of the assigned peak in the bee (1 1 0) of CoNiFeB film decreased as the concentration of tartaric acid was decreased. Moreover, the coercivity of the CoNiFeB film formed on a NiFe substrate exhibits lower coercivity than that formed on a Cu substrate. (c) 2007 Elsevier Ltd. All rights reserved.

    DOI

  • New formation process of plating thin films on several substrates by means of self-assembled monolayer (SAM) process

    Tetsuya Osaka, Masahiro Yoshino

    ELECTROCHIMICA ACTA   53 ( 2 ) 271 - 277  2007年12月  [査読有り]

     概要を見る

    This review describes our recent works on the preparation of Ni-alloy films deposited by electroless deposition as a diffusion barrier layer for ultra large-scale integration (ULSI) interconnects by using an all-wet process. In this process, we create a novel wet fabrication process including a self-assembled monolayer (SAM) as an attachment technique between diffusion barrier layer and a substrate. Our proposal process was applied to the substrates Of SiO2/Si and both organic (methyl silsesquioxane) and inorganic (hydrogen silsesquioxane) low-k dielectrics. The key technique of this proposed process is using SAM as a catalyst trapping layer. The Ni-alloy films such as NiB were deposited on catalyzed SiO2 or low-k substrates. The electrolessly deposited NiB films were found to exhibit sufficient thermal stability and an acceptable barrier property for preventing Cu diffusion into the SiO2 and low-k dielectrics. (c) 2007 Elsevier Ltd. All rights reserved.

    DOI

  • Electrodeposition of amorphous gold alloy films

    Masaru Katoa, Kazutaka Senda, Yuta Musha, Junji Sasano, Yutaka Okinaka, Tetsuya Osaka

    ELECTROCHIMICA ACTA   53 ( 1 ) 11 - 15  2007年11月  [査読有り]

     概要を見る

    The process for electroplating amorphous gold-nickel-tungsten alloy that we developed previously based on the addition of a gold salt to a known amorphous Ni-W electroplating solution was investigated further using the X-ray diffraction (XRD) method for the purpose of quickly surveying the effects of various experimental variables on the microstructure of the alloy. In this system the gold concentration in the plating bath was found to be critical; i.e., when it is either very low or very high, the deposit becomes crystalline to XRD. The deposit composition varies linearly with the mole ratio of An to Ni in solution, and the alloy deposit is amorphous to XRD when the atomic ratio of Au/Ni in the deposit is between 0.5 and 1.5. At suitable concentrations of the metal ions, the deposit contains essentially no tungsten. By extending the work on the Au-Ni-W system, an amorphous Au-Co alloy plating process was also developed. (C) 2007 Elsevier Ltd. All rights reserved.

    DOI

  • Microscopic magnetic property of perpendicular magnetic films of DyxCo100-x measured using soft X-ray magnetic circular dichroism

    Akane Agui, Masaichiro Mizumaki, Toru Asahi, Koji Matsumoto, Tsuyoshi Morikawa, Junichl Sayama, Tetsuya Osaka

    JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS   68 ( 11 ) 2148 - 2152  2007年11月  [査読有り]

     概要を見る

    We have carried out X-ray absorption measurements with its magnetic circular dichroism (MCD) of perpendicular magnetic films of DyxCo100-x (15 <= x <= 33) at Dy M-4,M-5 and Co L-2,L-3 absorption edges to investigate electronic and spin states of the Dy 4f and Co 3d states, respectively. The replacement of major spin between Dy 4f and Co3d is clearly observed in the spectra between 20 <= x <= 25. The expected values of the orbital angular moment vertical bar < L-z >vertical bar of Dy 4f were estimated to be 1.4-0.8 mu(B) while that of Co 3d was estimated to be around 0.2 mu(B). (c) 2007 Elsevier Ltd. All rights reserved.

    DOI

  • 日本応用磁気学会から日本磁気学会への会名変更にあたって : 新たな展開と発展に向けて

    逢坂 哲彌

    まぐね = Magnetics Japan   2 ( 10 ) 481 - 481  2007年10月

    CiNii

  • Synthesis of Fe3O4 nanoparticles with various sizes and magnetic properties 14 by controlled hydrolysis

    Hironori Iida, Kosuke Takayanagi, Takuya Nakanishi, Tetsuya Osaka

    JOURNAL OF COLLOID AND INTERFACE SCIENCE   314 ( 1 ) 274 - 280  2007年10月  [査読有り]

     概要を見る

    Nanoparticles of Fe3O4 were synthesized by hydrolysis in an aqueous solution containing ferrous and ferric salts at various ratios with 1,6-hexanediamine as a base. It was found that the ferrous to ferric ratio influences the reaction mechanism for the formation of Fe3O4. When the ratio of ferrous to ferric ions was increased, the formation of large hydroxide particles as a precursor of Fe3O4 was promoted, which resulted in an increase in the size of Fe3O4 nanoparticles. As a result, the mean diameter of Fe3O4 nanoparticles increased from similar to 9 to similar to 37 nm as the molar percentage of ferrous ions with respect to the total iron ions was increased from 33 to 100%. Furthermore, it was demonstrated that magnetic properties of Fe3O4 nanoparticles can be controlled by adjusting the molar ratio of ferrous to ferric ions as well as the particle diameter. (C) 2007 Elsevier Inc. All rights reserved.

    DOI

  • Synthesis of Fe3O4 nanoparticles with various sizes and magnetic properties by controlled hydrolysis.

    Hironori Iida, Kosuke Takayanagi, Takuya Nakanishi, Tetsuya Osaka

    Journal of colloid and interface science   314 ( 1 ) 274 - 80  2007年10月  [査読有り]  [国際誌]

     概要を見る

    Nanoparticles of Fe(3)O(4) were synthesized by hydrolysis in an aqueous solution containing ferrous and ferric salts at various ratios with 1,6-hexanediamine as a base. It was found that the ferrous to ferric ratio influences the reaction mechanism for the formation of Fe(3)O(4). When the ratio of ferrous to ferric ions was increased, the formation of large hydroxide particles as a precursor of Fe(3)O(4) was promoted, which resulted in an increase in the size of Fe(3)O(4) nanoparticles. As a result, the mean diameter of Fe(3)O(4) nanoparticles increased from approximately 9 to approximately 37 nm as the molar percentage of ferrous ions with respect to the total iron ions was increased from 33 to 100%. Furthermore, it was demonstrated that magnetic properties of Fe(3)O(4) nanoparticles can be controlled by adjusting the molar ratio of ferrous to ferric ions as well as the particle diameter.

    DOI PubMed

  • 会長就任にあたって : 新たな展開と発展に向けて

    逢坂 哲彌

    まぐね = Magnetics Japan   2 ( 7 ) 337 - 338  2007年07月

    CiNii

  • Effect of surface coverage of gold(111) electrode with cysteine on the chiral discrimination of DOPA (vol 19, pg 295, 2007)

    Mariko Matsunaga, Takuya Nakanishi, Toru Asahi, Tetsuya Osaka

    CHIRALITY   19 ( 6 ) 519 - 519  2007年06月  [査読有り]

    DOI

  • Fabrication of SmCo5 double-layered perpendicular magnetic recording media

    Tetsuya Osaka, Yuki Yamashita, Jumchi Sayama, Toru Asahi, Jun Ariake, Kiko Harada, Kazuhiro Ouchi

    IEEE TRANSACTIONS ON MAGNETICS   43 ( 6 ) 2109 - 2111  2007年06月  [査読有り]

     概要を見る

    We fabricated SmCo5 double-layered perpendicular magnetic recording media with high perpendicular magnetic anisotropy for realizing ultra high density recording. A double-layered medium with a Ru buffer layer introduced between a Cu/Ti intermediate layer and a Co-Zr-Nb soft magnetic underlayer exhibited high perpendicular magnetic anisotropy, whereas that without the Ru buffer layer did not. Auger electron spectroscopy revealed that the Ru buffer layer inhibited interdiffusion between the Cu/Ti intermediate layer and the Co-Zr-Nb soft magnetic underlayer. We report here for the first time the read-write characteristics of SmCo5 double-layered perpendicular magnetic recording media. The medium noise was small in the medium with a Sm-Co layer deposited under high Ar gas pressure owing to small magnetic clusters.

    DOI

  • Effect of surface coverage of gold(111) electrode with cysteine on the chiral discrimination of DOPA.

    Mariko Matsunaga, Takuya Nakanishi, Toru Asahi, Tetsuya Osaka

    Chirality   19 ( 4 ) 295 - 9  2007年05月  [国際誌]

     概要を見る

    The enantioselectivity imparted to a gold electrode by modifying its surface with a self-assembled monolayer (SAM) of cysteine (Cys) was investigated for the electrochemical redox reaction of 3,4-dihydroxyphenylalanine (DOPA). A cyclic voltammetric study of the redox reaction revealed that the enantioselectivity was determined by the surface coverage of the gold electrode with Cys molecules. The electrode modified with approximately 1.8 x 10(14) Cys molecules cm(-2) exhibited enantioselectivity in the voltammogram for the oxidation and reduction of DOPA, while the voltammograms obtained by the electrodes with either more or less surface coverages did not exhibit significant enantioselectivity. It is suggested that the accessibility of DOPA to that area of the gold surface which is not blocked by Cys molecules at an optimum surface coverage, is required for the enantioselective redox reaction of DOPA to proceed.

    DOI PubMed

  • Spectroelectrochemical phenomena on surface plasmon resonance of Au nanoparticles immobilized on transparent electrode

    Jong-Eun Park, Toshiyuki Momma, Tetsuya Osaka

    ELECTROCHIMICA ACTA   52 ( 19 ) 5914 - 5923  2007年05月  [査読有り]

     概要を見る

    Different shapes (nanosphere or nanorod) of gold nanoparticles (Au-NPs) were synthesized with and without ultrasonic irradiation in the presence of citric acid. Spherical-shaped and rod-shaped Au-NPs showed different surface plasmon resonance (SPR) absorption bands. The Au-NRs with different shapes were immobilized on a monolayer of 3-aminopropyltriethoxysilane (APS) coated on an indium-tin oxide (ITO) electrode. The potential dependence of the SPR band of different shaped Au-NPs in an aqueous solution was explored. The SPR band and intensity changes of the Au-NPs were found to depend on the applied potential. The spherical-shaped and rod-shaped Au-NPs showed different SPR absorption behaviors when potential was applied. These behavior changes were interpreted as the result of the potential-induced changes of the local dielectric environment around the nanoparticles due to molecular absorption/desorption and the charging/discharging of the particles. (C) 2007 Elsevier Ltd. All rights reserved.

    DOI

  • 科学、技術そして研究倫理

    逢坂 哲彌

    化学と工業 = Chemistry and chemical industry   60 ( 4 ) 421 - 421  2007年04月

    CiNii

  • Highly enantioselective discrimination of amino acids using copper deposition on a gold electrode modified with homocysteine monolayer

    Mariko Matsunaga, Takuya Nakanishi, Toru Asahi, Tetsuya Osaka

    ELECTROCHEMISTRY COMMUNICATIONS   9 ( 4 ) 725 - 728  2007年04月  [査読有り]

     概要を見る

    An extremely enhanced enantioselectivity was achieved for the detection of enantiomers of alanine (Ala), leucine (Leu), and 3,4-dihydroxyphenylalanine (DOPA) based on the voltammograms for the deposition of Cu from Cu complexes of the amino acids at an Au electrode modified with a self-assembled monolayer (SAM) Of L-homocysteine (Hcy). The enantioselective current density peak for the Cu deposition was found to change with increasing number of potential cycles after the addition of Cu(II), and the highest enantioselectivity was observed immediately after the addition of Cu(II). Besides, enantio selectivity was not observed with proline, whose five-membered ring contains the nitrogen atom of a secondary amino group, while some amino acids with a primary amine group such as Ala, Leu, and DOPA exhibited enantioselectivity. These results suggest that the chiral ligand exchange reaction at the L-Hcy SAM-modified Au electrode, namely, the enantioselective formation of diastereomeric complexes of Cu(II) with target enantiomers and L-Hcy self-assembled on the Au electrode, plays an important role in the chiral discrimination based on the Cu deposition. (c) 2006 Elsevier B.V. All rights reserved.

    DOI

  • An electrochemical investigation of additive effect in trench-filling of ULSI interconnects by electroless copper deposition

    Madoka Hasegawa, Noriyuki Yamachika, Yutaka Okinaka, Yosi Shacham-Diamand, Tetsuya Osaka

    ELECTROCHEMISTRY   75 ( 4 ) 349 - 358  2007年04月  [査読有り]

     概要を見る

    The filling of trenches in ULSI interconnect structure by electroless copper deposition was investigated for the effect of bath additives. The additive effect was found to depend strongly on the reducing agent used in the bath. Void-free trench-filling was achieved by using polyethylene glycol (PEG) as an inhibiting additive in the bath containing glyoxylic acid as the reducing agent, while the combined addition of 8-hydroxy-7-iodo-5-quinoline sulfonic acid (HIQSA) and PEG was necessary for achieving void-free filling in the bath containing formaldehyde as the reducing agent. The effect of PEG on trench filling in the former bath was studied in detail based on electrochemical measurements. It is suggested that the rinse water remaining in trenches before electroless deposition causes a decrease in PEG concentration at the trench bottom during copper filling. The addition of PEG was found to shift the deposition potential in the negative direction. A new potential measuring apparatus was devised and used in model experiments, which revealed that the deposition potential depends on the local concentration of PEG at the trench bottom, where it is expected to be low. The observed preferential growth of copper deposit at the trench bottom is thus attributed to the effects of the variation of PEG concentration within the trenches on the deposition rate and potential.

    DOI

  • Evidence for “Superfilling” of Submicrometer Trenches with Electroless Copper Deposit

    M. Hasegawa, N. Yamachika, Y. Shacham-Diamand, Y. Okinaka, T. Osaka

    Appl. Phys. Lett.   90 ( 10 ) 101916 - 101916  2007年03月  [査読有り]

    DOI

  • A Challenge of New Materials for Next Generation’s Magnetic Recording

    T. Osaka, J. Sayama

    Electrochim. Acta   52 ( 8 ) 2884 - 2890  2007年02月  [査読有り]

    DOI

  • A self assembly monolayer activated electroless deposition process for interconnect and contact applications

    Y. Shacham-Diamand, M. Yoshino, A. Duhin, Y. Sverdlov, T. Osaka

    Advanced Metallization Conference 2006 (AMC 2006)     657 - 662  2007年  [査読有り]

     概要を見る

    The use of self assembly monolayer has been demonstrated for direct plating on interlevel dielectric for interconnects applications. In this work we show an additional feature of that technique for direct deposition on contact application. We also present an integrated process where the self assembly activation is used for both the deposition of the barrier layer which can be used for both the contact material and the source for the silicidation process. Later all wet electroless process can be used for the contact buildup and the capping layer deposition. In this work we review the depositions of electroless Nickel alloy on various inter level dielectrics and on Si. We also discuss the integration process including deposition on exiting silicide or possible self silicidation for the formation of self aligned NiSi. We describe the process outlines and present material and electrical properties.

  • Sputter-deposited SmCo5 thin films with perpendicular magnetic anisotropy for high density magnetic recording media

    J. Sayama, Y. Yamashita, T. Asahi, T. Osaka

    ECS Transactions   3 ( 25 ) 307 - 313  2007年

     概要を見る

    Sputter-deposited SmCos thin films exhibiting high perpendicular magnetic anisotropy were studied for materializing ultra high density magnetic recording. This study put emphasis on the fabrication of SmCos double-layered perpendicular magnetic recording media. A double-layered medium with a Ru buffer layer introduced between a Cu/Ti intermediate layer and a Co-Zr-Nb soft magnetic underlayer exhibited high perpendicular magnetic anisotropy, whereas that without the Ru buffer layer did not. Auger electron spectroscopy revealed that the Ru buffer layer inhibited unfavorable interdiffusion between the Cu/Ti intermediate layer and the Co-Zr-Nb soft magnetic underlayer. In addition, the readwrite characteristics of the SmCos double-layered perpendicular magnetic recording media were evaluated for the first time. copyright The Electrochemical Society.

    DOI

  • High performance 1,5-diaminoanthraquinone/Multi-wall carbon nanotube(DAAQ/MWCNT) composite materials by different synthesis methods for supercapacitor

    H. I. Kim, J. G. Shin, H. J. Kim, J. E. Park, T. Osaka, S. G. Park

    ECS Transactions   3 ( 37 ) 17 - 22  2007年

     概要を見る

    DAAQ(1,5-diaminoanthraquinone)/MWCNT composites were prepared by chemical polymerization of DAAQ onto MWCNT and their capacitance was evaluated by means of cyclic voltammetry and charge-discharge cycling in 1M H2SO 4 electrolyte. The performances of such cells have been compared with pure MWCNT and DAAQ based electrodes. The SEM image shows that DAAQ was coated onto MWCNT during polymerization. The highest specific capacitance values of 210 F/g were observed. DAAQ/MWCNT composites also showed long cyclic stability in charge-discharge test. copyright The Electrochemical Society.

    DOI

  • Preparation and characterization of ZrO2/Ti electrode for waste water purification system

    Han-Joo Kim, Won-Keun Son, Tae-Il Kim, Kyung-Suk Kang, Tetsuya Osaka, Soo-Gil Park

    JOURNAL OF THE EUROPEAN CERAMIC SOCIETY   27 ( 13-15 ) 3749 - 3752  2007年  [査読有り]

     概要を見る

    We have investigated the effects of the etching method of a Ti substrate for a metal oxide electrode on the electrochemical characteristics of the electrode. The preparation method and electrochemical characterization of zirconium oxide films on etched Ti substrate has been also studied. The HCl etching was developed a fine and homogeneous roughness on the Ti substrate. Fabrication and material properties of the metal oxide electrode, which is known to be so effective to generate ozone and sodium hypochlorite (NaOCI) as power oxidant, were studied. A proper metal oxide material focus zirconium oxide through reference paper. A coating method to enhance the fabrication reproducibility of the zirconium oxide electrode was used dip-coating method by zirconium oxychloride. Zirconium oxide films on the Ti substrate were analyzed by SEM, XPS and cyclic voltaminetry. (C) 2007 Elsevier Ltd. All rights reserved.

    DOI

  • In situ stress transition observations of electrodeposited Sn-based anode materials for lithium-ion secondary batteries

    H. Mukaibo, T. Momma, Y. Shacham-Diamand, T. Osaka, M. Kodaira

    ELECTROCHEMICAL AND SOLID STATE LETTERS   10 ( 3 ) A70 - A73  2007年  [査読有り]

     概要を見る

    The stress of the electrodeposited pure Sn and the Ni-62 atom % Sn alloy thin film electrodes during cycling was measured in situ using an optical cantilever method. The results revealed that the Ni-62 atom % Sn alloy electrode with better cycle endurance actually experiences larger stress compared to the pure Sn electrode. Furthermore, the stress-release phenomenon during the open-circuit period has been confirmed for the first time. This paper demonstrates that the cantilever bending method is effective for the in situ study of the stress development, transition, and hence the phenomena taking place within the Sn-based electrodes. (c) 2007 The Electrochemical Society.

    DOI

  • An impedance analysis on properties of DMFC catalyst layers based on primary and secondary pores

    Satoshi Tominaka, Naohisa Akiyama, Toshiyuki Momma, Tetsuya Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   154 ( 9 ) B902 - B909  2007年  [査読有り]

     概要を見る

    An impedance analysis method for the catalyst layers of a direct methanol fuel cell is evaluated through demonstrating analyses and comparison of two types of the catalyst layers. The catalyst layers were prepared with different dispersing solvents: ethyleneglycol dimethyl ether or isopropyl alcohol aqueous solution. Methanol oxidation current of the catalyst layer prepared with the former solvent was more than twice that with the latter. The proposed method was revealed to have the potential for analyzing the difference clearly in terms of parameters, using our transmission-line equivalent circuit for the catalyst layers based on the assumption of primary and secondary pores. The parameters indicate that the main drawback of the catalyst layer prepared with the latter solvent is 85 times larger ionic resistance in the secondary pores. Moreover, precise analyses on the parameters indicate the microstructures of the catalyst layers, which correspond to a model reported previously. We conclude that this method is effective in analyzing the catalyst layer of the fuel cell. (C) 2007 The Electrochemical Society.

    DOI

  • Electrical and electrochemical properties of alkyl-monolayer modified Si(111) in the presence of water

    Tetsuya Osaka, Mariko Matsunaga, So Kudo, Daisuke Niwa, Yosi Shacham-Diamand, Wolfram Jaegermann, Ralf Hunger

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   154 ( 11 ) H919 - H926  2007年  [査読有り]

     概要を見る

    Fundamental electronic properties of methyl-modified n-Si(111) interfaces created by the displacement of Cl on Si(111) surface by the methyl group from Grignard reagents (RMgX; X=Br or Cl, R = methyl) were measured in the presence and absence of water. The presence of water played a significant role in determining the behavior of the devices. The structure of Ga-In/methyl monolayer/n-Si(111) was not rectifying but only consisted of series resistances. On the other hand, a diode-like rectifying property was observed with the water/methyl layers/n-Si(111) heterojunction structure. Functionalization of Si(111) surfaces with various alkyl moieties such as methyl, ethyl, propyl, butyl, and mixed methyl/propyl, was studied by electrochemical measurements performed in a mixture of 3 mM K3Fe(CN)(6)/3 mM K4Fe(CN)(6)/1 MKCl/H2O and by surface characterization with synchrotron radiation X-ray photoelectron spectroscopy. The transistor characteristics of field effect transistor-like devices with water/alkyl/n-Si(111) gate structures were investigated. The device properties clearly depended on the alkyl moiety: transistor-like behavior was observed only for devices with methyl moiety, and for those with a mixed methyl-propyl monolayer prepared by using Grignard reagents with mixed methyl and propyl (CH3MgBr:CH3CH2CH2MgBr=1:9) moieties, whereas no transistor-like behavior was observed for devices with butyl or ethyl moiety. (c) 2007 The Electrochemical Society.

    DOI

  • An electrodeposited Pd-Co cathode catalyst for a microfabricated direct methanol fuel cell

    S. Tominaka, S. Ohta, T. Momma, T. Osaka

    ECS Transactions   11 ( 1 ) 1369 - 1377  2007年

     概要を見る

    Pd-Co was electrodeposited as a rough cathode catalyst for a direct methanol fuel cell fabricated using micro-electromechanical systems technology. Pd-Co was electrodeposited at -10 mA/cm2 for 60 s or -200 mA/cm 2 for 5 s. The deposits were evaluated with respect to microstructures, electrochemical characteristics, and fuel cell performances. As a result, oxygen reduction activity of the sample prepared at -200 mA/cm 2 was higher than that prepared at 10 mA/cm , while the electrochemically active surface areas were almost the same. Microstructures of the former and the latter were observed dendritic and flat, respectively. We conclude that the difference of oxygen reduction activity is attributed to the difference of the microstructure. In addition, we modified the dendritic sample by depositing Pd-Co at -0.75 V vs. Ag/AgCl. The modification increased open circuit potential for oxygen reduction by 30 mV from 0.70 to 0.73 V. ©The Electrochemical Society.

    DOI

  • Electroless diffusion barrier process using SAM on low-k dielectrics

    M. Yoshino, T. Masuda, T. Yokoshima, J. Sasano, Y. Shacham-Diamand, I. Matsuda, T. Osaka, Y. Hagiwara, I. Sato

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   154 ( 3 ) D122 - D125  2007年  [査読有り]

     概要を見る

    A wet process based on electroless deposition is proposed for the formation of a diffusion barrier layer for Cu wiring in ultra-large scale integration (ULSI) technology. The diffusion barrier layer is formed on a low-dielectric constant (low-k) inter level film. In this process, a Pd-activated self-assembled monolayer as a seed/adhesion layer was used as a key step to allow electroless deposition on a dielectric film. The effectiveness of this approach was demonstrated by depositing an electroless NiB layer as the diffusion barrier layer. The electrolessly deposited NiB layer showed a uniform surface, a small grain size, and a high adhesion when deposited on various common inter level dielectric materials with low dielectric constant. The electrolessly deposited NiB layer formed on the low-k dielectric film by this method showed a high thermal stability of the effectiveness as a barrier to Cu diffusion at temperatures up to 400 degrees C for 30 min. The electroless process was found to be reproducible and did not affect dielectric properties of the underlying insulator. (c) 2007 The Electrochemical Society.

    DOI

  • Si圧痕のラマン分光解析

    柳沢雅広, 久保暢宏, 阪田薫穂, 加藤真裕, 本間敬之, 逢坂哲彌

    電子情報通信学会技術研究報告   107 ( 272(EMD2007 56-68) ) 51 - 54  2007年

    J-GLOBAL

  • 電気化学的手法による高機能磁性薄膜の開発と磁気記録デバイスへの応用

    逢坂哲彌

    まぐね   2 ( 1 ) 5 - 11  2007年

    J-GLOBAL

  • Origin of chiral discrimination by a two-dimensionally chiral self-assembled monolayer: A quantum chemical study

    Tomohiro Nishikawa, Tsukasa Torimoto, Takuya Nakanishi, Tetsuya Osaka, Bunsho Ohtani

    CHEMICAL PHYSICS LETTERS   432 ( 4-6 ) 502 - 507  2006年12月  [査読有り]

     概要を見る

    Structural and energetic investigations based on semiempirical PM5 and ab initio HF and MP2 calculations suggested that the self-assembled monolayer of an atropisomeric compound, (R)- or (S)-1,1'-binaphthalene-2,2'-dithiol (BNSH), on a gold (1 1 1) surface selectively adsorbs one enantiomer of phenylalanine (Phe), resulting in chiral discrimination, through hydrophobic, cation(-NH3+)-pi and NH(Phe)-pi (BNSH) interactions in a nanometer-sized screw-hole-like pocket composed of three BNSH molecules in the monolayer. (c) 2006 Elsevier B.V. All rights reserved.

    DOI

  • Enantioselectivity of redox reaction of DOPA at the gold electrode modified with a self-assembled monolayer of homocysteine.

    Takuya Nakanishi, Mariko Matsunaga, Makoto Nagasaka, Toru Asahi, Tetsuya Osaka

    Journal of the American Chemical Society   128 ( 41 ) 13322 - 3  2006年10月  [査読有り]  [国際誌]

     概要を見る

    The enantioselectivity of the self-assembled monolayer (SAM) of homocysteine formed on the (111)-oriented gold surface was investigated. We analyzed the redox behavior of 3,4-dihydroxyphenylalanine (DOPA), which is an electrochemically active chiral molecule, by means of cyclic voltammetry at a gold electrode modified with one enantiomeric form of homocysteine. It was demonstrated that the homocysteine SAM of one enantiomeric form blocked the redox reaction of only one enantiomer of DOPA, with cross inversion for the other enantiomer, in acidic solution.

    DOI PubMed

  • Preparation of magnetic iron-oxide nanoparticles by successive reduction-oxidation in reverse micelles: Effects of reducing agent and atmosphere

    Hironori Iida, Takuya Nakanishi, Harumi Takada, Tetsuya Osaka

    ELECTROCHIMICA ACTA   52 ( 1 ) 292 - 296  2006年10月  [査読有り]

     概要を見る

    The chemical reduction of ferrous or ferric ions to metallic iron by a reducing agent such as sodium borohydride (NaBH4), hydrazine (N2H4), or sodium phosphonate (NaH2PO2) and its subsequent oxidation were investigated for the preparation of iron-oxide nanoparticles in reverse micelles. The crystal structure and crystallinity of the oxide nanoparticles were found to depend on the oxidation potential of the reducing agent and the catalytic activity of the surface of deposited iron. In addition, it was demonstrated that the process used for oxidizing the metallic iron was critical for the formation of oxide nanoparticles, and that the enhancement of magnetic properties was achieved by providing a flow of oxygen during the oxidation process. (c) 2006 Elsevier Ltd. All rights reserved.

    DOI

  • Metallization on three dimensions microstructures using photoresist spray coating for microdirect methanol fuel cell

    Masanori Ishizuka, Hiroaki Houjou, Shinji Motokawa, Jun Mizuno, Toshiyuki Momma, Tetsuya Osaka, Shuichi Shoji

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   45 ( 10A ) 7944 - 7948  2006年10月  [査読有り]

     概要を見る

    High-efficientcy micro-electrochemical devices are realized by increasing electrode surface areas while maintaining keeping chip size. The use of three dimensional (3-D) electrodes instead of planar electrodes is effective for this purpose. To realize a metal pattern on 3-D structures, spray coating was utilized and the optimum condition for achieving a good photoresist step coverage was determined. A good step coverage of the photoresist was obtained on the obtuse corner formed by the anisotropic wet etching of (100) silicon and even on the vertical corner formed,by deep reactive ion etching (RIE). We applied this method to fabricate a high-performance micro direct methanol fuel cell (mu DMFC). An open circuit voltage of 548 mV and a maximum power density of 0.72 mW/cm(2) were obtained at room temperature with 2 M methanol.

    DOI

  • Electrochemical characteristics of layered LiNi1/3Co1/3Mn1/3O2 and with different synthesis conditions

    Ping He, Haoran Wang, Lu Qi, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   160 ( 1 ) 627 - 632  2006年09月  [査読有り]

     概要を見る

    LiNi1/3Mn1/3Co1/3O2 had been successfully prepared from spherical composite carbonate via a simple uniform-phase precipitation method [P. He, H. Wang, L. Qi, T. Osaka, J. Power Sources, in press] at normal pressure, using nickel, cobalt and manganese sulfate and ammonia bicarbonate as reactants. The preparation of spherical composite carbonate was significantly dependant on synthetic condition, such as the reaction temperature, feed rate, molar ratio of these reactants, etc. The optimized condition resulted in spherical composite carbonate of which the particle size distribution was uniform, as observed by scanning electronic microscopy (SEM). Calcination of the uniform composite carbonate with lithium carbonate at high temperature led to a well-ordered layer structured LiNi1/3Mn1/3Co1/3O2 as confirmed by X-ray diffraction (XRD), without obvious change in shape. Due to the homogeneity of the composite carbonate, the final product, LiNi1/3Mn1/3Co1/3O2, was also significantly uniform, i.e., the average particle size was of about 10 mu m in diameter and the distribution was relatively narrow. As a result, the corresponding tap density was also high, approximately 2.32 g cm(-3), of which the value is very near to that of commercialized LiCoO2. In the voltage range of 2.8-4.2, 2.8-1.35 and 2.8-4.5 V the discharge capacities of LiNi1/3Mn1/3Co1/3O2 electrode were 159, 168 and 179 mAh g(-1), respectively, with good cyclability. (c) 2006 Published by Elsevier B.V.

    DOI

  • Electrochemical formation of intermediate layer for Co/Pd multilayered media

    Jun Kawaji, Koji Kimura, Toru Asahi, Takayuki Homma, Tetsuya Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   303 ( 2 ) E128 - E132  2006年08月  [査読有り]

     概要を見る

    Pd nanocluster seeds were formed on a soft magnetic underlayer (SUL) using an electrochemical substitution reaction, and were utilized as an intermediate layer for a Co/Pd multilayered ([Co/Pd](n)) perpendicular magnetic recording medium. A CoNiFeB film prepared with electroless deposition was used as SUL, which was immersed into a PdCl2 solution for the formation of Pd seeds. The Pd seeds were found to effectively reduce the size of magnetic domains in the [Co/Pd](n) film deposited on them. The optimization of the concentration of the PdCl2 solution and the use of the pretreatment process with a SnCl2 solution were effective to obtain the smooth SUL surface with fine Pd seeds as small as 5 nm. The 20 nm-thick [Co/Pd] n film deposited on the optimized Pd seeds/CoNiFeB SUL exhibited a high coercivity of 7.8 kOe and a small magnetic domain size of 69 nm. These results indicated that the combination of the Pd seeds and the electroless-deposited SUL was desirable in terms of the improvement not only in the magnetic properties of [Co/Pd] n media but also in the mass productivity of the underlayer. (C) 2006 Elsevier B.V. All rights reserved.

    DOI

  • Crystallization of leucine on a self-assembled monolayer with covalently attached enantiomeric leucine molecules

    Takuya Nakanishi, Naoki Banno, Mariko Matsunaga, Toru Asahi, Tetsuya Osaka

    COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS   284   270 - 275  2006年08月  [査読有り]

     概要を見る

    Crystallization of chiral amino acid, leucine, on the gold substrate modified with a self-assembled monolayer (SAM) was investigated with X-ray diffraction (XRD) and atomic force microscopy (AFM). It was found that the formation of enantiomeric crystalline phase occurred enantioselectively when the specimen modified with the SAM, to which one enantiomeric form of leucine molecules was covalently attached, was immersed in a pure enantiomeric solution of leucine. On the contrary, a racemic crystalline phase was formed on both D- and L-leucine-attached SAMs after soaking in a racemic leucine solution. In non-racemic solutions, both enantiomeric and racemic crystalline phases were formed on the enantiomer-attached SAM when the one enantiomeric form with the same chirality as the attached enantiomer was contained in excess, while neither of the crystals was formed with the other enantiomeric form in excess. Changes in the surface morphology of the specimens accompanied with the growth of crystalline phases on the SAM, reflecting the crystallinity suggested from the XRD method, were observed by using AFM. (c) 2006 Elsevier B.V. All rights reserved.

    DOI

  • Study on N-2-added and B-doped effect in Co/Pd multilayered films using soft x-ray absorption and magnetic circular dichroism

    A. Agui, T. Asahi, J. Sayama, J. Kawaji, M. Mizumaki, M. Tanaka, T. Osaka

    JOURNAL OF PHYSICS D-APPLIED PHYSICS   39 ( 14 ) 2881 - 2885  2006年07月  [査読有り]

     概要を見る

    The soft x-ray absorption and magnetic circular dichroism spectra at the Co L-2,L-3-edges of [Co/Pd](20) and [CoB/Pd](20) multilayered films, which were sputter- deposited in Ar gas containing N-2 at room temperature, were measured to investigate the electronic and spin states of the films. The macroscopic magnetic properties, such as coercivity and saturation magnetization, and microstructural properties, such as grain size and preferred orientation, were markedly changed for the [Co/Pd](20) film by the B doping and N-2 addition. The B doping and/or the addition of N-2 gas caused appreciable changes not only in macroscopic magnetic properties but also in microscopic properties, such as the spin angular momentum and orbital angular momentum, throughout the multilayered film. On the other hand, a new spectral feature at the high energy side of the Co L-3-edge peak in x-ray absorption spectra was found in only the films with N-2 added. Thus, the microscopic properties, such as electronic and spin states, of the Co 3d electronic state for the [Co/Pd](20) and [CoB/Pd](20) films were changed by only the sputtering process with additive N-2 gas.

    DOI

  • Synthetic optimization of spherical LiCoO2 and precursor via uniform-phase precipitation

    Ping He, Haoran Wang, Lu Qi, Tetsuya Osaka

    JOURNAL OF POWER SOURCES   158 ( 1 ) 529 - 534  2006年07月  [査読有り]

     概要を見る

    LiCoO2 had been successfully prepared from spherical basic cobalt carbonate via a simple uniform-phase precipitation method at normal pressure, using cobalt sulfate and urea as the reactants. The preparation of spherical basic cobalt carbonate was significantly dependant on synthetic condition, such as the reactant concentration, reaction temperature and impeller speed, etc. The optimized condition resulted in spherical basic cobalt carbonate with uniform particle size distribution, as observed by scanning electron microscopy. Calcination of the uniform basic cobalt carbonate with lithium carbonate at high temperature led to a well-ordered layer-structured LiCoO2 without shape change, as confirmed by X-ray diffraction. Due to the homogeneity of the basic cobalt carbonate, the final product, LiCoO2, was also significantly uniform, i.e., the average particle size was of about 10 mu m in diameter and the distribution was relatively narrow. As a result, the corresponding tap-density was also high approximately 2.60 g cm(-3), of which the value is higher than that of commercialized LiCoO2 of Hunan Ruixing, co. In the voltage range 2.8-4.2, 2.8-4.3, and 2.8-4.4 V, the discharge capacities of LiCoO2 electrode were 153, 159, and 168 mAh g(-1), respectively, with better cyclability. (c) 2005 Elsevier B.V. All rights reserved.

    DOI

  • Development of Microfabrication Process of Mesoporous Pt via ”Solvent-Evaporation-Mediated Direct Physical Casting”: Selective Deposition into Sloped Microchannels

    Y. Yamauchi, H. Kitoh, T. Momma, T. Osaka, K. Kuroda

    Sci. Technol. Adv. Mater.   7 ( 5 ) 438 - 445  2006年07月  [査読有り]

    DOI

  • Development of new electrolytic and electroless gold plating processes for electronics applications

    Tetsuya Osaka, Yutaka Okinaka, Junji Sasano, Masaru Kato

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   7 ( 5 ) 425 - 437  2006年07月  [査読有り]

     概要を見る

    This article reviews results of our investigations, performed over the period of a decade, on gold plating for electronics applications. Three different topics are covered: (1) development of a new, non-cyanide, soft-gold electroplating bath containing both thiosulfate and sulfite as ligands; (2) evaluation of a known cyanide-based, substrate-catalyzed electroless bath for depositing pure soft gold, and subsequent development of an alternative, non-cyanide, substrate-catalyzed bath; and (3) development of a new process to electroplate amorphous hard-gold alloys for probable future applications as a contact material on nano-scale electronic devices. (c) 2006 NIMS and Elsevier Ltd. All rights reserved.

    DOI

  • Origin of perpendicular magnetic anisotropy of SMCo5 thin films with Cu underlayer

    J Sayama, K Mizutani, T Asahi, J Ariake, K Ouchi, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   301 ( 1 ) 271 - 278  2006年06月  [査読有り]

     概要を見る

    Effects of the Cu underlayer thickness and the addition Of Cu to a Sm-Co layer on magnetic properties and microstructure Of SmCo5 thin films exhibiting perpendicular magnetic anisotropy were studied. The origin of the perpendicular magnetic anisotropy was discussed from these experimental results. A thick Cu underlayer of more than 100 nm brought about high perpendicular magnetic anisotropy leading to the squareness ratio equal to unity. The Cu addition enhanced the perpendicular magnetic anisotropy and reduced the Cu underlayer thickness required to obtain the squareness ratio of unity. X-ray diffractometry showed that the crystalline orientation of the Sm-Co layer did not correlate with that of the Cu underlayer. Auger electron spectroscopy revealed that Cu atoms were diffused up to the Sm-Co layer from the Cu underlayer. From the results, Cu atoms existing in the Sm-Co layer were suggested to be strongly related with an appearance of the perpendicular magnetic anisotropy by introducing the Cu underlayer. (c) 2005 Elsevier B.V. All rights reserved.

    DOI

  • Adsorption of organic molecules by photochemical reaction on Cl : Si(111) and H : Si(111) evaluated by HREELS

    Katsuhiko Nishiyama, Yosuke Tanaka, Hiroshi Harada, Taro Yamada, Daisuke Niwa, Tomoyuki Inoue, Takayuki Homma, Tetsuya Osaka, Isao Taniguchi

    SURFACE SCIENCE   600 ( 10 ) 1965 - 1972  2006年05月  [査読有り]

     概要を見る

    The covalent attachment of alkyl groups to silicon surfaces, via carbon-silicon bond formation, has been attempted using gas-surface reactions starting from Cl-terminated Si(111) or H:Si(111) under ultraviolet light irradiation. The formation of Cl-terminated Si(111) and its resulting stability were examined prior to deposition of organic molecules. High-resolution electron energy loss spectroscopy (HREELS) was utilized for detecting surface-bound adsorbates. The detection of photo-deposited organic species on CI:Si(111) from gas-phase CH4 or CH2=CH2 was not significant. On H:Si(111), it was evident that after the photoreaction with gas-phase C2H5Cl, C2H5 groups were chemically bonded to the surface Si atoms through single covalent bonds. The C2H5 groups were thermally stable at temperatures below 600 K. Alkyl monolayers prepared on silicon surfaces by dry process will lead to a new prospective technology of nanoscale fabrication and biochemical applications. (c) 2006 Elsevier B.V. All rights reserved.

    DOI

  • Effect of substrate morphology on the crystallization of leucine on gold surface modified with a self-assembled monolayer

    Tetsuya Osaka, Mariko Matsunaga, Takuya Nakanishi, Toru Asahi, Naoki Banno

    CHEMISTRY LETTERS   35 ( 4 ) 438 - 439  2006年04月  [査読有り]

     概要を見る

    The effect of the surface morphology of gold-deposited quartz substrate on the enantioselective crystallization of leucine was investigated by using quartz crystal microbalance (QCM) and X-ray diffraction methods. The gold substrate was modified with a self-assembled monolayer with covalently attached D-leucine molecules. For a rough surface with root-mean-square (RMS) roughness of 17 nm, the QCM measurement showed a continuous decrease in frequency, while for a smooth surface with RMS roughness of 2 nm, essentially no change in frequency was observed. Nevertheless, leucine crystals with high crystallinity were clearly formed on the smooth surface.

    DOI

  • Synthesis of magnetic nanoparticles and their application to bioassays.

    Tetsuya Osaka, Tadashi Matsunaga, Takuya Nakanishi, Atsushi Arakaki, Daisuke Niwa, Hironori Iida

    Analytical and bioanalytical chemistry   384 ( 3 ) 593 - 600  2006年02月  [査読有り]  [国際誌]

     概要を見る

    Magnetic nanoparticles have been attracting much interest as a labeling material in the fields of advanced biological and medical applications such as drug delivery, magnetic resonance imaging, and array-based assaying. In this review, synthesis of iron oxide magnetic nanoparticles via a reverse micelle system and modification of their surface by an organosilane agent are discussed. Furthermore, as a practical biological assay system, the magnetic detection of biomolecular interactions is demonstrated by using the combination of a patterned substrate modified with a self-assembled monolayer and the magnetic nanoparticles.

    DOI PubMed

  • Enhancement of the ductility of electrodeposited copper films by room-temperature recrystallization

    M Hasegawa, Y Nonaka, Y Negishi, Y Okinaka, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   153 ( 2 ) C117 - C120  2006年  [査読有り]

     概要を見る

    In conjunction with a study of the copper electrodeposition process from the acid copper sulfate bath for the fabrication of interconnections of printed circuit boards and semiconductor devices, an investigation was performed of the effect of bath additives on the relationship between the ductility of the copper deposit and its crystallographic structure and electrical resistivity. Room-temperature recrystallization, or so-called self-annealing, is known to occur in copper electrodeposits obtained from baths containing Cl-, polyethylene glycol, and bis(3-sulfopropyl)disulfide as additives. Variation with time of the crystallographic orientation, grain size, and resistivity of the deposit was followed over a period of several weeks after the deposition. During the period of self-annealing, ductility was found to increase by a factor of 1.5. The increase in ductility is shown to be related to a change in microstructure of the copper deposit. (c) 2006 The Electrochemical Society.

    DOI

  • Fabrication of the electroless NiMoB films as a diffusion barrier layer on the low-k substrate

    M. Yoshino, T. Masuda, S. Wakatsuki, J. Sasano, I. Matsuda, Y. Shacham-Diamand, T. Osaka

    ECS Trans.   1   57 - 67  2006年

  • Soft X-ray absorption spectroscopy and magnetic circular dichroism study of electroless-deposited CoNiFe ternary alloy soft magnetic films

    Masahito Tanaka, Naomichi Nakamura, Torn Asahi, Toshihiro Tsumori, Akane Agui, Masaichiro Mizumaki, Tetsuya Osaka

    PHYSICA STATUS SOLIDI C - CURRENT TOPICS IN SOLID STATE PHYSICS, VOL 3, NO 8   3 ( 8 ) 2783 - +  2006年  [査読有り]

     概要を見る

    We studied microscopic magnetic properties of each consistent atom in boron added CoNiFe electroless-deposited soft magnetic films, which is a promising candidate for the soft magnetic underlayer of the perpendicular magnetic recording medium, by X-ray absorption spectra (XAS) and magnetic circular dichroism (MCD) measurement. It was found that various monoxides and Fe sesquioxide coexisted with the metals at the upper part of the films. The results of MCD sum rule showed the expected values of orbital angular moment <L-z> for the film with macroscopic magnetic domain boundaries were larger than those of without domains at Co and Ni atoms and smaller at Fe atom. The appearance of macroscopic magnetic domain boundaries probably originated from the increase in <L-z> of Co and/or Ni atoms. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

    DOI

  • Formation of soft magnetic thin films by means of electrochemical methods

    T. Osaka, A. Sugiyama, T. Asahi, J. Kawaji

    Proceedings - Electrochemical Society   PV2004-3   144 - 158  2006年

  • A novel approach for preparation of γ-Fe2O3 nanoparticles: Successive reduction-oxidation in reverse micelles

    H. Iida, H. Takada, T. Nakanishi, T. Osaka

    Proceedings - Electrochemical Society   PV2004-3   325 - 329  2006年

  • Application of a two-phase liquid-liquid system to the synthesis of iron-containing nanoparticles

    T. Nakanishi, H. Iida, H. Takada, T. Osaka

    Proceedings - Electrochemical Society   PV2004-3   330 - 335  2006年

  • New Propasal of Evaluation Method for DMFC Catalyst Layers by Means of Electrochemical Impedance Spectroscopy

    T. Osaka, T. Momma, S. Tominaka

    Chem. Lett.   35   10 - 11  2006年

  • Nano-tribological study on the smoothness of writing with a ball-point pen using friction force microscopy

    H Okuo, T Asahi, T Onoue, T Osaka

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   79 ( 1 ) 149 - 153  2006年01月  [査読有り]

     概要を見る

    The relationship between human sensation experienced in the use of a material and its physical properties was investigated for the case of writing with a ball-point pen containing water-based ink. Friction force microscopy (FFM) and a writing tester were used to measure friction in nano- and macro-scale, respectively, and their results were correlated with the smoothness of the act of writing. FFM allowed the determination of the optimum concentration of a specific lubricant to be incorporated in the ink to minimize the wear of the bearing material, although no significant relationship was observed with the writing tester. The nano-tribological measurements by FFM provide a significant means to understand the relationship between materials and the smoothness of the act of writing.

    DOI

  • パッシブ型DMFCの発電性能における電解質膜厚の影響

    清水 貴弘, モハメド モハメディ, 門間 聰之, 逢坂 哲彌

    Electrochemistry   74 ( 4 ) 326 - 331  2006年  [査読有り]

     概要を見る

    This paper describes characteristics of passive direct methanol fuel cell (DMFC), especially the effect of the thickness of electrolyte membrane. Cell performances were compared for membrane electrode assemblies (MEAs) made with Nafion 112, 115, and 117, whose typical thicknesses were 51 &micro;m, 127 &micro;m, and 183 &micro;m, respectively. The MEA made with Nafion 112 showed performance inferior to the other MEAs with thicker membranes. It appears that the mass of methanol permeated to the cathode through Nafion 112 was large, resulting in the loss of a large quantity of fuel, because its thickness was the smallest among the membranes used in this experiment. The observation of fuel level in the reservoir during open circuit stand indicated that most of the fuel was lost by methanol crossover and evaporation due to the rise in cell temperature. Also, the relationship between the concentration of methanol and the electrode potential at open circuit was investigated with a pseudo dynamic hydrogen electrode calibrated against an Ag/AgCl reference electrode. We found that it is essential to overcome the loss of fuel by methanol crossover and evaporation, which decreases the performance of the anode significantly even when the cell is in the stand-by mode.

    DOI CiNii

  • めっき法により作製したカスプコイル励磁型単磁極ヘッド

    田口香, 横島時彦, 内田勝, 高橋慎吾, 山川清志, 大内一弘, 逢坂哲彌

    日本応用磁気学会誌   30   353 - 356  2006年

  • Magnetic Properties and Domain Structure of SmCo5 Perpendicular Magnetization Films Prepared by Using a UHV Sputtering System

    J. Sayama, T. Asahi, Y. Yamashita, J. Ariake, K. Ouchi, T. Osaka

    J. Magn. Soc. Jpn.   30   423 - 428  2006年

  • 半導体技術を用いて作製した薄膜キャパシタの実装方法の検討

    渡辺充広, 小岩一郎, 小岩一郎, 本間英夫, 本間英夫, 足利欣哉, 照井誠, 白石靖, 安在憲隆, 大角卓史, 逢坂哲彌, 熊谷智弥, 佐藤善美, 橋本晃

    エレクトロニクス実装学会誌   9 ( 4 ) 282 - 288  2006年

     概要を見る

    Recently embedded passive devices have been actively investigated in an effort to save the surface area on printed circuit boards. About 60% of the area is occupied by the passive parts. As suggested in the previous paper, thin-film capacitors prepared using a semiconductor technology are one of the most promising candidates. In this paper, these film capacitors were embedded using two different methods. One was a conventional method using solder bump, and the other was a newly-developed method using conductive paste. The solder bump was formed using screen-printing following the wafer-level chip-size package (W-CSP) process. Since the solder bump is currently in practical use, high reliability should be expected. However, the chips formed by this method became thicker due to copper posts, solder bumps, and so on. The other method, using conductive paste, has the advantage of connection without any thickness problem. After embedding and solder heat tests, the capacitance of all the chips did not change, and the differences between before and after the tests are within the acceptable margin of error. However, in most cases, the loss (tan &delta;) increased slightly after the embedding and solder heat tests. In only one case did the solder heat test for an embedded BST capacitor chip connected by conductive paste show a lower tan &delta; value than that in the previous test. Based on all the results, the two methods used in this study are concluded to have a high potential for use in embedding methods. Further reliability tests are necessary for practical use.

    DOI CiNii J-GLOBAL

  • SmCo5垂直磁気ストレージ媒体の磁気的性質

    朝日透, 佐山淳一, 山下勇気, 逢坂哲彌

    日本応用磁気学会研究会資料   151   23 - 31  2006年

  • Magnetically induced orientation of mesochannels in 2D-hexagonal mesoporous silica films

    Yusuke Yamauchi, Makoto Sawada, Atsushi Sugiyama, Tetsuya Osaka, Yoshio Sakka, Kazuyuki Kuroda

    JOURNAL OF MATERIALS CHEMISTRY   16 ( 37 ) 3693 - 3700  2006年  [査読有り]

     概要を見る

    Mesoporous silica films with uniaxially oriented mesochannels were prepared by dip coating under a steady-homogeneous magnetic field parallel to a substrate. The effect of a strong magnetic field ( 12 Tesla) on the preparation of mesoporous silica films was systematically investigated by using two kinds of templates. When mesoporous silica films with a 2D-hexagonal structure were prepared by using an ionic CTAB ( hexadecyltrimethylammonium bromide)-based precursor solution, the in-plane XRD results of the films proved that the mesochannels were slightly oriented parallel to the magnetic field. When mesoporous silica films were prepared by using a non-ionic P123 ( polyethylene oxide - polypropylene oxide - polyethylene oxide triblock copolymer)- based precursor solution, the directional distribution of the mesochannels became narrow (FWHM was about 20 degrees). The use of large molecules such as triblock copolymers leads to successful magnetically induced orientation. The spatial orientations of the magnetically aligned mesochannels are elucidated by theta - 2 theta XRD, in-plane XRD, cross-sectional transmission electron microscopy (TEM), and high resolution scanning electron microscopy (HR-SEM).

    DOI

  • 軟磁性裏打ち層への無電解めっきCoNiFeBの適用-デュアル膜による低ノイズ化

    杉山敦史, 吉野正洋, 安達健, 菊池雄太, 朝日透, 逢坂哲彌, 逢坂哲彌

    電子情報通信学会技術研究報告   106 ( 142(MR2006 10-19) ) 53 - 58  2006年

    J-GLOBAL

  • Void-free trench-filling by electroless copper deposition using the combination of accelerating and inhibiting additives

    Madoka Hasegawa, Yutaka Okinaka, Yosi Shacham-Diamand, Tetsuya Osaka

    ELECTROCHEMICAL AND SOLID STATE LETTERS   9 ( 8 ) C138 - C140  2006年  [査読有り]

     概要を見る

    Electroless copper deposition was performed on submicrometer-trench patterned substrates with a bath containing 8-hydroxy-7-iodo-5-quinoline sulfonic acid (HIQSA) as an accelerating additive and polyethylene glycol (PEG) as an inhibiting additive. Void-free copper filling of trenches was achieved by the addition of both HIQSA and PEG at specific concentrations. Copper deposition rate measurements revealed that HIQSA accelerated the deposition only when it was added together with a very low concentration of PEG. The void-free filling is considered to have resulted from the significant acceleration brought about by HIQSA at the trench bottom, where the concentration of PEG is low. (c) 2006 The Electrochemical Society.

    DOI

  • Synthesis and characterization of mesoporous Pt-Ni (H-I-Pt/Ni) alloy particles prepared from lyotropic liquid crystalline media

    Yusuke Yamauchi, Sivakumar Sadasivan Nair, Toshiyuki Momma, Tetsu Ohsuna, Tetsuya Osaka, Kazuyuki Kuroda

    JOURNAL OF MATERIALS CHEMISTRY   16 ( 23 ) 2229 - 2234  2006年  [査読有り]

     概要を見る

    Mesoporous intermetallic Pt-Ni alloys with various compositions have been produced by the chemical reduction of two metal (nickel and platinum) salts dissolved in aqueous domains of a lyotropic liquid crystalline (LLC) phase. The mesoporous Pt-Ni alloys are small particles less than 100 nm in size and exhibit high specific surface areas higher than 40 m(2) g(-1). The ordering of the mesostructure decreases with increasing Ni content in the alloys. The high resolution scanning electron microscopic (HR-SEM) images show that the porous nanostructures are indeed formed over the entire area on the external surface of the particles. The lattice parameters of the alloys decrease with the increasing Ni content, implying the incorporation of Ni. The X-ray photoelectron spectroscopic (XPS) data show that Ni atoms in the alloys are thought to be in the zerovalent metallic state (Ni-0). The transmission electron microscopic (TEM) images prove that the lattice fringes assigned to a fcc structure are randomly oriented in the pore walls. The energy-dispersive X-ray spectroscopic (EDS) mapping shows uniform distribution of Ni atoms in the porous matrix. These results indicate the formation of mesoporous intermetallic Pt-Ni alloys.

    DOI

  • エレクトロニクセラミックス薄膜 磁気記録ヘッド用高Bs-CoFeめっき膜の開発

    逢坂哲彌, 杉山敦史, 横島時彦

    Materials Integration   19 ( 9 ) 39 - 45  2006年

    J-GLOBAL

  • 高密度用超小型磁気ヘッドの開発研究と実用化 (Development and Practical Use of the Electrodeposited CoFeNi Alloy Film for a High Density Magnetic Recording Head)

    T. Osaka, M. Takai, K. Ohashi, M. Saito, Y. Mizoshita, T. Koshikawa

    J. Surf. Finish. Soc. Jpn.   57   705 - 711  2006年

  • Unique microstructure of mesoporous Pt (H(I)-Pt) prepared via direct physical casting in lyotropic liquid crystalline media

    Y Yamauchi, T Momma, M Fuziwara, SS Nair, T Ohsuna, O Terasaki, T Osaka, K Kuroda

    CHEMISTRY OF MATERIALS   17 ( 25 ) 6342 - 6348  2005年12月  [査読有り]

     概要を見る

    Two-dimensional hexagonally ordered mesoporous Pt particles are prepared by Pt deposition in the aqueous domains of lyotropic liquid crystals (LLC) by chemical reduction with Zn powders. Interestingly, the framework is composed of connected nanoparticles of about 3 nm in size. Moreover, it is proved that the lattice fringes on the atomic crystallinity are coherently extended across the several nanoparticles in the framework. Such a framework composed of connected nanoparticles with extended crystallinity is uniquely created by using LLC as a soft template, which is not attainable by a traditional approach using mesoporous silica as a hard template. Through the structural identification, the formation mechanism of mesoporous Pt in the presence of LLC is thought to be continuous deposition of Pt nanoparticles from one nanoparticle.

    DOI

  • Fabrication of Mesoporous Pt inside Micrometer Channels via “Solvent-Evaporation-Mediated Direct Physical Casting”

    Y. Yamauchi, T. Momma, H. Kitoh, T. Osaka, K. Kuroda

    Electrochem. Commun.   7 ( 12 ) 1364 - 1370  2005年12月  [査読有り]

    DOI

  • Fabrication of patterned nanostructures with various metal species on Si wafer surfaces by maskless and electroless process

    N Kubo, T Homma, Y Hondo, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 834 - 837  2005年11月  [査読有り]

     概要を見る

    Maskless and electroless fabrication was demonstrated to form patterned nanostructures of various metal species, based upon the process previously developed by the authors. In this process, the metallic nanostructures were formed on the surface of clean, hydrogen terminated p-(1 0 0) Si wafer with pre-patterned nanoscopic defects, which were confirmed to possess higher activity for the reductive deposition reaction of the metal ion species. The deposition was achieved spontaneously and selectively at the defect sites on the wafer surface by immersing into dilute aqueous fluoride solution containing trace amount of metal ion species. By optimizing the formation condition of the patterned defects and composition of the solution, fabrication of patterned nanostructures of various metallic species such as Au, Ag, and Co, was achieved. Formation of the patterned nanostructures to 10 mu m(2) in extent, as well as control of the feature size of the deposits by adjusting the formation condition of the pattemed defects were also attempted. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Surface Modification of γ-Fe2O3 Nanoparticles with Aminopropylsilyl Groups and Interparticle Linkage with α,ω-Dicarboxylic Acids

    H. Iida, T. Nakanishi, T. Osaka

    Electrochim. Acta   51 ( 5 ) 855 - 859  2005年11月  [査読有り]

    DOI

  • Preparation and characterization of electroplated amorphous gold-nickel alloy film for electrical contact applications

    N Togasaki, Y Okinaka, T Homma, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 882 - 887  2005年11月  [査読有り]

     概要を見る

    A process for electroplating amorphous gold-nickel alloy with the atomic ratio of unity was developed. The plating bath was prepared by adding potassium cyanoaurate(I) into a known plating bath which produces amorphous nickel-tungsten alloy. At a sufficiently high gold concentration, the alloy deposit did not contain any tungsten. The amorphous nature of the Au-Ni alloy produced in the new bath was confirmed by using TEM and THEED. Hardness, resistivity, and contact resistance of this new alloy were determined, and the results are discussed for applications as an electrical contact material. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • All-wet fabrication process for ULSI interconnect technologies

    M Yoshino, Y Nonaka, J Sasano, Matsuda, I, Y Shacham-Diamand, T Osaka

    ELECTROCHIMICA ACTA   51 ( 5 ) 916 - 920  2005年11月  [査読有り]

     概要を見る

    "All-wet process" for fabrication of Cu wiring on a silicon chip was proposed as a novel ultra-large scale integration (ULSI) interconnect technology for integrated circuits (ICs) applications. Electroless-NiB film was deposited on SiO2/Si substrate modified by self-assembled-monolayer (SAM) activated with PdCl2. The NiB film formed by this method has highly uniform, with good adhesion to the substrate and with good diffusion barrier characteristics against Cu diffusion. Cu was electrodeposited directly on the electroless NiB film that acted as a seed layer. This was done without any conventional conductive or adhesive layer that is conventionally formed by physical vapor deposition (PDV). The thermal stability of electroless NiB layer as a barrier preventing copper from diffusing into the SiO2/Si substrate was evaluated by secondary ion mass spectroscopy (SIMS) and sheet resistance measurement at several annealing temperatures. It was confirmed that the electroless NiB film blocked Cu diffusion and kept the layer integrity under annealing temperatures of up to 400 degrees C for 30 min. The same process of electroless NiB was used for the capping layer that was also formed by "wet process", as the electroless NiB film deposited selectively onto a surface of Cu wiring was also applicable to a capping layer. We conclude that the proposed process is very promising for sub-100 nm technologies as it offers a variety of desirable properties: it has good step coverage while showing good barrier and seed layer properties. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • The study of antimicrobial activity and preservative effects of nanosilver ingredient

    KH Cho, JE Park, T Osaka, SG Park

    ELECTROCHIMICA ACTA   51 ( 5 ) 956 - 960  2005年11月  [査読有り]

     概要を見る

    In this study, we investigated the antimicrobial activity of silver nanoparticles (Ag-NPs) and platinum nanoparticles (Pt-NPs) aqueous solution, which were prepared using different stabilizer, such as sodium dodecylsulfate (SDS) and poly-(N-vinyl-2-pyrrolidone) (PVP), for Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) by measuring the minimum inhibitory concentration (MIC). Antimicrobial effect of Ag-NPs for S. aureus and E coli was investigated using cup diffusion method. The growth of Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria were inhibited by Ag-NPs. The MIC of Ag-NPs for S. aureus and E. coli were 5 and 10 ppm, respectively. But the Au-NPs stabilized with SDS did not show antimicrobial activity. Also, the Pt-NPs stabilized with PVP (or SDS) did not show antimicrobial activity for the test organisms. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • COST EFFECTIVE PLASTIC MICRO DIRECT METHANOL FUEL CELL (&micro;DMFC)

    Masanori Ishizuka, Takafumi Suzuki, Hidetoshi Shinohara, Hiroaki Houjou, Shinji Motokawa, Jun Mizuno, Toshiyuki Momma, Tetsuya Osaka, Shuichi Shoji

    Ninth International Conference on Miniaturized Systems for Chemistry and Life Sciences (&micro;TAS2005)     1212 - 1214  2005年10月

  • SmC0(5)-Based thin films with high magnetic Anisotropy for perpendicular magnetic recording

    J Sayama, K Mizutani, Y Yamashita, T Asahi, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   41 ( 10 ) 3133 - 3135  2005年10月  [査読有り]

     概要を見る

    An investigation was carried out on the effects of the addition of Cu and the thickness of the SmCo5-based thin film with perpendicular magnetic anisotropy upon its magnetic properties, with the aim of reducing the Cu/Ti underlayer thickness. As a result, the Cu/Ti underlayer thickness necessary to obtain the squareness ratio of unity was successfully reduced from 125 to 50 nm. Moreover, for the SmCo5 double-layered perpendicular magnetic recording media with a CoZrNb soft magnetic underlayer, the Cu/Ti underlayer thickness was further reduced to 35 nm. However, the magnetic cluster size and the values of coercivity and saturation field of the SmCo5 media were found to be too large. Thus, we recognized the need for adjusting the cluster size and the magnetic properties to appropriate values, and also the need for investigating the possibility of using this material as patterned media or thermally assisted recording media.

  • Three-dimensional microfabrication process using Bi electrodeposition for a highly sensitive X-ray imaging sensor

    H Sato, T Homma, H Kudo, T Izumi, T Osaka, S Shoji

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   584 ( 1 ) 28 - 33  2005年10月  [査読有り]

     概要を見る

    A microscale Bi electrodeposition process was developed and applied to the three-dimensional fabrication of a highly sensitive Xray imaging sensor, so called X-ray microcalorimeter, which has an array of sensing elements with a mushroom-shaped X-ray absorber. The composition and operating conditions for Bi electrodeposition were optimized and flat, smooth Bi deposits were obtained by applying additives such as diethylenetriamine pentaacetic acid (DTPA) and sodium n-dodecyl sulfate (SIDS). The results of ultraviolet (UV)-visible absorption spectroscopy and polarization curves from the Bi electrodeposition solution indicated that the formation of a DTPA-Bi(III) complex and an increase of overpotential for Bi electrodeposition in the presence of SDS improved the solution stability as well as the surface morphology of the deposited film. The mold for the mushroom-shaped microstructure array was formed from a single-layered photoresist coating by applying sequential exposure steps for the "stem" part and the "roof" part. The absorber array was successfully fabricated by the Bi electrodeposition into the mold, precise polishing, and mold removal processes. (c) 2004 Elsevier B.V. All rights reserved.

    DOI

  • Magnetic microstructure and noise property of electrolessly deposited CoNiFeB soft magnetic underlayer

    A Sugiyama, K Adachi, M Sakagami, M Yoshino, J Kawaji, T Asahi, T Tsumori, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   41 ( 10 ) 3163 - 3165  2005年10月  [査読有り]

     概要を見る

    A CoNiFeB soft magnetic underlayer (SUL) was prepared by electroless deposition using dimethylamineborane as the reducing agent. A 2.5-inch NiP/Al disk was used as the substrate, on which a Nil? nonmagnetic amorphous-layer was also electrolessly deposited. The coercivity H, of as-deposited CoNiFeB films in the direction parallel to the surface exhibited a convex-parabolic dependency on the film thickness. The in-plane M-H loops and the two-dimensional Kerr effect images of the CoNiFeB film showed a nearly isotropic character with H, of 25 Oe and no marked domain boundaries. From magnetic force microscope measurements, we confirmed that these behaviors resulted from the formation of striped magnetic domains caused by slightly perpendicular magnetic anisotropy of SUL. As far as the noise characteristics are concerned, dc noise was increased with H-c, while spike noise was suppressed.

    DOI

  • Development of high-performance magnetic thin film for high-density magnetic recording

    T Osaka, T Asahi, J Kawaji, T Yokoshima

    ELECTROCHIMICA ACTA   50 ( 23 ) 4576 - 4585  2005年08月  [査読有り]

     概要を見る

    This overview describes our recent study on fabrication processes of high-performance magnetic thin films for high-density magnetic recording. Particularly, it is emphasized that electrochemical processes play significant roles in fabricating the recording heads and media used for the high-density recording. Newly developed electrodeposition methods for fabricating CoNiFe and CoFe soft magnetic thin films with high-saturation magnetic flux density are shown, and the key points for obtaining them are highlighted. It is summarized that the effective seedlayers for the sputter-deposited [Co/Pd],, multilayered films, which are promising candidates as magnetic recording media with strong perpendicular magnetic anisotropy for the high-density magnetic recording, have been developed. We have recently succeeded in developing the novel electroless deposition methods for the CoNiFe-based soft magnetic underlayers of double-layered perpendicular magnetic recording media and for the patterned medium consisting of CoNiP magnetic nano-dot arrays, which are briefly explained. (C) 2005 Elsevier Ltd. All rights reserved.

    DOI

  • Changes of electro-deposited Sn-Ni alloy thin film for lithium ion battery anodes during charge discharge cycling

    H Mukaibo, T Momma, T Osaka

    JOURNAL OF POWER SOURCES   146 ( 1-2 ) 457 - 463  2005年08月  [査読有り]

     概要を見る

    We have reported in our past work that dectrodeposited Sn-Ni alloy with different composition show considerably different performance as anode materials for Li-ion batteries, and the performance was remarkably well (ca. 650mAh g(-1) at 70th cycle) when the composition was controlled to Sn62Ni38, In this work, structural changes during charge discharge cycling of Sn-Ni alloy with different composition were investigated to evaluate their differences in the cycle performance. From the XRD result, Ni3Sn4 phase was the main phase seen in Sn62Ni38, and its reversible reactivity with Li was confirmed. We suggest that this is the key phase for its high capacity and lengthened cycle life. From Sn54Ni46, which showed low capacity, only a metastable phase close to the structure of SnNi was confirmed. The results from Sn84Ni16 indicated the presence of pure Sn and Sn rich metastable phase would lead to relatively fast electrode degradation. (c) 2005 Elsevier B.V. All rights reserved.

    DOI

  • Organosilane self-assembled monolayer-modified field effect transistors for on-chip ion and biomolecule sensing

    D Niwa, K Omichi, N Motohashi, T Homma, T Osaka

    SENSORS AND ACTUATORS B-CHEMICAL   108 ( 1-2 ) 721 - 726  2005年07月  [査読有り]

     概要を見る

    Field effect transistors (FETs) modified with various functional monolayers, such as organosilane monolayer, were formed on the identical substrate by precise control of the fabrication processes. The devices showed a typical transistor property with a good stability in aqueous solutions. The amino monolayer-modified FET acted as an ion sensitive FET with a good pH sensitivity of 58 mV/pH, and the perfluoro-alkyl monolayer-modified FET worked as a reference device. Moreover, the device with enzyme immobilized onto amino modified gate electrode enabled to detect trace concentration (10(-9) to 10(-6) M) of urea with a high sensitivity of 64 mV/decade. These monolayer-modified devices were expected to be applied as working and reference electrodes for on-chip ion and biosensing. (c) 2004 Elsevier B.V. All rights reserved.

    DOI

  • Metallization on 3-D microstructures using spray coating for high performance micro direct methanol fuel cell (uDMFC)

    Hiroaki Houjou, Shinji Motokawa, Masanori.Ishizuka, Jun Mizuno, Toshiyuki Momma, Tetsuya Osaka, Shuichi Shoji

    Digest of Technical Papers, The 13th International Conference on Solid-State Sensors, Actuators and Microsystems     1437 - 1440  2005年06月

    DOI

  • High efficiency electrochemical immuno sensors using 3D comb electrodes.

    Nobuo Honda, Masashi Inaba, Takashi Katagiri, Shuichi Shoji, Hirotaka Sato, Takayuki Homma, Tetsuya Osaka, Mikiko Saito, Jun Mizuno, Yasuo Wada

    Biosensors & bioelectronics   20 ( 11 ) 2306 - 9  2005年05月  [査読有り]  [国際誌]

     概要を見る

    To realize highly sensitive electrochemical immunoassays, a micro-fabricated three-dimensional (3D) electrode was fabricated and applied to enzyme immuno assay based on production of a redox species. The dimensions of the electrodes are 10 microm in width and 30 microm in height, with 20 microm spacing in between, and the 30 pairs of anode and cathode electrodes made up a single sensor. This structure lead to enhancement of the electrochemical reaction, nearly 100% of trap ratio of redox species. It can be applied to highly sensitive enzyme immuno sensing based on p-aminophenylphosphate (PAPP). Applicability of this technique to the immuno assay for one of the clinical diagnostic marker proteins (alpha-fetoprotein; AFP) from 6 to 500 ng/mL was demonstrated.

    DOI PubMed

  • A micro direct methanol fuel cell using platinum and platinum-ruthenium electroplated microchannel electrodes

    S Motokawa, M Mohamedi, T Momma, S Shoji, T Osaka

    ELECTROCHEMISTRY   73 ( 5 ) 346 - 351  2005年05月  [査読有り]

     概要を見る

    This work studied the design, fabrication, and performance evaluation of a novel micro direct methanol fuel cell (mu-DMFC). A mu-DMFC of 0.018 cm(2) active area was prepared using a series of fabrication steps from micromachined silicon wafer including photolithography, deep reactive ion etching, and electron beam deposition. The novelty of this structure is that we have integrated the anodic and cathodic micro-channels arranged in plane onto a single silicon substrate. This architecture eliminates the need for the membrane electrode assembly (MEA) used in traditional polymer electrolyte-based fuel cells. Another original aspect is the successful electroplating of Pt and Pt-Ru catalysts in the microchannels. In addition, quasi-reference electrodes could be built in the prototype cell. The experimental trials were to verify the feasibility of this novel structure on basis of MEMS technology. The fuel and oxidant were supplied to the unit cell at a rate of 10 mu L/min. Preliminary test results were able to confirm that this new concept of mu-DMFC generates electricity. At ambient temperature under atmospheric pressure, the maximum power density was 0.44 mW/cm(2) at 3 mA/cm(2) with Pt anode catalyst, while the maximum power density reached 0.78 mW/cm(2) at 3.6 mA/cm(2) for cell with Pt-Ru anode catalyst.

  • μDMFC用マイクロチャネル電極作製条件の考察 (Fabrication Process in Fabrication of Micro Channel Electrodes for μ-DMFC)

    S. Motokawa, H. Obata, M. Mohamedi, T. Momma, S. Shoji, T. Osaka

    Electrochemistry   73 ( 5 ) 352 - 355  2005年05月  [査読有り]

  • Electrochemical formation process of Si macropore and metal filling for high aspect ratio metal microstructure using single electrolyte system

    H Sato, T Homma, K Mori, T Osaka, S Shoji

    ELECTROCHEMISTRY   73 ( 4 ) 275 - 278  2005年04月  [査読有り]

     概要を見る

    Array of macropores filled with electrodeposited Ni was formed on Si substrate applying the novel process, which consists of Si electrochemical etching and Ni electrodeposition using single electrolyte. This electrolyte contained HF as Si dissolution agent and Ni(OSO2NH2)(2) 4H(2)O as Ni2+ source for Ni electrodeposition. First, array of macropores was formed on Si (100) substrate by applying anodic current. The formation was carried out area-selectively by applying Au/Cr micropatterns formed at the back side surface of the substrate as the shade mask, which enables to control the illumination condition for hole generation condition. Subsequently, the applied bias was switched to cathodic current, and Ni was filled into c.a. 200 mu m depth Si macropores without void-like defects. Array of Ni needles with smooth surface was formed area-selectively by removal of the Si region of the Ni filled specimen with 25 wt% tetramethylammonium hydroxide (TMAH) aqueous solution at 90 degrees C.

  • Surface conductivity in methyl-monolayer/Si heterojunction structure in the presence of water

    D Niwa, H Fukunaga, T Homma, T Osaka

    CHEMISTRY LETTERS   34 ( 4 ) 520 - 521  2005年04月  [査読有り]

     概要を見る

    The heterojunction between Si(111) semiconductor and the well-ordered methyl monolayer was formed to investigate the channel conduction at the surface in the heterojunction structure. With the presence of water, the methyl monolayer/Si heterojunction structure showed switching action with a high trance-conductance of 2.8 x 10(-3) A/V under the application of bias voltage, while without the presence of water, such a switching behavior was not observed. The methyl monolayer/Si heterojunction structure worked as a p-type mode with the presence of water at the modified surface.

  • Area-selective formation of macropore array by anisotropic electrochemical etching on an n-Si(100) surface in aqueous HF solution.

    Takayuki Homma, Hirotaka Sato, Kentaro Mori, Tetsuya Osaka, Shuichi Shoji

    The journal of physical chemistry. B   109 ( 12 ) 5724 - 7  2005年03月  [査読有り]  [国際誌]

     概要を見る

    A photoassisted anodization process to fabricate arrays of uniform and straight macropores at selected areas of a Si wafer surface was developed. The front- and backside surfaces of n-type Si(100) wafers were coated with a thin Si(3)N(4) layer, and the frontside layer was micro-patterned using photolithography and reactive ion etching to form an array of microscopic openings at selected areas. The inverted pyramid-shape micropits were formed at these openings by anisotropic etching using aqueous KOH solution; these pits act as the initiation sites for the anodization to form macropores. The electrochemical etching was carried out in aqueous HF solution under illumination from the backside of the wafer, on which Au/Cr electric contact was formed following removal of the Si(3)N(4) layer. To improve the uniformity of the formation condition of the macropores at the selected area, holes were area-selectively generated by controlling the illumination condition during the anodization. For this, micropatterns were formed on the Au/Cr layer at the backside surface, which were aligned to those at the frontside surface. The parameters, such as HF concentration, current density, and wafer thickness, i.e., hole diffusion length, were optimized, and the arrays of uniform and high-aspect-ratio macropores were formed at the selected area of the domain at the silicon surface.

    DOI PubMed

  • Fabrication of amino silane-coated microchip for DNA extraction from whole blood.

    Takahito Nakagawa, Tsuyoshi Tanaka, Daisuke Niwa, Tetsuya Osaka, Haruko Takeyama, Tadashi Matsunaga

    Journal of biotechnology   116 ( 2 ) 105 - 11  2005年03月  [国際誌]

     概要を見る

    A simple microchip device for DNA extraction was constructed based on electrostatic interactions between surface amine groups and DNA. Microchannel was fabricated on silicon wafer by photolithography and coated with 3-aminopropyltriethoxysilane (APTES) or 3-[2-(2-aminoethylamino)-ethylamino]-propyltrimethoxysilane (AEEA) to introduce amine groups on the surface. Determination of the number of surface amine groups and optimization of DNA capture condition were demonstrated to characterize the microchip. Capacities of capturing DNA were approximately 97 ng/cm2 in APTES and 194 ng/cm2 in AEEA modified microchips, respectively. The amount of DNA captured in the microchip increased depending on surface amine density. Furthermore, DNA extraction using amine-coated microchip from whole blood was examined. Quantification of DNA and proteins in washing or eluting fraction indicates that proteins were removed at washing steps and only DNA was effectively eluted by changing alkalinity of buffer from pH 7.5 to 10.6. The amount of DNA extracted from whole blood was approximately 10 ng and its recovery ratio was 27-40%. Performance of PCR for the eluted fraction indicates that DNA extracted from whole blood was well purified using amine-coated microchip.

    PubMed

  • Microstructure of a Co/Pd multilayered perpendicular recording medium with Pd seeds prepared by electrochemical process

    M Tanaka, J Kawaji, K Kimura, T Asahi, T Homma, S Matsunuma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   188 - 192  2005年02月  [査読有り]

     概要を見る

    Effects of the Pd seeds formed by an electrochemical process on the microstructures of Co/Pd multilayered perpendicular recording media were investigated. By immersing a CoZrNb soft magnetic underlayer (SUL) into PdCl2 aqueous solution, island-like Pd clusters were deposited on the SUL, resulting from the electrochemical substitution reaction. Transmission electron microscopic observations revealed that the columnar Co/Pd multilayered grains with clear boundaries grew on the SUL with the Pd clusters. The clear grain boundaries, where the densities of Co and Pd elements were low, were thought to cause the magnetic exchange decoupling between the Co/Pd grains, leading to an increase of perpendicular coercivity and a decrease of magnetic cluster size of Co/Pd multilayered film. Consequently, lower medium noise was obtained for the Co/Pd multilayered medium with the Pd clusters than for that with a sputter-deposited Pd seedlayer. From these investigations, it was clarified that the SUL surface with Pd clusters provided the effective nucleation sites for a well-defined Co/Pd multilayered grain growth. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

  • Magnetic properties and microstructure of SmCo5 thin film with perpendicular magnetic anisotropy

    J Sayama, K Mizutani, T Asahi, J Ariake, K Ouchi, S Matsunuma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   239 - 244  2005年02月  [査読有り]

     概要を見る

    SmCo5 thin films with Cu seedlayer exhibiting perpendicular magnetic anisotropy were studied. The perpendicular magnetic anisotropy was enhanced using the Sm-Co layer formed by laminating Co and Sm sub-layers alternately. The Co/Sm laminate structure promoted the crystallization Of SmCo5 and the preferred orientation of its c-axis. The perpendicular magnetic anisotropy was further improved by suppressing the surface roughness of the Cu seedlayer. The SmCo5 thin film prepared in this study possesses an adequate corrosion resistance when judged by an electrochemical analysis. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

  • Area selective formation of magnetic nanodot arrays on Si wafer by electroless deposition

    J Kawaji, F Kitaizumi, H Oikawa, D Niwa, T Homma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   245 - 249  2005年02月  [査読有り]

     概要を見る

    Electroless deposition process for fabricating magnetic dot arrays was studied. A patterned Si substrate with a SiO2 resist was produced by processes combined with electron-beam lithography and reactive ion etching. By immersing the patterned Si substrate into a CoNiP electroless deposition bath, CoNiP was deposited only into the patterned pores, demonstrating a satisfactory area selectivity of the deposition. Excellent uniformity on the CoNiP deposition into the patterned pores with diameter less than 100 nm and high aspect ratio (&gt; 5) was achieved by applying chemical activation processes using a Pd solution prior to the deposition. The CoNiP dot arrays exhibited higher perpendicular squareness ratio than that of CoNiP continuous film and showed a clear magnetization state at DC-magnetized state, which originated from the shape anisotropy caused by high aspect ratio of the dot patterns. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

  • Electroless-deposited soft magnetic underlayer on silicon disk substrate for double-layered perpendicular magnetic recording media

    T Osaka, T Asahi, T Yokoshima, J Kawaji

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   292 - 297  2005年02月  [査読有り]

     概要を見る

    A novel fabrication process of a soft magnetic underlayer (SUL) for a double-layered perpendicular magnetic recording medium was presented. The CoNiFeB SUL was deposited on a silicon disk substrate using an electroless deposition. The Ni seed layer for the electroless deposition was prepared by an electrochemical process. The surface of the deposited SUL was subjected to a chemical mechanical polishing to be flattened, and R-a value of the SUL was less than 0.4 nm. A magnetic domain structure greatly depended on the electroless deposition condition. Particularly, the control of an agitation speed during electroless deposition is much effective for the suppression of distinct domain walls appearing in CoNiFeB underlayers. (C) 2004 Published by Elsevier B.V.

    DOI

  • Effect of N-2 additive gas during sputtering on magnetic properties and microstructure of CoB/Pd multilayered media

    T Asahi, M Tanaka, J Sayama, J Kawaji, S Matsunuma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   287   199 - 203  2005年02月  [査読有り]

     概要を見る

    Effects of N-2 additive gas and/or substrate heating during the sputtering of [CoB/Pd](20) multilayered films on the magnetic properties and microstructure were investigated. The [CoB/Pd](20) film fabricated at 20degreesC by adding N-2 gas during sputtering possessed the finest grain size and the smallest magnetic cluster size among media fabricated in this study although the film sputter-deposited at 260 degreesC by adding N-2 gas exhibited the weakest intergranular exchange coupling. It was revealed that the double-layered perpendicular magnetic recording medium that consisted of the [CoB/Pd](20) film fabricated at 20degreesC by adding N-2 gas exhibited the highest signal-to-noise ratio in the read write characteristics. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

  • 新しい研究創造と電気化学会

    T. Osaka

    Electrochemistry   73   267 - 268  2005年

  • Electrochimica Acta: Preface

    T. Osaka, T. Homma

    Electrochim. Acta   51   773 - 774  2005年

  • Structural and morphological moditications of a nanosized 62 atom percent Sn-Ni thin film anode during reaction with lithium

    H Mukaibo, T Momma, M Mohamedi, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   152 ( 3 ) A560 - A565  2005年  [査読有り]

     概要を見る

    Nanosized electrodeposited 62 atom % Sn-Ni alloy was tested to highlight the effects of volume changes on the cycling life of the electrode during lithiation and delithiation. X-ray diffraction showed that the Ni3Sn4 was the main phase of the as-deposited alloy. A unique feature of the 62 atom % Sn-Ni is that it exhibited a capacity recovery upon cycling. When cycled galvanostatically, the Sn62Ni38 offers low capacity fade while reversibly incorporating lithium up to 600 mAh/g. At the first charge LiSn alloy phases are formed. This led to volume expansion of the electrode causing the formation of cracks. At the following cycles the Ni3Sn4 phase was restored and preserved over extensive cycling revealing the reversibility of the reaction between Ni3Sn4 and Li+. As to the reasons of the capacity recovery noticed with this alloy, scanning electron microscopy images provided evidence of modifications of the surface condition accompanying a volume change during cycling. The chemical diffusion coefficient (D-Li) value determined from electrochemical impedence spectroscopy measurements during lithium insertion was within 10(-9) to 10(-10) 10 cm(2) S-1. (c) 2005 The Electrochemical Society. [DOI: 10.1149/1.1856913] All rights reserved.

  • Deposition behavior of Ni on Si(100) surfaces in an aqueous alkaline solution

    D Niwa, T Homma, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   152 ( 2 ) C54 - C59  2005年  [査読有り]

     概要を見る

    The spontaneous deposition of Ni on Si(100) surface in aqueous alkaline solution was investigated under various conditions. In a 0.1 M NiSO4 solution containing 0.2-0.5 M (NH4)(2)SO4, the optimum pH for the homogeneous deposition at 60-80degreesC at each set of operating conditions shifted in the high-pH direction as both (NH4)2SO(4) concentration and the operating temperature were decreased. The potential at which the deposition terminates and the deposition duration were determined from electrochemical open-circuit potential profiles. The different behaviors, observed at different pH levels, are discussed in terms of these potential measurements. Ultraviolet-visible absorption spectra of various Ni solutions used indicated that the deposition behavior was strongly affected by the composition of the Ni complex and the reactivity of Si surface. The deposition reaction efficiently proceeded when the Ni complex was present in a specific composition. The anodic reaction rate of Si decreased steeply when the solution temperature was lowered. The optimum condition for the homogeneous deposition was greatly affected by the reactivity of the Si surface rather than the composition of the complex, the higher pH favoring the overall reaction. (C) 2004 The Electrochemical Society. All rights reserved.

  • Effects of additives on copper electrodeposition in submicrometer trenches

    M Hasegawa, Y Negishi, T Nakanishi, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   152 ( 4 ) C221 - C228  2005年  [査読有り]

     概要を見る

    Effects of the conventional bath additives [chloride ions (Cl-), poly(ethylene glycol) (PEG), bis(3-sulfopropyl)disulfide(SPS), and Janus green B (JGB)] used in the damascene process on the filling of submicrometer trenches with electrodeposited copper were investigated by electrochemical polarization measurement and cross-sectional microscopy. The combination of Cl- and PEG inhibited copper deposition in the areas of opening of the trenches, while SPS accelerated it at the bottom. Polarization curves showed that the degree of acceleration of copper deposition by SPS increases with the concentration of SPS. This SPS concentration- dependent acceleration accounts for the observed bottom- up growth. The addition of JGB inhibited copper deposition at the later stages of the filling process, leading to the suppression of the overfill phenomenon, although the bottom-up growth was also inhibited at high JGB concentrations. Bath agitation significantly enhanced the inhibition effect of JGB on the overfill phenomenon, without disturbing the bottom-up growth. (c) 2005 The Electrochemical Society. All rights reserved.

    DOI

  • Synthesis and characterization of mesostructured alloys with controlled compositions

    Y Yamauchi, SS Nair, T Yokoshima, T Momma, T Osaka, K Kuroda

    NANOPOROUS MATERIALS IV   156   457 - 464  2005年  [査読有り]

     概要を見る

    This article summarizes our recent studies on the synthesis of highly ordered mesostructured Ni and Ni-Co alloys by electroless deposition method. We propose that a careful control over the nucleation as well as the grain growth by reducing agents can lead to the fort-nation of a highly ordered mesostructure from a lyotropic liquid crystalline phase (LLC). The sophisticated combination of dimethylamineborane (DMAB) and sodium borohydride (SBH) in an electroless plating bath produces highly ordered mesoporous Ni, and this technique can be extended to prepare a series of mesostructured Ni-Co alloys with various compositions. The composition of the alloys can be varied easily by controlling the metal compositions in the plating bath.

  • Highly ordered mesostructured Ni particles prepared from lyotropic liquid crystals by electroless deposition: the effect of reducing agents on the ordering of mesostructure

    Y Yamauchi, T Momma, T Yokoshima, K Kuroda, T Osaka

    JOURNAL OF MATERIALS CHEMISTRY   15 ( 20 ) 1987 - 1994  2005年  [査読有り]

     概要を見る

    Mesostructured Ni and Co particles are formed by metal deposition in the aqueous domains of lyotropic liquid crystals (LLC) using different reducing agents. We have investigated the role of reducing agents in metal deposition for the synthesis of highly-ordered mesoporous metals by electroless deposition. Slow metal deposition accompanied by the autocatalytic reaction of dimethylamineborane ( DMAB), caused by the combination of Ni and DMAB, led to the formation of highly-ordered mesostructured Ni.

    DOI

  • ウェットプロセスによる磁性ナノドットパターン膜形成の試み

    本間敬之, 川治純, 丹羽大介, 及川英幸, 亀尾亮平, 逢坂哲彌

    IEICE Tech. Rep.   MR2005-21   31 - 36  2005年

  • Direct physical casting of the mesostructure in lyotropic liquid crystalline media by electroless deposition

    Y Yamauchi, T Yokoshima, T Momma, T Osaka, K Kuroda

    ELECTROCHEMICAL AND SOLID STATE LETTERS   8 ( 10 ) C141 - C144  2005年  [査読有り]

     概要を見る

    Nickel particles with a highly ordered mesostructure are prepared by electroless deposition of Ni salts dissolved in aqueous domains of lyotropic liquid crystalline (LLC) media made of a nonionic surfactant (Brij 56) at a high concentration. The mesostructure inside the Ni particles after the electroless deposition has a macroscopic alignment of mesochannels derived from the LLC media which are composed of crystalline domains on a micrometer scale. It is proved that the arrangements of rod-like self-assemblies in the LLC indeed work as a scaffold to direct the grain growth of Ni. This is the first direct evidence of direct physical casting from LLC. (c) 2005 The Electrochemical Society.

    DOI

  • Preparation and Characterization of TiO2 Filled Sulfonated Poly(Ether Ether Ketone) Nanocomposite Membranes for Direct Methanol Fuel Cells

    H. Kim, P. Kalappa, W. Son, J. Park, T. Osaka, H. Kim, J. Hong, S. Park

    KIEE Inter. Trans. on EA   5-C   165 - 170  2005年

  • Preparation and Electrochemical Characteristics of CNFs/DAAQ Electrode for Energy Storage

    H. Kim, H. Kim, W. Choi, T. Osaka, S. Park

    KIEE Inter. Trans. on EA   5-C   171 - 175  2005年

  • 半導体技術を用いた薄膜キャパシタ受動部品の作製

    小岩 一郎, 橋本 晃, 足利 欣哉, 照井 誠, 白石 靖, 安在 憲隆, 大角 卓史, 逢坂 哲彌, 熊谷 智弥, 佐藤 善美

    エレクトロニクス実装学会誌   8 ( 6 ) 517 - 522  2005年  [査読有り]

     概要を見る

    Recently, there has been a strong demand for smaller electronic devices with improved. About 60% of the area is occupied by the passive components for packaging. To overcome this limitation, an embedded capacitor was prepared using semiconductor technologies and the process technology of ferroelectric random access memories. Eight micro capacitors were prepared in a 2 mm2 area. Two types of high dielectric constant material were used. The first one is Barium Strontium Titanium oxide (BST) for focusing high capacitance with high loss, and the other is Strontium Bismath Tantalum oxide (SBT) for focusing low loss with medium capacitance. The micro capacitor with BST, whose dielectric constant (&epsilon;) was 350, showed about 3200pF at 0 bias and its loss, tan &delta;, was a little lower than 0.01. The one with SBT, whose &epsilon; was 51, showed 470 pF, and its tan &delta; was about 0.001. It is concluded that micro capacitors with the requested characteristics were prepared.

    DOI CiNii

  • Picoliter Volume Glass Tube Array Fabricated by Si Electrochemical Etching Process

    H. Sato, T. Homma, K. Mori, T. Osaka, S. Shoji

    Electrochim. Acta   51   844 - 848  2005年

  • Density Functional Theory Study on the Oxidation Mechanisms of Aldehydes as Reductants for an Electroless Deposition Process

    T. Shimada, K. Sakata, T. Homma, H. Nakai, T. Osaka

    Electrochim. Acta   51   906 - 915  2005年

  • Characterization of Strained Silicon Wafer Surface by Density Functional Theory Analysis

    K. Sakata, T. Homma, H. Nakai, T. Osaka

    Electrochim. Acta   51   1000 - 1003  2005年

  • Incident Angle Dependence of MCD at the Dy M5-edge of Perpendicular Magnetic DyxCo100-x Films

    A. Agui, M. Mizumaki, T. Asahi, J. Sayama, K. Matsumoto, T. Morikawa, T. Matsushita, T. Osaka, Y. Miura

    J. Alloys Compd.   408-412   741 - 745  2005年

  • 精密電解めっき法による高飽和磁束密度軟磁性薄膜の開発 (Electrodeposition of Soft Magnetic Thin Films with High Saturation Magnetic Flux Density)

    T. Osaka, T. Yokoshima

    J. Magn. Soc. Jpn.   29   59 - 65  2005年

  • めっき磁気記録材料の発展を振り返って(Overview of Development of Magnetic Recording Materials Using Plating Technology)

    T. Osaka

    IEICE Tech. Rep.   105   27 - 32  2005年

  • 電気化学ナノテクノロジーの新展開 (New Approach on Electrochemical Nanotechnology)

    T. Osaka, J. Sayama

    J. Surf. Finish. Soc. Jpn.   56   723 - 729  2005年

  • Platinum thin film with a highly ordered mesostructure by contact plating

    Y Yamauchi, T Yokoshima, T Momma, T Osaka, K Kuroda

    CHEMISTRY LETTERS   33 ( 12 ) 1576 - 1577  2004年12月  [査読有り]

     概要を見る

    By a contact plating technique using a galvanic reaction between Al and An in the presence of Pt complex, we have for the first time succeeded in the formation of a highly ordered meso-structured Pt film on a An surface by reduction of Pt ions in the presence of lyotropic liquid crystals.

  • Thin films of SmCo5 with very high perpendicular magnetic anisotropy

    J Sayama, K Mizutani, T Asahi, T Osaka

    APPLIED PHYSICS LETTERS   85 ( 23 ) 5640 - 5642  2004年12月  [査読有り]

     概要を見る

    Thin films of SmCo5 with extraordinarily high perpendicular magnetic anisotropy were prepared by introducing a Cu/Ti dual underlayer and controlling the substrate temperature during the sputter deposition. Under optimized conditions, the magnetic anisotropy constant reached 4.0x10(7) erg/cm(3), and the coercivity and the remanence ratio in the direction perpendicular to the film surface were 12.0 kOe and unity, respectively. The high perpendicular magnetic anisotropy is attributed to the high degree of preferred orientation of the c axis; the full width at half maximum in the rocking curve of SmCo5(002) reflection was 3.1degrees. (C) 2004 American Institute of Physics.

    DOI

  • Detection of biomolecular interaction between biotin and streptavidin on a self-assembled monolayer using magnetic nanoparticles.

    Atsushi Arakaki, Sho Hideshima, Takahito Nakagawa, Daisuke Niwa, Tsuyoshi Tanaka, Tadashi Matsunaga, Tetsuya Osaka

    Biotechnology and bioengineering   88 ( 4 ) 543 - 6  2004年11月  [査読有り]  [国際誌]

     概要を見る

    For developing a magnetic bioassay system, an investigation to determine the presence of a specific biomolecular interaction between biotin and streptavidin was done using magnetic nanoparticles and a silicon substrate with a self-assembled monolayer. Streptavidin was immobilized on the magnetic particles, and biotin was attached to the monolayer-modified substrate. The reaction of streptavidin-modified magnetic particles on the biotin-modified substrate was clearly observed under an optical microscope. The magnetic signals from the particles were detected using a magnetic force microscope. The results of this study demonstrate that the combination of a monolayer-modified substrate with biomolecule-modified magnetic particles is useful for detecting biomolecular interactions in medical and diagnostic analyses.

    PubMed

  • Design and fabrication of pumpless small direct methanol fuel cells for portable applications

    T Shimizu, T Momma, M Mohamedi, T Osaka, S Sarangapani

    JOURNAL OF POWER SOURCES   137 ( 2 ) 277 - 283  2004年10月  [査読有り]

     概要を見る

    This work studied the design, fabrication, and performance evaluation of a 36 cm(2), passive, air-breathing, room-temperature, direct methanol fuel cell (DMFC). The cell is completely passive with no external pumps or other ancillary devices. It takes oxygen from the surrounding air, and the methanol solution is stored in a built-in reservoir. The fuel cell runs successfully with methanol concentration ranging from 0.5 to 4 M. It produced a power density of 11 mW cm(-2) reached with 4 M methanol at current densities as high as 36 mA cm(-2) and at a voltage of 0.3. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

  • 携帯機器用直接メタノール型燃料電池スタックの開発 (Development of a Passive Direct Methanol Fuel Cell Stack for Portable Applications)

    T. Shimizu, M. Mohamedi, T. Momma, T. Osaka

    Electrochemistry   72 ( 9 ) 637 - 640  2004年09月  [査読有り]

  • Prototype of the high sensitive X-ray microcalorimeter for X-ray imaging

    H Kudo, T Nakamura, T Arakawa, S Ohtsuka, T Izumi, S Shoji, H Sato, H Kobayashi, K Mori, T Homma, T Osaka, K Mitsuda, NY Yamasaki, R Fujimoto, N Iyomoto, T Oshima, K Futamoto, Y Takei, T Ichitsubo, T Fujimori, Y Ishisaki, U Morita, T Koga, K Sato, T Ohashi, Y Kuroda, M Onishi, K Otake, F Beppu

    SENSORS AND ACTUATORS A-PHYSICAL   114 ( 2-3 ) 171 - 175  2004年09月  [査読有り]

     概要を見る

    An X-ray microcalorimeter is a high performance X-ray spectrometer that can achieve both high energy resolution of conventional wavelength dispersive spectrometers (WDS) and high quantum efficiency of energy dispersive spectrometers (EDS). The energy resolution can be theoretically improved to about 1 eV, which value is 120 times better than that of conventional Si(Li) spectrometers and nearly 100% of quantum efficiency can be achieved using microabsorbers. In order to realize high energy-resolution X-ray imaging using an array of X-ray microcalorimeters, two types of 2 x 2 X-ray microcalorimeter arrays were fabricated and tested. Using an X-ray microabsorber so-called "mushroom-shaped" X-ray microabsorber, the filling factor was enhanced to about 70%. We tested Sn and Bi as an X-ray microabsorber. Consequently, the Sn absorber degrades the energy resolution because of the long time constant. This problem was cleared using the Bi microabsorber. The achievable energy resolution was also investigated. As a result, the energy resolution of 6.3 eV was obtained with the test device. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

  • Preparation of high-B-s, Co-Fe soft magnetic thin films by electrodeposition

    T Yokoshima, K Imai, T Hiraiwa, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   40 ( 4 ) 2332 - 2334  2004年07月  [査読有り]

     概要を見る

    Co-Fe soft magnetic thin films with high-saturation magnetic flux density B-s were prepared by electrodeposition. The B-s value of the Co-Fe alloy films deposited from the conventional cell system is lower than that of bulk alloys. With the use of a separated compartment dual cell system, the B-s value of the Co-Fe alloy films was reached the same as that of bulk alloy. The coercivity H-c values were higher than 12 Oe; however, the H-c value could be lowered to 8 Oe by annealing in vacuum with an applied magnetic field. It is suggested that decreasing H-c of the films by annealing is caused by relaxation of lattice distortion. In addition, the high-B-s Co-Fe films show good corrosion resistance.

    DOI

  • Novel soft magnetic underlayer for double-layered perpendicular magnetic recording media: Electroless-deposited films of CoNiFe-based alloy

    T Asahi, T Yokoshima, J Kawaji, T Osaka, H Ohta, M Ohmori, H Sakai

    IEEE TRANSACTIONS ON MAGNETICS   40 ( 4 ) 2356 - 2358  2004年07月  [査読有り]

     概要を見る

    We present a novel fabrication process for a soft magnetic underlayer of a CoNiFe-based alloy for a double-layered perpendicular magnetic recording medium using electroless deposition. The electroless-deposited CoNiFeP film is focused on as the soft magnetic underlayer. The CoNiFeP soft magnetic underlayer was fabricated on a 2.5-in glass disk with a Ni/Ti seed layer and the substrate was rotated in an electroless deposition bath under a magnetic field applied. The CoNiFeP underlayer as deposited was flattened using a chemical mechanical polishing, and the film thickness thereby became about 1 mum. The in-plane coercivity and saturation magnetic flux density of the CoNiFeP underlayer were less than 2 Oe and more than 12 kG, respectively. The magnetic domain observation revealed that the CoNiFeP underlayer electroless deposited under the magnetic field applied and the substrate rotated exhibited no marked domain boundary, vanishing a spike noise in read-write experiments. A double-layered perpendicular magnetic recording medium with the electroless-deposited CoNiFeP film showed a sufficient overwrite performance and high signal-to-noise ratio as compared with a typical soft magnetic underlayer fabricated using sputtering.

    DOI

  • Formation of Pd nanocluster seeds by electrochemical process for control of magnetic properties in Co/Pd multilayered film

    J Kawaji, M Tanaka, K Kimura, T Asahi, T Homma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   40 ( 4 ) 2473 - 2475  2004年07月  [査読有り]

     概要を見る

    Pd cluster seeds for a double-layered perpendicular magnetic recording medium composed of a Co/Pd multilayered film and a CoZrNb soft magnetic underlayer (SUL) were fabricated with an electrochemical treatment. By immersing the SUL into an aqueous PdCl2 solution, the substitution of Pd for Co at the surface of the SUL took place, which was caused by the difference in electrochemical redox potential between Pd and Co. Uniformly distributed Pd clusters with 8 nm in diameter were successfully formed with the treatment for the optimized duration. Use of the Pd clusters as the seeds for deposition of the Co/Pd multilayered film increased the perpendicular coercivity and reduced the size of magnetic cluster of the film. These results suggested that the Pd cluster seeds led to the formation of magnetically isolated Co/Pd multilayered grains, improving the magnetic properties of Co/Pd multilayered film.

    DOI

  • Microstructure and magnetic properties of a Co/Pd multilayer on a controlled Pd/Si seed layer for double-layered perpendicular magnetic recording media

    J Kawaji, T Asahi, H Hashimoto, J Hokkyo, T Osaka, S Matsunuma, G Safran, J Ariake, K Ouchi

    JOURNAL OF APPLIED PHYSICS   95 ( 12 ) 8023 - 8029  2004年06月  [査読有り]

     概要を見る

    A 10 nm Pd/Si dual thin film was developed as a seed layer for a Co/Pd multilayer in double-layered perpendicular magnetic recording media. The Pd/Si seed layer, sputter deposited under Ar sputtering gas containing N-2 and postannealed at 400 degreesC, markedly reduced intergranular exchange coupling of the Co/Pd multilayered film, resulting in a decrease in both the slope parameter, defined as 4pi(dM/dH)(H=Hc), and the magnetic cluster size. Consequently, medium noise was essentially reduced, thereby improving the signal-to-noise ratio of the Co/Pd recording media on a CoZrNb soft magnetic underlayer. The addition of N-2 gas effectively decreased the grain size of Pd in the seed layer. A Pd/Si seed layer prepared with both processes exhibited a granular structure of fine Pd-rich grains surrounded by a Si-rich amorphous region, which provided nucleation sites for the growth of well-separated Co/Pd multilayered grains. (C) 2004 American Institute of Physics.

    DOI

  • 高感度X線画像センサーの作製を目的としたBi電解析出プロセスの研究 (Development of Bi Electrodeposition Process for Fabricating Microabsorber Array for High Sensitive X-Ray Imaging Sensor)

    H. Sato, H. Kobayashi, H. Kudo, T. Izumi, T. Homma, T. Osaka, S. Shoji, Y. Ishisaki, R. Fujimoto

    Electrochemistry   72 ( 6 ) 424 - 426  2004年06月  [査読有り]

  • 無電解析出プロセスにおける還元剤TiCl3の電子放出機構のab initio分子軌道法による検討 (Ab Initio Molecular Orbital Study of the Electron Emission Mechanism of TiCl3 as a Reductant for an Electroless Deposition Process)

    T. Shimada, I. Komatsu, T. Homma, H. Nakai, T. Osaka

    Electrochemistry   72 ( 6 ) 462 - 465  2004年06月  [査読有り]

  • Electrochemical nano-processing and nano-technology

    T Osaka

    ELECTROCHEMISTRY   72 ( 6 ) 388 - 388  2004年06月  [査読有り]

  • MEMS-Based Design and Fabrication of a New Concept Micro Direct Methanol Fuel Cell (μ-DMFC)

    S. Motokawa, M. Mohamedi, T. Momma, S. Shoji, T. Osaka

    Electrochem. Commun. (Electrochemistry Communications 2007 Best Cited Paper Award)   6 ( 6 ) 562 - 565  2004年06月  [査読有り]

    DOI

  • Highly ordered mesoporous Ni particles prepared by electroless deposition from lyotropic liquid crystals

    Y Yamauchi, T Yokoshima, H Mukaibo, M Tezuka, T Shigeno, T Momma, T Osaka, K Kuroda

    CHEMISTRY LETTERS   33 ( 5 ) 542 - 543  2004年05月  [査読有り]

     概要を見る

    Highly ordered mesoporous Ni particles have been prepared by electroless deposition using lyotropic liquid crystals as templates. The bath conditions, in particular the kind of the reducing agents, greatly affected the degree of the ordering of mesostructures. By using well chosen appropriate reducing agents and combining those agents, we have succeeded in synthesizing Ni particles with highly ordered mesoporosity.

  • Optimized Sn/SnSb lithium storage materials

    H Mukaibo, T Osaka, P Reale, S Panero, B Scrosati, M Wachtler

    JOURNAL OF POWER SOURCES   132 ( 1-2 ) 225 - 228  2004年05月  [査読有り]

     概要を見る

    We report the synthesis of SnSb-based intermetallic with improved morphology. The electrochemical characterization shows that these materials have a good electrode behavior in a lithium cell. Capacities exceeding 800 mAh/g with a charge-discharge efficiency approaching 100%, have been obtained. In addition, the percent of the initial irreversible capacity is moderate. The capacity decreases upon cycling quite likely due to a still not optimized electrode structure. (C) 2004 Elsevier B.V. All rights reserved.

    DOI

  • Corrosion properties of high-performance CoNiFe based soft magnetic thin films prepared by electro or electroless deposition

    T Osaka, T Yokoshima

    CORROSION ENGINEERING SCIENCE AND TECHNOLOGY   39 ( 1 ) 38 - 44  2004年03月  [査読有り]

     概要を見る

    The corrosion behaviour of a CoNiFe film prepared by electrochemical processes has been investigated. Corrosion resistance is very important for materials to be used in electrical devices for practical use. For example, soft magnetic materials are used as the core materials of magnetic recording heads. In particular, electrodeposited CoNiFe thin films with a high saturation magnetic flux denisity are suitable for this application. The corrosion resistance of the CoNiFe film is strongly influenced by its composition, crystalline structure, and presence of impurities. A fine crystalline structure containing no impurities is one of the most important characteristics of CoNiFe soft magnetic thin films with high corrosion resistance.

    DOI

  • High sensitive X-ray microcalorimeter using Bi-Au microabsorber for imaging applications

    H Kudo, T Arakawa, S Ohtsuka, T Izumi, S Shoji, H Sato, H Kobayashi, K Mori, T Homma, T Osaka, N Iyomoto, R Fujimoto, K Mitsuda, NY Yamasaki, T Oshima, K Futamoto, Y Takei, T Ichitsubo, T Fujimori, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, T Ohashi, Y Kuroda, M Onishi, K Otake, F Beppu

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   43 ( 3 ) 1190 - 1195  2004年03月  [査読有り]

     概要を見る

    An X-ray microcalorimeter is a cryogenic energy-dispersive spectrometer, which has an energy resolution almost comparable to that of conventional wavelength-dispersive spectrometers. Using a transition edge sensor (TES) as a temperature sensor, the energy resolution can be further improved. We have developed a new method of achieving an array of TES microcalorimeters for the purpose of X-ray imaging. To achieve this, mushroom-shaped X-ray microabsorbers formed using electrodeposition were applied. The temperature of the TES, which is easily degraded by thermal diffusion, was kept sufficiently low throughout the process to achieve practical use. On the bases of this new method, a 2 x 2 (x 4) array of TES microcalorimeters was fabricated and tested. A high energy resolution of 13.0 eV at 6 keV was achieved and the filling factor was improved to 83%. Although several issues still need to be investigated, we verified that our method is useful for fabricating a Ti-Au TES microcalorimeter array.

    DOI

  • TES microcalorimeter development for future Japanese X-ray astronomy missions

    R Fujimoto, K Mitsuda, NY Yamasaki, N Iyomoto, T Oshima, Y Takei, K Futamoto, T Ichitsubo, T Fujimori, K Yoshida, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, H Kudo, H Sato, T Arakawa, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, Y Kuroda, M Onishi, M Goto, F Beppu, T Tanaka, T Morooka, S Nakayama, K Chinone

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1-3 ) 431 - 434  2004年03月  [査読有り]

     概要を見る

    We are developing a Ti/Au TES microcalorimeter array for future Japanese X-ray astronomy missions. The goal is an energy resolution of 2-5 eV at 6 keV, and an array of 100-1000 pixels to achieve a geometrical area of &gt;1 cm(2) and a moderate spatial resolution simultaneously. The energy resolution was improved to similar to6 eV at 6 keV with a very fast time constant (&lt;100 mus). To achieve a high coverage fraction, it is necessary to fabricate mushroom-shaped X-ray microabsorbers. We are developing an electrodeposition fabrication technique that is suitable for our process. Sn was used as absorber material, but the energy resolution was not good due to the existence of long-lived quasiparticles. Bi is also used, and the process is under optimization now. The readout strategy is to multiplex signals in the frequency domain, using a bridge circuit. So far, we succeeded in multiplexing two pixels modulated with 50 and 20 kHz at 440 mK. The energy resolution obtained at 110 mK was 33 eV (25 kHz). (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • Performance analyse's of TES microcalorimeters with mushroom shaped X-ray absorbers made of Sn or Bi

    Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, T Arakawa, H Kudo, H Sato, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, K Mitsuda, NY Yamasaki, R Fujimoto, N Iyomoto, T Oshima, K Futamoto, Y Takei, T Ichitsubo, T Fujimori, K Yoshida, Y Kuroda, M Onishi, M Goto, F Beppu

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1-3 ) 452 - 455  2004年03月  [査読有り]

     概要を見る

    Performance of microcalorimeters with a Ti/Au transition-edge sensor (TES) and an electrodeposited absorber has been investigated. The absorbers are in a mushroom-shape made of Sn or Bi. With an Sn absorber we observed a long time scale component of 1.8 ms for X-ray pulses, which is due presumably to recombination of quasiparticles into phonons. As a result, the energy resolution is not good with the Sn absorber. Better energy resolution of 28 +/- 1 eV was obtained with an incomplete-shaped Bi absorber, although the long component was also seen with smaller level. A calorimeter with only a neck of the An seed layer for the electrodeposition had the best energy resolution of 6.3 +/- 0.4 eV in spite of saturated pulses and relatively high transition temperature of 210 mK. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • Fabrication of multi-pixel TES microcalorimeters with an electrodeposited Sn absorber and Bi absorber

    T Arakawa, H Kudo, H Sato, H Kobayashi, T Izumi, S Ohtsuka, K Mori, S Shoji, T Osaka, T Homma, K Mitsuda, N Yamasaki, R Fujimoto, N Iyomoto, Y Ishisaki, U Morita, T Koga, K Shinozaki, K Sato, N Takai, T Ohashi, Y Kuroda, M Onishi, M Goto, F Beppu

    NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT   520 ( 1-3 ) 456 - 459  2004年03月  [査読有り]

     概要を見る

    We have developed multi-pixel TES microcalorimeters in order to realize high-energy resolution and X-ray imaging. A Sn absorber and a Bi absorber were formed on Si3N4 and SiO2 membrane using two-step exposure photolithography and electrodeposition. A FEM analysis was carried out to investigate the performance of the X-ray microabsorbers. In addition, a superconducting through-wafer interconnection was demonstrated considering the future X-ray imager using microcalorimeters. Detail of the fabrication techniques, characteristics and simulation results of two types of the microabsorbers, as well as those of the calorimeters are described. (C) 2003 Elsevier B.V. All rights reserved.

    DOI

  • 電気化学的手法による高機能材料の創製

    逢坂 哲彌

    化学と工業 = Chemistry and chemical industry   57 ( 3 ) 175 - 175  2004年03月

    CiNii

  • Enantioselective crystal growth of leucine on a self-assembled monolayer with covalently attached leucine molecules.

    Naoki Banno, Takuya Nakanishi, Mariko Matsunaga, Toru Asahi, Tetsuya Osaka

    Journal of the American Chemical Society   126 ( 2 ) 428 - 9  2004年01月  [国際誌]

     概要を見る

    Enantioselective crystal growth of leucine occurs on a solid surface modified with a self-assembled monolayer depending on the chirality of the enantiomer attached, as evidenced by the X-ray diffraction method.

    PubMed

  • Reduction of Medium Noise of Co-Pd Multilayered Perpendicular Magnetic Recording Media by a Thin Carbon Interlayer

    J. Sayama, J. Kawaji, T. Asahi, J. Hokkyo, T. Osaka

    IEEE Trans. Magn.   39   1059 - 1063  2004年

  • Maskless and Electroless Fabrication of Patterned Metal Nanostructures on Silicon Wafers by Controlling Local Surface Activities

    T. Homma, N. Kubo, T. Osaka

    Electrochim. Acta   48   3115 - 3122  2004年

  • Molecular Orbital Study on the Reaction Process of Dimethylamine Borane as a Reductant for Electroless Deposition

    T. Homma, A. Tamaki, H. Nakai, T. Osaka

    J. Electroanal. Chem.   559   131 - 136  2004年

  • Gelified co-continuous polymer blend system as polymer electrolyte for Li batteries

    S Passerini, M Lisi, T Momma, H Ito, T Shimizu, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   151 ( 4 ) A578 - A582  2004年  [査読有り]

     概要を見る

    In this work, the co-continuous polymer blend was synthesized for use as the electrolyte in lithium batteries. Such electrolytes were characterized by a co-continuous morphology consisting of two three-dimensionally interpenetrated polymer networks simply formed by hot-mixing two nonmiscible polymers. A preliminary electrochemical characterization of the gelified co-continuous polymer blend as electrolyte for lithium batteries is also reported. (C) 2004 The Electrochemical Society.

    DOI

  • Application of Soft X-Ray Magnetic Circular Dichroism Spectroscopy to the Investigation of [Co/Pd] Multilayered Perpendicular Magnetic Recording Media with Various Seedlayers

    A. Agui, M. Mizumaki, T. Matsushita, T. Asahi, J. Kawaji, J. Sayama, T. Osaka

    J. Appl. Phys.   95   7825 - 7831  2004年

  • Cu下地層を有するSmCo5垂直磁化膜の磁気特性 (Magnetic Properties of SmCo5 Perpendicular Magnetization Film with Cu Seedlayer)

    J. Sayama, K. Mizutani, T. Asahi, T. Osaka

    IEICE Tech. Rep.   MR2004-8   7 - 11  2004年

  • Deposition Mechanism of Ni on Si(100) Surfaces in Aqueous Alkaline Solution

    D. Niwa, T. Homma, T. Osaka

    J. Phys. Chem. B   108   9900 - 9904  2004年

  • Optimization of the Thickness Ratio of Pd/Si Intermediate Layer in a Co/Pd Multilayer Perpendicular Magnetic Recording Media

    J. Kawaji, H. Hashimoto, T. Asahi, J. Hokkyo, T. Osaka

    Trans. Magn. Soc. Jpn.   4   78 - 84  2004年

  • Direct Methanol Fuel Cells Research and Development at Applied Physical Chemistry Laboratory of Waseda University

    M. Mohamedi, T. Momma, T. Osaka

    Recent Research Developments in Electrochemistry   7   1 - 24  2004年

  • ポリイミド樹脂上への直接銅成膜の検討 (Direct Electroless Cu Plating on Polyimaide Film)

    M. Yoshino, T. Masuda, J. Sasano, I. Matsuda, T. Osaka

    J. Surf. Finish. Soc. Jpn.   55   960 - 961  2004年

  • Electrodeposition of Ag Film from Ammoniacal AgNO3 Bath Containing Polyethyleneimine

    T. Iida, M. Yoshino, J. Sasano, I. Matsuda, T. Osaka

    J. Surf. Finish. Soc. Jpn.   55   962 - 963  2004年

  • 微小流路を用いた無電解析出プロセスによる複合金属ナノ粒子の作製 (Preparation of Composite Metal Nanoparticles by Electroless-Deposition Process Using Microchannel Type Reactor)

    H. Sato, Y. Ohhinata, T. Homma, T. Osaka

    J. Surf. Finish. Soc. Jpn.   55   966 - 997  2004年

  • Fabrication of magnetic mesostructured nickel-cobalt alloys from lyotropic liquid crystalline media by electroless deposition

    Y Yamauchi, T Yokoshima, T Momma, T Osaka, K Kuroda

    JOURNAL OF MATERIALS CHEMISTRY   14 ( 19 ) 2935 - 2940  2004年  [査読有り]

     概要を見る

    Mesostructured binary Ni - Co alloys with various compositions are prepared for the first time by the electroless deposition of metal salts ( nickel and cobalt) dissolved in aqueous domains of the lyotropic liquid crystalline phases of a non-ionic surfactant ( Brij 56) at high concentrations. Mesostructured alloys with various Ni/Co ratios are easily obtained by changing the composition of the baths, leading to the control of saturation magnetization. The composition of the alloys affects the ordering of the mesostructure; higher Co content lowers the ordering.

    DOI

  • 無電解めっき法を用いた垂直2層膜媒体軟磁性裏打ち層の開発 (Electroless Deposition of Soft Magnetic Underlayer for a Double-Layered Perpendicular Recording Media)

    A. Sugiyama, T. Asahi, K. Adachi, M. Sakagami, J. Kawaji, M. Yoshino, T. Osaka, T. Tsumori

    IEICE Tech. Rep.   MR2004-48   15 - 20  2004年

  • MCD Measurement at the Tb M4,5-Edges of Tb17FexCo(83-x) Perpendicular Magnetization Films

    A. Agui, M. Mizumaki, T. Asahi, J. Sayama, K. Matsumoto, T. Morikawa, T. Nakatani, T. Matsushita T. Osaka, Y. Miura

    Trans. Magn. Soc. Jpn.   4   326 - 329  2004年

  • Chiral discrimination between thalidomide enantiomers using a solid surface with two-dimensional chirality.

    Takuya Nakanishi, Naoko Yamakawa, Toru Asahi, Norio Shibata, Bunsho Ohtani, Tetsuya Osaka

    Chirality   16 Suppl   S36-9 - S39  2004年  [査読有り]  [国際誌]

     概要を見る

    Chiral discrimination between thalidomide enantiomers was achieved using the self-assembled monolayer (SAM) of an atropisomeric compound, 1,1'-binaphthalene-2,2'-dithiol (BNSH), which takes a two-dimensional chiral arrangement on gold(111) surface. Interestingly, an "all-or-none" type enantioselectivity appears; one enantiomeric form of BNSH SAM allows the adsorption of only one enantiomer of thalidomide. In addition, the response of a racemic SAM of BNSH was revealed to be one-half of that caused by pure enantiomeric SAM.

    DOI PubMed

  • Formation of diffusion barrier layer on low-k material using wet fabrication process

    M. Yoshino, T. Yokoshima, T. Osaka, A. Hashimoto, Y. Hagiwara, I. Sato

    Proceedings - Electrochemical Society,   PV2004-17   251 - 263  2004年

  • Development of a micro calorimeter array for the Diffuse Intergalactic Oxygen Surveyor (DIOS) mission

    Y Ishisaki, T Ohashi, T Oshima, U Morita, K Shinozaki, K Sato, K Mitsuda, NY Yamasaki, R Fujimoto, Y Takei, H Sato, N Takahashi, T Homma, T Osaka

    HIGH-ENERGY DETECTORS IN ASTRONOMY   5501   123 - 134  2004年  [査読有り]

     概要を見る

    We are developing a superconducting transition-edge sensor (TES) microcalorimeter array for the Diffuse Intergalactic Oxygen Surveyor (DIOS) mission. DIOS is a relatively small Japanese X-ray mission which will study large-scale distribution of the warm-hot intergalactic medium (WHIM) using O-VII and O-VIII emission lines. The satellite weighs about 400 kg equipped with a four-reflection X-ray telescope (FXT) and a TES microcalorimeter array (XSA). The design goal of the observing system is an effective area larger than 100 cm 2 at the oxygen line energy, a field of view about 50 arcmin square, and an energy resolution about 2 eV in the energy range of 0.3-1 keV. The TES microcalorimeter array provides the large field of view and good energy resolution at the same time. We plan to install an array comprising 16 x 16 pixels with an overall size of 1 cm square, which is cooled with a cryogen-free cooler. Pixels are readout by multiplexing signals using a multi-input SQUID amplifier, with each input connected to a TES microcalorimeter which is AC biased with a different frequency. We report the design and present status of the XSA system development.

    DOI

  • Peak of a gyration tensor component of boracite crystals

    T Asahi, T Osaka, N Takahashi, K Saito, J Kobayashi

    COMPLEX MEDIUMS V: LIGHT AND COMPLEXITY   5508   277 - 284  2004年  [査読有り]

     概要を見る

    According to HAUP measurements, two ferroelectric boracites, Fe3B7O13I and Cu3B7O13CI, manifest peaks of a gyration component g(11) at each Curie point. These phenomena are entirely unintelligible from the usual concepts of the origin of ferroelectricity. Besides, the electrogyration effects of both crystals are also quite different. As has already been determined boracite crystals exhibit characteristic features of being improper ferroelectric. A phenomenological theory of improper ferroelectricity developed by Kobayashi is applied to these anomalous phenomena, and qualitative interpretations are successfully obtained.

    DOI

  • 中小受託加工企業へのアンケート調査でみるめっき業界の現状と将来像(前編)

    S. Hirose, I. Matsuda, T. Osaka, T. Kozima

    全鍍連   381   13 - 18  2004年

  • 中小受託加工企業へのアンケート調査でみるめっき業界の現状と将来像(後編)

    S. Hirose, I. Matsuda, T. Osaka, T. Kozima

    全鍍連   382   9 - 14  2004年

  • エレクトロニクス分野における高機能性薄膜の形成技術 (Formation of High Functional Thin Films in Electronics)

    T. Osaka, J. Sayama, M. Yoshino

    J. Surf. Finish. Soc. Jpn.   55   753 - 757  2004年

  • Influence of Capacity Fading on Commercial Lithium-Ion Battery Impedance

    T. Osaka, S. Nakade, M. Rajamaki, T. Momma

    J. Power Sources   119-121   929 - 933  2004年

  • Creation of highly functional thin films using electrochemical nanotechnology.

    Tetsuya Osaka

    Chemical record (New York, N.Y.)   4 ( 6 ) 346 - 62  2004年  [査読有り]  [国際誌]

     概要を見る

    This overview describes the results of our recent study of the application of electrochemical nanotechnology to the fabrication of magnetic recording materials, interconnects in ultra-large-scale integrated (ULSI) devices, energy storage materials, and on-chip biosensors. It is important to note that electrochemical processes play significant roles in developing and fabrication such sophisticated materials and devices. In the field of magnetic recording, electrodeposition methods for preparing CoNiFe and CoFe soft magnetic thin films with a high saturation magnetic flux density were newly developed, and the significant issues for obtaining those films are highlighted. In the area of ULSI interconnects, we developed a technique using a self-assembled monolayer (SAM) for direct bonding of the interconnect layer to SiO2, and proposed a novel electroless deposition method for fabricating a diffusion barrier layer. In the field of batteries, electrodeposited SnNi alloy was proposed as a future anode material for Li batteries, and electrochemical MEMS processes were shown to be useful for fabricating micro-sized direct methanol fuel cells (DMFCs) as portable batteries for electronics applications. In the area of chemical sensors, we developed a new process for fabricating field effect transistors (FETs) modified with SAMs for on-chip biosensing applications.

    DOI PubMed

  • Preparation of iron oxide nanoparticles via successive reduction-oxidation in reverse micelles

    T Nakanishi, H Iida, T Osaka

    CHEMISTRY LETTERS   32 ( 12 ) 1166 - 1167  2003年12月  [査読有り]

     概要を見る

    Nanometer-size particles of iron oxide were prepared by a successive reduction-oxidation of ferric or ferrous ions within reverse micelles. Nanoparticles of iron oxide were collected from reverse micellar solution as precipitates by adding modifier molecules. The X-ray diffraction patterns and magnetic properties of thus-prepared samples suggested the formation of nanocrystalline phase of maghemite, gamma-Fe2O3.

    DOI

  • Characteristics of interpenetrated polymer network system made of polyethylene oxide-LiBF4 complex and polystyrene as the electrolyte for lithium secondary battery

    T Momma, H Ito, H Nara, H Mukaibo, S Passerini, T Osaka

    ELECTROCHEMISTRY   71 ( 12 ) 1182 - 1186  2003年12月  [査読有り]

     概要を見る

    We propose a polymer blending method for preparing the PEO (polyethylene oxide)-LiBF4 complex electrolyte for lithium secondary battery applying to the IPN (interpenetrated polymer network) gel electrolyte. The polymer blend mixture of PEO-PS (polystyrene) -LiBF4 was prepared as a film by the hot-pressing method. The resulting IPN film was plasticized with the electrolyte solution of 0.5 M LiBF4/EC (ethylene carbonate) -PC (propylene carbonate) (I : I vol.), in which the formation of PEO-LiBF4 complex was confirmed by the Raman spectroscopy. The basic properties as an electrolyte of Li metal batteries, i.e., ionic conductivity, chemical stability at the polymer gel electrolyte/lithium metal interface, and charge-discharge performance of the Li/(PEO-LiBF4/PS) gel electrolyte/LiCoO2 cell were studied and discussed.

  • Simulations on the optimum conditions for propargyl alcohol to function as a shape control agent in the process of nickel electrodeposition onto a micropatterned substrate

    Matsuda, I, F Asa, T Osaka

    ELECTROCHEMISTRY   71 ( 11 ) 912 - 919  2003年11月  [査読有り]

     概要を見る

    It was found that the addition of propargy alcohol (PA) to a nickel sulfamate solution was effective for controlling the shape of deposit in the process of nickel electrodeposition onto a micropatterned substrate. The factors, i.e. the electrode potential, the thickness of diffusion layer and the concentration of PA, that affect the shape control function of PA were simulated by the boundary element method, based on the assumption that PA is consumed by diffusion-adsorption-reduction mechanism and that the concentration of PA vary along the cathode/solution interface. The function that represents the variation of PA concentration along the interface was used for the boundary values. The results of simulation explained well the difference in growing habit of the deposits obtained experimentally at different potentials, and figured out the important factors for suppressing the growth in horizontal direction. The optimum conditions for obtaining probe shape deposits were proposed.

  • Sn electrodeposition process for fabricating microabsorber arrays for an X-ray microcalorimeter

    T Homma, H Sato, H Kobayashi, T Arakawa, H Kudo, T Osaka, S Shoji, Y Ishisaki, T Oshima, N Iyomoto, R Fujimoto, K Mitsuda

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559   143 - 148  2003年11月  [査読有り]

     概要を見る

    Sn electrodeposition was employed for fabricating an array of microabsorbers with a 'mushroom-shaped' microstructure for a precision X-ray microdetector, the so called X-ray microcalorimeter. A deposition process for flat and smooth Sn films, which was suitable for the use of the absorber material, was developed by optimizing the conditions of additives such as o-cresol-4-sulfonic acid and polyethyleneglycol (PEG) to the Sn bath. The Sn films exhibited suitable properties, i.e. a higher superconducting transition temperature than the operating temperature of the X-ray microcalorimeter. The mushroom-shaped absorber array was successfully fabricated by Sn electrodeposition in combination with a photolithographic technique. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI

  • Survey of the metal nucleation processes on silicon surfaces in fluoride solutions: from dilute HF to concentrated NH4F solutions

    M Chemla, T Homma, Bertagna, V, R Erre, N Kubo, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   559   111 - 123  2003年11月  [査読有り]

     概要を見る

    As is well known, contamination of the silicon surface by trace metal impurities is responsible for detrimental effects in the production of ULSI circuits. An extensive experimental study of the factors influencing the spontaneous metal nucleation from fluoride solutions on Si substrates was undertaken. In acidic media (dilute HF solution) only noble metals can be deposited. The mechanism for the formation of Cu element nuclei was chosen as a model example. The first stage was the appearance of Cu crystals of a nanoscopic scale, observed by AFM microscopy. These nuclei soon induce corrosion pits due to the formation of a short-circuited electrochemical cell. In concentrated NH4F solutions, the open circuit potential (ocp) of Si samples is highly negative and provides an efficient driving force for nucleation even for common metals like Fe. Our results show that the deposition of Fe is hardly observable when Fe only is present, but in the presence of Cu, a catalytic effect is observed leading to the co-deposition of Fe + Cu nuclei. In all cases surface defects on the Si substrate are generated by the corrosion pits. (C) 2002 Elsevier Science B.V. All rights reserved.

    DOI

  • Electrodeposited Sn-Ni alloy film as a high capacity anode material for lithium-ion secondary batteries

    H Mukaibo, T Sumi, T Yokoshima, T Momma, T Osaka

    ELECTROCHEMICAL AND SOLID STATE LETTERS   6 ( 10 ) A218 - A220  2003年10月  [査読有り]

     概要を見る

    Thin Sn-alloy films containing various Sn/Ni ratios were prepared by electrodeposition and characterized as lithium-ion secondary battery anodes. The initial drop in discharge capacity varied with the Sn content of the sample; i.e., for samples with 54 atom % Sn and 62 atom % Sn, the drop was less than 100 mAh/g, whereas for those with 84 atom % Sn and 92 atom % Sn, the drop exceeded 500 mAh/g. Among these thin films, the 62 atom % Sn film showed the highest reversible capacity of ca. 650 mAh/g at about the 70th cycle, whereas the other samples (54 atom % Sn, 84 atom % Sn, 92 atom % Sn! showed a capacity of 300 mAh/g. (C) 2003 The Electrochemical Society.

    DOI

  • Detection of C-Si covalent bond in CH3 adsorbate formed by chemical reaction of CH3MgBr and H:Si(111).

    Taro Yamada, Tomoyuki Inoue, Keiko Yamada, Nao Takano, Tetsuya Osaka, Hiroshi Harada, Katsuhiko Nishiyama, Isao Taniguchi

    Journal of the American Chemical Society   125 ( 26 ) 8039 - 42  2003年07月  [査読有り]  [国際誌]

     概要を見る

    High-resolution electron energy loss spectroscopy (HREELS) yielded evidence for the formation of single covalent bonds between Si(111) surface atoms and CH(3) groups from the reaction of CH(3)MgBr and hydrogen-terminated H:Si(111)(1 x 1). The vibration at 678 cm(-)(1), assigned to the C-Si bond, was isolated within the spectrum of CH(3) on deuterium-terminated D:Si(111)(1 x 1). The CH(3) groups were thermally stable at temperatures below 600 K. The C-Si bonds are essential for enhancing the usefulness of alkyl moieties, which will lead to a new prospective technology of nanoscale fabrication and biochemical application.

    DOI PubMed

  • Microfabrication of electro- and electroless-deposition and its application in the electronic field

    T Osaka, N Takano, T Yokoshima

    SURFACE & COATINGS TECHNOLOGY   169   1 - 7  2003年06月  [査読有り]

     概要を見る

    The recent topics of our researches concerned with the electrochemical fabrication process of highly functionalized metal thin films and minute structures are reviewed. We present three topics; the soft magnetic materials of Co alloys by electro- and electroless-plating, the micro-dot formation by Ni electroless deposition, and fabrication of barrier layer on SiO2 by electroless deposition for ULSI technology. The magnetic property of electrodeposited CoNiFe film was deteriorated by the co-deposition of a small amount of sulfur, whereas the carbon co-deposition improved resistivity of the film. The electroless soft magnetic materials were also proposed for future extremely high-density recording system. As the fine dot formation, the electroless deposition processes for producing fine metal structures were demonstrated. For advanced nano-scale patterning technology, an organic monolayer directly grafted to the Si surface was applied to a novel process of selective metal deposition. Another type of organic monolayer. a self-assembled monolayer of organosilane, was also utilized as an adhesive/ catalytic layer for fabrication of a diffusion barrier layer on SiO2 for future ULSI technology. (C) 2003 Elsevier Science B.V All rights reserved.

  • Characterization of chemically-deposited NiB and NiWB thin films as a capping layer for ULSI application

    T Osaka, N Takano, T Kurokawa, T Kaneko, K Ueno

    SURFACE & COATINGS TECHNOLOGY   169   124 - 127  2003年06月  [査読有り]

     概要を見る

    NiB and NiWB films fabricated by electroless deposition were evaluated aiming for the application to a metal cap in the copper interconnects technology. The content of B and W was varied by adjusting the concentration of components in electroless deposition baths in order to clarify the effect of co-deposited element on thermal stability of the films. The thermal stability was evaluated by Auger electron spectroscope, X-ray diffractometer (XRD) and sheet resistance measurement. By measuring the variation in sheet resistance with annealing temperature, it was confirmed that the NiB films showed good thermal stability up to 450 degreesC, whereas the NiWB films deteriorated at 300 degreesC. The effect of co-deposited element was discussed based on the results obtained by XRD as well as that of sheet resistance measurement. (C) 2003 Elsevier Science B.V. All rights reserved.

  • Particle size and performance of SnS2 anodes for rechargeable lithium batteries

    H Mukaibo, A Yoshizawa, T Momma, T Osaka

    JOURNAL OF POWER SOURCES   119   60 - 63  2003年06月  [査読有り]

     概要を見る

    We have proposed SnS2 as promising Li-ion battery anode materials in our previous study. Nanoparticles of this material were synthesized by a sonochemical method. In this work, smaller SnS2 particles were obtained by diluting the starting solution of the synthesis, and particles of 30 nm were observed in the Field Emission SEM (FE-SEM) images. From such SnS2 particles, higher discharge capacity of 620 mAh/g and suppressed electrode degradation were observed in charge-discharge experiments. This indicates that the enlargement of the surface area was effective in facilitating the Li-ion diffusion through the active material, in simplifying the electrochemical reaction and in restraining the stress within the electrode, caused during charge and discharge.
    The discharge capacity in the 30th cycle was improved from 319 to 404 mAh/g by annealing the sample. It is suggested that this may be due to the change in its structure. (C) 2003 Elsevier Science B.V. All rights reserved.

    DOI

  • Nickel electroless deposition process on chemically pretreated Si(100) wafers in aqueous alkaline solution

    D Niwa, N Takano, T Yamada, T Osaka

    ELECTROCHIMICA ACTA   48 ( 9 ) 1295 - 1300  2003年04月  [査読有り]

     概要を見る

    Pretreating Si wafer surfaces with hydrochloric acid and hydrogen peroxide mixture (HPM) or ethanol was found to enhance the reactivity of chemical Ni deposition on Si(100) wafers in a simple bath of NiSO4-(NH4)(2)SO4 at pH 9.0. This phenomenon was identified as the acceleration of anodic reaction involved in chemical Ni deposition reaction on Si wafer surfaces, namely oxidation process of surface Si. Just after immersing into the alkaline bath, a reactive surface where oxidation reaction of Si was accelerated was formed on Si wafer surface with HPM or ethanol pretreatment. On the reactive surface, uniform and glossy Ni deposition film was obtained. In order to clarify the effects of HPM- or ethanol-pretreatment on anodic reaction, the pretreated Si(100) wafers were immersed into aqueous alkaline solution excluding NiSO4, resulting acceleration of Si oxidation compared to the unpretreated Si(100) surface. The progress of surface reactivity was also clarified by open circuit potentials (OCP), XPS, and ex-situ ATR FTIR. Moreover, by using this pretreatment, selective deposition onto nano-patterned Si substrate was performed. A two-dimensional array of fine Ni dots (diameter ca. 80 nm) was successfully fabricated. (C) 2003 Elsevier Science Ltd. All rights reserved.

    DOI

  • A high moment CoFe soft magnetic thin film prepared by electrodeposition

    T Osaka, T Yokoshima, D Shiga, K Imai, K Takashima

    ELECTROCHEMICAL AND SOLID STATE LETTERS   6 ( 4 ) C53 - C55  2003年04月  [査読有り]

     概要を見る

    A CoFe binary alloy film with 24 kG of saturation magnetic flux density, B-s, was prepared by electrodeposition. The B-s value of the CoFe alloy film prepared by electrodeposition from the conventional bath is usually equal to 21 kG. With the addition of trimethylamineborane, a well-known reducing agent, the B-s value was found to increase to 23 kG. Furthermore, with the use of a separated compartment dual cell system, a B-s value as high as 24 kG was reached. For obtaining the highest B-s, it was found to be essential to avoid the oxidation of ferrous ion to ferric ion in the plating bath. The coercivity, H-c, values were 15, 14, and 15 Oe for the films with 20, 23, and 24 kG of B-s, respectively. The key for obtaining high B-s materials is to avoid the oxidation of ferrous ions in the bath. In addition, it was found that the H-c value of 15 Oe for CoFe film with the highest B-s value of 24 kG could be lowered to 8 Oe by annealing in an applied magnetic field of 500 Oe. (C) 2003 The Electrochemical Society.

    DOI

  • Present performance of a single pixel Ti/Au bilayer TES calorimeter

    Y Ishisaki, U Morita, T Koga, K Sato, T Ohashi, K Mitsuda, NY Yamasaki, R Fujimoto, N Iyomoto, T Oshima, K Futamoto, Y Takei, T Ichitsubo, T Fujimori, S Shoji, H Kudo, T Nakamura, T Arakawa, T Osaka, T Homma, H Sato, H Kobayashi, K Mori, K Tanaka, T Morooka, S Nakayama, K Chinone, Y Kuroda, M Onishi, K Otake

    X-RAY AND GAMMA-RAY TELESCOPES AND INSTRUMENTS FOR ASTRONOMY, PTS 1 AND 2   4851   831 - 841  2003年  [査読有り]

     概要を見る

    We are developing a superconducting transition-edge sensor (TES) calorimeter for future Japanese X-ray astronomy missions (e.g. NeXT mission). The performance of our single pixel TES calorimeter is presented. We fabricated a Ti/Au (40 nm/110 nm) bilayer TES on a thin silicon-nitride membrane, which is adjusted to have a transition temperature of about 100 mK. The size of the TES is 500 mum x 500 mum, and 300 mum x 300 mum gold with a thickness of 300 nm is deposited with sputtering as an X-ray absorber. The TES calorimeter was installed in a dilution refrigerator operated at similar to 40 mK, with a combination of 400-series SQUID array as an ammeter. Collimated 5.9 keV X-rays (200 pm in diameter) from 55 Fe isotope were irradiated and X-ray pulses were obtained. Simultaneously with a fast falling time constant of 74.2 mus, the energy resolution of 6.6 +/- 0.4 eV was attained, while the baseline noise was 6.4 eV. The contents of the energy resolution are 5.1 eV of the excess noise, 3.3 eV of the readout noise, 1.6 eV of the pulse by pulse variation, and 1.9 eV of the intrinsic noise. The baseline noise are dominated by an unknown excess noise, which increases roughly in proportion to the inverse of the TES resistance. The pulse height is sensitive to the operating conditions, and the superconducting shield appears to have improved it by a factor of similar to 2. The calorimeter works fine over six months surviving five thermal cycles, even though it is kept in air.

  • Multi-pixel readout of TES calorimeters

    N Iyomoto, T Ichitsubo, T Oshima, K Mitsuda, R Fujimoto, K Futamoto, Y Takei, T Fujimori, T Miyazaki, Y Ishisaki, T Hiroike, NY Yamasaki, T Koga, K Sato, T Ohashi, S Shoji, H Kudo, T Nakamura, T Arakawa, H Sato, H Kobayashi, T Homma, T Osaka, S Nakayama, T Morooka, K Chinone, K Tanaka, Y Kuroda, M Onishi, M Goto, U Morita

    X-RAY AND GAMMA-RAY TELESCOPES AND INSTRUMENTS FOR ASTRONOMY, PTS 1 AND 2   4851   965 - 974  2003年  [査読有り]

     概要を見る

    We are developing a superconducting Transition-Edge Sensor (TES) calorimeter array. We adopt calorimeter multiplex in frequency domain to read signals from the calorimeter array with a small number of front-end electronics and wirings. We further utilize Calorimeter Bridge Biased by an AC Generator (CABBAGE) approach(1,2) to eliminate the AC carrier in the output. We tested the method using a TES calorimeter, which has a transition temperature of 390 mK. Because of the high operating temperature, energy resolution (DeltaE) of the calorimeter is limited to 200 eV at 5.9 keV even when it is biased with a DC current. We operated the calorimeter in CABBAGE circuit with 30 kHz sinusoidal bias and obtained DeltaE of 250 eV. We found that there remains a small-amplitude residual in the output even at the bridge balance point. The residual contains not only 30 kHz component but also odd-order harmonics. We consider that this is due to the variation of the TES resistor with the bias current. Some of the degradation of DeltaE from DC bias to AC bias can be explained by the fact that some of signal power is carried in the odd-order harmonics, which we did not utilize in the data reduction process. We also succeeded in operate the CABBAGE by 100 kHz, although DeltaE was degraded to 380 eV because of unstable bath temperature during the data acquisition and probably because of low response of the signal readout circuit at the frequency.

  • High-Frequency Properties of CoZrNb/Fe-C Multilayer Films

    K. Choi, T. Murase, T. Yokoshima, T. Osaka, Y. Kitamoto, Y. Yamazaki

    Trans. Magn. Soc. Jpn.   3   55 - 58  2003年

  • 電析ニッケルマイクロプローブの形状制御に及ぼす添加剤構造の影響

    淺富士夫, 河南賢, 杉本怜子, 横島時彦, 門間聰之, 松田五明, 本間英夫, 逢坂哲彌

    表面技術   54   300 - 305  2003年

  • 無電解めっき法による磁性ナノドットアレイの作製(Fabrication of Magnetic Nanodot Arrays by Using Electroless Deposition Process)

    J. Kawaji, F. Kitaizumi, T. Homma, T. Osaka

    IEICE Tech. Rep.   MR2003   1 - 5  2003年

  • Measurement of circular dichroism of ferroelectric fresnoite Ba2Si2TiO8

    T Asahi, T Osaka, SC Abrahams, R Matsuki, H Asai, S Nanamatsu, J Kobayashi

    COMPLEX MEDIUMS IV: BEYOND LINEAR ISOTROPIC DIELECTRICS   5218   223 - 232  2003年  [査読有り]

     概要を見る

    The urgent goal of the optical polarimetry of solids is simultaneous and accurate measurements of circular dichroism together with circular birefringence. Needless to say, measurements of circular phenomena are extremely difficult compared with those of linear ones. As for circular bireffingence, 170 years elapsed since its discovery by Arago until the development of the HAUP method, by which the accurate measurements of the gyration tensor components of a solid became possible for the first time. Subsequent to appearance of the HAUP method, attempts to extend the HAUP theory to being applicable for measurements of circular dichroism of crystals were followed by several authors. However any applications to real crystal were not fully successful. We completed fresh the theory of the extended HAUP. This paper reports the extended HAUP measurement of both circular birefringence and dichroism of fresnoite Ba2Si2TiO8. It is clearly found that the circular dichroism abruptly appears at the transition temperature, where the crystal changes from the high temperature 4mm phase to the low temperature mm2 phase. It increases with decrease of temperature together with circular birefringence. This is the first proof that the HAUP method provides with sufficiently accurate data of circular dichroism of crystals. It is important to note that the circular dichroism affects only theta(0), which is one of the salient parameter characterizing the HAUP method. It means that the HAUP is an exclusive method for measuring circular dichroism of crystals.

  • 電気化学的手法を用いた垂直二層膜媒体用下地層の作製(Preparation of Underlayer for Double-Layered Perpendicular Magnetic Recording Media with Electrochemical Process)

    J. Kawaji, T. Asahi, M. Tanaka, K. Kimura, T. Homma, T. Osaka

    IEICE Tech. Rep.   MR2003   7 - 11  2003年

  • All-Wet Barrier-Layer Fabricating Process on SiO2 for ULSI Cu Interconnections

    T. Osaka, T. Yokoshima, T. Nakanishi

    Proc. 2002 ECS International Semiconductor Technology Conference    2003年

  • Influence of carbon inclusion on properties of electrodeposited CoNiFeMo thin films

    T Yokoshima, A Kawashima, T Nakanishi, T Osaka, M Saito, K Ohashi

    MAGNETIC MATERIALS, PROCESSES, AND DEVICES VII AND ELECTRODEPOSITION OF ALLOYS, PROCEEDINGS   2002 ( 27 ) 365 - 375  2003年  [査読有り]

     概要を見る

    An application of electrodeposited CoNiFeMoC soft magnetic thin films, which have high saturation magnetic flux density and high resistivity, to the magnetic recording head was investigated. Because the ductility of the CoNiFeMoC films was low, the head core using the CoNiFeMoC films was difficult to be prepared without being cracked. The ductility of CoNiFeMoC films was improved by the addition of saccharin in the bath which lowered carbon content of the films. By using such ductility-enhanced CoNiFeMoCS thin films, the structure of the magnetic recording head was successfully fabricated with no cracks.

  • Fabrication of CoNiP dot arrays for patterned magnetic recording media with electroless deposition process

    J Kawaji, F Kitaizumi, T Homma, T Osaka

    MAGNETIC MATERIALS, PROCESSES, AND DEVICES VII AND ELECTRODEPOSITION OF ALLOYS, PROCEEDINGS   2002 ( 27 ) 473 - 482  2003年  [査読有り]

     概要を見る

    Magnetic dot arrays were fabricated onto n-type Si substrate with patterned SiO2 resist by electroless deposition process. Electroless CoNiP bath producing the magnetic thin film with perpendicular magnetic anisotropy was applied for the fabrication of the dot arrays. The fabrication of the CoNiP dot arrays with 200-270 nin diameter was achieved with sufficient selectivity only by immersing the pre-treated substrate into the bath, verifying the validity of the electroless deposition process. Moreover, the deposited magnetic dots possessed clear magnetization state in single state with no distribution at dc-remanent state, while reversed domains were observed if the CoNiP was formed as continuous film, suggesting that the shape anisotropy in the perpendicular direction of the dot arrays with high aspect ratio enhanced the formation of the single domain state.

  • Fabrication of Organic Monolayer Modified Ion-Sensitive Field Transistors with High Chemical Durability

    D. Niwa, T. Homma, T. Osaka

    Jpn. J. Appl. Phys.   43   L105 - L107  2003年

  • Formation of Micro and Nanoscale Patterns of Monolayer Templates for Position Selective Immobilization of Oligonucleotide Using Ultraviolet and Electron Beam Lithography

    D. Niwa, K. Omichi, N. Motohashi, T. Homma, T. Osaka

    Chem. Lett.   33   176 - 177  2003年

  • Effects of Sputtering Conditions on Magnetic Properties of Co/Pd Multilayered Films

    J. Sayama, M. Tanaka, J. Kawaji, T. Asahi, S. Matsunuma, T. Osaka

    Trans. Mater. Res. Soc. Jpn.   28   1165 - 1168  2003年

  • The Proposal of All-Wet Fabrication Process for ULSI Interconnects Technologies—Application of Electroless NiB Deposition to Capping and Barrier—

    M. Yoshino, T. Yokoshima, T. Osaka

    Proc. Electrochemical Society   PV2003   137 - 145  2003年

  • Electrochemical Behavior of Methyl- and Butyl- Terminated Si(111) in Aqueous Solution

    D. Niwa, T. Inoue, H. Fukunaga, T. Akasaka, T. Yamada, T. Homma, T. Osaka

    Chem. Lett.   33   284 - 285  2003年

  • Formation of Molecular Templates for Fabricating On-Chip Biosensing Devices

    D. Niwa, Y. Yamada, T. Homma, T. Osaka

    J. Phys. Chem. B   108   3240 - 3245  2003年

  • 高Bs軟磁性材料—ヘッド・媒体への展開—

    T. Osaka, T. Yokoshima

    Proc. Magn. Soc. Jpn.   128   69 - 75  2003年

  • Development of high-performance soft magnetic thin films by electroless deposition and their application to magnetic recording devices

    T Osaka, T Yokoshima

    MAGNETIC MATERIALS, PROCESSES, AND DEVICES VII AND ELECTRODEPOSITION OF ALLOYS, PROCEEDINGS   2002 ( 27 ) 290 - 297  2003年  [査読有り]

     概要を見る

    High-performance soft magnetic thin films prepared by electroless deposition were overviewed and application of electroless deposition to write head core was demonstrated. In addition, our recent topics of new high B-s materials prepared by electrodeposition were introduced.

  • Newly Developed SmCo5 Thin Film with Perpendicular Magnetic Anisotropy

    J. Sayama, T. Asahi, K. Mizutani, T. Osaka

    J. Phys. D: Appl. Phys.   37   L1 - L4  2003年

  • Preparation and methanol permeability of polyaniline/nafion composite membrane

    T Shimizu, T Naruhashi, T Momma, T Osaka

    ELECTROCHEMISTRY   70 ( 12 ) 991 - 993  2002年12月  [査読有り]

     概要を見る

    In order to realize an electrolyte membrane for DMFC having low methanol permeability, suppression of methanol permeability of Nafion by introducing polyaniline (PAn) was attempted. The membrane obtained by the electropolymerization of aniline at Nafion-coated Pt electrode had bi-layered morphology, and it showed lower ionic conductivity and lower methanol permeability compared with those of Nafion, compared to PAn introduced Nafion membrane by the chemical oxidative polymerization of aniline in Nafion. The PAn introduced Nafion by chemical oxidative polymerization showed superior characteristics to Nafion from the viewpoint of conductivity and methanol permeability.

  • Addition of ionic conductivity to engineering polymers by means of polypyrrole

    T Momma, T Naruhashi, T Shimizu, T Osaka

    ELECTROCHEMISTRY   70 ( 12 ) 994 - 997  2002年12月  [査読有り]

     概要を見る

    In order to realize an electrolyte membrane for DMFC having low methanol permeability, addition of ionic conductivity by the introduction of polypyrrole into engineering polymers was attempted. By the chemical oxidation of pyrrole monomer inside the polymer matrix, the composite films of polypyrrole (PPy) and engineering plastics were prepared. By the PPy introduction to poly (ethyleneterephthalate) (PET) the ionic conductivity across the film was increased. Methanol permeability was also examined to assess the performance of the film as the DMFC electrolyte. The composite film of PPy/PET, which was formed by pyrrole oxidation, showed better performance of high ionic conductivity and low methanol permeability.

  • マイクロパターン上へのニッケルめっきにおけるプロパギルアルコールの形状制御機能のシミュレーション

    松田 五明, 淺 富士夫, 逢坂 哲彌

    表面技術 = The Journal of the Surface Finishing Society of Japan   53 ( 11 ) 751 - 758  2002年11月

     概要を見る

    The shape control function of propargyl alcohol (PA) in the electrodeposition of nickel onto a micropatterned substrate was simulated under the condition that the rate of PA reduction was equal to the rate of PA diffusion at every point of the cathode surface, the concept of which was derived from the results obtained in the previous paper. The function of PA was related to higher diffusion rate and higher interfacial concentration, and consequently higher surface coverage of PA at the edge of the cathode surface, as compared with those at the center of the surface. The simulation showed that the function of PA was active in the initial stage of electrodeposition; it was more effective at less negative potentials, for example at -0.80V vs. Ag/AgCl, and less effective at more negative potentials, for example at -0.85V. The simulation also showed, however, that the function became ineffective as the deposit grew, showing that the diffusion rate and the interfacial concentration tended to be uniform on the grown surface. These results of the simulation explained the experimental results well, and showed this simulation method to be useful for the investigation of the behavior of additives.

    DOI CiNii

  • ニッケル電析抑制機能に及ぼすプロパギルアルコールの拡散速度, 被覆率および還元速度の影響

    松田 五明, 淺 富士夫, 河南 賢, 小林 洋介, 横島 時彦, 逢坂 哲彌

    表面技術 = The Journal of the Surface Finishing Society of Japan   53 ( 11 ) 744 - 750  2002年11月

     概要を見る

    The inhibiting function of propargyl alcohol in nickel electrodeposition was studied by observing the cathodic polarization curves on nickel RDE in nickel sulfamate baths. The behavior of propargyl alcohol inhibiting the electrodeposition was analyzed based on the diffusion-adsorption-reduction model. The variations of the diffusion rate, the interfacial concentration and the coverage of propargyl alcohol with the electrode potential were simulated based on the reduction rate estimated from the model and the experimental results. The results of the simulation explained the experimental results well. Such a simulation gives useful information on the investigation of the additive behavior and the current distribution in the electrodeposition onto a micropatterned substrate.

    DOI CiNii

  • Preparation and Electrochemical Properties of Zn-Doped LiNi0.8Co0.2O2

    G. T. K. Fey, J. G. Chen, V. Subramanian, T. Osaka

    J. Power Sources   112 ( 2 ) 384 - 394  2002年11月  [査読有り]

  • Electroless nickel ternary alloy deposition on SiO2 for application to diffusion barrier layer in copper interconnect technology

    T Osaka, N Takano, T Kurokawa, T Kaneko, K Ueno

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   149 ( 11 ) C573 - C578  2002年11月  [査読有り]

     概要を見る

    Electroless NiWP and NiReP films were investigated with the aim of application to barrier and capping layers in interconnect technology. These alloys containing a refractory metal with a high melting point were expected to have the ability to avoid diffusion of Cu into the interlevel dielectric. The composition and resistivity of these films were investigated first in order to know the relation between the composition and its thermal stability. The thermal stability was investigated by measuring the sheet resistance and the cross-sectional observation with field emission scanning electron microscope. Additionally, an electroless Ni alloy deposition on the SiO2 layer without a sputtered seed layer was also examined by utilizing a self-assembled monolayer (SAM) as an adhesion and catalytic layer. Since an alkaline solution damaged the SiO2 surface, a two-step process, which consists of a nucleation step performed in an acid electroless deposition bath and a barrier layer formation step carried out in an alkaline bath, is employed in order to fabricate a consistently uniform barrier film on the SAM/SiO2 surface. It was found that the NiReP films formed on SAM/SiO2 surfaces were stable up to 400degreesC, and are feasible for the barrier layer for the Cu interconnect technology. (C) 2002 The Electrochemical Society.

    DOI

  • Microstructure and magnetic properties of Co/Pd multilayered thin films with C or Si seedlayer

    T Onoue, T Asahi, K Kuramochi, J Kawaji, T Osaka, J Ariake, K Ouchi, G Safran, N Yaguchi

    JOURNAL OF APPLIED PHYSICS   92 ( 8 ) 4545 - 4552  2002年10月  [査読有り]

     概要を見る

    Microstructure and magnetic properties of sputter deposited Co/Pd multilayered perpendicular magnetization films with amorphous C or Si seedlayer were investigated. The angstrom scale surface roughness of the seedlayer causes fine crystal grains to form in the Co/Pd multilayer and to decrease the extent of intergranular exchange coupling, while it obstructs the formation of a regular interface between Co and Pd layers. The Si seedlayer, which exhibits a surface roughness lower than the C seedlayer, yields Co/Pd multilayered films with the lowest intergranular exchange coupling and the highest coercivity. The improvement in magnetic properties of the Co/Pd film with Si seedlayer is attributable mainly to the formation of Pd2Si at the interface between the Co/Pd layer and the Si seedlayer. The Pd2Si provides suitable nucleation sites for the grain growth of Co/Pd multilayered film that can be utilized as a perpendicular magnetic recording medium. (C) 2002 American Institute of Physics.

    DOI

  • Enhancement of magnetic properties of Co/Pd multilayered perpendicular magnetic recording media by using Pd/Si dual seedlayer

    J Kawaji, T Asahi, T Onoue, J Sayama, J Hokkyo, T Osaka, K Ouchi

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   251 ( 2 ) 220 - 228  2002年10月  [査読有り]

     概要を見る

    Effects of the introduction of a Pd/Si dual seedlayer on the microcrystalline structure and magnetic properties of [Co/Pd](n) multilayered perpendicular magnetic recording media were investigated. The Pd/Si dual seedlayer was composed of a Pd upper seedlayer and a Si under seedlayer. The Pd upper seedlayer with a thickness of up to 10 nm markedly increased the coercivity of [Co/Pd](n) multilayered media in the direction perpendicular to the film surface. The highest coercivity of 7.8kOe was obtained for the [Co/Pd](10) medium with a Pd (10nm)/Si (100nm) dual seedlayer. The Pd upper seedlayer not only facilitated the formation of regular interfaces between the Co and Pd layers, but also reduced the thickness of the deteriorated initial layer in the [Co/Pd](n) multilayer, resulting in enhancement of the magnetic anisotropy field. The [Co/Pd](n) multilayered medium with the Pd/Si dual seedlayer exhibited weak intergranular exchange coupling between [Co/Pd](n) grains, which led to excellent read-write characteristics. (C) 2002 Elsevier Science B.V. All rights reserved.

  • Enhancement of magnetic properties of Co/Pd multilayered perpendicular magnetic recording media by using Pd/Si dual seedlayer

    J Kawaji, T Asahi, T Onoue, J Sayama, J Hokkyo, T Osaka, K Ouchi

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   251 ( 2 ) 220 - 228  2002年10月  [査読有り]

     概要を見る

    Effects of the introduction of a Pd/Si dual seedlayer on the microcrystalline structure and magnetic properties of [Co/Pd](n) multilayered perpendicular magnetic recording media were investigated. The Pd/Si dual seedlayer was composed of a Pd upper seedlayer and a Si under seedlayer. The Pd upper seedlayer with a thickness of up to 10 nm markedly increased the coercivity of [Co/Pd](n) multilayered media in the direction perpendicular to the film surface. The highest coercivity of 7.8kOe was obtained for the [Co/Pd](10) medium with a Pd (10nm)/Si (100nm) dual seedlayer. The Pd upper seedlayer not only facilitated the formation of regular interfaces between the Co and Pd layers, but also reduced the thickness of the deteriorated initial layer in the [Co/Pd](n) multilayer, resulting in enhancement of the magnetic anisotropy field. The [Co/Pd](n) multilayered medium with the Pd/Si dual seedlayer exhibited weak intergranular exchange coupling between [Co/Pd](n) grains, which led to excellent read-write characteristics. (C) 2002 Elsevier Science B.V. All rights reserved.

  • Increase of the resistivity of electroless-deposited high-B-s CoNiFeB thin films

    M Sobue, T Segawa, T Yokoshima, T Osaka, D Kaneko, A Tanaka

    IEEE TRANSACTIONS ON MAGNETICS   38 ( 5 ) 2228 - 2230  2002年09月  [査読有り]

     概要を見る

    In order to increase the resistivity of electroless-deposited high-Bs CoNiFeB thin films, it was decided to investigate the effect of adding a beta-alanine containing complexing agent to the plating bath. The resistivity (rho) gradually increased as the beta-alanine concentration was increased. CoNiFeB thin films with desirable soft magnetic properties, B-s = 17-17.5 kG and H-c &lt; 3.0 Oe, were obtained under these conditions with rho value (70-90 muOmega cm) dependant on carbon incorporation in the films. It has been suggested that carbon impurities in the films resulting from the use of the beta-alanine complexing agent containing -NH2 group causes electron scattering, leading to an increase in the resistivity.

    DOI

  • Alkyl monolayers on Si(111) as ultrathin electron-beam patterning media

    T Yamada, N Takano, K Yamada, S Yoshitomi, T Inoue, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   532 ( 1-2 ) 247 - 254  2002年09月  [査読有り]

     概要を見る

    A process of electron-beam patterning of the surface of a Si(111) wafer was developed by utilizing alkyl monolayers as ultrathin patterning media. We performed chemical benchmark tests of the electron-beam patterning of alkyl monolayers on Si(111) in ambient oxygen, followed by the deposition of a metal on bombarded areas by immersion into an aqueous solution containing metal ions of the metal to be deposited. We investigated practically important issues related to this process, such as the robustness of organic monolayers against oxidation in aqueous media, the contrast enhancement of the bombarded areas by metal deposition, and the delectability of electron-bombarded areas of the monolayers by scanning tunneling microscopy (STM). The alkyl-covered Si(111) surface was significantly resistant to the oxidation by dissolved O-2 in pure water, compared to hydrogen-terminated Si(111). By immersion into a solution containing CuSO4 + HF + NH4F, electron-bombarded areas were visualized by the presence of the deposit of Cu. Electron-bombarded areas were also distinguishable from intact areas in terms of height contrast or roughness measured by STM. These results indicate the usefulness of alkyl monolayers for nano-scale patterning on silicon wafers. Published by Elsevier Science B.V.

  • Micropattern formation for magnetic recording head using electroless CoFeB deposition

    T Yokoshima, S Nakamura, D Kaneko, T Osaka, S Takefusa, A Tanaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   149 ( 8 ) C375 - C382  2002年08月  [査読有り]

     概要を見る

    The method of electroless deposition of CoFeB thin films has been improved and used to fabricate the write head core for magnetic recording. The currently available method is poorly selective in depositing thin films on surfaces patterned with photoresist; i.e., the deposition occurs not only on the catalytic surface but also on the surface of the photoresist. To improve the selectivity, the effects of bath agitation and organic additives were investigated. Extraneous deposition on the photoresist was decreased by deposition with agitation in a paddle plating cell system and/or by adding thiodiglycolic acid in the bath without any effect on the coercivity of the resulting thin film. The new techniques enabled consistently uniform deposition of the film on the patterned surface of the write head core. The improved electroless deposition system operated under optimized conditions is suitable for future applications involving the deposition of the alloy in fine-patterned structures. (C) 2002 The Electrochemical Society.

    DOI

  • 記憶素子用薄膜材料の解析

    逢坂哲弥, 小岩一郎, 朝日透, 川治純, 浅見勝彦

    新素材設計開発施設共同利用研究報告書   2001   106 - 107  2002年06月

    J-GLOBAL

  • Thermal desorption high-resolution mass spectrometry of mixed self-assembled monolayers on gold

    T Shibue, T Nakanishi, T Matsuda, T Asahi, T Osaka

    LANGMUIR   18 ( 5 ) 1528 - 1534  2002年03月  [査読有り]

     概要を見る

    Thermal desorption high-resolution mass spectrometry (TD-HRMS) is examined as a characterization tool for mixed self-assembled monolayers (SAMs) on gold. TD-HRMS provides a novel spectral view of the adsorption state of thiol and dithiol on gold, and it is confirmed in this study that thiolates, not thiols, are formed on the surface of gold by chemical bonding. Mass shifts in the TD-HRMS spectra indicate the number of Au-S bonds per thiol molecule and allow the accurate identification of the molecular formula of both single and mixed SAMs. The technique is also successfully used to observe the symmetric and asymmetric dimerization between constituent molecules of the SAM on gold. TD-HRMS is shown to provide information regarding the thermal desorption behavior of mixed SAMs, with clear distinctions between chemisorbed molecules and physisorbed molecules. TD-HRMS is demonstrated to be a useful means of estimating the surface molar ratio of mixed SAMs in that the molar ratio of mixed SAMs on gold is directly reflected in the obtained molecular ion intensity of constituent alkanethiols.

    DOI

  • Substrate (Ni)-Catalyzed Electroless Gold Deposition from a Noncyanide Bath Containing Thiosulfate and Sulfite I.Reaction Mechanism

    M. Kato, J. Sato, H. Otani, T. Homma, Y. Okinaka, T. Osaka, O. Yoshioka

    J. Electrochem. Soc.   149 ( 3 ) C164 - C167  2002年03月  [査読有り]

    DOI

  • Substrate (Ni)-Catalyzed Electroless Gold Deposition from a Noncyanide Bath Containing Thiosulfate and Sulfite II.Deposit Characteristics and Substrate Effects

    J. Sato, M. Kato, H. Otani, T. Homma, Y. Okinaka, T. Osaka, O. Yoshioka

    J. Electrochem. Soc.   149 ( 3 ) C168 - C172  2002年03月  [査読有り]

    DOI

  • Enantioselective Adsorption of Phenylalanine onto Self-Assembled Monolayers of 1,1’-Binaphthalene-2,2’-Dithiol on Gold

    T. Nakanishi, N. Yamakawa, T. Asahi, T. Osaka, B. Ohtani, K. Uosaki

    J. Am. Chem. Soc.   124 ( 5 ) 740 - 1  2002年02月  [査読有り]  [国際誌]

    DOI PubMed

  • 新しい時代の変革期に

    T. Osaka

    エレクトロニクス実装学会誌   5   1 - 1  2002年

  • Fabrication of electroless NiReP barrier layer on SiO2 without sputtered seed layer

    T Osaka, N Takano, T Kurokawa, K Ueno

    ELECTROCHEMICAL AND SOLID STATE LETTERS   5 ( 1 ) C7 - C10  2002年01月  [査読有り]

     概要を見る

    A new fabrication process for an electrolessly deposited NiReP barrier layer on SiO2 is proposed for ultralarge scale integration applications. The NiReP film was formed electrolessly without sputtered seeds by utilizing a self-assembled monolayer (SAM) as an adhesion and catalyst layer. For the electroless deposition on the SiO2 layer covered with SAM, an acid or a neutral electroless deposition bath was suitable whereas an alkaline solution damaged the SiO2 surface. To fabricate a consistently uniform barrier film on the SAM/SiO2 surface, a two-step process, consisting of a nucleation step performed in an acid electroless deposition bath and a barrier layer formation step carried out in an alkaline bath, is proposed. The two-step process yielded satisfactory results, and the electroless NiReP barrier layer was successfully formed on the SAM/SiO2 surface in a high pH bath. (C) 2001 The Electrochemical Society.

    DOI

  • Analysis of Microstructures for Co/Pd Multilayer Perpendicular Magnetic Recording Media with Carbon Underlayer

    T. Asahi, K. Kuramochi, J. Kawaji, T. Onoue, T. Osaka, M. Saigo

    J. Magn. Magn. Mater.   235   87 - 92  2002年

  • Relationship between Surface Energy and Preferred Orientation of CoCr Alloy Magnetic Thin Films Deposited on C and TiCr Underlayers

    H. Okuo, T. Onoue, T. Asahi, T. Osaka

    J. Magn. Magn. Mater.   235   98 - 103  2002年

  • Pulsed Electrodeposition of Nanocrystalline CoNiFe Soft Magnetic Thin Films

    T. Nakanishi, M. Ozaki, H. S. Nam, T. Yokoshima, T. Osaka

    J. Electrochem. Soc.   148   C627 - C631  2002年

  • 記録層への非磁性層導入による[Co/Pd]n 垂直磁気記録媒体の低ノイズ化(Reduction of Medium for [Co/Pd]n Perpendicular Magnetic Recording Media by Addition of Non-Magnetic Layer to the Recording Layer)

    J. Kawaji, J. Sayama, T. Asahi, J. Hokkyo, T. Osaka

    IEICE Tech. Rep.   MR2002   35 - 40  2002年

  • ニッケル電析抑制機能に及ぼすプロパギルアルコールの拡散速度,被覆率および還元速度の影響

    I. Matsuda, F. Asa, K. Kanan, Y. Kobayashi, T. Yokoshima, T. Osaka

    J. Surf. Finish. Soc. Jpn.   53   40 - 46  2002年

  • マイクロパターン上へのニッケルめっきにおけるプロパギルアルコールの形状制御機能のシミュレーション

    I. Matsuda, F. Asa, T. Osaka

    J. Surf. Finish. Soc. Jpn.   53   47 - 54  2002年

  • Effect of the Preparation Conditions of a Pd/Si Dual Seedlayer on the Magnetic Properties of Co/Pd Multilayered Perpendicular Magnetic Recording Media

    J. Kawaji, T. Asahi, H. Hashimoto, T. Osaka, K. Asami

    Trans. Magn. Soc. Jpn.   3   1 - 7  2002年

  • Influence of Sputtering Conditions for Co/Pd Multilayer on Its Magnetic Properties and Crystalline Microstructure

    J. Sayama, J. Kawaji, M. Tanaka, T. Asahi, S. Matsunuma, T. Osaka

    Trans. Magn. Soc. Jpn.   3   8 - 12  2002年

  • Electro Beam Nanometer-Scale Fabrication of Si(111) Using Alkyl Monolayers

    T. Yamada, N. Takano, T. Osaka

    RIKEN Review   45   9  2002年

  • pH感応性絶縁性ポリピロールを用いたバイオセンサの構築および小型センサシステムの開発(Construction and Development of New Biosensing System Built up with pH Sensitive Insulating Polypyrrole)

    T. Osaka, D. Niwa, Y. Yamada

    J. Soc. Plant Engineers Jap.   14   77 - 83  2002年

  • 遷移金属・貴金属系磁気記録材料の磁気物性と磁区構造 —イントロダクション—

    朝日透, 川治純, 尾上貴弘, 法橋滋郎, 逢坂哲彌

    日本応用磁気学会研究会資料   122   1 - 4  2002年

  • エレクトロニクス分野への電気化学プロセスの応用

    T. Osaka, T. Yokoshima

    化学工業   53   40 - 44  2002年

  • めっき法による微細構造構築とエレクトロニクス部品への応用 (1)

    T. Osaka, T. Yokoshima

    Electrochemistry   70   802 - 806  2002年

  • 表面処理加工における技能の技術化

    T. Osaka

    精密工学会誌   68   1299 - 1301  2002年

  • めっき先端加工技術の現状と展望

    T. Osaka

    先端加工技術   58   1  2002年

  • 表面処理技術の新分野開拓

    逢坂 哲彌

    表面技術 = The Journal of the Surface Finishing Society of Japan   52 ( 12 ) 797 - 797  2001年12月

    CiNii

  • Formation and analysis of high resistivity electroless NiReB films deposited from a sodium citrate bath

    M Kim, T Yokoshima, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   148 ( 11 ) C753 - C757  2001年11月  [査読有り]

     概要を見る

    An electroless NiB plating bath including ammonium perrhenate was used to investigate the effect of Re and B on the resistivity and the structure of NiReB film. The Re content in the film increased rapidly while the B content decreased with increasing ammonium perrhenate concentration of the electrolyte. The films exhibit an increasing specific resistance (rho) and decreasing temperature coefficient of resistance (TCR) as the Re content increased. For films with less than 14 wt % Re content, the value of TCR is stable until a 300 degreesC heat-treatment; its stability is maintained until 500 degreesC for the higher Re content films. According to X-ray diffraction measurement, the as-deposited films were amorphous for the low Re content films, while a fine devitrified structure of hexagonal close-packed ReNi was observed for films with a high Re content. After heat-treating the low Re content film at 500 degreesC crystallized the forming face-centered cubic NiRe and Ni3B phases. On the other hand, the crystalline structure of the high Re content films was not altered by annealing to 500 degreesC (C) 2001 The Electrochemical Society.

    DOI

  • Mechanism of sulfur inclusion in soft gold electrodeposited from the thiosulfate-sulfite bath

    T Osaka, N Kato, J Sato, K Yoshizawa, T Homma, Y Okinaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   148 ( 10 ) C659 - C662  2001年10月  [査読有り]

     概要を見る

    The hardness of the soft gold electrodeposited from the thiosulfate-sulfite mixed ligand bath which we developed recently, has previously been found to increase with increasing sulfur content of the gold deposit. In the present study the mechanism of the sulfur inclusion was investigated by analyzing for sulfur gold deposits produced under various experimental conditions and also by observing weight gains resulting from the adsorption of sulfur-containing species on gold using the quartz crystal microbalance (QCM) technique. The results led us to conclude that the origin of the included sulfur is primarily the adsorbed Au(I)-thiosulfate species, (Au2S2O3)(ads), formed as an intermediate in the gold deposition reaction. (C) 2001 The Electrochemical Society.

  • Improvement of signal to noise ratio for Co/Pd multilayer perpendicular magnetic recording media by the addition of an underlayer

    T Onoue, T Asahi, K Kuramochi, J Kawaji, T Homma, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   235 ( 1-3 ) 40 - 44  2001年10月  [査読有り]

     概要を見る

    Signal and noise characteristics of Co/Pd multilayer perpendicular magnetic recording media are discussed based upon MFM analysis. The noise of the Co/Pd multilayer media is originated mainly from irregularities in the magnetic transition regions, and can be drastically suppressed by increasing the thickness of the carbon underlayer although a large number of reversed magnetic domains between the magnetic transitions still exist. The fine magnetic clusters formed in the medium with a thick carbon underlayer result in clear magnetic transition boundaries of recorded bits in the high recording density region. By examining the profile of the M-H loops. the decrement in the x value, which is defined as the slope of M-H loop at the value of coercivity, improves the signal to noise (S/N) ratio for the Co/Pd multilayer media. (C) 2001 Elsevier Science B.V. All rights reserved.

  • Effect of underlayers on magnetic properties of Co/Pd multilayer perpendicular magnetic recording media

    T Onoue, J Kawaji, K Kuramochi, T Asahi, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   235 ( 1-3 ) 82 - 86  2001年10月  [査読有り]

     概要を見る

    Amorphous C and Si films were sputter-deposited as underlayers of Co/Pd multilayer perpendicular magnetic recording media. The magnetic properties of the media were significantly affected by the underlayer thickness; namely, the values of coercivity He and nucleation field -H-n increased and the value of alpha decreased with merely increasing the thickness of C or Si underlayer. where alpha is the derivative of M-H loop at the value of coercivity. The coercivity was not always affected by magnetic anisotropy constant K-u for the Co/Pd media. In read-write experiments, the higher S/N ratio was obtained for the media with the thicker C or Si underlayer, which exhibited low alpha and high H-c. In the time decay experiments of magnetization, the Co/Pd multilayer media with C or Si underlayer possessed good thermal stability. This study demonstrated that the introduction of C or Si underlayer greatly improves magnetic properties, read-write characteristics, and thermal stability of Co/Pd multilayer perpendicular magnetic recording media. (C) 2001 Elsevier Science B.V. All rights reserved.

  • Introduction of electrochemical microsystem technologies (EMT) from ultra-high-density magnetic recording

    T Osaka

    ELECTROCHIMICA ACTA   47 ( 1-2 ) 23 - 28  2001年09月  [査読有り]

     概要を見る

    An introduction on electrochemical microsystem technologies (EMT), and the technology of ultra-high-density magnetic recording is reviewed mainly from the viewpoint of EMT as an example is presented in this article. The plated permalloy film has played an important role since 1979 as a key material for the head core of thin film head, ever since IBM shipped the first hard disk drive (HDD) using a thin film head in 1979. Recently, we developed a plated CoNiFe film with a higher B-s (saturation magnetic flux density). which made it possible to shrink the GMR head size to less than 10 mum in yoke length. On the other hand, the size of the magnetic medium is progressively decreasing, and the sputtered magnetic layer such as CoCrPtTa or CoCrPtB possesses such a fine grain structure that the magnetic domain size has become smaller than 100 grains for one bit cell. This is exactly the art of fabrication controlling materials on the atomic scale. At this stage, the perpendicular recording medium becomes important to avoid the diminution of the recorded magnetization against thermal fluctuation. Moreover, in the future the patterned media formed with nanometer-dot arrays will become a candidate for recording densities beyond several hundred GB per square inch. To produce such patterned media, electrochemical processes will become important for mass productivity. (C) 2001 Elsevier Science Ltd. All rights reserved.

  • Evaluation of organic monolayers formed on Si(111): Exploring the possibilities for application in electron beam nanoscale patterning

    T Yamada, N Takano, K Yamada, S Yoshitomi, T Inoue, T Osaka

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   40 ( 8 ) 4845 - 4853  2001年08月  [査読有り]

     概要を見る

    The methods of preparing organic monolayers on Si(111). the effects of electron-beam irradiation onto these monolayers. and the deposition of metal atoms over the irradiated areas have been investigated in order to develop a process of mass-scale production of nanometer-scale patterns on Si(111) wafer surfaces. The organic monolayers were fabricated on hydrogen-terminated Si(111) wafer surfaces using previously reported methods for the electrolysis of para-substituted benzenediazoniurn salts and the Grignard reaction with various alkyl moieties and reaction procedures. Using these electrolysis methods, partially well-defined two-dimensional monolayers were formed, which were, however, obscured by precipitated by-products. The Grignard reaction deposited homogeneous monolayer moieties of alkyl groups which were randomly arranged and are suitable for surface passivation. Electron-beam bombardment of the organic monolayers on Si(111) was performed in an atmosphere of O-2 or H2O. The bombarded area was effectively oxidized in a well-controlled manner. By immersing the bombarded specimen into an aqueous NiSO4 + (NH4)(2)SO4 solution, Ni was selectively impregnated only within the area of electron bombardment. Based on these results, application of organic monolayers for fabricating nanometer-scale monolayer patterns is proposed.

  • ポリイオンコンプレックス複合電解重合絶縁性ポリ-1-アミノピロールを用いたポテンショメトリックアセチルコリンセンサの作製(Preparation of Potentiometric Acetylcholine Sensor Using Electropolymerized Insulating Poly-1-Aminopyrrole with Polyion Complex)

    T. Kuwahara, N. Yamakawa, T. Momma, T. Osaka

    Electrochemistry   69 ( 8 ) 598 - 602  2001年08月  [査読有り]

  • Co-continuous polymer blend based lithium-ion conducting gel-polymer electrolytes

    S Passerini, F Alessandrini, T Momma, H Ohta, H Ito, T Osaka

    ELECTROCHEMICAL AND SOLID STATE LETTERS   4 ( 8 ) A124 - A126  2001年08月  [査読有り]

     概要を見る

    In this work we report the synthesis and characterization of gel-polymer electrolytes based on co-continuous polymer blends. Such blends are characterized by a bicontinuous morphology consisting of two three-dimensionally interpenetrated polymer networks. Go-continuous polymer blends are simply formed by hot-blending two immiscible polymers. The intrinsic advantage of co-continuous polymer blends consists in the possibility of selecting the polymers. One polymer (e.g., polystyrene) imparts the desired mechanical properties and the other polymer [e.g., poly(ethylene oxide)] enables the ionic conductivity via formation of a gel which contains the electrolytic solution. (C) 2001 The Electrochemical Society.

  • SnS2 anode for rechargeable lithium battery

    T Momma, N Shiraishi, A Yoshizawa, T Osaka, A Gedanken, JJ Zhu, L Sominski

    JOURNAL OF POWER SOURCES   97-8   198 - 200  2001年07月  [査読有り]

     概要を見る

    SnS2 powder made by sonochemistry was applied and examined for anode material of Li ion battery. The annealed SnS2 at 400 degreesC showed a higher capacity of 600 mAh g(-1) than the nan-annealed SnS2. The cell with annealed SnS2 anode and LiCoO2 cathode worked well. From the results, SnS2 material was revealed to be one of the candidates of the anode materials for future Li ion batteries. (C) 2001 Elsevier Science B.V. All rights reserved.

  • Studies of the interface between lithium electrodes and polymeric electrolyte systems using in situ FTIR spectroscopy

    O Chusid, Y Gofer, D Aurbach, M Watanabe, T Momma, T Osaka

    JOURNAL OF POWER SOURCES   97-8   632 - 636  2001年07月  [査読有り]

     概要を見る

    This paper describes studies of the interface between Lithium electrodes and solid electrolyte systems using in situ FTIR spectroscopy in a single internal reflectance mode. In this method, the masking effect of the electrolyte matrix components is largely avoided. We studied gel electrolytes based on polyvinylidene difluoride-hexafluoropropylene with cyclic alkyl carbonates as plasticizers, suitable for ambient temperatures, and a solvent free polymer, derivatives of polyethylene oxide (PEO) with a branched structure: poly[ethyleneoxide-2-(2-methoxyethoxy)ethyl glycidyl ether] at elevated temperatures. We found that the surface chemistry of Li electrodes in contact with the gel matrixes is dominated by alkyl carbonate solvent reduction to ROCO2Li surface species. In the case of the PEG-based polymer, the surface reactions of Li electrodes are dominated by salt and trace water reduction. The polymer itself seems to be stable with lithium even at 60 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.

  • CoCrPtTa and Co/Pd perpendicular magnetic recording media with amorphous underlayers

    T Onoue, T Asahi, K Kuramochi, J Kawaji, T Homma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   37 ( 4 ) 1592 - 1594  2001年07月  [査読有り]

     概要を見る

    The effect of amorphous carbon underlayers on magnetic properties and read-write characteristics of Co73Cr18Pt6Ta3 single layer and Co/Pd multilayer perpendicular magnetic recording media were investigated. The increase in H-c and decrease in alpha, defined as 4 pi (dM/dH)(H=Hc), were observed by increasing the underlayer thickness for both Co-73 Cr18Pt6Ta3 and Co/Pd media. The media with a low alpha value, suggesting a decrease in the exchange coupling, exhibited the higher coercivity and the improvement of S/N ratio. In read-write experiments, the improvement of S/N ratio for the Co/Pd media was achieved up to 400 kFRPI or even higher in the recording density by increasing carbon underlayer thickness, while that for the Co73Cr18Pt6Ta3 media was obtained up to ca. 250 kFRPI.

  • Effects of impurities on resistivity of electrodeposited high-B-s CoNiFe-based soft magnetic thin films

    T Osaka, T Yokoshima, T Nakanishi

    IEEE TRANSACTIONS ON MAGNETICS   37 ( 4 ) 1761 - 1763  2001年07月  [査読有り]

     概要を見る

    Controlling the very small amount of inclusion of impurity elements by addition to the plating bath of various organic additives was found to be very effective in developing electrodeposited high-B-s CoNiFe soft magnetic thin films with desirably high resistivity. Included impurities were suggested to cause not only electron scattering but also decreasing grain size, both of which led to an increase of the resistivity. Chemical state of impurities was indicated to be controllable by selection of additives based on the functional group for adsorption.

  • Lithium metal/polymer battery

    T Osaka, T Momma

    JOURNAL OF POWER SOURCES   97-8   765 - 767  2001年07月  [査読有り]

     概要を見る

    Trend and state of the affairs for Li ion polymer battery were summarized. Also the situation of the research and development for the Li metal battery was introduced. (C) 2001 Elsevier Science B.V. All rights reserved.

  • 強誘電体メモリ用薄膜材料の解析

    逢坂哲弥, 小岩一郎, 吉江智寿, 村上義弘, 浅見勝彦

    新素材設計開発施設共同利用研究報告書   2000   129 - 130  2001年06月

    J-GLOBAL

  • Amperometric sensing system for the detection of urea by a combination of the pH-stat method and flow injection analysis

    K Yoneyama, Y Fujino, T Osaka, Satoh, I

    SENSORS AND ACTUATORS B-CHEMICAL   76 ( 1-3 ) 152 - 157  2001年06月  [査読有り]

     概要を見る

    A new type of amperometric sensing system for urea was constructed based on combining the pH-stat method and the Bow injection analysis (EIA) to solve the problem of potentiometry of dependency on the buffer concentration to the response of urea and moreover to eliminate the response to interfering substances. In the new system, the response to urea was independent of the buffer concentration and the relation between current response and urea concentration became linear. The possibility of automatic operation of this system with a potentiostatic feed back circuit was also confirmed. In this system, the relationship between urea concentration and current response was found to be linear up to 600 muM (=6.0 x 10(-4) mol dm(-3)). Since the sample path was separated from the electrolysis path, no current response of interfering substances such as ascorbic acid and uric acid occurred at the physiological level. Thus, the possibility of amperometric sensing of urea which has a merit of no dependency on the buffer concentration and moreover no influence of interfering substances was demonstrated. (C) 2001 Elsevier Science B.V. All rights reserved.

  • New insights into the carbon/polymer electrolyte interface in the electric double layer capacitor

    XJ Liu, T Osaka

    ELECTROCHEMISTRY   69 ( 6 ) 422 - 427  2001年06月  [査読有り]

     概要を見る

    To use a polymer electrolyte successfully in the electric double-laver capacitor (EDLC), it is important to design the interface between the carbon electrode and the polymer electrolyte. In this work, interfacial properties of carbon/poly (ethylene oxide) (PEO) solid electrolyte and carbon (or activated carbon)/polymer gel electrolyte were investigated. The all-solid-state EDLC with a pair of isotropic high-density graphite (HT)G) electrodes possesses a high capacitance in PEO/LiClO4 ([EO]/[Li+] = 8) solid polymer electrolyte. The capacitance of HDG electrode was strongly influ enced by temperature and the degree of crystallinity of PEO-LiClO4. Furthermore, various gel electrolytes were evaluated. The PMMA (poly(methyl methacrylate)), PVdF (poly(vinylidene fluoride)) and PVdF-HFP (poly(vinylidene fluoride-hexafluoropropylene) based gel electrolytes show a good electrochemical stability on the HDG electrode and a sufficient mechanical strength. In the case of using activated carbon (AC) powder las well as ordinary carbon powder) as the electrode material for EDLC with PVdF-HFP gel electrolyte, the electrode composed of AC (or carbon powder) and the gel electrolyte exhibits a higher specific capacitance and a lower ion diffusion resistance than does the electrode prepared with a dry polymer binder. The highest specific capacitance of 123 F g(-1) was achieved with a composite electrode containing AC powder with a specific surface area of 2500 m(2) g(-1).

  • pHスタット型尿素センシングシステムにおける緩衝能依存及び妨害物質の影響

    米山 健司, 山田 祐規子, 小岩 一郎

    Proceedings of the Chemical Sensor Symposium   32 ( Supplement A ) 148 - 150  2001年04月  [査読有り]

    CiNii J-GLOBAL

  • Microstructure of electroplated soft magnetic CoNiFe thin films

    HS Nam, T Yokoshima, T Nakanishi, T Osaka, Y Yamazaki, DN Lee

    THIN SOLID FILMS   384 ( 2 ) 288 - 293  2001年03月  [査読有り]

     概要を見る

    The microstructural and crystallographic characteristics of electroplated soft magnetic CoNiFe thin films were investigated by transmission electron microscopy. Dark field images showed that the film with fcc-bcc dual crystals has a smaller grain size than the fee or bcc single phase film. The fee films were found to have a unique microstructure with twin-like stacking faults with relatively uniform grain size distribution, and such twins were also found in the dual phase films. Some coarse grains were found in the bcc films with a twin-free microstructure. The film prepared from the thiourea bath had a smaller grain size than that of the film from the saccharin bath. It is suggested from the diffraction patterns that the fee and bcc components of the films are substitutional solid solutions of Co, Ni and Fe. The lattice constants of fee CoNiFe films are determined by atomic concentrations of the three elements. The crystal structures of bcc films are determined by Fe, and the lattice constants are slightly changed by the incorporation of Co and Ni into the bcc lattice of Fe. The CoNiFe films obtained from saccharin and thiourea baths have different lattice constants, because of different sulfur contents of the films. (C) 2001 Elsevier Science B.V. All rights reserved.

  • Optical study on a phase transition of fresnoite Ba2Si2TiO8

    T Asahi, T Osaka, J Kobayashi, SC Abrahams, S Nanamatsu, M Kimura

    PHYSICAL REVIEW B   63 ( 9 ) 1 - 13  2001年03月  [査読有り]

     概要を見る

    Fresnoite Ba2Si2TiO8 is a ferroelectric with promising piezoelectric uses that exhibits unusual pyroelectric, elastic, and other property anomalies close to 433 K. X-ray diffraction analyses at 297 and 573 K by Markgraf et al. determined the space group to be P4bm at both temperatures and appeared to exclude the possibility of these anomalies bring caused by a structural phase transition; a convincing alternative interpretation of the origin of these anomalies has not yet been reported. The high accuracy universal polarirneter (HAUP) method offered an alternative investigative approach. A primary difficulty in the present study was ensuring that the illuminated volume of the sample crystal was single and without domain texture. After having solved this problem, the method has established the point group of fresnoite as 4mm above 433 K, and as optically active below it. The single gyration tensor component g(12) appears abruptly but continuously on cooling below this temperature and increases with decreasing temperature, reaching 5.8x10(-6) at 360 K. Thus fresnoite is found to undergo a structural phase transition of second order from a 4mm phase to an optically active nonenantiomorphic point group. Combining the change of optical activity with that of the birefringence leads us to the conclusion that the point group below 433 K is mm2. The present study illustrates the unique and deep insight the HAUP method can provide into condensed-matter phase transitions.

  • Ab initio molecular orbital study of the oxidation mechanism of hypophosphite ion as a reductant for an electroless deposition process

    H Nakai, T Homma, Komatsu, I, T Osaka

    JOURNAL OF PHYSICAL CHEMISTRY B   105 ( 9 ) 1701 - 1704  2001年03月  [査読有り]

     概要を見る

    The oxidation (electron emission) mechanism of a hypophosphite ion (H2PO2, which is a representative reducing agent for an electroless deposition process, was studied by an ab initio molecular orbital method. Two types of reaction pathways were examined, namely, the pathway via three-coordinate compound obtained by primary dehydrogenation, and the one via five-coordinate compound by primary addition of OH-. The calculated energy profile showed that the oxidation reaction occurs via five-coordinate compounds. The solvation effect is clarified to make the reaction endothermic, indicating that the reaction preferably proceeds at the solid/ liquid interface, i.e., the surface of the deposits. rather than in the solution bulk. The catalytic activity of the metal surfacer which is one of the most significant factors for the electroless deposition process, was also investigated using Pd-n (n = 4-7) clusters as a model surface. It was found that one of the most important characters determine the catalytic activity of the deposited metal is the electron-accepting ability from the reductant.

  • NETs連載講座 超高記録密度HDDの実現技術(3)超高密度HDDに向けた記録ヘッドと媒体の材料設計

    逢坂 哲彌

    日経エレクトロニクス   2.12 ( 789 ) 192 - 203  2001年02月

    CiNii

  • Application of organic monolayers formed on Si(1 1 1): Possibilities for nanometer-scale patterning

    Taro Yamada, Nao Takano, Keiko Yamada, Shuhei Yoshitomi, Tomoyuki Inoue, Tetsuya Osaka

    Electrochemistry Communications   3 ( 2 ) 67 - 72  2001年

     概要を見る

    The modification of hydrogen-terminated Si(1 1 1) wafer surfaces was reproduced by previously reported methods of the electrolysis of para-substituted benzendiazonium salts and the Grignard reaction with various alkyl moieties. The electrolysis methods formed partially ordered two-dimensional monolayers, which were however obscured by precipitation of by-products. The Grignard reaction deposited a monolayer of moieties of alkyl groups randomly arranged, which are more suitable for surface passivation. Aiming for the application to nanometer-scale monolayer patterning of the Si(1 1 1) wafer surface, the organic-monolayer-covered Si(l 1 1) surfaces were subjected to electron beam bombardment. After electron bombardment with ambient O2 or H2O introduced, adsorption of oxygen was observed within the beam spot. By immersing the bombarded specimen into an aqueous NiSO4 + (NH4)2SO4 solution, the oxygen-deposited portions selectively included Ni atoms. This will be useful in constructing nanometer-scale metallic structures over Si wafer surfaces. © 2001 Elsevier Science B.V.

    DOI

  • 電気化学マイクロシステムテクノロジー (EMT) への期待

    T. Osaka

    Hyomen Kagaku   22   349 - 349  2001年

  • 高アスペクト比を有する電析Niマイクロプローブの試作 (Fabrication of Electrodeposited Ni Microprobes with a High Aspect Ratio)

    T. Osaka, F. Asa, M. Kawaminami, T. Yokoshima, T. Momma, H. Honma

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   52   130 - 134  2001年

  • MFMによる垂直磁気記録媒体の磁化状態の解析手法の検討 (Analysis for Magnetized State of Perpendicular Magnetic Recording Media Using MFM)

    M. Kawakami, T. Onoue, T. Asahi, J. Hokkyo, T. Osaka

    J. Magn. Soc. Jpn.   25   571 - 574  2001年

  • カーボン下地層を有するCo/Pd多層膜垂直磁気記録媒体の作製 (Preparation of Co/Pd Multilayer Perpendicular Magnetic Recording Media with Carbon under Layer)

    T. Asahi, K. Kuramochi, J. Kawaji, T. Onoue, T. Osaka

    J. Magn. Soc. Jpn.   25   575 - 578  2001年

  • アモルファスSi中間層を用いた垂直面内複合型媒体の作製 (Preparation of a Perpendicular/Longitudinal Composite Medium with a Silicon Intermediate Layer)

    Y. Morita, T. Onoue, T. Asahi, T. Homma, T. Osaka

    J. Magn. Soc. Jpn.   25   619 - 622  2001年

  • CoCrPtTa/NiCr媒体における膜厚方向の微細構造変化 (Changes of Microstructure Versus Film Thickness in CoCrPtTa/NiCr Media)

    K. Kurasawa, M. Kawakami, T. Onoue, T. Asahi, T. Osaka

    J. Magn. Soc. Jpn.   25   623 - 626  2001年

  • CoCrPtTaおよび[Co/Pd]n単層垂直媒体の電磁変換特性(Read/Write Characteristics of CoCrPtTa and [Co/Pd]n Single Layer Perpendicular Magnetic Recording Media)

    T. Onoue, T. Asahi, T. Homma, T. Osaka

    IEICE Tech. Rep.   25   13 - 18  2001年

  • 高分子ゲル電解質を用いたリチウム二次電池 (Secondary Li Batteries Using Polymer Gel Electrolytes)

    T. Momma, T. Osaka

    GS NEWS TECHNICAL REPORT   60   1 - 4  2001年

  • Molecular orbital study on the reaction mechanisms of electroless deposition processes

    T. Homma, I. Komatsu, A. Tamaki, H. Nakai, T. Osaka

    Electrochim. Acta   47   47 - 53  2001年

  • アモルファス下地層Co/Pd多層膜垂直磁気記録媒体の磁気特性と微細構造

    朝日透, 尾上貴弘, 逢坂哲彌

    日本応用磁気学会研究会資料   118   69 - 74  2001年

  • Polarimetry of electromagnetic materials

    T Asahi, T Osaka, J Kobayashi

    COMPLEX MEDIUMS II: BEYOND LINEAR ISOTROPIC DIELECTRICS   4467   20 - 30  2001年  [査読有り]

     概要を見る

    The goal of the polarimetry of electromagnetic solids is the thorough determinations of not only the linear and circular birefringences (LB and CB) but also the linear and circular dichroisms (LD and CD). Needless to say, measurements of circular phenomena are exceedingly more difficult than those of linear ones. For instance, the long period of 170 years elapsed from the discovery of CB by Arago in 1811 until the development of high accuracy universal polarimeter (HAUP) by Kobayashi in 1983, when the first perfect measurements of CB of solids became possible. Subsequent to the appearance of the HAUP method, attempts of extending HAUP theory to be applicable to CD measurements were followed by Moxon and Renshaw, and Dijkstra, Kremers, and Meekes by using Jones matrix calculus. However, their measurements to NiSO4. 6H(2)O were not fully satisfactory. We completed afresh the theory of the extended HAUP and measured successfully LD of a high temperature superconductor Bi2Sr2CaCU2O8. An important fact was clarified; the extended HAUP theory indicates that CD can be obtained exclusively through accurate measurements of theta (0), a characteristic angle introduced in the original HAUP method. It means that there would be no ways for measuring CD of solids except for the HAUP method. Preliminary results of applying our theory to silver thiogallate are shown finally.

  • 情報エレクトロニクス社会を造った無機材料

    T. Osaka

    化学と教育   48   798 - 802  2001年

  • 情報産業で活躍する電気化学

    T. Osaka, T. Onoue

    Electrochemistry   68   1034 - 1035  2001年

  • Co/Pd多層膜垂直磁気記録媒体の微細構造と電磁変換特性

    T. Osaka, T. Onoue, T. Asahi

    IDEMA Japan News   42   7 - 11  2001年

  • 無電解析出法による傾斜機能磁性薄膜の作製 (Preparation of Functionally Graded Magnetic Thin Films by Electroless Deposition Process)

    T. Homma, T. Osaka, H. Sato

    Hyomen Kagaku   22   350 - 356  2001年

  • 高機能デバイスのための電気化学的薄膜形成プロセス

    T. Osaka

    Electrochemistry   69   522 - 522  2001年

  • 下地触媒型無電解金めっき (Substrate-Catalyzed Electroless Gold Plating)

    M. Kato, J. Sato, Y. Okinaka, T. Osaka

    J. Surf. Finish. Soc. Jpn.   52   600 - 606  2001年

  • リチウム二次電池分野における高分子材料の活躍

    T. Osaka, T. Momma, T. Naruhashi

    Chemistry and Chemical Industry   75   518 - 522  2001年

  • CoCrPtTa single layer perpendicular magnetic recording media with carbon underlayer

    T Onoue, A Takizawa, T Asahi, T Osaka

    JOURNAL OF APPLIED PHYSICS   88 ( 11 ) 6645 - 6651  2000年12月  [査読有り]

     概要を見る

    Sputter-deposited amorphous carbon was applied as an underlayer for a Co73Cr18Pt6Ta3 Single layer perpendicular magnetic recording medium. It is shown that the amorphous carbon underlayer can control the Co [001] preferred orientation of the Co73Cr18Pt6Ta3 magnetic recording layer and that the microcrystalline structure, magnetic properties, and read-write characteristics of Co73Cr18Pt6Ta3 media are greatly dependent on the carbon underlayer thickness. By x-ray diffraction experiments and transmission electron microscopy observations, it was confirmed that the distribution of the c-axis orientation of Co grains becomes broader in the direction perpendicular to the film surface with increasing carbon underlayer thickness. Furthermore, the Co73Cr18Pt6Ta3 medium with a thick carbon underlayer indicated a relatively high perpendicular coercivity of 2800 Oe and an excellent signal to noise ratio in read-write characteristics. (C) 2000 American Institute of Physics. [S0021-8979(00)03324-7].

  • Electrochemical studies on the deposition process of electroless CoNiP films with graded magnetic properties

    T Homma, Y Kita, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   147 ( 11 ) 4138 - 4141  2000年11月  [査読有り]

     概要を見る

    In order to clarify the origin of the graded magnetic properties by the substrate rotational speed for electroless CoNiP films, electrochemical characteristics such as mixed potential and polarization behaviors were investigated. The results of mixed potential analysis revealed that the cathodic and anodic partial reactions in this system were diffusion- and reaction-controlled stale, respectively. It was shown that the mixed potential of the CoNiP deposition with the substrate rotational speed was dominated mainly by the deposition reaction of Co. The results of the polarization curves for each metal ion clarified that the Co deposition is in the diffusion-controlled state, whereas such a tendency did not appear for the deposition of Ni. This suggests that such a difference in deposition behaviors between Co and Ni with respect to the rotational speed of the substrate results in the formation of graded film properties. (C) 2000 The Electrochemical Society. S0013-4651(00)02-081-4. All rights reserved.

  • 尿素検出を目的としたpHスタット型フローアンペロメトリックセンシングシステムの開発

    米山 健司, 山田 祐規子, 小岩 一郎

    Proceedings of the Chemical Sensor Symposium   31 ( Supplement B ) 4 - 6  2000年09月  [査読有り]

    CiNii J-GLOBAL

  • pHスタット型フローアンペロメトリックセンシングシステムの尿素分析への応用

    米山 健司, 山田 祐規子, 小岩 一郎

    Proceedings of the Chemical Sensor Symposium   31 ( Supplement B ) 7 - 9  2000年09月  [査読有り]

    CiNii J-GLOBAL

  • Electroless CoNiFeB soft magnetic thin films with high corrosion resistance

    T Yokoshima, D Kaneko, M Akahori, HS Nam, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   491 ( 1-2 ) 197 - 202  2000年09月  [査読有り]

     概要を見る

    A new soft magnetic CoNiFeB thin film with high saturation magnetic flux density, B-S and good corrosion resistance has been prepared by using an electroless deposition method. The electroless CoFeB thin film has high B-S but a poor corrosion resistance compared with the electrodeposited NiFe (80-permalloy) film. The addition of Ni to the CoFeB film improves corrosion resistance without affecting its soft magnetic properties. One of the best CoNiFeB films prepared had a composition of Co77Ni13Fe9B1 with excellent magnetic and electrical properties (high B-S = 1.5-1.7 T, low coercivity, H-C = 1.2 Oe, low magnetostriction, lambda (S) = 2.0 x 10(-6), and moderate resistivity, rho = 40 mu Ohm cm). The new CoNiFeB thin film is suitable for use as a core material for the next generation of merged MR-heads. (C) 2000 Elsevier Science B.V. All rights reserved.

  • Control of crystal orientation of ferroelectric SrBi2Ta2O9 thin films with multi-seeding layers

    T Osaka, T Yoshie, T Hoshika, Koiwa, I, Y Sawada, A Hashimoto

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   39 ( 9B ) 5476 - 5480  2000年09月  [査読有り]

     概要を見る

    A Bi-Ta multi-seeding layer system is proposed to improve the ferroelectric properties of SrBi2Ta2O9 (SBT) thin films prepared by a sol-gel method for applications to nonvolatile memories. For seeding layers composed of different ratios of Bi to Ta, three different structures were observed after heat treatment at 800 degreesC: gamma -Bi2O3, Bi3TaO7 and Bi1.4Ta2O6.75, gamma -Bi2O3 With a sillenite structure exhibited a plate-like surface morphology. Bi3TaO7 with a fluorite structure exhibited a flat surface morphology. Bi1.4Ta2O6.75 With a pyrochlore structure exhibited a rough surface morphology. Because a flat surface morphology with a fluorite structure is desirable for a seeding layer, the Bi-Ta seeding layers, with a Bi to Ta ratio equal to 3 to 1, were used as multi-seeding layers. When the seeding layers were-sandwiched between SET thin films, multi-seeding layers provided, after heat treatment at 800 degreesC, a higher degree of crystal orientation in the a- or b-axis direction than a simple SBT thin film without seeding layers. Orientation in the a or b-axis direction is desirable for SET thin films to obtain improved ferroelectric properties, especially high remanent polarization values. The SET thin film with Bi-Ta multi seeding layers was found to have higher saturation characteristics than that without seeding layers, which suggests that the former type of SET thin film has a good potential for low-voltage operation. The multi-seeding method is thus effective for improving ferroelectric properties of SET thin films far nonvolatile memories.

  • High-frequency permeability and thermal stability of electrodeposited high-B-s CoNiFe thin films

    S Mizutani, T Yokoshima, HS Nam, T Nakanishi, T Osaka, Y Yamazaki

    IEEE TRANSACTIONS ON MAGNETICS   36 ( 5 ) 2539 - 2541  2000年09月  [査読有り]

     概要を見る

    The thermal stability and high-frequency permeability of high-B-s CoNiFe thin films were investigated, CoNiFe films exhibited excellent soft magnetic properties and good thermal stability up to 350 degrees C, Annealing in longitudinal magnetic field enabled to achieve H-k as high as 35 Oe, while the H-k value after annealing in a transverse magnetic field was less than 20 Oe, By suppressing the core loss, the effective permeability of high-B-s CoNiFe thin film at high frequencies was improved successfully.

  • Metallic bismuth on strontium-bismuth tantalate thin films for ferroelectric memory application

    K Asami, T Osaka, T Yamanobe, Koiwa, I

    SURFACE AND INTERFACE ANALYSIS   30 ( 1 ) 391 - 395  2000年08月  [査読有り]

     概要を見る

    Strontium-bismuth tantalate (SBT) has been actively investigated as an attractive candidate for non-volatile ferroelectric random access memories because of its high resistance to fatigue. However, the ferroelectric property of SET is easily affected by fabrication process parameters. The relationship between the surface chemistry of SET thin films and the fabrication process parameters, such as crystallization temperature, upper Pt electrode, annealing in oxygen after Pt electrode fabrication (= the second annealing), hydrogen sintering and ion etching, were examined mainly by XPS analysis. In all specimens, metallic Pi, which is one of the main causes for deterioration of their performances, was observed in addition to oxidic Pi, Sr and Ta, The deposition of an upper Pt electrode resulted exclusively in an increase in metallic Pi content. Sintering in a hydrogen atmosphere and ion etching increased the ratio of metallic Pi to total Pi, The second annealing was effective in suppressing the metallic Pi content. Copyright (C) 2000 John Wiley & Sons, Ltd.

  • Control of Pythium root rot on hydroponically grown cucumbers with silver-coated cloth

    AH Zhao, SI Kusakari, K Okada, A Miyazaki, T Osaka

    BIOSCIENCE BIOTECHNOLOGY AND BIOCHEMISTRY   64 ( 7 ) 1515 - 1518  2000年07月  [査読有り]

     概要を見る

    Silver-coated cloth (SCC) effectively controlled root rot that was caused by Pythium aphanidermatum in hydroponically grown cucumber plants. The presence of SCC in the hydroponic solution reduced the root rot from 100% to 10% 20 days after inoculation with zoo-spores of P. aphanidermatum. It was suggested that the inhibition of SCC was caused not only by the silver ion dissolved from SCC, but also by the metallic silver and silver compounds formed on the surface of the root.

  • 強誘電体メモリ用薄膜材料の解析

    逢坂哲弥, 小岩一郎, 吉江智寿, 村上義弘, 浅見勝彦

    新素材設計開発施設共同利用研究報告書   1999   80 - 81  2000年06月

    J-GLOBAL

  • Electrochemical molecular sieving of the polyion complex film for designing highly sensitive biosensor for creatinine

    T Osaka, S Komaba, A Amano, Y Fujino, H Mori

    SENSORS AND ACTUATORS B-CHEMICAL   65 ( 1-3 ) 58 - 63  2000年06月  [査読有り]

     概要を見る

    On the basis of our success on creatinine sensor composed of immobilization of creatinine iminohydrolase by polyion complexes (PIC) with a combination of interfacial pH change detection by using inactive polypyrrole film, we investigated various combination of PIC and their sensitivities. The sensitivity of the creatinine sensor was dependent strongly on the distance of the functional units of the anionic species of PIG. The dependence of sensitivity was related to the molecular sieving of the PIC used for the immobilization of the enzyme, i.e., the diffusion of the analytes in the PIG. (C) 2000 Elsevier Science S.A. All rights reserved.

  • Influence of substrates on magnetic property and crystalline orientation of CoCrTa/TiCr perpendicular magnetic recording medium

    T Asahi, M Ikeda, A Takizawa, T Onoue, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   212 ( 1-2 ) 293 - 299  2000年03月  [査読有り]

     概要を見る

    The influence of substrates on magnetic property and crystalline orientation of CoCrTa/TiCr perpendicular magnetic recording medium was investigated using a glass plate and a Si(1 0 0) single crystal. Magnetic measurements revealed that the film sputtered on a Si(1 0 0) substrate possessed a higher perpendicular coercive force than that on glass, where the pretreatment of the Si(1 0 0) substrate by aqueous HF solution effectively improved the magnetic properties. X-ray diffraction analysis of the films indicated that the crystallinity of the TiCr layer formed on the Si(1 0 0) substrate with the HF pretreatment was higher than that on the glass substrate. It was also found that CoCrTa and TiCr layers on the Si(1 0 0) substrate with the KF pretreatment had a narrower distribution of their c-axis orientation than those on glass substrate. The results of X-ray diffraction analysis were consistent with those of the TEM observation for cross-section bright- and dark-field images and the corresponding THEED patterns. These results suggest that the crystalline surface of the Si(1 0 0) substrate with HF pretreatment has the effect of inducing preferred orientation in the TiCr underlayer, which leads to a decrease in distribution of the c-axis orientation of Co grains in the CoCrTa layer, resulting in an increase in the perpendicular coercive force. (C) 2000 Elsevier Science B.V. All rights reserved.

  • Evaluation of substrate (Ni)-catalyzed electroless gold plating process

    T Osaka, T Misato, J Sato, H Akiya, T Homma, M Kato, Y Okinaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   147 ( 3 ) 1059 - 1064  2000年03月  [査読有り]

     概要を見る

    The substrate (Ni)-catalyzed electroless gold plating process invented by Iacovangelo and Zarnoch has been investigated for plating gold on electroless nickel substrates for application to bonding of electronic devices. The process was found to yield uniform and adherent gold films on Ni-B substrates, whereas on Ni-P substrates acceptable gold films were obtained only when the P content was low and a pretreatment procedure was introduced to prevent the formation of surface oxide or to remove it completely. Unlike the conventional galvanic displacement process, the substrate-catalyzed process does not attack the nickel substrates and yields gold films with a very low porosity. Compared with autocatalytic electroless gold plating baths, the substrate-catalyzed bath is inherently more stable, although the maximum gold thickness obtainable is naturally limited. Results of these evaluations are presented in detail. (C) 2000 The Electrochemical Society. S0013-4651(99)106-062-0. All rights reserved.

  • Microstructural Study on the Functionally Graded Magnetic Thin Films Prepared by Electroless Deposition

    T. Homma, Y. Kita, T. Osaka

    J. Electrochem. Soc.   147   160 - 163  2000年

  • Nickel deposition behavior on n-type silicon wafer for fabrication of minute nickel dots

    N Takano, D Niwa, T Yamada, T Osaka

    ELECTROCHIMICA ACTA   45 ( 20 ) 3263 - 3268  2000年  [査読有り]

     概要を見る

    The present study is a part of our systematic development of mass-scale production processes of nanometer-scale arrays of metal dots on silicon wafer surfaces. Metallic Ni was deposited onto Si(100) wafer surfaces electrolessly or galvanostatically, for surveying appropriate methods for formation of minute structures. Within an electroless bath of simple NiSO4-(NH4)(2)SO4 solution, metallic Ni was deposited, accompanied by the oxidation of the Si surface. Wet pretreatment of the Si surfaces in HPM (HCl and H2O2 mixture) or in ethanol drastically improved the uniformity of Ni layer and the rate of deposition. The electrolytic deposition with applying a potential at the Si wafer resulted in formation of Ni deposit which were easily peeled off. Based on the knowledge obtained, a two-dimensional array of minute Ni dots (diameter ca. 270 nm) was successfully fabricated. (C) 2000 Elsevier Science Ltd. All rights reserved.

  • アモルファス下地層付与による垂直磁気記録単層媒体の微細構造制御(Control of Microcrystalline Structure of a Perpendicular Singe-Layered Medium by Using Amorphous Underlayers)

    T. Onoue, T. Asahi, H. Okuo, Y. Morita, T. Osaka

    IEICE Tech. Rep.   100   5 - 10  2000年

  • 無電解NiReBC合金皮膜の結晶構造に及ぼす共析元素の影響 (Effect of Co-Deposited Elements on Structure of Electroless NiReBC Alloy Films)

    M. Kim, T. Yokoshima, T. Kubonuya, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   51   617 - 624  2000年

  • リングヘッド/垂直単層磁気記録媒体系におけるトラック端部磁化状態の解析 (Analysis of the Magnetization State at Track Edges for a Ring-Type Head and Single-Layered Perpendicular Magnetic Recording Medium)

    T. Hirayama, T. Onoue, T. Asahi, T. Homma, J. Hokkyo, T. Osaka, K. Ohashi

    J. Magn. Soc. Jpn.   24   223 - 226  2000年

  • Ni系合金面内記録層を有する垂直面内複合型媒体の作製 (Preparation of Perpendicular/Longitudinal Composite Medium with a Ni-Alloy Magnetic Underlayer)

    K. Kawakami, K. Kurasawa, M. Ikeda, T. Onoue, T. Asahi, T. Osaka

    J. Magn. Soc. Jpn.   24   263 - 266  2000年

  • Ge下地層を有する垂直単層磁気記録媒体の作製 (Fabrication of a Single-Layered Perpendicular Magnetic Recording Medium with a Ge Underlayer)

    Y. Morita, K. Kuramoti, T. Onoue, T. Asahi, T. Homma, T. Osaka

    J. Magn. Soc. Jpn.   24   271 - 274  2000年

  • Mo共析による高Bs高ρCoNiFe系電析薄膜の作製 (Preparation of Electrodeposited High-Bs and High-γ CoNiFe Thin Films by Mo Addition)

    Y. Sogawa, A. Kawashima, T. Yokoshima, T. Nakanishi, H. -S. Nam, T. Osaka

    J. Magn. Soc. Jpn.   24   699 - 702  2000年

  • 精密めっき法による軟磁性薄膜の微細構造制御 (Controlling Microstructure of Soft Magnetic Thin Films by the Electrodeposition Method)

    T. Osaka, T. Yokoshima

    J. Magn. Soc. Jpn.   24   1333 - 1342  2000年

  • Fabrication High-Bs Soft Magnetic Thin Films by an Electrodeposition Technique for Next-Generation Magnetic Recording Field

    T. Osaka, T. Yokoshima, T. Nakanish

    Proceedings - Electrochemical Society   PV2000-29   161 - 175  2000年

  • Pulsed Electrodeposition of Soft Magnetic CoNiFe Thin Films

    T. Nakanishi, M. Ozaki, H.-S. Nam, T. Yokoshima, T. Osaka

    Proceedings - Electrochemical Society   PV2000-29   176 - 184  2000年

  • Micro-Pattern Formation for Magnetic Recording Heads Using Electroless CoFeB Deposition

    T. Yokoshima, S. Nakamura, D. Kaneko, T. Osaka, S. Takefusa, A. Tanaka

    Proceedings - Electrochemical Society   PV2000-29   297 - 308  2000年

  • Microscopic characterization of electrochemical properties of silicon wafer surfaces

    T Homma, T Kono, T Osaka, M Watanabe, K Nagai

    HIGH PURITY SILICON VI   4218   621 - 633  2000年  [査読有り]

     概要を見る

    Microscopic mapping of electrochemical characteristics of silicon wafer surfaces correlates with their microstructural properties was demonstrated in order to elucidate the spontaneous nucleation (or "contamination") process of trace metals during wafer cleaning processes. Nucleation conditions of trace metals were investigated and the microstructural properties of the sites for the preferential nucleation, such as nanometer-scale defects, were characterized. Then electrochemical properties of these sites were investigated using an electric force microscope (EFM) which is based on a scanning probe microscopy, as well as potentiometric analysis. It was clarified that the defect sites (typically in the order of several to tens of nm) of clean H-Si(100) wafer surfaces possess electrochemically negative potential with respect to non-defected area, indicating that these sites were more active for the reductive deposition of the trace meal ions. The metal particles deposited at these sites were also found to possess negative potential. However, when the wafer surface was covered by oxide, the negative shift at the defect sites was not observed, although the defects did exist topographically. Based upon these results, mechanism of trace metal nucleation at defect sites is discussed.

  • Deposition mechanism of trace metals on silicon wafer surfaces in ultra pure water

    T Homma, J Tsukano, T Osaka, M Watanabe, K Nagai

    HIGH PURITY SILICON VI   4218   670 - 676  2000年  [査読有り]

     概要を見る

    Spontaneous deposition of trace metal contaminants such as Cu onto silicon wafer surfaces in ultra pure water (UPW) was investigated, focusing upon the reaction pathways of their deposition processes. Scanning probe microscopy analysis revealed that 10-20 nm diameter Cu particles were formed by reductive deposition of ionic species to the metals, which was enhanced under deoxygenated condition. On the other hand, dissolved oxygen enhanced the formation of oxide layer at silicon surface as well as inclusion of the metal species into the layer to develop rougher surface. These variation in the characteristics of metal contaminants such as chemical state and dispersion condition in microscopic scale, caused by the difference in dissolved oxygen concentration, should be one of the significant issues to optimize precision device processes.

  • 金属を使用する抗菌技術の現状とその応用

    趙志宏, 草刈真一, 逢坂哲彌

    環境管理技術   18   28 - 36  2000年

  • Electrodeposition of highly functional thin films for magnetic recording devices of the next century

    T Osaka

    ELECTROCHIMICA ACTA   45 ( 20 ) 3311 - 3321  2000年  [査読有り]

     概要を見る

    A review is presented of the recent progress in research and development of soft magnetic films for magnetic recording heads of the future primarily on the basis of the work performed by the author's research group. Films of CoNiFe ternary alloy with high saturation magnetic flux density B-S and low coercivity, H-C were successfully produced by electrodeposition. A typical film, designed as 'HB-CoNiFe', had the composition of Co65Ni12Fe23 (at.%) with B-S = 2.0-2.1 T and H-C &lt; 2 Oe. Properties other than B-S and H-C were also investigated; namely, magnetostriction, lambda(S), corrosion properties, and film resistivity rho. The key to the success in obtaining low H-C with high B-S was to form film with very fine crystals. The inclusion of small amount of sulfur was found to be essential for producing such a film with the desired magnetic properties. The firm has been applied to the construction of a new type of merged-GMR head, which is considered as a breakthrough for materializing ultra high-density magnetic recording. (C) 2000 Elsevier Science Ltd. All rights reserved.

  • Formation of microprobe using nickel electrodeposition

    Y Sugai, F Asa, Y Okada, T Yokoshima, T Momma, T Osaka, T Ito

    ELECTROCHEMISTRY   67 ( 12 ) 1150 - 1152  1999年12月  [査読有り]

     概要を見る

    Formation of Ni microstructure with high aspect ratio without thicker photoresist was tried by an electrodeposition method. The Ni microprobes thicker than photoresist thickness were electrodeposited on a patterned substrate using thin photoresist patterned with UV radiation. It was-important for preparing Ni microprobe with high aspect ratio to keep the overpotential of patterned cathode higher, and moreover the agitation using a paddle plating cell system was so effective to form uniform microprobes.

  • Improved morphology of plated lithium in poly(vinylidene fluoride) based electrolyte

    T Osaka, M Kitahara, Y Uchida, T Momma, K Nishimura

    JOURNAL OF POWER SOURCES   81   734 - 738  1999年09月  [査読有り]

     概要を見る

    The morphology of electrodeposited lithium was observed in the gel electrolyte consisting of the poly(vinylidene fluoride)hexafluoropropylene (PVdF-HFP) copolymer as a host polymer, LiClO4, and the propylene carbonate (PC)/ethylene carbonate (EC) organic solvents. The dendritic deposition was effectively suppressed in the PVdF-HFP gel electrolyte compared to the LiClO4-PC/EC liquid electrolyte or the polyethylene oxide (PEO) based gel electrolyte. Charge-discharge efficiency of the lithium metal anode was higher in the PVdF-HFP gel electrolyte than that in the liquid or the PEO gel electrolyte, and it was enhanced by CO, addition as well as observed in the LiClO4-PC/EC Liquid electrolyte. (C) 1999 Elsevier Science S.A. All rights reserved.

  • Effects of saccharin and thiourea on sulfur inclusion and coercivity of electroplated soft magnetic CoNiFe film

    T Osaka, T Sawaguchi, F Mizutani, T Yokoshima, M Takai, Y Okinaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   146 ( 9 ) 3295 - 3299  1999年09月  [査読有り]

     概要を見る

    During the course of our recent work performed to develop an electroplated CoNiFe ternary alloy with high saturation magnetic flux density and low coercivity for use in magnetic recording heads, it was observed that two common sulfur-containing additives, saccharin and thiourea, behave differently with respect to the dependence of sulfur inclusion and coercivity of the alloy film on the additive concentration in the plating bath. To understand the cause of this difference, scanning tunneling microscopy (STM) was performed, using Au(111) as the substrate, to examine the structure of the adsorbed layers of the additive molecules. The result revealed that the nature of adsorption is fundamentally different for the two different additives; i.e., the adsorption of saccharin is physical and reversible, whereas thiourea undergoes irreversible chemisorption. This finding is consistent with the known behaviors of the two additives in the electroplating of nickel. In this paper the different effects of saccharin and thiourea in the electrodeposition of CoNiFe alloy are interpreted based on the STM results and relevant information available in the literature on the electrodeposition of nickel. (C) 1999 The Electrochemical Society. S0013-4651(98)12-087-6. All rights reserved.

  • Increasing the resistivity of electrodeposited high B-S CoNiFe thin film

    T Yokoshima, M Kaseda, M Yamada, T Nakanishi, T Momma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   35 ( 5 ) 2499 - 2501  1999年09月  [査読有り]

     概要を見る

    In order to increase the resistivity of electrodeposited high B-S CoNiFe thin film, the effect of an organic additive such as diethylenetriamine (DET) added to the plating bath was investigated. The values of rho and H-C were gradually increased as a function of DET concentration. The desirable soft magnetic CoNiFe thin film with rho = 25-90 mu Omega-cm under the conditions of B-S &gt; 1.9 T and H-C &lt; 2.5 Oe was developed as function of carbon in the deposited films. Additionally, the high resistivity CoNiFe thin film with rho = 130 mu Omega-cm was established under the conditions of B-S = 1.7 T and H-C &lt; 6 Oe.

  • Research and development of high performance soft magnetic thin films

    T Osaka, T Momma, T Yokoshima

    ELECTROCHEMISTRY   67 ( 9 ) 894 - 899  1999年09月  [査読有り]

     概要を見る

    Soft magnetic films for head core materials mainly electrodeposited CoNiFe based films developed by us were introduced. Electrodeposited CoNiFe thin film has high saturation magnetic flux density (B-s) and low coercivity. Magnetic properties except for B-s and corrosion properties of these films were depended on very small amount of inclusion such as S and H elements. The increase in resistivity (rho) on the base of this high B-s CoNiFe thin film was developed by controlling very small amount of C inclusion. Finally, application of the film to new type of magnetic recording head was reported.

  • Corrosion properties of electroplated CoNiFe films

    M Saito, K Yamada, K Ohashi, Y Yasue, Y Sogawa, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   146 ( 8 ) 2845 - 2848  1999年08月  [査読有り]

     概要を見る

    Electroplated CoNiFe films with a saturation flux density as high as 2.1 T are potentially useful in high-density magnetic recording heads. We found that films electroplated at a high current density (15 mA/cm(2)) from a bath without saccharin have a sufficient anodic pitting-corrosion potential (-65 mV). We also found that the pitting-corrosion potential of films electroplated under a low current density (5 mA/cm(2)) from saccharin-free baths have anodic pitting-corrosion potentials of less than -300 mV. However, the corrosion resistance improved after annealing at temperatures above 100 degrees C. The crystal-grain boundaries in the as-plated film that electroplated under a low current density from saccharin-free baths are not clear (i.e., that the phase is amorphous). But the crystal grain boundaries in the annealed film are clear. Films electroplated from baths containing saccharin also have anodic pitting-corrosion potentials of less than -300 mV. Their corrosion resistance did not improve when they were annealed at 250 degrees C. The deterioration of the corrosion resistance is attributed to the defects that increase the face-centered cubic (111) lattice constant. One of the most important characteristics of a highly corrosion-resistant CoNiFe film is fine crystal structure with very few defects. (C) 1999 The Electrochemical Society. S0013-4651(98)06-043-1. All rights reserved.

  • 最新電池材料

    門間 聰之, 逢坂 哲彌

    電気学会誌 = The journal of the Institute of Electrical Engineers of Japan   119 ( 7 ) 408 - 411  1999年07月

    DOI CiNii

  • Influence of crystalline structure and sulfur inclusion on corrosion properties of electrodeposited CoNiFe soft magnetic films

    T Osaka, M Takai, Y Sogawa, T Momma, K Ohashi, M Saito, K Yamada

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   146 ( 6 ) 2092 - 2096  1999年06月  [査読有り]

     概要を見る

    The corrosion resistance of soft magnetic films is an important property to be considered in the manufacture of magnetic devices. We investigated the corrosion behavior of the electrodeposited CoNiFe him with desired soft magnetic properties by varying the crystalline structure and the amount of included sulfur. The corrosion property in 2.5% NaCl solution depends largely on the sulfur content and also on the structure of the film. Although the CoNiFe film contains more than 13 atom % Fe, the film of face-centered to body-centered cubic mixed crystals exhibits a high anticorrosion property because of very small grain size with essentially no sulfur inclusion (&lt;0.1 atom %). (C) 1999 The Electrochemical Society. S0013-4651(98)07-027-X. All rights reserved.

  • An electrochemical double layer capacitor using an activated carbon electrode with gel electrolyte binder

    T Osaka, XJ Liu, M Nojima, T Momma

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   146 ( 5 ) 1724 - 1729  1999年05月  [査読有り]

     概要を見る

    An electric double layer capacitor (EDLC) was prepared with an activated carbon powder electrode with poly(vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) based gel electrolyte. Ethylene carbonate (EC) and propylene carbonate (PC) were used as plasticizer and tetraethylammonium tetrafluoroborate (TEABF(4)) was used as the supporting electrolyte. An optimized gel electrolyte of PVdF-HFP/PC/EC/TEABF(4) = 23/31/35/11 mass ratio exhibited high ionic conductivity of 5 x 10(-3) S cm(-1), high electrode capacitance, and good mechanical strength. An electrode consisting of activated carbon (AC) with the gel electrolyte as the binder (AC/PVdF-HFP based gel, 7/3 mass ratio) showed a higher specific capacitance and a lower ion diffusion resistance within the electrode than a carbon electrode, prepared with PVdF-HFP binder without plasticizer. This suggests that an electrode mixed with the gel electrolyte has a lower ion diffusion resistance inside the electrode. The highest specific capacitance of 123 F g(-1) was achieved with an electrode containing AC with a specific surface area of 2500 m(2) g(-1). A coin-type EDLC cell with optimized components showed excellent cycleability exceeding 10(4) cycles with ca. 100% coulombic efficiency achieved when charging and discharging was repeated between 1.0 and 2.5 V at 1.66 mA cm(-2). (C) 1999 The Electrochemical Society. S0013-4651(98)09-016-8. All rights reserved.

  • Performance of a lithium metal anode in poly(vinylidene fluoride)-type gel electrolyte

    T Osaka, S Komaba, Y Uchida, M Kitahara, T Momma, N Eda

    ELECTROCHEMICAL AND SOLID STATE LETTERS   2 ( 5 ) 215 - 217  1999年05月  [査読有り]

     概要を見る

    The performance of a lithium metal anode was studied in a poly( vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) gel electrolyte. By using the PVdF-HFP gel electrolyte, we obtained a higher coulombic efficiency (ca. 85%) and a more uniform morphology of the lithium metal anode than those obtained with the propylene carbonate liquid or the poly( ethylene oxide) gel system. Additionally, the CO2 addition to the PVdF-HFP gel system improved both the the uniformity in morphology of the lithium anode and the coulombic efficiency further to ca. 95%. (C) 1999 The Electrochemical Society. S1099-0062(98)03-079-X. All rights reserved.

  • Mechanism of the chemical deposition of nickel on silicon wafers in aqueous solution

    N Takano, N Hosoda, T Yamada, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   146 ( 4 ) 1407 - 1411  1999年04月  [査読有り]

     概要を見る

    The deposition of metallic nickel on n-Si(100) wafers was performed without external potential control in aqueous NiSO4 solutions of different compositions at pH 8.0. Without giving any catalyzation treatment, the deposition of nickel on hydrogen-terminated Si(100) was confirmed in a conventional electroless plating bath containing NaH2PO2 as the reducing agent, sodium citrate as the complexing agent, and (NH4)(2)SO4 as the buffering agent. The deposition of nickel was found to take place also in a bath without the reducing agent, and even in a simple solution consisting of NiSO4 and (NH4)(2)SO4. By using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer, the cross sections of the films deposited from these solutions were examined, which revealed formation of silicon oxide between the Ni deposit and Si substrate. Based on these results, the mechanism of the entire process of electroless Ni deposition on Si is discussed. (C) 1999 The Electrochemical Society. S0013-4651(98)06-101-1. All rights reserved.

  • アルカリ性水溶液中でのクロラニル酸の電気化学特性と二次電池用電極活物質としての可能性 (Electrochemical Properties of Chloranilic Acid and its Application to the Anode Material of Alkaline Secondary Batteries)

    T. Osaka, T. Momma, S. Komoda, N. Shiraishi, S. Kikuyama, K. Yuasa

    Electrochemistry   67 ( 3 ) 238 - 242  1999年03月  [査読有り]

  • ゾル-ゲル法とスチーム処理を併用したSrBi_2Ta_2O_9薄膜の検討

    澤田 佳宏, 小針 英也, 佐藤 善美, 橋本 晃, 小岩 一郎, 加藤 博代, 逢坂 哲彌

    電子情報通信学会技術研究報告. SDM, シリコン材料・デバイス   98 ( 592 ) 9 - 14  1999年02月  [査読有り]

     概要を見る

    近年、SrBi_2Ta_2O_9(SBT)薄膜が膜疲労の起こらない強誘電体薄膜材料として注目を浴び活発に研究されている。我々は、加水分解を行い分子構造の組成制御性を高めた加水分解型ゾル-ゲル塗布液を独自に開発してきた。今回、この塗布液とスチーム処理を併用するSBT薄膜の成膜プロセスを検討した。その結果、ゾル-ゲル法の改良による低温結晶化およびスチーム処理により配向性が改善することを見出したので報告する。

    CiNii

  • High sensitivity flow injection analysis of urea using composite electropolymerized polypyrrole-polyion complex film

    T Osaka, S Komaba, Y Fujino, T Matsuda, Satoh, I

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   146 ( 2 ) 615 - 619  1999年02月  [査読有り]

     概要を見る

    A highly sensitive and rapid flow injection system for urea analysis was constructed with a composite film of electropolymerized inactive polypyrrole (PPy) and a polyion complex incorporating urease. This system shows a sensitivity of 120 mV decade(-1) and a lifetime of more than 80 assays. The origin of the high sensitivity of this system is attributed to an additional potential response of inactive PPy to ammonia or ammonium ion superimposed on the response to pH change. By injecting a concentrated buffer solution immediately after the sample injection, this system is capable of assaying more than 15 samples per hour. (C) 1999 The Electrochemical Society. S0013-4651(98)05-073-3. All rights reserved.

  • Characterization of ferroelectric SrBi2Ta2O9 thin films prepared from alkoxide solutions

    S Ono, A Sakakibara, T Osaka, Koiwa, I, J Mita, K Asami

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   146 ( 2 ) 685 - 690  1999年02月  [査読有り]

     概要を見る

    SrBi2Ta2O9 thin films prepared by chemical liquid deposition using alkoxide precursor solutions, followed by annealing at various temperatures, were characterized with a focus on the correlation between composition, microstructure, and ferroelectric properties. P-E hysteresis loops of the films exhibited well-defined shapes at temperatures above 700 degrees C, and the leakage current decreased with increasing annealing temperature, except for a film annealed at 750 degrees C. The crystal growth proceeded and ferroelectric properties of the films improved with increasing annealing temperature, whereas a large leakage current was observed for the film annealed at 750 degrees C. Quantitative X-ray photoelectron spectroscopic analysis and high-resolution transmission electron microscopic observation indicated the presence of a substantial amount of metallic bismuth in all films, predominantly in microcrystallite regions and on film surfaces, including the inner surface of cavities. The atomic fraction of metallic bismuth increased upon slight argon etching; however, the total bismuth content was significantly reduced. The metallic bismuth was amorphous and detected as vibrating spherical particles measuring approximately 5 nm under electron irradiation. The discontinuity in morphology, such as cavities at the interface between large single-crystal grains and microcrystallite regions, was most remarkable in the film annealed at 750 degrees C. The condensation of metallic bismuth at the cavities is believed to increase the leakage current when the path formed by cavities penetrates through the him. (C) 1999 The Electrochemical Society. S0013-4651(98)03-078-X. All rights reserved.

  • Analysis of the Degradation Mechanisms of Pt/SrBi2(Ta/Nb)2O9/Pt Capacitors During Reductive Annealing

    A. Tofuku, T. Yoshie, T. Osaka, I. Koiwa, H. Kobayashi, Y. Sawada, A. Hashimoto

    Integr. Ferroelectr.   25   245 - 264  1999年

  • Preparation and noise properties of perpendicular longitudinal composite media prepared by electroless-deposition method

    T Onoue, N Miyamoto, J Hokkyo, T Homma, T Osaka

    PROCEEDINGS OF THE FIFTH INTERNATIONAL SYMPOSIUM ON MAGNETIC MATERIALS, PROCESSES, AND DEVICES   98 ( 20 ) 231 - 241  1999年  [査読有り]

     概要を見る

    Perpendicular magnetization/ longitudinal magnetization composite recording media were fabricated by the two methods; the all preparation was done by an electroless-deposition method, while the preparation by combination of an electroless deposition method and an sputtering deposition method. Their recording characteristics, especially noise properties, were mainly investigated. The noise of a composite medium, which consisted of an electroless-CoNiReP perpendicular magnetization upperlayer and an electroless-CoP longitudinal magnetization underlayer, mainly arises from the CoP underlayer. Next, a sputter-deposited CoCrPtTa longitudinal magnetization film, which possessed low noise property, was applied for the underlayer instead of CoP film. By a Pd-treatment to the surface of the CoCrPtTa underlayer, unfavorable epitaxial growth in the electroless-deposited CoNiReP upperlayer was suppressed, then the upperlayer which has strong perpendicular magnetic anisotropy was obtained. The new composite medium, which consisted of electroless-CoNiReP upperlayer and sputter-CoCrPtTa underlayer, exhibited low noise property.

  • Functionally graded magnetic thin films prepared by electroless deposition

    T Homma, Y Kita, T Osaka

    PROCEEDINGS OF THE FIFTH INTERNATIONAL SYMPOSIUM ON MAGNETIC MATERIALS, PROCESSES, AND DEVICES   98 ( 20 ) 599 - 606  1999年  [査読有り]

     概要を見る

    Gradient control of magnetic properties in electroless-deposited CoNiP films was attempted and the origin of graded properties was investigated By rotating the substrate during the deposition and changing the speed of the rotation, magnetic properties such as coercivity He, of the deposited films was varied Moreover programmed control of the gradient in Hc was achieved by the sequential control of rotating speed of substrates during the deposition. The results of cross-sectional SEM and TEM investigation clarified that the size of the crystallites was changed according to the speed of the rotation forming the "graded" microstructure toward the film thickness direction. These procedures are expected to be useful for controlling the graded magnetic properties of the films for the use of various magnetic devices.

  • New trends on head core materials for next generation magnetic recording

    T Osaka, T Yokoshima

    PROCEEDINGS OF THE FIFTH INTERNATIONAL SYMPOSIUM ON MAGNETIC MATERIALS, PROCESSES, AND DEVICES   98 ( 20 ) 473 - 487  1999年  [査読有り]

     概要を見る

    Soft magnetic films for head core materials with high saturation magnetic flux density and/or high resistivity prepared by electroplating or electroless-plating were introduced. Especially, for mainly electroplated CoNiFe based films, electroplated NiFe based films, and electroless-plated CoFe based films developed by us, the magnetic properties were summarized.

  • The 2nd International Symposium on Electrochemical Microsystem Technologies - Preface

    T Osaka

    ELECTROCHIMICA ACTA   44 ( 21-22 ) 3603 - 3604  1999年  [査読有り]

  • Ab initio molecular orbital study on the oxidation mechanism for dimethylamine borane as a reductant for an electroless deposition process

    Homma, T, Nakai, H, Onishi, M, Osaka, T

    Journal of Physical Chemistry B   103 ( 10 ) 1774 - 1778  1999年  [査読有り]

    DOI

  • 無電解NiBめっきにおける複合錯化剤の影響 (Effect of Mixed Complexing Agents on Electroless NiB Plating)

    M. Kim, A. Iizuka, T. Kubomiya, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   50   294 - 300  1999年

  • スパッタ法による垂直面内複合型媒体の作製

    瀧澤 敦尚, 尾上 貴弘, 池田 真, 平山 貴邦, 朝日 透, 逢坂 哲彌, 酒井 浩志

    日本応用磁気学会誌   23 ( 4 ) 973 - 976  1999年

     概要を見る

    Perpendicular/longitudinal composite media were fabricated by sputtering. It is hard to deposit a perpendicular upper layer on a longitudinal underlayer because of the epitaxy between the layers. Therefore, it is important to prevent the epitaxial growth between the perpendicular upper layer and the longitudinal underlayer. For this purpose, we attempted to apply an amorphous carbon interlayer. First, the magnetic properties of perpendicular single media with Ti-Cr and C underlayers were compared. As a result, it was found that a perpendicular single medium with a C underiayer had the same property as a medium with a Ti-Cr underlayer. In accordance with these results, a perpendicular layer was deposited onto a longitudinal layer with a C interlayer. Consequently, the thickness of the C interlayer was optimized. As a result, a perpendicular/longitudinal composite medium was successfully fabricated using 5-nm C interlayer.

    DOI CiNii

  • スパッタ法により作製した垂直面内複合型媒体のノイズ特性 (Noise Properties of a Perpendicular/Longitudinal Composite Medium Prepared by Sputtering)

    T. Onoue, A. Takizawa, T. Hirayama, M. Ikeda, T. Homma, J. Hokkyo, T. Osaka, H. Sakai, T. Yoshikawa

    J. Magn. Soc. Jpn.   23   977 - 980  1999年

  • 垂直単層媒体および垂直面内複合型媒体におけるベースラインシフト (Baseline Shift of Perpendicular Single-Layered Media and Perpendicular/Longitudinal Composite Media)

    T. Onoue, T. Hirayama, A. Takizawa, M. Ikeda, J. Hokkyo, T. Osaka, H. Sakai, T. Yoshikawa

    J. Magn. Soc. Jpn.   23   981 - 984  1999年

  • 無電解CoFeBめっきを用いた磁気ヘッドコア作製プロセスの基礎的検討 (Investigation of Fabrication Process for Writing-Head Cores Using Electroless CoFeB Plating)

    T. Yokoshima, D. Kaneko, T. Osaka, S. Takefusa, M. Oshiki

    J. Magn. Soc. Jpn.   23   1397 - 1400  1999年

  • 高Bs-CoNiFe電析膜の軟磁気特性に及ぼす成膜条件の影響 (Effect of Operating Conditions on the Soft Magnetic Properties of Electrodeposited High-Bs CoNiFe Films)

    Y. Sogawa, S. Mizutani, T. Momma, T. Osaka, M. Saito, K. Ohashi, K. Yamada

    J. Magn. Soc. Jpn.   23   1405 - 1408  1999年

  • 無電解NiB皮膜の結晶構造に及ぼす共析元素の影響 (Effect of Co-Deposited Elements on Structure of Electroless NiB Plating)

    M. Kim, A. Iizuka, T. Kubomiya, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   50   353 - 358  1999年

  • Mechanism of direct copper plating on nonconducting substrates

    S Ono, T Osaka, K Naitoh, Y Nakagishi

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   146 ( 1 ) 160 - 166  1999年01月  [査読有り]

     概要を見る

    The mechanism of direct copper plating on nonconducting resin substrates was investigated by high resolution transmission electron microscopy and scanning electron microscopy observation and surface analysis techniques. The substrates were catalyzed by Pd/Sn mixed catalyst and accelerated in an alkaline solution containing copper ions and a reductant before the direct plating. After the acceleration, copper crystalline particles measuring approximately 300 nm were found to be dispersed at the population density of 1.4 X 10(11) m(-2) in addition to adsorbed palladium colloids. The colloids formed clusters measuring 20 to 50 nm which consist of individual particles measuring approximately 2 nm. The addition of copper ions in the acceleration solution exerted a remarkable promotion effect on the speed of lateral propagation of direct plating. This effect can be explained by a modified stepwise propagation mechanism in which dispersed copper particles formed in the Cu(II) containing accelerating solution play a critical role in determining the propagation speed. The copper particles also play an important role in determining the uniformity of the propagation of copper plating. (C) 1999 The Electrochemical Society. S0013-4651(98)01-058-1. All rights reserved.

  • Effect of Deposition Site Condition on the Initial Growth Process of Electroless CoNiP Films

    K. Itakura, T. Homma, T. Osaka

    Electrochim. Acta   44   3707 - 3711  1999年

  • Initial propagation stage of direct copper plating on non-conducting substrates

    S Ono, K Naitoh, T Osaka

    ELECTROCHIMICA ACTA   44 ( 21-22 ) 3697 - 3705  1999年  [査読有り]

     概要を見る

    The initial propagation stage of direct copper plating on non-conducting resin substrates was studied by a high resolution transmission electron microscope, an electron diffraction and a scanning electron microscope analysis to confirm the mechanism. In this process, ABS resin substrate was catalyzed by Pd/Sn mixed catalyst and accelerated in a solution containing copper ions before the direct plating. Cubic Cu2O crystals approximately 20-50 nm in size were formed along the migration front of direct copper plating to provide stepping stones for copper propagation, while few such crystals were found on a residual uncovered catalyst area, At the thicker copper plated area, Cu2O crystals were embedded in a flat copper deposit which was composed of small crystals 10-20 nm in size. The Cu2O crystals should be activation sites for copper deposition by the formation of additive free metallic copper according to disproportionation reaction and so that promote the propagation speed. This effect can be explained by ia modified stepwise propagation mechanism' in which Cu2O crystals act a critical roll for the copper propagation as stepping stones in addition to dispersed Cu particle seeds and Pd catalyst cluster seeds. (C) 1999 Elsevier Science Ltd. All rights reserved.

  • Effect of oxidized silicon surface on chemical deposition of nickel on n-type silicon wafer

    N Takano, N Hosoda, T Yamada, T Osaka

    ELECTROCHIMICA ACTA   44 ( 21-22 ) 3743 - 3749  1999年  [査読有り]

     概要を見る

    The effect of oxidation of silicon surface on chemical deposition of nickel was investigated in aqueous basic baths containing Ni2+. On H-terminated Si(100), Ni was deposited obviously but partially. On oxidized Si(100), Ni was deposited on the whole surface with a higher rate than on H-Si(100). The deposits were examined by scanning electron microscopy (SEM) and Auger electron spectroscopy (AES). Selective nickel deposition was performed on oxidized Si(100) patterned with a layer of plasma-CVD SiO2. Ni dots with diameters about 1 mu m were formed by dipping the patterned Si(100) wafers first into a Ni bath containing no reducing agent for nuclei formation, and then into a Ni bath with reducing agent for growing particles. (C) 1999 Elsevier Science Ltd. All rights reserved.

  • 垂直磁気記録単層媒体における記録磁化状態とノイズ特性 (Study on Medium Noise and Remanent Magnetization State for Single-Layer Perpendicular Magnetic Recording Media)

    T. Onoue, T. Asahi, T. Hirayama, J. Hokkyo, T. Osaka

    J. Magn. Soc. Jpn.   23   973 - 976  1999年

  • Pd/Sn混合触媒を用いた銅ダイレクトプレーティングにおける導体化過程の解析 (Analysis of Conversion on Direct Copper Plating Using Pd/Sn Mixed Catalyst)

    A. Iizuka, G. Nakamoto, K. Naito, T. Homma, H. Nakao, K. Okuno, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   50   915 - 922  1999年

  • Analysis of the degradation mechanism of Pt/SrBi2(Ta/Nb)(2)O-9/Pt capacitors during reductive annealing

    A Tofuku, T Yoshie, T Osaka, Koiwa, I, H Kobayashi, Y Sawada, A Hashimoto

    INTEGRATED FERROELECTRICS   25 ( 1-4 ) 585 - 604  1999年  [査読有り]

     概要を見る

    Degradation mechanism of the Pt/SrBi2Ta2xO9/Pt and Pt/SrBi2(Ta1-x/Nb-x)(2)O-9/Pt capacitors exposed to the hydrogen attack has been analyzed. The capacitors were fabricated from thin-films consisting of SrBi2Ta2xO9 (1 less than or equal to x less than or equal to 1.1) and SrBi2(Ta1-x/Nb-x)(2)O-9 (0 less than or equal to x less than or equal to 1) (SBTN) that were formed using a sol-gel process. In most capacitors, SBTN thin-films were short-circuited while annealing in the reducing atmosphere. In contrast, excessive Ta addition could hold back the short circuit. Analysis of the degradation mechanism were carried our by means of the XRD, TEM and XPS, which revealed that the most significant alteration took place in the vicinity of crystal grain boundaries. It was also found that the film with excessive Ta concentration contains the pyrochlore phase in the grain boundary layers. These findings suggest that the stabilization of grain boundary layers is effective to realize capacitors resistant to process conditions.

  • A study on low-temperature crystallization of SrBi2Ta2O9 thin films prepared by sol-gel method using steam curing process

    Y Sawada, H Kobari, Y Sato, A Hashimoto, Koiwa, I, H Kobayashi, T Osaka

    INTEGRATED FERROELECTRICS   26 ( 1-4 ) 889 - 897  1999年  [査読有り]

     概要を見る

    We have been developing our original hydrolyzed sol-gel coating solutions for the SrBi2Ta2O9 (SBT) thin film. The molecular structure of the solution can be controlled by hydrolysis. We studied the SBT thin film forming process using these coating solutions with the steam curing process used together and observed lower crystallization temperature and improvement of crystal orientation.

  • めっき膜の抗菌作用とその応用(Inhibitory Ability of Plated Coatings to the Bacterial Growth and Its Application)

    Z. Zhao, S. Kusakari, Y. Sakagami, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   50   25 - 30  1999年

  • 最新電池材料 (New Trends on Battery Materials)

    T. Momma, T. Osaka

    Trans. Inst. Electr. Eng. Jpn.   119   408 - 411  1999年

  • 次世代研究開発

    T. Osaka

    Electrochemistry   67   743 - 743  1999年

  • Lithium Ion Batteries on the Upswing

    T. Osaka

    The Electrochemical Society Interface fall 1999 Japan Watch   8   9 - 9  1999年

  • Recent development of Magnetic recording head core materials by plating method

    T Osaka

    ELECTROCHIMICA ACTA   44 ( 21-22 ) 3885 - 3890  1999年  [査読有り]

     概要を見る

    Soft magnetic films for Magnetic recording head core materials with high saturation magnetic flux density and/or high resistivity prepared by electroplating or electroless-plating were introduced. Especially, for mainly electroplated CoNiFe based films, electroplated NiFe and NiFeP based films, and electroless-plated NiFeB and CoFeB based films developed by us, the magnetic properties were summarized. (C) 1999 Elsevier Science Ltd. All rights reserved.

  • 次世代電子デバイス開発におけるブレイクスルー

    T. Osaka, N. Takano, M. Kitahara

    Materia Japan   38   260 - 260  1999年

  • 集積回路配線における精密めっき技術

    逢坂 哲彌, 高野 奈央

    応用物理   68 ( 11 ) 1237 - 1242  1999年

     概要を見る

    近年のULSIデバイスの高速化・高集積化によって配線断面積が減少し,そのために配線抵抗の上昇,電流密度の増加が引き起こされ,これらが療因となって生じる信号遅延やエレクトロマイグレーションの影響がこれまで以上に問題視されるようになってきた.これらの問題を解決する手段の一つとして,従来のAIに代わりCuを配線材料として適用ずることが考えられ,'97年IBM社によってCu配線の実用化が発表された.このCu配線では,コスト面で有利な電気Cuめっき法が利用されており,さらに従来Ou配線の実現に際して困難な点の一つとされていたCuのエッチングがCMP技術によって莞腺されたことで,実用化されるようになった.現在主流となっているのは,デュアルダマシンプロセスとよばれる方法であり,高アスペクト比のパターンにおいて,ボイド,シームのない良好な埋め込みを実現している.本論文では,デュアルダマシンプロセスにおいて不可欠である精密めっき技術について紹介する.

    DOI CiNii

  • 新しい軟磁性材料の開発--高密度磁気記録への道を拓く

    逢坂 哲弥

    現代化学   333 ( 333 ) 24 - 30  1998年12月

    CiNii

  • Biological determination of Ag(I) ion and arginine by using the composite film of electroinactive polypyrrole and polyion complex

    S Komaba, Y Fujino, T Matsuda, T Osaka, Satoh, I

    SENSORS AND ACTUATORS B-CHEMICAL   52 ( 1-2 ) 78 - 83  1998年09月  [査読有り]

     概要を見る

    The urea biosensor based on the combination of electropolymerized insulating polypyrrole (PPy) with urease was used for the determination of Ag(I) ion and arginine. The inhibition ratio of urease with Ag(I) ion was evaluated from the urea response of the sensor. This method enabled the detection of 1.0 x 10(-7) to 1.0 x 10(-4) mol dm(-3) of Ag(I) ion. With the addition of EDTA as a masking agent for interfering heavy metal ions, the selectivity for Ag(I) ion was improved. Furthermore, arginine detection was carried out with the PPy electrode using bienzymatic combination of urease and arginase. The calibration curve for arginine was obtained in the concentration range of 1.0 x 10(-5) to 1.0 x 10(-3) mol dm(-3) with a sensitivity of 50 mV decade(-1). (C) 1998 Elsevier Science S.A. All rights reserved.

  • Effects of H2 Sintering and Pt Upper Electrode on Metallic Bi Content in Sr0.9Bi2.1Ta2O9 Thin Films for Ferroelectric Memories Prepared by Sol-Gel Method

    I. Koiwa, T. Kanehara, H. Kato, S. Ono, A. Sakakibara, T. Osaka, K. Asami

    Jpn. J. Appl. Phys.   37 ( 9B ) 5192 - 5197  1998年09月  [査読有り]

  • Flow injection analysis of potassium using an all-solid-state potassium-selective electrode as a detector

    S Komaba, J Arakawa, M Seyama, T Osaka, Satoh, I, S Nakamura

    TALANTA   46 ( 6 ) 1293 - 1297  1998年08月  [査読有り]

     概要を見る

    The concentration of potassium was determined by a combination of flow injection analysis (FIA) with an all-solid-state potassium sensor detection. The all-solid-state potassium-selective electrode possessing long-term potential stability was fabricated by coating an electroactive polypyrrole/poly(4-styrenesulfonate) film electrode with a plasticized poly(vinyl chloride) membrane containing valinomycin. The simple FIA system developed in this laboratory demonstrated sensitivity identical to that in the batch system and achieved considerably rapid assay (150 samples h(-1)). Analyses of soy sauce and control serum samples by this FIA system yielded results in good agreement with those obtained by conventional measurements. (C) 1998 Elsevier Science B.V. All rights reserved.

  • Impedance analysis of electrodeposited insulating polypyrrole

    S Komaba, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   453 ( 1-2 ) 19 - 23  1998年08月  [査読有り]

     概要を見る

    To develop a general quantitative method of analyzing the process of electrodeposition of high resistance materials, the electrical resistance of electrochemically deposited insulating polypyrrole (PPy) film was measured in situ by ac impedance. By considering the potential drop across the PPy film during its formation by constant potential electrolysis, the growth of the insulating PPy film was analyzed, and an equivalent circuit describing the interfacial structure was proposed. (C) 1997 Elsevier Science S.A. All rights reserved.

  • 白金電極の配向性がゾル・ゲル法により作製したSrBi_2Ta_2O_9薄膜特性に与える影響

    小岩 一郎, 加藤 博代, 金原 隆雄, 橋本 晃, 澤田 佳宏, 一ノ瀬 昇, 逢坂 哲彌

    電子情報通信学会技術研究報告. SDM, シリコン材料・デバイス   98 ( 194 ) 55 - 60  1998年07月  [査読有り]

     概要を見る

    白金電極を用いても分極反転による膜疲労が生じない材料としてBi層状構造を有するSrBi_2Ta_2O_9(SBT)薄膜の研究が活発に進められている。本研究においては、異なる配向性を有する白金電極の上に我々が独自に開発したゾル・ゲル法によるSBT薄膜を形成し、電極の配向性がSBT薄膜の膜特性に与える影響を検討した。(111)と(200)面配向の白金電極を酸素雰囲気で750℃30分の熱処理を行うと(111)面の強度が高まる事が明らかになった。しかし、白金電極の配向性がSBT薄膜の特性に与える影響は小さい事が明らかとなった。また、SBT薄膜を白金電極上に形成することにより、白金の熱処理変化は抑制されることが明らかとなった。

    CiNii

  • Sr_2Bi_2TaO_9薄膜の成膜におけるゾル-ゲル法の利点

    澤田 佳宏, 橋本 晃, 小岩 一郎, 加藤 博代, 金原 隆雄, 逢坂 哲彌

    電子情報通信学会技術研究報告. ICD, 集積回路   98 ( 196 ) 61 - 66  1998年07月  [査読有り]

     概要を見る

    近年、SrBi_2Ta_2O_9(SBT)薄膜が膜疲労の起こらない強誘電体薄膜材料として注目を浴び活発に研究され始めた。この薄膜の成膜方法は有機金属分解(MOD)法が主流になっている。本報告では、我々が独自に開発した加水分解型ゾルーゲル塗布液と、この塗布液から成膜したSBT薄膜のプロセス上の利点について紹介する。

    CiNii

  • Newly developed inductive write head with electroplated CoNiFe film

    K Ohashi, Y Yasue, M Saito, K Yamada, T Osaka, M Takai, K Hayashi

    IEEE TRANSACTIONS ON MAGNETICS   34 ( 4 ) 1462 - 1464  1998年07月  [査読有り]

     概要を見る

    A newly developed CoNiFe film is investigated from the viewpoint of its application to MR write heads. Film composition is Co65Ni12Fe23, prepared by electroplating to obtain a b.c.c. plus f.c.c. mixed phase at that composition. Films with mixed phases improve soft magnetic properties (B-s is 2.0-2.1 T and the magnetostriction coefficient is +1.8x10(-6) to +7.4x10(-6)) and also show improved corrosion resistance. Performance of a head with a double layer structure of a 0.3 mu m CoNiFe film and a 4.1 mu m NiFe film is investigated, and a short throat height is found to give better overwrite performance.

  • Fabrication of nickel dots using selective electroless deposition on silicon wafer

    T Osaka, N Takano, S Komaba

    CHEMISTRY LETTERS   27 ( 7 ) 657 - 658  1998年07月  [査読有り]

     概要を見る

    The selective deposition of nickel on n-Si(100) wafer in aqueous solution was investigated. It was confirmed by cross-sectional FE-TEM examination that the deposition of nickel occurred from a solution of nickel ions prepared by excluding the hypophosphite reducing agent from the conventional electroless nickel plating bath, and that this deposition reaction accompanied the formation of SiO2. This finding shows that the electrons needed to reduce the nickel ions to the metal are supplied directly from the Si wafer. By utilizing this galvanic displacement reaction, nickel metal in the form of minute dots measuring 1 mu m in diameter was selectively deposited using a silicon oxide layer as the resist in combination with a two-step process, which consisted of the first step of immersing a Si wafer into a solution containing nickel ions but no reducing agent to form nuclei of nickel metal, and the second step of immersing the wafer with the nuclei into a conventional electroless nickel plating bath to cause the growth of the nuclei to the desired size.

  • Study of the structural change due to heat-treatment in high resistivity electroless NiPC film

    T Osaka, T Higashikawa, A Iizuka, M Takai, M Kim

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   145 ( 7 ) 2419 - 2424  1998年07月  [査読有り]

     概要を見る

    Structural changes caused by heat-treatment of newly developed electroless NiPC films were investigated. The NiPC films containing a few atom percent of carbon, which exhibit an exceptionally high resistivity (p) and an excellent temperature coefficient of resistance value were prepared by using diethylenetriamine and beta-alanine as complexing agents. The p value of this film decreased upon heat-treatment. The differential scanning calorimetry measurements showed that the NiPC films exhibit peaks which are distinct from the peaks of the conventional NiP film. The X-ray diffraction results indicated that these peaks could be associated with structural changes. In fact, observed crystallization temperatures of the NiPC films were higher than that of the NiP film. Gas components desorbed from the NiPC films during annealing were identified. It is evident that the NiPC films contain various organic elements and water. Transmission electron microscope bright-field images for the NiPC films reveal unique bean-like features. The bean-like features are retained even after crystallization and presumably affect the resistivity. The high resistivity is associated with organic elements incorporated in the film as well as the bean-like features.

  • Acetylene black poly(vinylidene fluoride) gel electrolyte composite electrode for an electric double-layer capacitor

    T Osaka, XJ Liu, M Nojima

    JOURNAL OF POWER SOURCES   74 ( 1 ) 122 - 128  1998年07月  [査読有り]

     概要を見る

    A composite electrode with carbon powder and poly(vinylidene fluoride) (PVdF) gel electrolyte is prepared and investigated as an electrode for an electric double-layer capacitor (EDLC). PVdF-based gel, with a mixture of ethylene carbonate (EC) and propylene carbonate (PC) as plasticizer, and tetraethylammonium tetrafluoroborate (TEABF(4)) is used as the electrolyte of the EDLC. The composite electrode shows a higher specific capacitance and lower ion-diffusion resistance inside the electrode than those studied previously with carbon electrodes prepared with PVdF binder only. The highest specific capacitance, 4.1 F g(-1), is achieved for an acetylene black (AB)/PVdF gel composite electrode with a PVdF content of 30 wt.%. This is because the electrode has the best contact stale between AB and PVdF gel electrolyte. Finally, the performance of an EDLC with AB/PVdF gel composite electrodes is evaluated and an excellent cyclability over 10(5) cycles with similar to 100% coulombic efficiency is achieved during charge-discharge between 1.0 and 2.0 V at 1.66 mA cm(-2). (C) 1998 Elsevier Science S.A. All rights reserved.

  • New Soft Magnetic CoNiFe Plated Films with High Bs=2.0-2.1T

    T. Osaka, M. Takai, K. Hayashi, Y. Sogawa, K. Ohashi, Y. Yasue, M. Saito, K. Yamada

    IEEE Trans. Magn.   34 ( 4 ) 1432 - 1434  1998年07月  [査読有り]

  • Toxicity of hydrogen peroxide produced by electroplated coatings to pathogenic bacteria

    ZH Zhao, Y Sakagami, T Osaka

    CANADIAN JOURNAL OF MICROBIOLOGY   44 ( 5 ) 441 - 447  1998年05月  [査読有り]

     概要を見る

    The ability of various electroplated coatings (cobalt, zinc, copper, and cobalt-containing alloys of nickel, zinc, chromium, etc.) to inhibit the growth of pathogenic bacteria (Gram-positive bacteria Enterococcus faecalis and methicillin-resistant Straphylococcus aureus and Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae) was determined by a drop-method antibacterial experiment. The amounts of H2O2 produced and metal ions dissolved from the surfaces of various electroplated coatings were measured and it was found that the inhibitory ability of coatings corresponded to the amounts of H2O2 produced. The more significant the inhibition of the coating to bacterial growth, the greater the amount of H2O2 production. In addition, the bacterial survival rates on the surfaces of coatings were almost zero when H2O2 was produced in amounts greater than 10(-6) mmol/cm(2). However, the dominant concentrations of metal ions dissolved from coatings were outside of the bacterial lethal range.

  • Relationship between residual metal ions in a solution and the inhibitory capability of the metal ions for pathogenic bacterial growth

    ZH Zhao, Y Sakagami, T Osaka

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   71 ( 4 ) 939 - 945  1998年04月  [査読有り]

     概要を見る

    The inhibitory capability of various low concentrations of six kinds of metal ions [silver(I), copper(II), cobalt(II), nickel(II), zinc(II), and dichromate] for pathogenic bacterial (gram-positive bacteria Staphylococcus aureus and MRSA, gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa) growth was quantitatively determined exactly. Residual metal-ion concentrations in a phosphate buffer solution after being incubated with pathogenic bacteria were then measured by an atomic-absorption spectrophotometer. We found that the inhibitory capability of metal ions correlated with the residual metal concentrations. Based on the biochemical and chemical situation, the mechanisms of the inhibitory capability of the metal ions are discussed. In addition, the determined minimum inhibitory concentration (MIC) values of metal ions on tested bacteria are considered.

  • Electrochemical formation of polypyrrole/SiO2 composite film and its application to organic electroluminescence devices

    S Komaba, K Fujihana, T Osaka, S Aiki, S Nakamura

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   145 ( 4 ) 1126 - 1130  1998年04月  [査読有り]

     概要を見る

    A uniform composite film of polypyrrole and silanol was prepared by electropolymerizing pyrrole in acetonitrile electrolyte containing silanol. By annealing this composite film at 400 degrees C, a polypyrrole/silicon oxide (PPy/SiO2) composite film was obtained. This composite film evaluated by Auger electron spectroscopy, UV-vis spectroscopy, and atomic force microscopy. The PPy/SiO2 composite film was applied as a hole transporting layer of the organic electroluminescence durability (EL) device with an emission layer of coumarin 6 to enhance the durability of this EL device.

  • Crystallization Process of Sr0.7Bi2.3Ta2O9 Thin Films with Different Crystal Orientation Prepared by Chemical Liquid Deposition Using Alkoxide Precursor

    I. Koiwa, T. Kanehara, J. Mita, T. Osaka, S. Ono, A. Sakakibara, T. Seki

    IEICE Trans. Electronics   E81C ( 4 ) 552 - 559  1998年04月  [査読有り]

  • Structural Defects of Sr0.7Bi2.3Ta2O9 Thin Film for Ferroelectric Memory

    T. Osaka, S. Ono, A. Sakakibara, I. Koiwa

    IEICE Trans. Electronics   E81C ( 4 ) 545 - 551  1998年04月  [査読有り]

  • A soft magnetic CoNiFe film with high saturation magnetic flux density and low coercivity

    T Osaka, M Takai, K Hayashi, K Ohashi, M Saito, K Yamada

    NATURE   392 ( 6678 ) 796 - 798  1998年04月  [査読有り]

     概要を見る

    Magnetic materials are classed as 'soft' if they have a low coercivity (the critical field strength H-c required to flip the direction of magnetization). Soft magnetic materials are a central component of electromagnetic devices such as step motors, magnetic sensors, transformers and magnetic recording heads. Miniaturization of these devices requires materials that can develop higher saturation flux density, B-s, so that the necessary flux densities can be preserved on reducing device dimensions, while simultaneously achieving a low coercivity. Common high-B-s soft magnetic films currently in use are electroplated CoFe-based alloys(1-4), electroplated CoNiFe alloys(5-7), and sputtered Fe-based nanocrystalline(8-11) and FeN films(12-14). Sputtering is not suitable, however, for fabricating the thick films needed in some applications, for which electrochemical methods are preferred. Here we report the electrochemical preparation of a CoNiFe film with a very high value of B-s (2.0-2.1T) and a low coercivity. The favourable properties are achieved by avoiding the need for organic additives in the deposition process, which are typically used to reduce internal stresses. Our films also undergo very small magnetostriction, which is essential to ensure that they are not stressed when an external magnetic field is applied (or conversely, that external stresses do not disrupt the magnetic properties). Our material should find applications in miniaturization of electromechanical devices and in high-density magnetic data storage.

  • Highly sensitive microbiosensor for creatinine based on the combination of inactive polypyrrole with polyion complexes

    T Osaka, S Komaba, A Amano

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   145 ( 2 ) 406 - 408  1998年02月  [査読有り]

     概要を見る

    Potentiometric creatinine microsensors were fabricated by use of a composite film consisting of polyion complex (PIG), which contains creatinine iminohydrolase (CIH), and the electrochemically inactive polypyrrole (iPPy). The PPy/PIC-CIH composite film electrode displayed potential response to creatinine concentration owing to a pH change occurring during the enzymatic reaction. The sensitivity was varied by using different polyions of the PIG. With poly-L-lysine and sebacic acid, the iPPy/PIC-CIH electrode demonstrated a high sensitivity (29.8 mV decade(-1)) and a low detection limit (1 x 10(-6) mol dm(-3)) which allow one to monitor creatinine concentration in the physiological range.

  • Phase transition in ferroelectric SrBi2Ta2O9 thin films with change of heat-treatment temperature

    T Osaka, A Sakakibara, T Seki, S Ono, Koiwa, I, A Hashimoto

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   37 ( 2 ) 597 - 601  1998年02月  [査読有り]

     概要を見る

    Changes in the composition and the crystal structure of micro-grains have been studied using transmission electron microscopy (TEM) and energy dispersive X-ray microanalysis in order to clarify the phase formation of ferroelectric SrBi2Ta2O9 (SBT) with heat-treatment at 650-750 degrees C. Micrograins crystallized at 650 degrees C begin to change to bismuth-layer-structure-family (BLSF) grains at temperatures exceeding 700 degrees C, and form pure-BLSF phase grains at 800 degrees C, Hence, a micrograins phase exists in thin films at 650-750 degrees C and we determined that the bismuth composition in these grains decreases. Using selected diffraction and high-resolution TEM, we found that a pyrochlore phase was formed in the bismuth-poor micrograins that were heat treated at 750 degrees C, The formation of pyrochlore made pure-phase BLSF difficult to obtain.

  • Electroless NiB deposition for micro-patterned formation

    M Takai, S Takefusa, T Yokoshima, T Osaka

    PROCEEDINGS OF THE SYMPOSIUM ON FUNDAMENTAL ASPECTS OF ELECTROCHEMICAL DEPOSITION AND DISSOLUTION INCLUDING MODELING   97 ( 27 ) 358 - 369  1998年  [査読有り]

     概要を見る

    Micro-patterned formation on a patterned substrate, which was formed by photoresist, from electroless NiB bath using dimethylamine borane as a reducing agent was investigated. The electroless NiB micro-patterned formation showed that the deposition of films occurred not only on the catalytic surface but also on the photoresist which had no catalytic surface. Addition of organic stabilizers, as a catalyst poison, such as 2,2'-thiodiglycolic acid, 2-aminothiazole or thiourea, to plating bath prevented the NiB deposition only on the micro-patterned photoresist, accompanying the depression of deposition rate. Moreover, the stabilizers having amino group were especially effective for the micro-patterned formation of electroless NiB deposition.

  • キャパシタ技術委員会設立にあたって

    T. Osaka

    Electrochemistry   66   883 - 883  1998年

  • 研究開発と産学協力

    T. Osaka

    日本応用磁気学会誌   22   1299 - 1300  1998年

  • Diamond-like carbon films deposited without deposition particles of large incidence angles by sputtering

    I. Koiwa, H. Kato, T. Kanehara, A. Hashimoto, Y. Sawada, N. Ichinose, T. Osaka

    IEICE Tech. Rep.   SDM98-100   55 - 60  1998年

  • Gradient Control of Magnetic Properties in Electroless Deposited CoNiP Films

    T. Homma, M. Suzuki, T. Osaka

    J. Electrochem. Soc.   145   134 - 138  1998年

  • 電析法によるNiFeP薄膜の高比抵抗化 (Increasing the Resistivity of NiFeP Films by Means of Electrodeposition)

    M. Takai, F. Mera, M. Kaseda, T. Osaka

    J. Magn. Soc. Jpn.   22   629 - 632  1998年

  • 電析法による高比抵抗Ni-Fe系軟磁性薄膜の作製 (Electrodeposition of Soft Magnetic Ni-Fe Based Film with High Resistivity)

    M. Takai, A. Kondo, F. Mera, M. Kaseda, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   49   292 - 296  1998年

  • Pd/Sn混合触媒を利用した銅のダイレクトプレーティング導体化過程の解析

    小野幸子, 逢坂哲彌, 内藤和久, 中岸豊

    表面技術   49   625 - 631  1998年

  • Assessment of lithium ion doping into low crystallized carbonaceous materials using molecular orbital calculations

    S Komoda, M Watanabe, S Komaba, T Osaka, S Kikuyama, K Yuasa

    ELECTROCHIMICA ACTA   43 ( 21-22 ) 3127 - 3133  1998年  [査読有り]

     概要を見る

    Using molecular orbital calculation, the Li doping reaction in low crystallized carbonaceous material was investigated. As the Li doping reaction occurs on the surface of the graphite layer, the influence on the electric charge of the graphite layer was examined with graphitic models attached with functional groups (-OH, -CHO). As a result, it is suggested that Li was doped at the different parts of the graphite layer after the typical intercalation reaction into the stacking structure. Furthermore, the structure doped with lithium became more stable when Li was doped on the negatively charged-carbon atom. It was concluded that the localization of charge densities of the structure of carbon conjugated-material effected strongly the Li induced adsorption at different parts of the graphite layer. (C) 1998 Elsevier Science Ltd. All rights reserved.

  • Influence of Crystallline Structure and Sulful Inclusion on Corrosion Properties of Electrodeposited CoNiFe Soft Magnetic Films

    T. Momma, Y. Sogawa, T. Osaka

    Proceedings - Electrochemical Society   PV98-20   572 - 580  1998年

  • 電気化学的手法による磁気的機能傾斜薄膜の作製

    本間敬之, 喜多洋介, 逢坂哲彌

    日本金属学会誌   62   1025 - 1030  1998年

  • 無電解NiBめっきを用いたマイクロパターニングにおける錯化剤の影響

    横島時彦, 湯浅寛子, 金満, 逢坂哲彌

    表面技術   49   1336 - 1342  1998年

  • 無電解CoNiP傾斜機能磁性薄膜の断面構造解析

    喜多洋介, 本間敬之, 逢坂哲彌

    表面技術   49   1358 - 1359  1998年

  • モバイル時代を支えるキーデバイス-最新二次電池探検隊

    逢坂哲彌, 門間聰之, 竹下秀夫

    エレクトロニクス   43   17 - 18  1998年

  • 急伸する高密度小形二次電池

    逢坂哲彌

    エレクトロニクス   43   18 - 19  1998年

  • Development of Soft Magnetic Materials with High Bs by the Electroplating Method and Their Application to an MR Write Core Head

    T. Osaka, M. Takai, K. Ohashi

    J. Magn. Soc. Jpn.   22   1182 - 1188  1998年

  • Oxide films formed on magnesium and magnesium alloys by anodizing and chemical conversion coating

    S Ono, T Osaka, K Asami, N Masuko

    CORROSION REVIEWS   16 ( 1-2 ) 175 - 190  1998年  [査読有り]

  • Tapping mode atomic force microscopy analysis of the growth process of electroless nickel-phosphorus films an nonconducting surfaces

    T Homma, M Tanabe, K Itakura, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   144 ( 12 ) 4123 - 4127  1997年12月  [査読有り]

     概要を見る

    The growth process of electroless nickel-phosphorous (NiP) films on nonconducting substrate was investigated quantitatively using tapping mode atomic force microscopy (TMAFM) with focus upon the nucleation density on the substrate surface. Three kinds of catalyzing processes were used for polyimide substrates to obtain nucleation densities of 900, 750, and 550 nuclei/mu m(2). The TMAFM observation showed that the film growth proceeds mainly through successive nucleation of fine ''particles'' with several nanometers in diameter and their three-dimensional growth, and that the nucleation density influences the state of aggregation of the particles and hence the resulting surface topography The lower nucleation density developed the rougher surface with larger ''grains'' with a diameter of ca. 80 nm. However, the effect of nucleation density decayed with film growth and eventually vanished at a thickness of ca. 2000 nm due to successive nucleation. For comparison, the growth process of NiP on NiP coated Al substrate, which is used for rigid magnetic disk applications and has a higher nucleation density of 3000 nuclei/mu m(2), was also examined. This process resulted in a smooth surface without the formation of ''aggregates.'' Bated upon these results, the root-mean-square roughness and scaling analyses were performed to evaluate quantitatively the differences in growth process.

  • Diamond-like carbon films deposited without deposition particles of large incidence angles by sputtering

    Y Hoshi, E Suzuki, T Osaka

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   176 ( 1 ) 51 - 55  1997年12月  [査読有り]

     概要を見る

    Deposition of diamond-like carbon (DLC) films at liquid nitrogen temperature (77 K) under the control of the angular distribution of depositing particles was attempted using a DC facing target sputtering system. The film deposited at 77 K, the liquid-nitrogen temperature, has a much higher density and higher hardness than the him deposited at room temperature. Removal of the depositing particles having high incidence angles was found to be effective for increasing the hardness of the film.

  • Performances of lithium gel electrolyte polypyrrole secondary batteries

    T Osaka, T Momma, H Ito, B Scrosati

    JOURNAL OF POWER SOURCES   68 ( 2 ) 392 - 396  1997年10月  [査読有り]

     概要を見る

    Poly(methylmethacrylate) (PMMA)- and poly(acrylonitrile) (PAN)-based gel electrolytes were applied to Li/polypyrrole (PPy) battery and its performance was investigated, These batteries showed excellent performance with 3 V output voltage and 90-100% coulombic efficiency. Using chemically more stable PMMA gel electrolyte, long charge/discharge cycle life more than 8000 cycles at 0.1 mA cm was obtained. (C) 1997 Elsevier Science S.A.

  • Electrodeposition of soft gold from a thiosulfate-sulfite bath for electronics applications

    T Osaka, A Kodera, T Misato, T Homma, Y Okinaka, O Yoshioka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   144 ( 10 ) 3462 - 3469  1997年10月  [査読有り]

     概要を見る

    The possibility of electrodeposition of soft gold from a thiosulfate-sulfite bath was explored for electronics applications. The bath does not contain cyanide, and it is operated at a near neutral pH and a mildly elevated temperature. The bath is stable, does not undergo spontaneous decomposition without the addition of any stabilizer, and yields gold deposits with a hardness sufficiently low for use as gold bumps on semiconductor devices. Factors affecting the hardness were investigated in detail. It is shown that the use of high concentrations of the complexing agents and/or the addition of thallium(I) ions decreases both hardness and sulfur content of the deposit. The lowest Vickers hardness values achieved were approximately 80 kg mm(-2) in the as-deposited state and 50 kg mm(-2) after annealing at 350 degrees C for 30 min in air. The relationship between hardness and microstructure of the deposit was also examined.

  • Effect of carbon dioxide on lithium anode cycleability with various substrates

    T Osaka, T Momma, Y Matsumoto, Y Uchida

    JOURNAL OF POWER SOURCES   68 ( 2 ) 497 - 500  1997年10月  [査読有り]

     概要を見る

    The effect on the enhancement of the charge/discharge behavior of electrodeposited lithium metal on various substrates with CO, was investigated in LiClO4/propylene carbonate electrolyte. The lithium cycleability was enhanced with CO2 addition to the electrolyte solution when using nickel and titanium substrates, whereas no apparent enhancement was observed with copper and silver substrates. The results obtained from voltammetry indicated that the reduction of CO2 did not occur on nickel and titanium, but on copper and silver. It is suggested that the enhancement with CO2 addition is effective with the substrates which do not reduce CO2 in the electrolyte before lithium deposition. (C) 1997 Elsevier Science S.A.

  • Properties of electric double-layer capacitors with various polymer gel electrolytes

    XJ Liu, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   144 ( 9 ) 3066 - 3071  1997年09月  [査読有り]

     概要を見る

    Polyethylene oxide (PEG), polymethyl methacrylate (PMMA), and polyacrylonitrile (PAN) based gel electrolytes with a mixture of ethylene carbonate and propylene carbonate as plasticizer and lithium perchlorate were used to fabricate an electric double-layer capacitor (EDLC). The performance of EDLCs with these gel electrolyes was investigated by using isotropic high-density graphite electrodes. The ion conductivities of various gel electrolytes were of the order of 10(-4) to 10(-3) S cm(-1), and they decreased in the order PAN &gt; PEO &gt; PMMA at ambient temperature. Capacitances approaching the value of EDLCs using organic liquid electrolyte, 20 mF cm(-2), with an isotropic high-density graphite electrode were obtained in PAN and PMMA gel electrolytes. The EDLC with PMMA-based gel electrolyte showed good charge-discharge behavior over 10(4) cycles at a charge potential of 3.0 V.

  • Classification of the pore structure of n-type silicon and its microstructure

    T Osaka, K Ogasawara, S Nakahara

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   144 ( 9 ) 3226 - 3237  1997年09月  [査読有り]

     概要を見る

    Porous silicon samples were grown under various anodization conditions on {100} oriented n-silicon substrates. Scanning and transmission electron microscope observations have shown that the microstructure of porous silicon primarily falls into three categories, which can be classified as single layer, double layer, and large macropore types. These three types differ not only in their microstructural details, but also in luminescence properties. In all three types of samples, the inner surface of pores created by anodization is coated with a low density amorphous material, which contained silicon and oxygen. In addition, all the pore surfaces were roughened by anodization, leaving nanoscale crystalline silicon asperities.

  • Compositional inhomogeneity in electroless-deposited CoNiP films studied by spin-echo Co-59 nuclear magnetic resonance

    T Homma, Y Sezai, T Osaka, Y Maeda, DM Donnett

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   173 ( 3 ) 314 - 320  1997年09月  [査読有り]

     概要を見る

    A compositionally inhomogeneous state in electroless-deposited CoNiP films with perpendicular magnetic anisotropy is investigated using spin-echo Co-59 nuclear magnetic resonance (NMR), focusing on its correlation with magnetic properties. Bf adjusting pH of the electroless-deposition bath-films were prepared which possess almost the same average composition (Co42Ni50P8) and crystal orientation, but the differing values of coercivity (H-c). By analyzing the shift in peak resonance frequency of NMR spectra of the CoNiP films with respect to that of bulk CoNi alloys, we observed the formation of a compositionally inhomogeneous slate in the film which possesses high H-c of 2600 Oe, whereas formation of inhomogeneities was not observed for the low-H-c films. By assuming that a Go-enriched ferromagnetic component detected by NMR was separated from a non-magnetic amorphous NI-P component, we found that the high-H-c film consists of Co42Ni26 and Ni24P8. Moreover, the results of high spatial resolution X-ray microanalysis on the high-H-c film showed a tendency that the Go-enriched ferromagnetic component segregates to the center of grains and the Ni-P non-magnetic component segregates to grain boundaries. Such evidence indicates that compositional inhomogeneities could be one of the origins of high-H-c in CoNiP films.

  • Panel discussion - Future prospects of lithium batteries

    B Owens, T Osaka, A Ohta, E Takeuchi, T Takamura, F Gibbard, KM Abraham, S Megahed, A Kozawa, R Ishikawa, CR Walk, G Blomgren, T Imai, H Kurokawa, J Schoonman, K Nakajima, R Atanasoski, T Tanaka, R Moy, R Yazami, M Broussely, E Yagasaki, CY Yao, K Suzuki, J Besenhard, E Peled, M Kuroki, S Levy, K Tatsumi, M Armand

    JOURNAL OF POWER SOURCES   68 ( 1 ) 173 - 186  1997年09月  [査読有り]

  • The inhibitory capability of decorative plated coatings for the growth of bacteria

    ZH Zhao, K Hasebe, Y Sakagami, T Osaka

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   70 ( 7 ) 1631 - 1637  1997年07月  [査読有り]

     概要を見る

    The antibacterial activity of various electroplated coatings (cobalt, zinc, copper, and cobalt-containing alloys of nickel, zinc, chromium) was determined by a ''Drop-method'' antibacterial experiment against pathogenic bacteria (gram-positive bacterial S. aureus, MRSA, and gram-negative bacteria E. coli, P aeruginosa). It was found that all of them possessed a higher antibacterial activity than stainless steel. The relationship between the inhibitory capability for the growth of bacteria and the rest potential of the electroplated coatings was also investigated. A significant antibacterial activity of the coatings was apparently displayed by a rest-potential shift to more negative values. It was suggested that all of the tested bacteria fell closely within the lethal range when the rest potentials were lower than -543 mV. However, some amount of metal ions dissolved from various from various electroplated coatings was measured; accordingly, the inhibitory capability of the simulated dissolution concentrations of metal ions the growth of bacteria is discussed.

  • Correlation between composition, microstructure, and ferroelectric properties of SrBi2Ta2O9 thin films

    S Ono, A Sakakibara, T Seki, T Osaka, Koiwa, I, J Mita, T Iwabuchi, K Asami

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   144 ( 7 ) L185 - L187  1997年07月  [査読有り]

     概要を見る

    SrBi2Ta2O9 thin films prepared by a solution-deposition process were formed at various annealing temperatures. P-E hysteresis loops of the films exhibited well-defined shapes, and the leakage current decreased with increasing annealing temperature except for one annealed at 750 degrees C. The considerable amount of metallic Bi on the film surface diffused from the inner part was evaluated by a quantitative x-ray photoelectron spectroscopic analysis. A discontinuity in morphology such as cavities detected by transmission electron microscopic observation at grain boundaries between large single-crystal grains and microcrystallite regions, which was pronounced in the film annealed at 750 degrees C, is suggested as inducing an increase in leakage current by the condensation of metallic Bi at the cavities.

  • Correlation between Composition,Microstructure,and Ferroelectrric Properties of SrBi2Ta2O9 Thin Films

    S. Ono, A. Sakakibara, T. Seki, T. Osaka, I. Koiwa, J. Mita, T. Iwabuchi, K. Asami

    J. Electrochem. Soc.   144 ( 7 ) L185 - L187  1997年07月  [査読有り]

  • Electrochemical preparation of soft magnetic CoNiFeS film with high saturation magnetic flux density and high resistivity

    M Takai, K Hayashi, M Aoyagi, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   144 ( 7 ) L203 - L204  1997年07月  [査読有り]

     概要を見る

    A soft magnetic CoNiFeS film as a write head core material for the next generation was prepared by electrodeposition. In this system, thiourea was used as an additive in the CoNiFe ternary alloy plating bath. The most suitable magnetic properties were obtained at the film composition of (Co73Ni12Fe15)(99.1)S-0.9 [atomic percent (a/o)] with a high saturation magnetic flux density (B-s) of 1.7 T, a high resistivity (rho) of 51 mu Omega cm, and a low saturation magnetostriction (lambda(s)) of 4.4 x 10(-6). The film consisted of fine minute crystal grains 5 to 10 nm in diameter. The S content of ca. 0.9 a/o is believed to be responsible for the formation of small crystal grains with low coercivity and high resistivity.

  • Electroluminescence properties of electropolymerized poly(para-phenylene) films by means of electrochemical oxidation and reduction

    S Komaba, A Amano, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   430 ( 1-2 ) 97 - 102  1997年06月  [査読有り]

     概要を見る

    We investigated electroluminescence (EL) properties of electropolymerized poly-p-phenylene (PPP) films formed by means of electro-oxidative and electro-reductive methods. Electro-oxidatively polymerized PPP (O-PPP) and electro-reductively polymerized PPP (R-PPP) clearly demonstrated different light emitting behavior. In the case of electro-oxidative PPP, the intensity of light emission decreased with increasing quantity of polymerization charge, whereas with electro-reductive PPP, it increased with increasing quantity of polymerization charge. These different types of behavior of the two kinds of PPP films suggested the difference in depth profile of the regularity of molecular structures formed by the two different methods. (C) 1997 Elsevier Science S.A.

  • Surface characterization of electrodeposited lithium anode with enhanced cycleability obtained by CO2 addition

    T Osaka, T Momma, Y Matsumoto, Y Uchida

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   144 ( 5 ) 1709 - 1713  1997年05月  [査読有り]

     概要を見る

    Electrodeposited lithium produced with and without CO2 in LiClO4/propylene carbonate electrolytes was investigated for charge-discharge cycleability, surface morphology, and composition of he surface layer. The addition of CO2 in the electrolyte enhances the cycleability, produces smoother surface morphology, and forms Li2CO3 in the inner region of the surface film. This paper describes experimental results showing those three different effects of CO2 addition, and discusses the interrelation among them.

  • Orientation Control of Sr0.7Bi2.3Ta2O9 Thin Films by Chemical Process Liquid Deposition

    I. Koiwa, T. Kanehara, J. Mita, T. Iwabuchi, T. Osaka, S. Ono

    Jpn. J. Appl. Phys.   36 ( 3B ) 1597 - 1601  1997年03月  [査読有り]

  • Orientation Control of Sr0.7Bi2.3Ta2O9 +a Thin Films by Chemical Liquid Deposition

    I. Koiwa, T. Kanehara, J. Mita, T. Iwabuchi, T. Osaka, S. Ono

    Jpn. J. Appl. Phys.   36 ( 3B ) 1597 - 1601  1997年03月

  • 電気自動車用パワーキャパシタ特性シミュレーション (Simulation of Power Capacitor Properties for Electric Vehicle Power Supply)

    T. Momma, S. Komaba, T. Osaka

    DENKI KAGAKU (presently Electrochemistry)   65 ( 2 ) 115 - 120  1997年02月  [査読有り]

  • Organic electroluminescence device based on an electrodeposited poly(3-substituted thiophen) film

    T Osaka, S Komaba, K Fujihana, N Okamoto, T Momma, N Kaneko

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   144 ( 2 ) 742 - 748  1997年02月  [査読有り]

     概要を見る

    An electrochemically deposited composite film of poly(3-substituted thiophen) and insulating nitrile butadiene rubber (NBR) was used as the emission layer of a polymer electroluminescence (EL) device. The composite film on an ITO substrate was uniform, and by using this film current leakage was prevented. The device with the composite film as the EL emission layer shows rectification properties, the emitted color depending on the substituent of thiophen units. By coating with NBR after the electrodeposition of a poly(3-substituted thiophen) film, EL characteristics were improved compared with the device with NBR coating performed before electropolymerization. Moreover, by using electropolymerized poly(3-n-octylthiophen) film as a hole transporting layer, the luminance of an organic EL device with a poly(N-vinylcarbazole) dip-coating layer was remarkably enhanced. The addition of the hole transporting layer reduced the turn-on bias voltage and increased the emission intensity to 700 ed m(-2).

  • Tapping mode atomic force microscopy analysis of electroless-deposition process

    T Homma, M Tanabe, M Suzuki, T Osaka

    PROCEEDINGS OF THE THIRD SYMPOSIUM ON ELECTROCHEMICALLY DEPOSITED THIN FILMS   96 ( 19 ) 46 - 54  1997年  [査読有り]

     概要を見る

    The growth process of electroless nickel-phosphorus(NiP) films was quantitatively analyzed using tapping mode atomic force microscopy(TMAFM). It was observed that the nucleation density depends on the catalyzing process used, which affects the growth process of the film at the initial stages. The films were evaluated in terms of the root-means-square(RMS) roughness and the scaling analysis. The RMS roughness of all films decreased with increasing thickness up to several hundred nanometers in thickness. Values of RMS roughness were different for different catalyzing processes. That this difference results from the state of aggregation of small NiP particles was quantitatively shown by the scaling analysis.

  • Preparation and properties of high resistivity electroless NiP films

    A Iizuka, T Higashikawa, T Osaka

    PROCEEDINGS OF THE THIRD SYMPOSIUM ON ELECTROCHEMICALLY DEPOSITED THIN FILMS   96 ( 19 ) 184 - 193  1997年  [査読有り]

     概要を見る

    New high resistivity NiP films were investigated for thermal stability and microstructure. NiP films with resistivities markedly higher than those for conventional NiP films were obtained by using a specific complexing agent in the electroless plating solution. The specific resistance decreased after heat-treatment, however, the values remained higher than those of conventional NiP films. The high resistivity films showed features grown vertically to the surface and measuring approximately 10nm in width.

  • 外国からの受賞を受けて (Received Awards from Abroad)

    T. Osaka

    The Tower   69   16 - 18  1997年

  • 97電気化学秋季大会を早稲田大学理工学部で迎えるにあたって

    T. Osaka

    DENKI KAGAKU (presently Electrochemistry)   65   613 - 613  1997年

  • 電解酸化重合法および電解還元重合法によるポリパラフェニレン薄膜の作製

    駒場慎一, 門間聰之, 臼居亜美, 逢坂哲彌

    DENKI KAGAKU (presently Electrochemistry)   65   204 - 207  1997年

  • Magnetic Properties of Electrodeposited Higher BsCoNiFe Thin Films

    M. Takai, S. Takefusa, T. Yokoshima, T. Osaka

    Proceedings - Electrochemical Society   97-27   585 - 588  1997年

  • 無電解NiBめっきによるマイクロパターニング (Micro-Patterning of NiB Films by Means of Electroless Plating)

    M. Takai, S. Takefusa, T. Yokoshima, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   48   98 - 99  1997年

  • Potentiometric biosensor for urea based on electropolymerized electroinactive polypyrrole

    S Komaba, M Seyama, T Momma, T Osaka

    ELECTROCHIMICA ACTA   42 ( 3 ) 383 - 388  1997年  [査読有り]

     概要を見る

    A urea biosensor was developed by immobilizing urease into an electropolymerized electroinactive polypyrrole (PPy) on a platinum electrode. This enzyme-immobilized PPy electrode showed a stable potential response to urea based on the pH response of the electroinactive PPy film electrode. The electropolymerization conditions were optimized, and thus the biosensor showed a Nernstian response with a slope of 31.8 mV decade(-1) over concentration range of 1 x 10(-4)-0.3 mol dm(-3) urea. Copyright (C) 1996 Elsevier Science Ltd

  • CoCrTa/Cr磁性薄膜におけるSi基板前処理効果の検討 (Effect of Pre-Treatment of Si Substrate in CoCrTa/Cr Magnetic Films)

    T. Osaka, T. Homma, Y. Kurokawa, T. Taguchi, A. Takizawa

    J. Magn. Soc. Jpn.   21   213 - 216  1997年

  • On the possibility of hydrogen intercalation of graphite-like carbon materials - Electrochemical and molecular orbital studies

    M Watanabe, M Tachikawa, T Osaka

    ELECTROCHIMICA ACTA   42 ( 17 ) 2707 - 2717  1997年  [査読有り]

     概要を見る

    Graphite-like carbon materials were investigated to learn whether they form hydrogen-graphite intercalation compounds (H-GICs), which would be useful as hydrogen storage materials in rechargeable batteries. The ability of graphite-like materials to absorb hydrogen was examined with cyclic voltammetry (CV) and constant-current charge and discharge tests in 6 mol dm(-3) KOH. It was concluded that H-GICs did not form under our experimental conditions. In order to understand the difference between hydrogen and lithium ions in ability to form the intercalation compounds with graphite-like carbon materials, molecular orbital analyses were carried out. The results demonstrate that lithium-graphite intercalation compounds (Li-GICs) are stable because of the presence of lithium 2p-orbitals, whereas such stable graphite intercalation compounds do not form with hydrogen ions because no three-dimensional p-orbitals are available.

  • In situ observation of lithium deposition processes in solid polymer and gel electrolytes

    T Osaka, T Homma, T Momma, H Yarimizu

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   421 ( 1-2 ) 153 - 156  1997年01月  [査読有り]

     概要を見る

    Deposition processes of lithium in solid polymer [poly(ethylene oxide) (PEG)8+LiClO4] and gel [PEO8+propylene carbonate(PC) +LiClO4] electrolytes, as well as in the liquid (PC+LiClO4) one, were observed in situ using an optical microscope and their difference is discussed. It was confirmed that the dendritic growth of lithium, which appeared in the liquid electrolyte, is suppressed in the solid polymer due to the immobility of the electrolyte molecules, although non-uniform coverage of the cathode was observed because of its low conductivity. In contrast, the gel electrolyte possessed advantages of both the liquid and solid electrolytes, resulting in a smooth and uniform deposition in the current density region up to 2.0 mA cm(-2).

  • 高比抵抗無電解NiP薄膜の熱安定性 (Thermal Stability of High Resistivity NiP Thin Film Resistor Formed by Means of an Electroless Deposition)

    T. Osaka, M. Takai, T. Higashikawa, A. Iizuka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   48   476 - 477  1997年

  • A Study on Gowth Processes of CoNiP Perpendicular Magnetic Anisotropy Films Electroless-Deposited at Room Temperature

    T. Homma, Y. Sezai, T. Osaka

    Electrochim. Acta   42   3041 - 3047  1997年

  • リングヘッド−垂直面内複合型媒体系におけるスペーシングの影響 (The Effect of Head-Medium Spacing for Ring-Type Head/Perpendicular-Longitudinal Composite Medium System)

    Y. Kurokawa, T. Onoue, N. Miyamoto, T. Homma, T. Osaka

    J. Magn. Soc. Jpn.   21   163 - 168  1997年

  • 垂直面内複合型媒体の記録再生特性 (Recording Characteristics of Perpendicular-Longitudinal Composite Media Evaluated by Using Ring-Type Heads)

    Y. Kurokawa, T. Homma, T. Osaka

    J. Magn. Soc. Jpn.   21   977 - 982  1997年

  • Study on Head Core Materials with High Bs by Plating Methods

    T. Osaka, M. Takai

    J. Magn. Soc. Jpn.   21   433 - 437  1997年

  • High Frequency Permeability of Electrodeposited CoNiFeS Film with High Bs And γ

    M. Takai, K. Hayashi, M. Aoyagi, T. Osaka

    J. Magn. Soc. Jpn.   21   443 - 446  1997年

  • Corrosion resistance and antibacterial activity performances of Ni-TiO2 composite coatings

    ZH Zhao, Y Sakagami, T Osaka

    CHEMISTRY LETTERS   26 ( 9 ) 909 - 910  1997年  [査読有り]

     概要を見る

    The novel properties for the corrosion resistance in a 5% NaCl salt-spray-test and the inhibitory capability of Ni-TiO2 composite coating for the growth of pathogenic bacteria (E. faecalis. E coli, and P. aeruginosa), under fluorescent irradiation and using a ''drop-method'' antibacterial experiment was set forth in this paper. The antibacterial activity of Ni-TiO2 composite coating became more significant by increasing the TiO2 contents in the composite coatings.

  • Noise Properties of an Electroless-Deposited CoNiReP Perpendicular Magnetic Recording Medium and a Perpendicular/Longitudinal Composite Medium

    J. Hokkyo, T. Onoue, N. Miyamoto, T. Homma, T. Osaka

    J. Magn. Soc. Jpn.   21   525 - 528  1997年

  • 無電解NiBめっきにおける錯化剤の影響 (Effect of Complexing Agents on Electroless NiB Plating)

    M. Kim, T. Higashikawa, A. Iizuka, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   48   1099 - 1104  1997年

  • Impedance Analysis of the Electrodeposited Insulating Polypyrrole

    S. Komaba, T. Osaka

    J. Electroanal. Chem.   432   137 - 141  1997年

  • Effect of Ti Addition in Cr Underlayer on the Heat Treatment Behavior of CoCrTa/Cr Thin Films Deposited on Si Substrate

    T. Osaka, J. Hokkyo, A. Takizawa, T. Taguchi, T. Onoue

    J. Magn. Soc. Jpn.   21   529 - 532  1997年

  • 湿式法による高Bsヘッド磁極材料の開発 (Development of Head Core Materials with High Bs by Means of Wet Processes)

    M. Takai, T. Osaka

    J. Magn. Soc. Jpn.   21   51 - 57  1997年

  • 電気自動車用電源

    逢坂哲彌, 門間聰之

    新素材   8   44 - 46  1997年

  • ポリマー電池における高分子材料の役割と期待 (Possibility of Polymer Materials for Polymer Batteries)

    T. Osaka, S. Komaba

    Plastics   48   10 - 12  1997年

  • リチウム金属を用いた2次電池

    T. Osaka, T. Momma

    電子材料   36   40 - 44  1997年

  • 電池の新展開

    T. Osaka

    化学と教育   45   522 - 526  1997年

  • 薄膜磁気ヘッド用軟磁性めっき膜の動向

    篠浦治, 逢坂哲彌

    表面技術   49   734 - 739  1997年

  • Electrochemical formation and microstructure in thin films for high functional devices

    T Osaka

    ELECTROCHIMICA ACTA   42 ( 20-22 ) 3015 - 3022  1997年  [査読有り]

     概要を見る

    Some of the recent topics on electrochemically formed thin films for high functionality devices were overviewed based upon our results. Characteristic microstructures of electroless-deposited cobalt alloy films for perpendicular magnetic recording media, electrolytic and electroless-deposited soft magnetic thin films, an electropolymerized active polymer films for batteries, ionic sensors and also inactive polymer films for biosensor devices, and porous silicon films formed on the surface of n-type single crystalline silicon by anodization for an electroluminescence device, were described and reviewed on the basis of our research works, and the correlation between them and their functional properties were discussed. It is demonstrated that the electrochemical processes have high potential for fabrication of the films for high functionality applications. (C) 1997 Published by Elsevier Science Ltd.

  • Urea biosensor based on the composite film of electroinactive polypyrrole and urease modified with polyanion

    S Komaba, M Seyama, K Tanabe, T Osaka

    DENKI KAGAKU   64 ( 12 ) 1228 - 1233  1996年12月  [査読有り]

     概要を見る

    A urea sensor based on the composite film of electroinactive polypyrrole (PPy) and urease (Urs) modified with polyanion nas fabricated by electropolymerization. This sensor showed the potential response to urea based on the detection of pH-change during the enzymatic reaction by Urs. The sensitivity of this sensor was 53 mV decade(-1) which was higher than that of the PPy film coated electrode in which Urs was entrapped physically as previously reported. The high sensitivity nas considered to be attributed to the increase in the number of immobilized Urs with the covalent bonding with carboxyl groups of PAA. This urea sensor showed linear potential response between 1 x 10(-4) mol dm(-3) and 1 x 10(-1) mol dm(-3).

  • All-solid-state electric double-layer capacitor with isotropic high-density graphite electrode and polyethylene oxide/LiClO4 polymer electrolyte

    XJ Liu, T Osaka

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   143 ( 12 ) 3982 - 3986  1996年12月  [査読有り]

     概要を見る

    An isotropic high-density graphite was used as a polarizable electrode of all-solid state electric double-layer capacitor using polyethylene oxide (PEG) or gel PEO electrolyte. The all-solid-state capacitor with high-density graphite electrodes possesses higher differential capacity than the other flat electrodes in PEO/LiClO4 ([EO]/[Li+] = 8:1) solid polymer electrolyte at 80 degrees C or PEO/PC/LiClO4 ([EO]/[PC]/[Li+] = 8:8:1) gel electrolyte at ambient temperature. The capacitance of the electric double layer of the high-density graphite electrode was strongly influenced by the cell temperature and concentration of LiClO4, because of the different state of the polymer crystallinity and different interface contact state between the high-density graphite electrode and the solid electrolyte. The all-solid-state capacitor with PEO/LiClO4 ([EOI/[Li+] = 8:1) solid polymer electrolyte and PEO/PC/LiClO4 ([EOI/[PC]/[Li+] = 8:8:1) gel electrolytes showed good charge/discharge behavior with a relatively high capacitance at 80 and 20 degrees C, respectively.

  • ゾルゲル法によるPZT薄膜の構造および強誘電体特性に及ぼす仮焼成温度の効果

    小野 幸子, 前田 将克, 逢坂 哲彌, 小岩 一郎, 金原 隆雄, 見田 充郎, 橋本 晃, 澤田 佳宏

    電気化学および工業物理化学 : denki kagaku   64 ( 11 ) 1166 - 1173  1996年11月  [査読有り]

    DOI CiNii

  • Formation and evaluation of high functionality thin films for electronics application

    T Osaka

    TRANSACTIONS OF THE METAL FINISHERS ASSOCIATION OF INDIA   5 ( 4 ) 207 - 211  1996年10月  [査読有り]

     概要を見る

    Some of recent topics on electrochemically formed thin films for high functional devices are overviewed based upon our results. Characteristic microstructures of electroless deposited cobalt alloy films for perpendicular magnetic recording media, electrolytic and electroless deposited soft magnetic thin films for magnetic head device and electroless deposited nickel alloy films for resistors, are described and the correlation between them and their functional properties are discussed. It is demonstrated that the electrochemical processes have high potential for fabrication of the films with high functionality.

  • New preparation of soft magnetic materials for high density MR head core by means of electrodeposition

    M Takai, K Hayashi, M Aoyagi, T Osaka

    TRANSACTIONS OF THE METAL FINISHERS ASSOCIATION OF INDIA   5 ( 4 ) 213 - 216  1996年10月  [査読有り]

     概要を見る

    The paper gives the results of electrodeposition and characterization of composite CoNiFe magnetic films for high density magneto-resistive (MR) head core.

  • High-sensitivity urea sensor based on the composite film of electroinactive polypyrrole with polyion complex

    T Osaka, S Komaba, M Seyama, K Tanabe

    SENSORS AND ACTUATORS B-CHEMICAL   36 ( 1-3 ) 463 - 469  1996年10月  [査読有り]

     概要を見る

    A high-sensitivity urea sensor consisting of the composite film of electropolymerized electroinactive polypyrrole (PPy) with the polyion complex containing urease (Urs) was fabricated. This sensor showed potential response to urea within 20 s by detection of pH change during enzymatic reaction with a pH-sensitive electroinactive PPy. The urea response became higher with the slope of 110 mV decade(-1). This high sensitivity was attributed to the effective immobilization of the large number of Urs by electropolymerization on the electrode pre-coated with polyion complex.

  • Effect of perpendicular layer thickness on read/write characteristics of perpendicular/longitudinal composite media using ring-type head

    Y Kurokawa, A Nagasaki, T Homma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   32 ( 5 ) 3810 - 3812  1996年09月  [査読有り]

     概要を見る

    The effects of perpendicular layer thickness on remanent magnetization states and recording characteristics of perpendicular-longitudinal composite media were investigated. The contribution of perpendicular magnetic reversal is varied due to a change in the thickness of perpendicular layer; the transition length of the thinner perpendicular layer medium was broader than that of thicker perpendicular medium. The medium with thicker perpendicular layer shown better performance not only in recording density response but also peak shift characteristics. In order to realize excellent read/write characteristics, optimization of the thickness of perpendicular layer becomes one of the important factors, in addition to the optimization of the underlayer parameters.

  • 再アノード酸化によるアルミニウムの多孔質/バリヤー複合皮膜 (Porous/Barrier Composite Films Formed on Aluminum by Re-Anodizing)

    S. Ono, T. Osaka, N. Masuko

    DENKI KAGAKU (presently Electrochemistry)   64 ( 9 ) 1005 - 1011  1996年09月  [査読有り]

  • Crystallization of Sr0.7Bi2.3Ta2O9 +α Thin Films by Chemical Liquid Deposition

    I. Koiwa, T. Kanehara, J. Mita, T. Iwabuchi, T. Osaka, S. Ono, M. Maeda

    Jpn. J. Appl. Phys.   35 ( 9B ) 4946 - 4951  1996年09月  [査読有り]

  • Effect of perpendicular layer thickness on read/write characteristics of perpendicular/longitudinal composite media using ring-type head

    Y Kurokawa, A Nagasaki, T Homma, T Osaka

    IEEE TRANSACTIONS ON MAGNETICS   32 ( 5 ) 3810 - 3812  1996年09月  [査読有り]

     概要を見る

    The effects of perpendicular layer thickness on remanent magnetization states and recording characteristics of perpendicular-longitudinal composite media were investigated. The contribution of perpendicular magnetic reversal is varied due to a change in the thickness of perpendicular layer; the transition length of the thinner perpendicular layer medium was broader than that of thicker perpendicular medium. The medium with thicker perpendicular layer shown better performance not only in recording density response but also peak shift characteristics. In order to realize excellent read/write characteristics, optimization of the thickness of perpendicular layer becomes one of the important factors, in addition to the optimization of the underlayer parameters.

  • MgO粉末の製造方法がAC型PDP印刷保護膜の活性化に与える影響

    Kanehara Takao, Koiwa Ichiro, Mita Juro, 小野 幸子, 逢坂 哲彌

    テレビジョン学会誌   50 ( 8 ) 1125 - 1131  1996年08月  [査読有り]

     概要を見る

    印刷保護膜に用いるMgO粉末の特性が, 活性化に及ぼす影響について解明するため, 数種のMgO粉末について評価した.MgO粉末の特性を決定する因子として粒径, 表面積, 製造方法(気相法, 海水法)を取り上げた.最初に, , 各粉末を, FTIR, DSCおよぴTEMにより評価した.その結果, 気相法の粉末は, 海水法の粉末に比べ, 結晶性が高ぐ, 表面がなめらかであり, 凝集しておらず, 活性化エネルギーが低いことがわかった.次に, 各粉末を用いてパネルを作製し, 活性化処理を施した.活性化の評価は, 活性化温度およびエージング時間に対する放電電圧依存性から行った.パネルの測定結果から, 気相法粉末を用いたパネルは, 300℃の温度で充分に活性化でき, かつ, わずか20分で放電電圧が安定すやことがわかった.

    DOI CiNii

  • 湿式法による導電性酸化物電極が強誘電体薄膜の特性に与える影響

    小岩 一郎, 金原 隆雄, 見田 充郎, 佐藤 豊作, 逢坂 哲彌, 小野 幸子, 前田 将克

    電気化学および工業物理化学 : denki kagaku   64 ( 8 ) 903 - 908  1996年08月  [査読有り]

    DOI CiNii

  • 国際交流についての一考

    逢坂 哲彌

    表面技術 = The Journal of the Surface Finishing Society of Japan   47 ( 8 ) 645 - 645  1996年08月

    CiNii

  • アノード酸化アルミナ皮膜の二層構造と結晶化 (Duplex Structure and Crystallization of Anodic Alumina Films)

    S. Ono, T. Osaka, N. Masuko

    DENKI KAGAKU (presently Electrochemistry)   64 ( 7 ) 819 - 824  1996年07月  [査読有り]

  • Dependence on the electrolyte solution of the capacitance of active carbon fiber electrode for electric double layer capacitor

    XJ Liu, T Momma, T Osaka

    DENKI KAGAKU   64 ( 7 ) 831 - 835  1996年07月  [査読有り]

     概要を見る

    Double layer capacitance of phenoric-resin based active carbon fiber (ACF) electrode was enhanced by a method of electrochemical treatment in various acidic electrolytes. Oxidic acids, especially perchloric acid solution, showed higher enhancement of the ACF capacitance by the electrochemical treatment. Thus, the capacitor was constructed with using 1.0 mol dm(-3) HClO4 electrolyte solution and ACF electrode oxidized at 1.0 V vs. SCE for 1 h. The capacitor gives charging-discharging characteristics better than that of H2SO4 electrolyte system.

  • CoCrTa/Cr磁性薄膜のSi(100)基板上への成膜における基板前処理効果 (Effect of Pretreatment of Si(100) Substrate on CoCrTa/Cr Magnetic Thin Films)

    T. Osaka, T. Homma, Y. Kurokawa, T. Taguchi

    DENKI KAGAKU (presently Electrochemistry)   64 ( 7 ) 850 - 851  1996年07月  [査読有り]

  • Electrochemical modification of active carbon fiber electrode and its application to double-layer capacitor

    T Momma, XJ Liu, T Osaka, Y Ushio, Y Sawada

    JOURNAL OF POWER SOURCES   60 ( 2 ) 249 - 253  1996年06月  [査読有り]

     概要を見る

    Electrochemical oxidation of an active carbon fiber (ACF) electrode showed an enhancement effect of the electrode capacitance. The modification of ACF, however, increased the electrode inner resistance with an increase in the capacitance. Au deposition, the deaeration and the electrochemical reduction (discharge) after the modification showed a decrease in the inner resistance. Thus, the capacitor using the modified ACF electrodes with deaeration, Au deposition and/or discharge treatment showed an enhancement of capacitance with decreasing inner resistance.

  • Analysis of the long-term potential stability of an all-solid-state potassium-selective electrode with electroactive polypyrrole film

    T Momma, M Yamamoto, S Komaba, T Osaka

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   407 ( 1-2 ) 91 - 96  1996年05月  [査読有り]

     概要を見る

    By coating an electroactive polypyrrole (PPy) film electrode with a plasticized poly(vinyl chloride) (PVC) membrane containing valinomycin, an all-solid-state potassium-selective electrode was fabricated. The polymerizing conditions of the PPy film were optimized for stable ionic responses. The electrochemical characteristics of these electrode systems were evaluated by an a.c. impedance method with respect to the mechanism of potential drift. The steady-state response over several days, which depended on the electrode configuration, was related to the impedance behavior of the electrode systems.

  • MgO powders for protective layer of alternating current plasma display panel

    Koiwa, I, T Kanehara, J Mita, S Ono, T Osaka

    ELECTRONICS AND COMMUNICATIONS IN JAPAN PART II-ELECTRONICS   79 ( 4 ) 55 - 66  1996年04月  [査読有り]

     概要を見る

    The MgO powder used for a screen-printed protective layer on plasma display panels was evaluated. The MgO powder was formed by either vapor-phase oxidation or decomposition of Mg(OH)(2). For the same BET value, the diameter of MgO particles formed by the latter method was larger than that by the former method. It was found that the particle diameter calculated by Scherrer's equation using the half-value width of an X-ray diffraction pattern was less than one-fifth of that calculated using the BET value. When the distribution of the particle size was evaluated by the centrifuge precipitation method, it was found that both the median and modal diameters of the MgO powders formed by the latter method were larger than that by the former method. The powder formed by the latter method also contained powder with diameters of less than 20 nm; the weight ratio of the fine powder to the entire MgO powder was 5.5 similar to 15.9 wt%. The transmission electron microscopy (TEM) observation revealed that the powder formed by the former method had a higher crystallinity and that the powder formed by the latter method tended to segregate.

  • Structure of anodic films formed on magnesium

    S Ono, K Asami, T Osaka, N Masuko

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   143 ( 3 ) L62 - L63  1996年03月  [査読有り]

     概要を見る

    The cylindrical pore structure and barrier layer of anodic films formed on magnesium which are similar to the Keller's model of anodic alumina are determined by direct cross-sectional observation. The ratios of cell diameter and barrier layer thickness to the forming voltage are notably smaller than those associated with anodic alumina. It is assumed that anodic film growth proceeds mainly by the formation of MgF2 and Mgx+y/2Ox(OH)(y) (magnesium oxyhydroxide) at the metal/film interface and the dissolution of the film at pore bases.

  • Magnetic force microscopy analysis of the micromagnetization mode of double-layered perpendicular magnetic recording media

    T Homma, Y Kurokawa, T Nakamura, T Osaka, Otsuka, I

    JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B   14 ( 2 ) 1184 - 1187  1996年03月  [査読有り]

     概要を見る

    The micromagnetization mode of double-layered (DL) perpendicular magnetic recording (PMR) media. as well as the single-layered one, was investigated by a magnetic force microscopy (MFM) in order to clarify the origin of their recording characteristics. The DL media were flexible disks consisting of a CoNiReP PMR layer and a CoB (soft magnetic) or CoNiP (hard magnetic) underlayer, which wen recorded using a ring-type head. Due to the variation in the underlayer characteristics. a clear difference in the stray field gradient at the transition region of the recorded magnetization was observed for the first time, which proved the validity of the presumed model for their magnetization mode. Such a direct analysis of the micromagnetization mode is possible only by MFM, and this technique is considered to be indispensable for optimizing the total design of PMR systems. (C) 1996 American Vacuum Society.

  • 活性炭電極の電気化学的酸化還元処理の電気二重層・キャパシター特性への影響 (Improvement of Active Carbon Fiber Electrode for Electric Double Layer Capacitor by Electrochemical Redox Pretreatment)

    X. Liu, T. Momma, T. Osaka

    DENKI KAGAKU (presently Electrochemistry)   64 ( 2 ) 143 - 148  1996年02月  [査読有り]

  • In-Situ Analysis of the Deposition Process of Electrochemical CoNiP Perpendicular Magnetic Recording Media

    T. Homma, J. Shiokawa, Y. Sezai, T. Osaka

    Proc. Electrochem. Soc.   95   181 - 190  1996年

  • Correlation between Magnetic Properties and Phase-Separated Microstructure of Electroless CoNiP Perpendicular Magnetic Recording Media

    T. Homma, T. Osaka, Y. Yamazaki, T. Namikawa

    Script. Met.   33   1569 - 1573  1996年

  • Preparation of Soft Magnetic FePCo Thin Films with High Bs by Means of Electrodeposition

    M. Takai, A. Nakamura, R. Shigemoto, F. Asa, T. Osaka

    Proc. Electrochem. Soc.   95   552 - 562  1996年

  • Magnetic Properties of Electroless-Deposited NiFeB and Electrodeposited NiFe Alloy Thin Films

    M. Takai, K. Kageyama, S. Takefusa, T. Osaka

    Proc. Electrochem. Soc.   95   570 - 585  1996年

  • Decorative coatings of plating with antibacterial activity

    ZH Zhao, S Eguchi, Y Okada, T Osaka

    CHEMISTRY LETTERS   25 ( 1 ) 55 - 56  1996年  [査読有り]

     概要を見る

    Electroplated coatings of cobalt, zinc, copper and cobalt-containing alloys of nickel zinc and chromium were found to have bactericidal action. The electroless plated coating of silver also hindered against proliferate of bacteria. Especially, they have bactericide properties to methicillin-resistant strains of Staphylococcus aureus (MRSA) in all. in addition, we discussed the relationship between rest potentials of various electroplated coatings and bactericidal action.

  • リングヘッド/垂直面内複合型媒体系のピークシフト特性 (Peak Shift Characteristics of Ring-Type-Head and Perpendicular-Longitudinal Composite Medium System)

    Y. Kurokawa, A. Nagasaki, T. Homma, T. Osaka

    J. Magn. Soc. Jpn.   20   141 - 144  1996年

  • 電析法による軟磁性FeP/M(M=Ni,CoP)/FeP積層膜の磁歪制御 (Control of Magnetostriction on Soft Magnetic FeP/M(M=Ni,CoP)/FeP Laminated Film by an Electrodeposition Method)

    M. Takai, A. Nakamura, K. Hayashi, F. Asa, T. Osaka

    J. Magn. Soc. Jpn.   20   433 - 436  1996年

  • マグネシウムダイカストAZ91Dの化成処理により成長した表面皮膜の構造と生成機構 (Structure and Formation Mechanism of Surface Films Formed on Magnesium Die Cast AZ91D by Chemical Conversion Coating)

    S. Ono, M. Saito, M. Horiguchi, K. Terashima, K. Matsusaka, A. Shida, T. Osaka, N. Masuko

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   47 ( 3 ) 263 - 267  1996年

    DOI

  • マグネシウムダイカストAZ91Dの陽極酸化により生成した皮膜の構造と成長機構 (Structure and Growth Mechanism of Anodic Films Formed on Magnesium Die Cast AZ91D)

    S. Ono, M. Saito, M. Horiguchi, K. Terashima, K. Matsusaka, A. Shida, T. Osaka, N. Masuko

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   47 ( 3 ) 268 - 272  1996年

    DOI

  • Fabrication of porous silicon-based all-solid state multicolor EL device with hole injecting film formed by electropolymerization

    T Osaka, K Ogasawara, T Okamura, S Komaba

    CHEMISTRY LETTERS   25 ( 8 ) 653 - 654  1996年  [査読有り]

     概要を見る

    By using electropolymerized poly(N-vinylcarbazole) (PVCz) as a hole injecting film on porous n-silicon (PS), an all-solid state multicolor EL device on the basis of PS was able to be fabricated. The electroluminescence (EL) from the PVCz/PS device under forward bias was enhanced as compared with the device without PVCz film. An EL peak-shift of this device was observed with an increase in applied forward bias.

  • All-solid state electric double layer capacitor using polymer electrolyte and isotropic high density graphite electrodes

    XJ Liu, T Momma, T Osaka

    CHEMISTRY LETTERS   25 ( 8 ) 625 - 626  1996年  [査読有り]

     概要を見る

    Isotropic high density graphite (HDG) was used as the polarizable electrode of electric double layer capacitors (EDLC) with a solid electrolyte consisting of PEO/LiClO4([EO]/L[i(+)]=8:1) at 80 degrees C or with a gel electrolyte consisting of PEO/PC/LICLO(4) ([EO]/[PC]/[Li+]=8:8:1) at room temperature. The all-solid state capacitor with HDG electrodes works satisfactorily as a EDLC with a relatively high capacitance, as well as the EDLC with gel electrolyte PEO/PC/LiC1O(4). These EDLCs with solid polymer electrolyte PEO/LiClO4 and gel electrolyte PEO/PC/LiClO4 show good charge/discharge behavior when charged to 1.5 V at 80 degrees C and 20 degrees C, respectively.

  • 無電解析出法による高比抵抗NiP皮膜の作製とその特性 (Preparation and Its Properties of High Resistivity NiP Films by Means of Electroless Deposition)

    T. Hatsukawa, T. Higashikawa, T. Osaka, H. Nakao

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   47   779 - 783  1996年

  • 垂直面内複合型媒体のリングヘッドによる評価 (Evaluation of Perpendicular/Longitudinal Composite Media with Ring-Type Heads)

    Y. Kurokawa, A. Nagasaki, T. Onoue, T. Osaka

    IEICE Technical Report   MR96   15 - 22  1996年

  • 電析法によるCoNiFe薄膜の作製とその磁気特性 (Preparation and Magnetic Properties of CoNiFe Thin Film by Electrodeposition)

    A. Nakamura, M. Takai, K. Hayashi, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   47   934 - 938  1996年

  • 高速銅電析によるプリント配線板用銅箔の表面モルフォロジー制御因子 (Factors Controlling the Surface Morphology of Copper Foil for Printed Wiring Board Electrodeposited at High Speed)

    T. Osaka, K. Tamura, A. Sakakibara, Y. Okinaka

    J. Jpn. Inst. Intercon. Pack. Electronic Circuits   11   487 - 493  1996年

  • 高速銅電析によるプリント配線板用銅箔のモルフォロジーに及ぼす塩素イオンとにかわの相乗作用

    逢坂 哲彌, 榊原 彰良, 田村 圭有, 本間 敬之, 沖中 裕

    回路実装学会誌   11 ( 7 ) 494 - 499  1996年

     概要を見る

    高速銅電析による電解銅箔のピラミッド状析出表面モルフォロジーの制御因子のなかで添加剤である塩素イオン, およびにかわの効果に着目して詳細な検討を加えた。Cl-50ppmおよびにかわ2ppmを添加した場合の標準浴条件において, 表層付近ほど柱状組織が明確に発達していることを確認した。この柱状組織形成において塩素イオンは促進作用, にかわは抑制作用があり, 〈110〉配向の結晶粒子が優先的に成長した結果である。成長面 (マット面) の観察から, にかわがピラミッド状析出の鋭角化および均一性向上に寄与していることが明らかとなった。

    DOI CiNii

  • Characterization of Chemical Conversion Coating Films Grown on Magnesium

    S. Ono, K. Asami, T. Osaka

    Proc. 13th Int. Corrosion Conf.   Paper 080   1 - 6  1996年

  • Orientation Control of Sr0.7Bi2.3Ta2O9 Thin Films by Chemical Process

    I. Koiwa, T. Kanehara, J. Mita, T. Iwabuchi, T. Osaka, S. Ono

    Extended Abstracts of the 1996 International Conference on Solid State Devices and Materials     628 - 630  1996年

  • 化学センサ1995/96 イオンセンサ (Chemical Sensors 1995/96 —Ion Sensors—)

    S. Komaba, M. Seyama, T. Osaka

    Chemical Sensors   12   97 - 112  1996年

  • リチウムポリマ-2次電池はどこまで可能か?-未来型高エネルギー密度2次電池の動向

    T. Momma, T. Osaka

    エレクトロニクス   41   62 - 64  1996年

  • 湿式法による高機能性薄膜形成とその応用 (Formation of the High Functionality Thin Films by Wet Processes and Its Application)

    T. Osaka, M. Takai

    Chemical Industry   47   909 - 915  1996年

  • ENHANCEMENT PROPERTIES OF ORGANIC ELECTROLUMINESCENCE DEVICE USING ELECTROPOLYMERIZED POLY(3-N-OCTYLTHIOPHEN) THIN-FILM

    T OSAKA, S KOMABA, K FUJIHANA, N OKAMOTO, N KANEKO

    CHEMISTRY LETTERS   24 ( 11 ) 1023 - 1024  1995年11月  [査読有り]

     概要を見る

    By using electropolymerized poly(3-n-octylthiophen) (PAT8) film as a hole transporting layer, the light-emission of an organic electroluminescence layer of poly(N-vinylcarbazole) dip-coating layer doped with 2,5-bis(1-naphthyl)-1,3,4-oxadiazole and 3-(2'-benzothiazolyl)-7-diethylaminocoumarin, was remarkably enhanced as compared with the layer without PAT8 layer. The addition of the hole transporting layer made the turn-on bias reduce and the emission intensity increase to be 600 cd m(-2).

  • MAGNETIC-PROPERTIES OF ELECTROLESS-DEPOSITED NIFEB AND ELECTRODEPOSITED NIFE ALLOY THIN-FILMS

    M TAKAI, K KAGEYAMA, S TAKEFUSA, A NAKAMURA, T OSAKA

    IEICE TRANSACTIONS ON ELECTRONICS   E78C ( 11 ) 1530 - 1535  1995年11月  [査読有り]

     概要を見る

    The magnetic properties and the structure of electroless-deposited NiFeB films were investigated in comparison with those of electrodeposited NiFe films. The electroless-deposited NiFeB film with 27 at% Fe content had the lowest coercivity, H-c, as low as 0.5 Oe with a saturation magnetic flux density, B-s, of 1.0 T. The saturation magnetostriction, lambda(s), and the uniaxial magnetic anisotropy, H-k, were 5.0x10(-6) and 10 Oe, respectively, which were larger than H those of the conventional, electrodeposited permalloy film. The permeability of as-deposited Ni70F27B3 film was 1000 at 1 MHz. In order to improve the permeability, the film was heated at 200 degrees C in a magnetic field applied in the hard-axis direction to decrease the H-k value, and the permeability became 2000 at 1 MHz. The crystal structure and grain size of NiFeB and NiFe films were investigated by XRD, THEED and TEM. Both films with low H-c had an fcc structure; the grain size of the NiFeB film was smaller than 10 nm, while that of the NiFe film was larger, approximately 20 nm. The results suggested that the electroless-deposited NiFeB film had a larger magnetic anisotropy than the electrodeposited NiFe film. Moreover, the films with H-c less than 10 Oe did not show clear difference between their TEM bright images and THEED patterns.

  • EFFECTS OF HEAD PARAMETERS ON READ WRITE CHARACTERISTICS OF PERPENDICULAR LONGITUDINAL COMPOSITE MEDIA

    Y KUROKAWA, A NAGASAKI, T HOMMA, T OSAKA

    IEEE TRANSACTIONS ON MAGNETICS   31 ( 6 ) 3102 - 3104  1995年11月  [査読有り]

     概要を見る

    Effects of saturation flux density (Bs) of read/write head on the recording characteristics of perpendicular/longitudinal composite medium were investigated. It was found that the recording sensitivity was improved by applying the higher Bs head. In higher density region, the reproduced-voltage-enhancement was enlarged with high Bs head, however, at the higher MMF region, the read/write characteristics was worse because the head field penetration becomes broad. Therefore, it was necessary to optimize the medium parameters in account to the head parameter.

  • APPLICATION OF ELECTROPOLYMERIZED POLY(THIOPHEN DERIVATIVE)/NBR COMPOSITE FILM TO AN ELECTROLUMINESCENCE EMISSION LAYER

    S KOMABA, K FUJIHANA, N KANEKO, T OSAKA

    CHEMISTRY LETTERS   24 ( 10 ) 923 - 924  1995年10月  [査読有り]

     概要を見る

    A semiconducting composite film of poly(3-substituted thiophen) and insulating nitrile butadiene rubber (NBR) was applied to an emission layer of polymer electroluminescence device. The uniform composite was deposited by electropolymerization of phenyl-, hexyl- and octylthiophen onto an indium-tin oxide glass pre-coated with NBR thin film. By utilizing indium as rectifying contact, visible light was observed from the composites under forward bias. The emission color depended on the substituents in thiophen units.

  • CONTROL OF THE POROUS STRUCTURE OF N-TYPE SILICON AND ITS ELECTROLUMINESCENCE PROPERTIES

    T OSAKA, K OGASAWARA, M KATSUNUMA, T HOMMA

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   396 ( 1-2 ) 69 - 75  1995年10月  [査読有り]

     概要を見る

    During the galvanostatic preparation of n-type porous silicon samples, the saturated photocurrent density was found to be the key factor determining the structure of the porous layer, which was either a homogeneously nanoporous monolayer or a double layer consisting of a nanoporous top layer and a macroporous underlayer. The electroluminescence (EL) properties of two different samples with the different layer structures showed a difference in the peak wavelength range of the spectral dependence on negative bias. The EL spectra from the samples with the double layer structure were observed over a larger spectral range than that of the samples with the monolayer structure. These results suggest that the luminescence wavelength range of n-type porous silicon can be changed by adjusting the saturated photocurrent density during anodization. Furthermore, an attempt was made to explain the blue-shift phenomenon of the EL wavelength with an increase in applied negative bias, on the basis of the correlation between the porous layer structure and the luminescence wavelength.

  • AC-PDP用MgO印刷保護層の膜質に対するMgOバインダ添加効果

    小岩 一郎, 金原 隆雄, 見田 充郎, 小野 幸子, 逢坂 哲彌

    テレビジョン学会誌   49 ( 9 ) 1171 - 1176  1995年09月  [査読有り]

     概要を見る

    スクリーン印刷法により, AC-PDPのMgO保護膜の膜質へのMgO液体バインダ, 焼成によりMgOになる安定化したマグネシウムジエトキシド溶液の添加効果を検討した.液体バインダ添加量の増加により乾燥後の膜厚は増加するが, 焼成後の膜厚は減少する.液体バインダ添加量が10wt%までは, バインダの焼失の際に発生する有機成分ガスによる膜のポーラス化が支配的であるために, 膜の密度は減少し, 表面ラフネスも増大する.この効果により, 発光効率が向上する.液体バインダの添加量が10wt%を超える領域では, バインダが粒子同志を繋ぎ止めることによる膜の緻密化が支配的になるために, 膜の密度が高くなり, 表面ラフネスも小さくなる.この効果により, 発光開始電圧(Vf)が低電圧化する.以上より, 液体バインダの添加量が膜質に重大な影響を与え, パネルの表示特性を決定する重大な因子であることが明らかとなった.

    DOI CiNii

  • ELECTROCHEMICAL REACTION OF ELECTROACTIVE POLYPYRROLE POLYSTYRENESULFONATE COMPOSITE FILM

    T MOMMA, A USUI, T OSAKA

    RUSSIAN JOURNAL OF ELECTROCHEMISTRY   31 ( 9 ) 891 - 895  1995年09月  [査読有り]

     概要を見る

    An electrochemical reaction of a composite film of p-type electroactive polymer with polyanion was investigated. A polypyrrole doped with polystyrenesulfonate was formed by electropolymerization with various polymerization charges, The redox potential of the thin composite film was influenced by the salt concentration of the electrolyte. The charge transfer resistance of the composite film was not influenced by the film thickness,while the limiting low frequency capacitance showed a linear relationship to the film formation charge.

  • ELECTROCHEMICAL REDOX PROPERTIES OF POLYPYRROLE/NAFION COMPOSITE FILM IN A SOLID POLYMER ELECTROLYTE BATTERY

    T MOMMA, S KAKUDA, H YARIMIZU, T OSAKA

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   142 ( 6 ) 1766 - 1769  1995年06月  [査読有り]

     概要を見る

    Nafion(R) was introduced into a polypyrrole (PPy) matrix, and the redox performance of the PPy/Nafion electrode was investigated in a poly(ethylene oxide) (PEO)-LiClO4 electrolyte. A rougher interface between polymer cathode and polymer electrolyte is usually needed for an all-solid battery, however, the PPy/Nafion cathode works well regardless of the flat surface of the PPy/Nafion film. When compared to a PPy film doped with ClO4- anions with a similar morphology, the PPy/Nafion film showed better redox performance. The results of ac impedance spectroscopy and potential-step chronoamperometry confirmed that the improvement in the redox reaction of the PPy/Nafion film was due to the enhancement of the ion diffusion rate in the film. Thus, the PPy/Nafion film showed good charging-discharging properties in a rechargeable Li/PEO-LiClO4/(PPy/Nafion) battery.

  • ENHANCEMENT OF ELECTROLUMINESCENCE FROM N-TYPE POROUS SILICON AND ITS PHOTOELECTROCHEMICAL BEHAVIOR

    K OGASAWARA, T MOMMA, T OSAKA

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   142 ( 6 ) 1874 - 1880  1995年06月  [査読有り]

     概要を見る

    In a study of the electroluminescence (EL) of porous silicon on an n-type Si wafer using an S2O82- electrolyte solution, the addition of C2H5OH: to the solution was found to enhance the intensity of EL from the porous silicon. The porous silicon structure was classified into two types which were prepared based on whether the anodizing current density for forming the porous n-Si was above or below the saturated photocurrent. A single layer of fine pores was formed galvanostatically with illumination at a current density below the saturated photocurrent density, and a double layer of fine and rough pores was formed under the same conditions but at a current density above the saturated photocurrent density. The electrochemical and enhanced electroluminescent properties of the two types of porous silicon were studied.

  • ALL-SOLID-STATE POTASSIUM-SELECTIVE ELECTRODE USING DOUBLE-LAYER FILM OF POLYPYRROLE/POLYANION COMPOSITE AND PLASTICIZED POLY(VINYL CHLORIDE) CONTAINING VALINOMYCIN

    T MOMMA, S KOMABA, M YAMAMOTO, T OSAKA, S YAMAUCHI

    SENSORS AND ACTUATORS B-CHEMICAL   25 ( 1-3 ) 724 - 728  1995年04月  [査読有り]

     概要を見る

    All-solid-state potassium-selective electrodes have been constructed on a Pt disk electrode using a double-layer film of polypyrrole/poly(4-styrenesulfonate) (PPy/PSS) composite covered with a plasticized poly(vinyl chloride) (PVC) membrane containing valinomycin. The lower composite layer is formed by electropolymerization of pyrrole in an aqueous solution containing poly(sodium 4-styrenesulfonate), and the upper PVC layer is formed by casting. The double-layer film electrode using this composite shows no overshoot and lower drift of the standard potential than both a single PVC-coated electrode and a double-layer electrode using polypyrrole doped with ClO4-. This is due to both the highly electrochemical activity of the lower PPy/PSS and the cation-exchange ability between the PPy/PSS and the potassium-selective membrane.

  • ENHANCEMENT OF LITHIUM ANODE CYCLABILITY IN PROPYLENE CARBONATE ELECTROLYTE BY CO2 ADDITION AND ITS PROTECTIVE EFFECT AGAINST H2O IMPURITY

    T OSAKA, T MOMMA, T TAJIMA, Y MATSUMOTO

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   142 ( 4 ) 1057 - 1060  1995年04月  [査読有り]

     概要を見る

    The charge-discharge behavior of a lithium metal anode in propylene carbonate (PC) electrolyte containing added CO2 was investigated using in situ ac impedance measurements during galvanostatic cycling. In PC electrolyte with CO2, the anode's cycle life was twice as long and its charge transfer resistance was smaller than in the same electrolyte without CO2. These enhancements are observed only when lithium is electrodeposited in the presence of CO2 on nickel substrate; the enhancement does not occur when lithium is deposited without CO2 and is cycled with CO2. Even large amounts of H2O in the electrolyte during cycling do not adversely affect the cycle life enhancement by CO2. The CO2 enhancement seems to be due to products formed by reaction of lithium with CO2 on the electrodeposited lithium surface.

  • ジッパー効果

    門間 聰之, 逢坂 哲彌

    高分子   44 ( 2 ) 77b - 77b  1995年

    DOI CiNii

  • Ambient-Temperature,Rechargeable All-Solid Lithium/Polypyrrole Polymer Batteries

    S. Kakuda, T. Momma, T. Osaka, G. B. Appetecchi, B. Scrosati

    J. Electrochem. Soc.   142 ( 1 ) L1 - L2  1995年01月  [査読有り]

  • Enhancement Effect of Carbon Dioxide on Lithium Anode Cyclability

    T. Osaka, Y. Matsumoto, T. Momma

    Proc. International Workshop on Advanced Batteries     171 - 178  1995年

  • CATION SENSITIVITY OF A POLYPYRROLE/POLYANION COMPOSITE FILM ELECTRODE

    T MOMMA, S KOMABA, T OSAKA, S NAKAMURA, Y TAKEMURA

    BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN   68 ( 5 ) 1297 - 1304  1995年  [査読有り]

     概要を見る

    Polypyrrole (PPy)/polyanion composite films were formed electrochemically in coexistence with a polymer electrolyte (poly(sodium 4-styrenesulfonate) (PSS) or poly(acrylic acid) (PAA)) in the polymerizing solution. The potential response behaviors of the PPy/PSS and PPy/PAA composites to cation activities were investigated, and the PPy/PSS electrode showed a better Nernstian response than that of the PPy/PAA electrode. The selection of incorporated polyanions and the polymerizing conditions, which were determined in this paper, affected the response behavior. The resultant PPy/PSS electrode showed a good Nernstian response only to monovalent cations with 58 mV/decade. The electrode indicated the equilibrium potential in a few seconds at the change of cation activity. It was found that the potential response was influenced by both the electroactivity of PPy and the PSS content in the PPy matrix.

  • 電子部品用接点材料としての無電解Pd‐Pめっき皮膜へのNi添加効果

    逢坂 哲彌, 小沢 進, 岡部 知生, 吉岡 修, 沖中 裕

    回路実装学会誌   10 ( 4 ) 253 - 257  1995年

     概要を見る

    接点材料への応用を目的として, 比較的単純なアンモニアのみを錯化剤とする浴から得られた無電解Pd-Ni-Pめっき皮膜の構造解析および耐食性, はんだぬれ性, 電気抵抗特性の各物性値の検討を行った。ベースとしたPd-Pめっき浴から得られた皮膜は今回測定を行った中では, その浴pHが低くP含有量が大きいほど各物性値が優れていた。Niを共析させるとはんだぬれ性は劣化するものの, 耐食性にはさほど影響を与えず, 電気抵抗特性および内部応力には大きな改善がみられた。はんだぬれ性の劣化はNi酸化物によるものと考えられ, 耐食性および電気抵抗特性には皮膜の結晶構造が大きく関与することが示唆された。

    DOI CiNii

  • リングヘッド−垂直面内複合型媒体の記録再生特性 (Recording Characteristics of Ring-Type-Head/Perpendicular-Longitudinal Composite Media System)

    Y. Kurokawa, T. Osaka

    J. Magn. Soc. Jpn.   19   131 - 139  1995年

  • 走査トンネル顕微鏡による銀電析過程の観察 (Scanning Tunneling Microscopy Study on Electrodeposition Process of Silver)

    T. Nakamura, M. Tanabe, T. Homma, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   46   956 - 959  1995年

  • AC-PDP印刷保護膜に用いるMgO粉末の検討 (A Study on MgO Powder for Protective Layer of AC-PDP)

    I. Koiwa, T. Kanehara, J. Mita, S. Ono, T. Osaka

    IEICE Technical Report   J78-C-II   534 - 543  1995年

  • Effect of CO2 on the cycleability of lithium metal anode

    T Momma, Y Matsumoto, T Osaka

    MATERIALS FOR ELECTROCHEMICAL ENERGY STORAGE AND CONVERSION - BATTERIES, CAPACITORS AND FUEL CELLS   393   223 - 228  1995年  [査読有り]

  • リチウム二次電池用高分子正極材料 (Electroactive Polymer Materials for Rechargeable Lithium Battery Cathode)

    T. Osaka, T. Momma

    Kobunshi   44   64 - 67  1995年

  • Ion Sensors

    T. Osaka, S. Komaba, M. Seyama

    Chemical Sensors   11   218 - 224  1995年

  • Thin Films: Electrochemically Deposited Thin Films for Magnetic Recording Devices

    T. Osaka, T. Homma

    Interface (USA)   4   42 - 46  1995年

  • 電解重合膜による表面修飾 (Surface Modification of Functional Electrodes with Using Electropolymerization Films)

    T. Momma, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   46   287 - 291  1995年

  • ポリマー電池の可能性 (Potentials of Lithium/Polymer Batteries)

    T. Osaka, T. Momma, H. Ito

    Battery Technology   7   39 - 47  1995年

  • 走査トンネル顕微鏡による銀電析過程の観察 (Deposition of Diamond-Like Carbon Films with Ultra High Hardness by Sputtering)

    Y. Hoshi, E. Suzuki, T. Osaka

    J. Magn. Soc. Jpn.   19   104 - 107  1995年

  • PREPARATION OF ELECTROLESS-DEPOSITED COFEB SOFT-MAGNETIC FILMS WITH HIGH SATURATION MAGNETIC-FLUX DENSITY

    T OSAKA, T HOMMA, K KAGEYAMA, Y MATSUNAE

    DENKI KAGAKU   62 ( 10 ) 987 - 988  1994年10月  [査読有り]

  • ELECTROCHEMICAL PROPERTIES OF A POLYPYRROLE POLYSTYRENESULFONATE COMPOSITE FILM AND ITS APPLICATION TO RECHARGEABLE LITHIUM BATTERY CATHODES

    T MOMMA, K NISHIMURA, T OSAKA, N KONDO, S NAKAMURA

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   141 ( 9 ) 2326 - 2331  1994年09月  [査読有り]

     概要を見る

    The performance of a composite film of polypyrrole (PPy) and poly(4-styrenesulfonate) (PSS) was studied in combination with an organic electrolyte as a possible lithium battery cathode. The composite film had a fairly flat morphology and exhibited electroactivity in organic electrolyte solutions using dimethylsulfoxide and propylene carbonate (PC) solvents. We confirmed that during the redox process the film charge was compensated with cations. A lithium cell consisting of the composite film as a cathode and a LiClO4-PC electrolyte worked as a rechargeable battery. The energy density of the PPy/PSS cathode was calculated to be 220 Wh liter-1 and the average output voltage of the rechargeable cell was 2.9 V.

  • インピーダンス測定法Ⅵ.応用 (2) 電池系における交流インピーダンス測定法 (Electrochemical Impedance Methods for Battery Systems)

    T. Momma, T. Osaka

    DENKI KAGAKU (presently Electrochemistry)   62 ( 8 ) 676 - 680  1994年08月  [査読有り]

  • APPLICATION OF SOLID POLYMER ELECTROLYTE TO LITHIUM POLYPYRROLE SECONDARY BATTERY SYSTEM

    T OSAKA, T MOMMA, K NISHIMURA, S KAKUDA, T ISHII

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   141 ( 8 ) 1994 - 1998  1994年08月  [査読有り]

     概要を見る

    An all solid-state lithium/polypyrrole (PPy) battery using polyethylene oxide (PEO)-LiClO4 as a solid polymer electrolyte was assembled, and the effects of the morphology of the PPy film and the concentration of LiClO4 on battery performance were investigated. Optimum conditions for the redox properties of PPy films in PEO-LiClO4 at 80-degrees-C were obtained with an LiClO4 concentration of n = 8 - 20 (n=[EO]/[Li]) when using rough PPy film. A Li/PPy battery using PEO-LiClO4 with optimized conditions exhibited high coulombic efficiency, above 90% at 0.1 mA cm-2 at 80-degrees-C. Cyclability of 1400 cycles with high coulombic efficiency was attained.

  • ELECTROCHEMICAL PROCESS OF FORMATION OF AN INSULATING POLYPYRROLE FILM

    T OSAKA, T MOMMA, S KOMABA, H KANAGAWA, S NAKAMURA

    JOURNAL OF ELECTROANALYTICAL CHEMISTRY   372 ( 1-2 ) 201 - 207  1994年07月  [査読有り]

     概要を見る

    Insulating and electroinactive polypyrrole (PPy(NaOH)) film can be synthesized by electropolymerization from an NaOH aqueous solution containing pyrrole at a highly positive, potential. The synthesis of this electroinactive PPy(NaOH) was investigated using in situ UV and X-ray photoelectron spectroscopy, and was compared with the irreversible oxidation (''overoxidation'') of electroactive PPy under a highly positive potential. Overoxidation made the PPy inactive. However, the formation of PPy (NaOH) started above 0.5 V vs. Ag/AgCl, and the ''overoxidation'' began simultaneously in the polymerizing solution. Overoxidation with nucleophilic hydroxide ions caused a structural change in the PPy molecule, which destroyed the original pi-conjugated system.

  • ENHANCEMENT OF ELECTROLUMINESCENCE AT POROUS SILICON ELECTROLYTE INTERFACE

    K OGASAWARA, T MOMMA, T OSAKA

    CHEMISTRY LETTERS   23 ( 7 ) 1243 - 1246  1994年07月  [査読有り]

     概要を見る

    An Electroluminescence (EL) of porous silicon in the electrolyte of Na2SO4 + S2O82- at cathodic bias was greatly enhanced as much as 30 times by adding C2H5OH. The dependence of EL spectra on cathodic bias potential was also detected similarly to as that without C2H5OH. The dependence of EL spectra on cathodic bias potential was also detected similarly to as that without C2H5OH. The enhancement mechanism of EL was discussed considering with the current density dependence during EL emission in the electrolyte with and without C2H5OH.

  • OPTIMIZATION OF HEAD-MEDIUM PARAMETERS FOR ELECTROLESS CONIREP/NIFEP DOUBLE-LAYERED MEDIA USING RING-TYPE HEADS

    T OSAKA, T HOMMA, T WATANABE, Y KUROKAWA

    JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS   134 ( 2-3 ) 331 - 335  1994年06月  [査読有り]

     概要を見る

    Optimization of head/medium parameters for perpendicular recording on the electrolessly deposited CoNiReP/NiFeP double-layered (DL) media was examined in combination with ring-type heads. Higher reproduced voltage was obtained in the DL medium with higher underlayer coercivity, H(c)(u), (160 Oe) due to the 'phase synchronization' (PS) effect. It was necessary to adjust the perpendicular magnetization layer thickness, delta(p), in accordance with the head B(s) in order to obtain sufficient PS effect. In the higher recording density region, the combination of a small gap head (0.08 mum) and a medium with thicker delta(p) (0.3 mum) and lower H(c)(u) (50 Oe) was optimal, due to higher crystal orientation at the medium surface and improvement of head field penetration.

  • PREPARATION OF NI-SN ALLOYS BY AN ELECTROLESS-DEPOSITION METHOD

    H SHIMAUCHI, S OZAWA, K TAMURA, T OSAKA

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   141 ( 6 ) 1471 - 1476  1994年06月  [査読有り]

     概要を見る

    Electroless-deposited Ni-Sn alloy films were investigated to increase tin content in the deposit. The maximum tin contents of electroless Ni-Sn-P and Ni-Sn-B were ca. 30 atom percent (a/o) and 42 a/o, respectively. The maximum tin content in the case of Ni-Sn-B was nearly equal to that of electrodeposited Ni-Sn alloy already reported. The crystallinity of Ni-Sn-P and Ni-Sn-B alloys was raised up with an increase in tin content. The corrosion resistance of Ni-Sn-P and Ni-Sn-B alloys was between that of amorphous and crystalline electroless-deposited Ni-P. Codeposition of tin into Ni-P films improved solderability, but into the Ni-B films, the solderability of Ni-Sn-B films situated in the region between those of Ni-P and NiB, because the solderability of NiB is higher.

  • PREPARATION OF SOFT-MAGNETIC FEP FILMS BY MEANS OF ELECTRODEPOSITION METHOD

    T OSAKA, M TAKAI, A NAKAMURA, F ASA

    DENKI KAGAKU   62 ( 5 ) 453 - 454  1994年05月  [査読有り]

  • PROTECTION AGAINST H2O IMPURITY FOR CYCLABILITY OF LITHIUM ANODE IN PROPYLENE CARBONATE ELECTROLYTE BY AN EXISTENCE OF CO2

    T OSAKA, T MOMMA, T TAJIMA, Y MATSUMOTO

    DENKI KAGAKU   62 ( 5 ) 451 - 452  1994年05月  [査読有り]

  • EVALUATION OF DOUBLE-LAYERED MAGNETIC RECORDING MEDIUM COMPOSED OF PERPENDICULAR AND LONGITUDINAL ANISOTROPY LAYERS

    T OSAKA, T HOMMA, T WATANABE, Y KUROKAWA

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   33 ( 4B ) L594 - L596  1994年04月  [査読有り]

     概要を見る

    A double-layered (DL) medium composed of a CoNiReP perpendicular anisotropy top layer (0.20 mum thick) and CoP longitudinal anisotropy underlayer (0.05 mum thick) was fabricated and its recording characteristics were investigated with a combination of a ring-type head. The reproduced voltage of the DL medium was enhanced to be larger than that of the simple summation of the reproduced voltage of the CoNiReP single-layered medium and that of the CoP one. Moreover, the reproduced waveform of the DL medium showed a single peak pulse and it did not change even at higher recording magnetomotive force (MMF). These results suggest that the reproduced voltage enhancement comes from the phase synchronization effect even at higher recording MMF.

  • IN-SITU AC-IMPEDANCE MEASUREMENT DURING GALVANOSTATIC DEPOSITION AND DISSOLUTION OF LITHIUM

    T OSAKA, T MOMMA, T TAJIMA

    DENKI KAGAKU   62 ( 4 ) 350 - 351  1994年04月  [査読有り]

  • CoB軟磁性膜の磁場中熱処理による透磁率の制御

    逢坂 哲彌, 高井 まどか, 影山 謙介

    表面技術   45 ( 2 ) 213 - 217  1994年

     概要を見る

    An effort has been made to improve the properties and specifically the permeability &mu;, of CoB soft magnetic films produced by electroless plating by application of heat treatment in a 2 kOe magnetic field. The optimum treatment conditions were found to be 150&deg;C for 30min with the field applied along the hard magnetization axis of the film, and this treatment increased &mu; to 2000. The magnetic anisotropy field Hk decreased from 40 Oe to 8 Oe. The microstructure of films treated at various temperatures was also investigated. As-plated films consisted of fine hcp crystallite grains about 100&Aring; in diameter, and this was retained with treatment up to 300&deg;C. At above 350&deg;C, fine, uniform grains grew locally and the formation of an fcc phase was detected. It is suggested that the improvement in permeability was due to an appropriately low value of Hk for the conditions at which the fine crystal grains were retained.

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  • STABILITY OF CONDUCTANCE IN ELECTROINACTIVE POLYPYRROLE

    T OSAKA, ZY JIANG, T MOMMA, H KANAGAWA

    THIN SOLID FILMS   237 ( 1-2 ) 268 - 271  1994年01月  [査読有り]

     概要を見る

    The stability of conductance in electropolymerized insulating polypyrrole under application of a high voltage was investigated using a metal-insulator-metal-type diode device. The conductance varied over time due to application of the voltage, and the current-time profiles were classified into three types according to the level of the applied voltage. In the very low voltage region the conductance was stable; in the middle voltage region the conductance increased to a stable value; and in the high voltage region the conductance first increased and then decreased. The mechanism of the change in conductance, the W-Vis absorption spectra and the photo-radiated current behaviour are dismissed.

  • A Mechanism for Enhancing the Reproduced Voltage on the Ring-Type-Head/Electroless-Deposited Perpendicular Double-Layered Media System

    T. Osaka, T. Homma, T. Watanabe, Y. Kurokawa, M. Yamamoto, F. Goto

    IEEE Translation Journal on Magnetics in Japan   9 ( 4 ) 63 - 67  1994年

     概要を見る

    A mechanism was investigated for enhancing the reproduced voltage of a recording system combining a ring head with a electroless-deposited perpendicular double-layered medium. The mechanism of enhancement is thought to consist of the following two effects: the “phase synchronization” (PS) effect, due to a semi-hard magnetic underlayer, and the “double-layering” (DL) effect, due to the soft magnetic underlayer. By proper ac erasing of the reproduced signal through the action of the underlayer (at an underlayer coercivity of Hc(u)=50 Oe) in a CoNiReP/CoB double-layered medium, the PS effect was confirmed to appear at recording densities up to about 90 kFRPI. The enhancement of the reproduced voltage at densities higher than 90 kFRPI was still observed after such ac erasure, and originates solely in the DL effect. © 1994 IEEE

    DOI

  • High Energy Density Rechargeable Lithium Batteries Using Polymer Materials

    T. Osaka

    Battery Technology   6   129 - 144  1994年

  • 高飽和磁化軟磁性用FeP電析浴の開発

    高井 まどか, 中村 明義, 浅 富士夫, 逢坂 哲彌

    表面技術   45 ( 4 ) 431 - 432  1994年

    DOI CiNii

  • 無電解Ni‐P皮膜物性に与える錯化剤の影響

    初川 拓朗, 逢坂 哲彌, 千葉 国雄, 福田 豊, 中尾 英弘

    表面技術   45 ( 5 ) 543 - 546  1994年

     概要を見る

    Effects of complexing agents and ammonium ion on physical properties of electroless Ni-P films were systematically studied as a function of bath pH using citrate and glycine baths, with and without ammonium sulfate. The deposition rate and the phosphorus content of Ni-P films were strongly influenced by the species of complexing agent and the presence of ammonium ion in the bath. The physical properties of Ni-P films, such as deposition rate, saturation magnetization and specific resistance were discussed as a function of phosphorus content. Internal stress of Ni-P films, however, could not be determined as a function of phosphorus content.

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  • 無電解CoNiP垂直磁気記録媒体の微細構造解析 (Microstructural Analysis on Electroless CoNiP Perpendicular Magnetic Recording Media)

    T. Homma, Y. Iizuka, T. Osaka

    IEICE Technical Report   MR94   15 - 21  1994年

  • CoNiP Perpendicular Magnetic Recording Medium Electroless-Deposited from Single-Complextant Bath at Room-Temperature

    T. Homma, T. Nakamura, J. Shiokawa, T. Osaka

    J. Magn. Soc. Jpn.   18   73 - 76  1994年

  • Soft Magnetic Properties of Electroless-Deposited CoFeB Films

    T. Osaka, T. Homma, K. Kageyama, Y. Matsunae, O. Shinoura

    J. Magn. Soc. Jpn.   18   183 - 186  1994年

  • Preparation of Electrodeposited FeP Films and Their Soft Magnetic Properties

    T. Osaka, M. Takai, A. Nakamura, F. Asa, K. Ohashi, H. Tachibana

    J. Magn. Soc. Jpn.   18   187 - 190  1994年

  • Underlayer Magnetization Effect on Read/Write Characteristics of Perpendicular/Longitudinal Composite Media with Ring-Type Head

    Y. Kurokawa, A. Nagasaki, T. Homma, T. Osaka

    J. Magn. Soc. Jpn.   18   455 - 458  1994年

  • 特集 めっき膜の構造とその電子材料への応用 めっき法による軟磁性材料の作製とその特性

    高井 まどか, 逢坂 哲彌

    表面科学   15 ( 10 ) 645 - 649  1994年

     概要を見る

    めっき法により作製した軟磁性材料の代表的な合金はパーマロイで,NiFe系の合金である。パーマロイは保磁力が小さく透磁率が高いことから古くから磁気ヘッドや,磁気シールド材へ応用されてきた。最近HDD(ハードディスクドラィブ)の小型化,大容量化にともなった磁気記録媒体の要求に対応すべく,書き込み能力に優れた高い飽和磁束密度を合わせもつ軟磁性材料が磁気ヘッド材料として必要とされ,高密度磁気記録HDDにおいて採用されている薄膜磁気ヘッドは,ヘッドコア部にパーマロイめっき技術が用いられている。そこで,本解説では薄膜磁気ヘッドが生まれた経緯を概説し,磁気ヘッドコア材として使用されているパーマロイめっき膜の特性について述べる。さらに高飽和磁束密度をもつ軟磁性材料のめっきに関するわれわれの最近の研究を取りあげ紹介する。

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  • 無電解NiReP合金薄膜抵抗体へのパルス加熱法の適用

    川口 純, 逢坂 哲彌

    表面技術   45 ( 11 ) 1146 - 1151  1994年

     概要を見る

    The thermal stability of the electrical resistance properties of electroless NiReP alloy films with three levels of Re content was evaluated, using a pulse heating method that provided a very high heating rate (up to 105Kmin-1) and very short heating time (200ms). The temperature coefficient of resistance (TCR) of the three films had a range of only -100&sim;250ppmK-1, and the amorphous structure in the as-deposited condition was maintained for all three films even by pulse heating, although, the specific resistance changed slightly. After annealing at 500&deg;C, the specific resistance (340&mu;&Omega;cm) and TCR (18ppmK-1) of the film with the greatest Re content (Ni51Re44P5) was not changed by pulse heating. It was found that the electroless NiReP alloy films were much more stable under pulse heating, than were the electroless NiWP and NiMoP alloy films with good thermal stability.

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  • Electroluminescence at the Interface between Electrolyte and Porous Silicon

    T. Momma, K. Ogasawara, T. Osaka

    Proc. the Second Interenational Symposium on Electrochemical Microfabrication   94-32   290 - 298  1994年

  • 楽しい化学の実験室 (38) 電気でつくる、電気をためる変色プラスチック (Electrochemically Synthesized Conductive Polymers and Its Application to Energy Storage)

    T. Osaka, T. Momma

    Chemistry Today   278   50 - 55  1994年

  • ポリマー電池の可能性 (Potentials of Lithium/Polymer Batteries)

    T. Osaka

    Battery Technology   6-5   1 - 10  1994年

  • 磁性材料と新しい機能めっき (Magnetic Materials Prepared by Plated Methods)

    T. Osaka, Y. Kurokawa

    Uyemura Tech. Rep.   31   3 - 9  1994年

  • 薄膜技術の現状と展開‐これからの薄膜‐ 薄膜と表面技術

    逢坂 哲彌, 黒川 義昭

    表面技術   45 ( 12 ) 1172 - 1178  1994年

    DOI CiNii

  • 薄膜磁気ヘッド用メッキ形高飽和磁束密度材料 (Electrochemical Deposited High Bs Materials for Thin-Film Head)

    T. Osaka, M. Takai

    電子材料   33   41 - 46  1994年

  • ELECTROCHEMICAL EVALUATION OF A POLYANILINE/POLYPYRROLE DUAL-LAYER FOR RECHARGEABLE LITHIUM BATTERY CATHODE

    T OSAKA, T MOMMA, K SHIOTA, S NAKAMURA

    DENKI KAGAKU   61 ( 12 ) 1361 - 1365  1993年12月  [査読有り]

     概要を見る

    A polyaniline/polypyrrole (PAn/PPy) dual-layer was prepared by electropolymerization of aniline onto a PPy pre-deposited electrode. The electrochemical properties and battery cathode performance were investigated and the correlation between them was discussed. The effect of the properties of PPy underlayer on the electrochemical properties seemed to lessen with an increase in the thickness of PAn upperlayer, however, the cathode performance of the dual-layer was much influenced by the properties of PPy underlayer.

  • IMPEDANCE ANALYSIS OF ELECTROPOLYMERIZED CONDUCTING POLYMERS FOR POLYMER BATTERY CATHODES

    T OSAKA, T MOMMA

    ELECTROCHIMICA ACTA   38 ( 14 ) 2011 - 2014  1993年10月  [査読有り]

     概要を見る

    The electrochemically polymerized conductive polymers were evaluated by an ac impedance measurement for use in a Li/polymer battery. The validity and the limit of ac impedance analysis for this case are discussed.

  • IN-SITU OBSERVATION AND EVALUATION OF ELECTRODEPOSITED LITHIUM BY MEANS OF OPTICAL MICROSCOPY WITH ALTERNATING-CURRENT IMPEDANCE SPECTROSCOPY

    T OSAKA, T MOMMA, K NISHIMURA, T TAJIMA

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   140 ( 10 ) 2745 - 2748  1993年10月  [査読有り]

     概要を見る

    Electrodeposited lithium was evaluated by ac impedance measurement and optical microscopy in two solutions containing LiClO4; a propylene carbonate (PC) solution and a blended solution consisting of PC and 1,2-dimethoxyethane (DME)(volume ratio = 1:1). The ac impedance data were analyzed in the higher frequency region, where the charge-transfer resistance (R(ct)) of Li+ + e- reversible Li can be evaluated. The value of R(ct) was always larger in the PC electrolyte solution than in the PC-DME(1:1) electrolyte solution, and R(ct) depended on the lithium deposition charge. Microscopic observation indicated that lithium deposited more uniformly in PC-DME (1:1) than in PC solution. The results of morphological evaluation of the electrodeposited lithium using optical microscopy corresponded to the variations in the value of R(ct) obtained from ac impedance measurements, showing that the behavior of R(ct) accurately represented the morphological state. The cycleability of the lithium anode was investigated by charge-discharge testing. The cycle efficiency was worse in PC than in PC-DME (1:1) solution; this seems to be related to the morphological properties of the lithium deposits.

  • 無電解めっきCoB軟磁性膜の磁場中熱処理効果 (Effect of Heat Treatment in Magnetic Field on Electroless-Plated CoB Soft Magnetic Films)

    T. Osaka, T. Homma, C. Tsai, M. Takai, K. Kageyama

    DENKI KAGAKU (presently Electrochemistry)   61 ( 8 ) 1017 - 1018  1993年08月  [査読有り]

  • RECHARGEABLE LITHIUM POLYPYRROLE BATTERY USING SOLID POLYMER ELECTROLYTE

    T OSAKA, T MOMMA, K NISHIMURA

    DENKI KAGAKU   61 ( 7 ) 722 - 723  1993年07月  [査読有り]

  • APPLICATION OF ELECTROINACTIVE POLYPYRROLE FILM TO THE PH SENSOR ELECTRODE

    T OSAKA, T FUKUDA, H KANAGAWA, T MOMMA, S YAMAUCHI

    SENSORS AND ACTUATORS B-CHEMICAL   13 ( 1-3 ) 205 - 208  1993年05月  [査読有り]

     概要を見る

    On the basis of a metal/insulator/metal (MIM) device using electroinactive polypyrrole (PPy) film as an insulator, an amperometric pH sensor device for a very small test solution (4 mul) was developed using the structure of Au/PPy/Au with a window hole. Electropolymerized thin PPy film formed from alkaline solution is used for the ion-selective membrane. The Au/PPy/Au device with a d.c. voltage supply from 0 to 0.2 V works well as an amperometric pH sensor, that is, the gradient of the Cottrell plot within 10 s corresponds exactly to the pH value.

  • ELECTROPOLYMERIZATION CONDITIONS FOR PRODUCING INSULATOR POLYPYRROLE FILMS

    T OSAKA, T MOMMA, H KANAGAWA

    CHEMISTRY LETTERS   22 ( 4 ) 649 - 652  1993年04月  [査読有り]

     概要を見る

    By using the electropolymerization of pyrrole from aqueous solutions of Na2CO3 or NaHCO3, flat and pinhole-less insulating films were obtained due to the self-leveling and self-saturation effects. The influences of the supporting electrolyte and of the additive (N-methylpyrrole) to the NaOH polymerization solution were also investigated to produce the insulating PPy films having some different properties.

  • 選択化学エッチング法による無電解CoNiP垂直磁気記録媒体の微細偏析構造の解析 (An Analysis of the Segregated Microstructure of Electroless-Deposited CoNiP Perpendicular Magnetic Recording Using Selective Chemical Etching)

    T. Homma, K. Ohrui, Y. Iizuka, T. Osaka, Y. Yamazaki, T. Namikawa

    J. Magn. Soc. Jpn.   17   105 - 108  1993年

  • リングヘッド/無電解めっき垂直二層膜媒体系における再生出力増大機構 (A Mechanism for Enhancing the Reproduced Voltage on the Ring-Type-Head/Electroless-Deposited Perpendicular Double-Layered Media System)

    T. Osaka, T. Homma, T. Watanabe, Y. Kurokawa, M. Yamamoto

    J. Magn. Soc. Jpn.   17   131 - 134  1993年

  • 無電解NiReP合金皮膜の電気抵抗特性と構造に及ぼす熱処理効果

    川口 純, 府川 真, 石井 賢哉, 逢坂 哲彌

    表面技術   44 ( 5 ) 418 - 424  1993年

     概要を見る

    The effects of heat treatment on electroless amorphous NiReP alloy films of various compositions were systematically investigated in respect to their electrical properties (specific resistance and TCR), film structure (X-ray diffraction, TEM and TREED) and crystallization process (DSC). On the basis of heat treatment behavior, the four representative films may be divided into two groups, a lower Re content group (Ni75.9Re1.4P22.7, Ni72.1Re8.3P19.6 and Ni64.8Re21.7P13.7), and a higher Re content group (Ni51.2Re44.0P4.8).<br>In the lower content group, heat teatment produces abrupt reduction in electrical resistance properties at a certain temperature due to precipitation of a Ni3P phase. In the higher content group, resistance properties show an abrupt drop in specific resistance with heat treatment to 200&deg;C, and thereafter are insensitive to heat treatment temperature. The films of higher content group precipitate only metal phases (fcc Ni and hcp Re) under heat treatment, and the insensitivity of the resistance properties is attributed to the fact that the crystallized metal phases contain many grain boundaries (or defects) even under HRTEM (High Resolution Transmission Electron Microscope) at very high magnification.

    DOI CiNii

  • リングヘッド−垂直面内二層膜媒体における下地膜保磁力の影響 (The Effect of Underlayer Coercivity on the Recording Characteristics of Perpendicular-Longitudinal Double Layered Media Using Ring-Type Head)

    T. Osaka, T. Homma, Y. Kurokawa, M. Yamamoto, A. Nagasaki

    J. Magn. Soc. Jpn.   17   103 - 108  1993年

  • Effect of Solid Polymer Electrolyte Characteristics on Redox Properties of Polypyrrole in All Solid Sate Lithium Battery

    T. Osaka, T. Momma, K. Nishimura, S. Kakuda

    Proc. Symp. New Batteries and Supercapacitors   93   178 - 188  1993年

  • Application of Polypyrrole/Polystyrenesulfonate Composite Film to Rechargeable Lithium Battery Cathode

    T. Osaka, T. Momma, K. Nishimura, A. Usui, S. Nakamura

    Proc. Symp. New Batteries and Supercapacitors   93   199 - 205  1993年

  • Preparation of NiSn Alloys by an Electroless-Plating Method

    H. Shimauchi, S. Ozawa, T. Osaka

    Proc. 2nd Symp. on Electrochemical Tech. Applications in Electronics   93   185 - 195  1993年

  • Perpendicular Magnetic Recording Characteristics of Electroless-Deposited Double-Layered Media Using Ring-Type Head

    T. Osaka, T. Homma, T. Watanabe, Y. Kurokawa

    Proc. 2nd Symp. on Electrochemical Tech. Applications in Electronics   93   438 - 468  1993年

  • Segregated Microstructure of Electroless-Deposited CoNiP Films for Perpendicular Magnetic Recording Media

    T. Homma, K. Ohrui, Y. Iizuka, T. Osaka, Y. Yamazaki, T. Namikawa

    Proc. 2nd Symp. on Electrochemical Tech. Applications in Electronics   93   459 - 468  1993年

  • 無電解CoB薄膜の軟磁気特性と微細構造

    高井 まどか, 影山 謙介, 本間 敬之, 逢坂 哲彌

    表面技術   44 ( 12 ) 1134 - 1137  1993年

     概要を見る

    The correlation between the microstructure and the soft magnetic properties of electroless-deposited CoB films was investigated. Adding aminoacetic acid in various concentration to the CoB bath made it possible to control the coercivity of the films without changing their other magnetic properties such as saturation magnetization and squareness. Coercivity was also found to depend on film thickness. TEM observation demonstrated that the difference in coercivity is due to the microstructure, mostly the grain size in the initial deposition region. Films with low coercivity consisted of fine grains (about 10&sim;20nm in diameter), while those with high coercivity consisted of large grains (about 100nm in diameter). Although no clear differences in microstructure could be observed at the optimum film thickness of 0.5&mu;m, it is suggested that films with low coercivity consist of fine grains from the initial deposition stage.

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  • 無電解コバルト合金二層膜の結晶配向制御

    本間 敬之, 黒川 義昭, 山本 真由美, 逢坂 哲彌

    表面技術   44 ( 12 ) 1099 - 1103  1993年

     概要を見る

    Control of the crystal orientation of electroless-deposited CoNiReP/CoP double-layered (DL) film for perpendicular magnetic recording media was attempted in order to optimize the magnetic properties. The CoP single-layered (SL) film consists of c-axis longitudinally oriented hcp structure while the CoNiReP SL one consists of c-axis perpendicularly oriented hcp structure. The CoNiReP layer deposited directly onto the CoP layer grew epitaxially, however, resulting in deteriorated properties as a perpendicular recording medium. On the other hand, when the surface of the CoP layer was treated using a SnCl2/PdCl2 catalyzing process prior to CoNiReP deposition, the epitaxial growth was disturbed and a c-axis perpendicularly oriented hcp structure was formed, resulting in properties comparable to those of the CoNiReP SL film. It is suggested that such precise controllability of the crystal orientation (i.e., the magnetic properties) of the film will be very advantageous for the fabrication of multilayered devices with higher functional properties.

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  • An Analysis of the Segregated Microstructures of Electroless-Deposited CoNiP Perpendicular Magnetic Recording Media Using Selective Chemical Etching

    T. Homma, K. Ohrui, Y. Iizuka, T. Osaka, Y. Yamazaki, T. Namikawa

    IEEE Translation Journal on Magnetics in Japan   8 ( 12 ) 853 - 857  1993年

     概要を見る

    The segregated microstructures of electroless-deposited CoNiP perpendicular magnetic recording media with various Hc(⊥) values-500, 1000 and 1500 Oe–were investigated using a selective chemical etching technique, in which Co-rich ferromagnetic regions were preferentially dissolved with an etchant of sodium hydroxide-m-nitrobenzenesulfonic acid-ethylenediamine aqueous solution. TEM observations of the etched 1500 Oe film revealed an "asteroid" pattern with sixfold symmetry, which was inferred to be a substructure with Ni-rich composition. It is thought that the Co-rich regions are segregated between the "arms" of the asteroid substructure. The shape of the substructure varied with the Hc(⊥) of the films
    no substructure was observed in the 500 Oe film, while a substructure with a needlelike shape as well as a quasi-asteroid shape were observed in different regions of the 1000 Oe film. The differences in the segregation conditions are strongly dependent on the Hc(⊥) of the films. Further investigation of the 1500 Oe film in the thickness direction clearly indicated that the segregation occurs even in the initial deposition region (30 nm), and that the size of the substructure becomes larger with increasing film thickness. © 1993 IEEE

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  • 磁気記録材料の最近の動向 (Recent Trend on Magnetic Recording Materials)

    T. Osaka, Y. Yamazaki

    DENKI KAGAKU (presently Electrochemistry)   61 ( 1 ) 48 - 49  1993年01月  [査読有り]

  • プリント回路分野における基礎研究 (Fundamental Researches in the Field of Printed Circuit)

    T. Osaka

    Circuit Tech. Jpn.   8   1  1993年

  • 材料は21世紀を制するか? (Do New Materials Create 21st Century?)

    T. Osaka

    Chemistry and Chemical Industry   46   1402 - 1403  1993年

  • Advanced Surface Finishing Technology for Electronics Application

    T. Osaka

    Proc. 80th Tech. Conf. Amer. Electroplaters and Surf. Finish. Soc.     421 - 424  1993年

  • 無電解めっき薄膜の高機能性エレクトロニクス材料への応用 (Application of the Electroless-Deposition Thin Films to the High-Functionally Electronics Materials)

    T. Osaka

    表面   31   463 - 473  1993年

  • ポジ型フォトレジストの高解像化の動向 (Trend of High Resolution for Positive Photoresists)

    S. Asaumi, T. Osaka

    J. Met. Finish. Soc. Jpn. (presently J. Surf. Finish. Soc. Jpn. )   44   473 - 477  1993年

  • High Density Magnetic Recording Media Prepared by Electroless-Plating Method

    T. Osaka, T. Homma

    New Trends and Applications in Electrochemical Technology     13 - 37  1993年

  • Creation of High-Functionality Magnetic Thin Films by Electrochemical Method

    T. Osaka, T. Homma

    New Functionality Materials     267 - 272  1993年

  • Scanning Tunneling Microscopy Study of Electroless-Deposition Process

    T. Homma, T. Osaka

    Proc. Symp. Electrochemically Deposited Thin Films   93   58 - 69  1993年

  • Plated Media for High Density Magnetic Recording

    F. Goto, T. Osaka

    Proc. 2nd Symp. on Electrochemical Tech. Applications in Electronics   93   410 - 422  1993年

  • めっき法による磁性膜作製技術 (Process Technology for Magnetic Films by Electrochemical Method)

    T. Osaka

    J. Magn. Soc. Jpn.   17   23 - 30  1993年

  • AN ANALYSIS ON MICROSTRUCTURAL GROWTH-PROCESS IN ELECTROLESS CONIREP FILMS FOR PERPENDICULAR MAGNETIC RECORDING MEDIA

    T HOMMA, T OSAKA

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   139 ( 10 ) 2925 - 2929  1992年10月  [査読有り]

     概要を見る

    The segregated microstructure and the growth process of electroless CoNiReP films were examined using selective chemical etching and heat-treatment methods. The segregated condition in the film changes with an increase in the film thickness up to ca. 200 nm, while it keeps a constant nature with a further increase in the film thickness of up to 2 mum. In the region of thickness over 200 nm, the film consists of high-crystallized particles with 20 nm diam segregating in the nonmagnetic region with low crystallinity. Such a segregation is confirmed to occur from the nucleation stage before forming a continuous film, and the segregated structure is stable with heat-treatment up to 500-degrees-C.

  • AN ANALYSIS ON MICROSTRUCTURAL GROWTH-PROCESS IN ELECTROLESS CONIREP FILMS FOR PERPENDICULAR MAGNETIC RECORDING MEDIA

    T HOMMA, T OSAKA

    JOURNAL OF THE ELECTROCHEMICAL SOCIETY   139 ( 10 ) 2925 - 2929  1992年10月  [査読有り]

     概要を見る

    The segregated microstructure and the growth process of electroless CoNiReP films were examined using selective chemical etching and heat-treatment methods. The segregated condition in the film changes with an increase in the film thickness up to ca. 200 nm, while it keeps a constant nature with a further increase in the film thickness of up to 2 mum. In the region of thickness over 200 nm, the film consists of high-crystallized particles with 20 nm diam segregating in the nonmagnetic region with low crystallinity. Such a segregation is confirmed to occur from the nucleation stage before forming a continuous film, and the segregated structure is stable with heat-treatment up to 500-degrees-C.

  • NMR-STUDY ON COMPOSITIONAL INHOMOGENEITY IN ELECTROLESS DEPOSITED CONIP FILMS FOR PERPENDICULAR MAGNETIC RECORDING

    T HOMMA, H ASAI, T OSAKA, K TAKEI, Y MAEDA

    CHEMISTRY LETTERS   21 ( 9 ) 1783 - 1786  1992年09月  [査読有り]

     概要を見る

    Compositional inhomogeneity in electroless-deposited CoNiP films with perpendicular magnetic anisotropy was examined using the spin echo Co-59-NMR technique for the first time. The existence of a Co-rich component was observed which was thought to cause the formation of an hcp structure and produce high perpendicular coercivity, Hc(perpendicular-to). An increment in the Co-rich component by heat-treatment was also observed which might be an origin of the increase in Hc(perpendicular-to).

  • ELECTROACTIVITY CHANGE OF ELECTROPOLYMERIZED POLYPYRROLE POLYSTYRENESULFONATE COMPOSITE FILM IN SOME ORGANIC ELECTROLYTES

    T OSAKA, T MOMMA, K NISHIMURA

    CHEMISTRY LETTERS   21 ( 9 ) 1787 - 1790  1992年09月  [査読有り]

     概要を見る

    Electroactivity of polypyrrole/polystyrenesulfonate composite film obtained from an aqueous solution was examined in various organic electrolytes. The composite film worked like electroinactive film in electrolyte using propylene carbonate or some solvents except in the case of DMF or DMSO electrolytes, however, the film changed from electroinactive to electroactive even in propylene carbonate and some organic electrolytes after an electrochemical potential application to the film while in DMF or DMSO electrolytes.

  • CONDUCTION MECHANISM IN INDIUM TIN OXIDE ELECTROINACTIVE POLYPYRROLE INDIUM TIN OXIDE SANDWICH STRUCTURES

    T OSAKA, T FUKUDA, K OUCHI, T MOMMA

    THIN SOLID FILMS   215 ( 2 ) 200 - 202  1992年08月  [査読有り]

     概要を見る

    The electrical conduction mechanism for the indium tin oxide (ITO)/polypyrrole (PPy)/ITO sandwich type of metal-insulator-metal element was investigated, where electroinactive PPy polymerized in aqueous NaOH solution was used as an insulator. The ITO/PPy/Au element demonstrated a non-linear J-V response exactly the same as that of the ITO/PPy/ITO element, indicating that the carriers do not come from the interface but the bulk of an insulator. For the temperature dependence of the J-V responses of the ITO/PPy/ITO element, Poole-Frenkel emission is confirmed to be a dominant conduction mechanism. The activation energy of PPy electropolymerized for 60 min was calculated to be 0.46 eV on the basis of Poole-Frenkel emission. The activation energy and the conductivity of the PPy film were dependent on polymerization time.

  • PREPARATION OF ELECTROLESS-PLATED NIREP ALLOY-FILMS FOR A THIN-FILM RESISTOR

    T OSAKA, M FUKAWA, J KAWAGUCHI

    DENKI KAGAKU   60 ( 6 ) 523 - 530  1992年06月  [査読有り]

     概要を見る

    An electroless plating bath for amorphous NiReP alloy films was developed for a thin film resistor, and resistance properties of the films were investigated from a view point of Re codeposition effect. The rhenium content is varied from 0 to 44 at% with changing ammonium perrhenate concentration in the bath containing 0.40 mol dm-3 trisodium citrate and at pH 9.0. We focus on the NiReP film containing higher 44 at% Re content, which has high specific resistance, while being thermally unstable under as-plated conditions. This film possesses an excellent TCR after 500-degrees-C heat treatment. The film under as-plated conditions was suggested by XPS measurement that adsorption of water molecule or hydroxyl group causes high specific resistance. The film annealed maintains the amorphous structure after heat treatment at 500-degrees-C, thus showing on excellent TCR of 18 ppm K-1. The resistivity of the film annealed at 500-degrees-C was thermally stable, therefore, Re codeposition into electroless amorphous NiP alloys was proved to be effective for improving their thermal stability.