Degree 【 display / non-display 】

Degree 【 display / non-display 】

• 早稲田大学   工学博士

Professional Memberships 【 display / non-display 】

Professional Memberships 【 display / non-display 】

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  American Chemical Society

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  日本粘土学会

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  日本セラミックス協会

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  日本化学会

Research Areas 【 display / non-display 】

Research Areas 【 display / non-display 】

• Inorganic compounds and inorganic materials chemistry

Research Interests 【 display / non-display 】

Research Interests 【 display / non-display 】

• Inorganic Materials Chemistry

Papers 【 display / non-display 】

Papers 【 display / non-display 】

• Preparation of Siloxane‐based Microporous Crystal from Hydrogen Bonded Molecular Crystal of Cage Siloxane

  Naoto Sato, Yoshiyuki Kuroda, Hiroaki Wada, Atsushi Shimojima, Kazuyuki Kuroda

  Chemistry – A European Journal   in press  2018.11  [Refereed]

• Effect of Intercalated Amide Molecules on Interlayer Condensation of Layered Silicate RUB-15

  Masakazu Koike, Yusuke Asakura, Yoshiyuki Kuroda, Hiroaki Wada, Atsushi Shimojima, Kazuyuki Kuroda

  Clay Science   22   1 - 11  2018.06  [Refereed]

• Formation of Single-Digit Nanometer Scale Silica Nanoparticles by Evaporation-Induced Self-Assembly

  Shigeru Sakamoto, Masashi Yoshikawa, Kota Ozawa, Yoshiyuki Kuroda, Atsushi Shimojima, Kazuyuki Kuroda

  Langmuir   34 ( 4 ) 1711 - 1717  2018.01  [Refereed]

  　View Summary

  There are emerging demands for single-digit nanoscale particles in multidisciplinary fields, such as nanomedicine, optics, catalysis, and sensors, to create new functional materials. Here, we report a novel route to prepare silica nanoparticles less than 3 nm in size via the evaporation-induced self-assembly of silicate species and quaternary trialkylmethylammonium surfactants, which usually form reverse micelles. The solvent evaporation induces a local concentration increase and simultaneous polycondensation of silicate species within the hydrophilic region of the surfactant mesophases. Extremely small silica nanoparticles in the silica-surfactant mesostructures can be stably dispersed in organic solvents by destroying the mesostructure, which is in clear contrast to the preparation of silica nanoparticles using the conventional reverse micelle method. The surface chemical modification of the formed silica nanoparticles is easily performed by trimethylsilylation. The particle size is adjustable by changing the ratio of the surfactants to the silica source because the hydrophobic/hydrophilic ratio determines the curvature and diameter of the resulting spherical silica-surfactant domains in the mesostructure. The versatility of this method is demonstrated by the fabrication of very small titania nanoparticles. These findings will increase the designability of oxide nanoparticles at the single-digit nanoscale because conventional methods based on the generation and growth of nuclei in a solution cannot produce such nanoparticles with highly regulated sizes.

  DOI

• Formation of Concentric Silica Nanogrooves Guided by the Curved Surface of Silica Particles

  Shintaro Hara, Keiya Hirota, Yuka Tabe, Hiroaki Wada, Atsushi Shimojima, Kazuyuki Kuroda

  Langmuir   34 ( 4 ) 1733 - 1741  2018.01  [Refereed]

  　View Summary

  The flexible control of nanopatterns by a bottom-up process at the nanometer scale is essential for nanofabrication with a finer pitch. We have previously reported that for the fabrication of linear nanopatterns with sub-5 nm periodicity on Si substrates the outermost surfaces of assembled micelles facing the substrates can be replicated with soluble silicate species generated from the Si substrates under basic conditions. In this study, concentrically arranged nanogrooves with a sub-5 nm periodicity were prepared on Si substrates by replicating the outermost surfaces of bent micelles guided by silica particles. The Si substrates, where silica particles and surfactants films were deposited, were exposed to an NH3-water vapor mixture. During the vapor treatment, cylindrical micelles became arranged in concentric patterns centered on the silica particles, and their outermost surfaces facing the substrates were replicated by soluble silicate species on the Si substrates. The thinness of the surfactant film on the substrate is crucial for the formation of concentric silica nanogrooves because the out-of-plane orientations of the micelles are suppressed at the interface. Surprisingly, the domains of the concentric silica nanogrooves spread to much larger areas than the maximum cross-sectional areas of the particles, and the size of the domains increased linearly with the radii of the particles. The extension of concentric nanogrooves is discussed on the basis of the orientational elastic energies of the micelles around one silica particle. This study of the formation of bent nanogrooves guided by the outlines of readily deposited nanoscale objects provides a new nanostructure-guiding process.

  DOI

• Transformation of Mesostructured Silica Nanoparticles into Colloidal Hollow Nanoparticles in the Presence of a Bridged-Organosiloxane Shell

  Eisuke Yamamoto, Saki Uchida, Atsushi Shimojima, Hiroaki Wada, Kazuyuki Kuroda

  Chemistry of Materials   30 ( 2 ) 540 - 548  2018.01  [Refereed]

  　View Summary

  Hollow siloxane-based nanoparticles (HSNs) have attracted significant attention because of their unique properties and applications. Recently, it was discovered that the simple covering of silica nanoparticles with an organosiloxane shell leads to the spontaneous formation of HSNs
  however, the detailed mechanism of their formation has not yet been established. In this study, colloidal 30 nm HSNs were prepared by adding organically bridged alkoxysilane to an aqueous dispersion of mesostructured silica-surfactant composite nanoparticles, and the temporal changes of the morphology and chemical state of the nanoparticles were monitored to elucidate the formation mechanism. Core silica was dissolved after the formation of the core-shell structured nanoparticles, and almost all the dissolved silicate species were incorporated in the organosiloxane shell, changing the shell thickness. Two conditions were essential for silica dissolution induced by covering with organosiloxane: (i) presence of a sufficient amount of uncondensed Si-OH groups in the organosiloxane shell, and (ii) elevated temperature and pH for the promotion of the hydrolysis of silica. These findings will enable the fabrication of various HSNs through organosiloxane-induced silica dissolution and redeposition.

  DOI

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Misc 【 display / non-display 】

Misc 【 display / non-display 】

• Formation of ordered silica-organic hybrids by self-assembly of hydrolyzed organoalkoxysilanes with long organic chains

  Kazuyuki Kuroda, Atsushi Shimojima

  Materials Research Society Symposium - Proceedings   707   61 - 72  2002.12

  　View Summary

  Various layered hybrid films prepared from organoalkoxysilanes with long organic chains, based on the self-assembly of the hydrolyzed species, are reviewed. Morphological control of transparent and oriented films was achieved by cohydrolysis and polycondensation with tetraalkoxysilanes, followed by dip- or spin-coating. In addition to alkytrialkoxysilanes, alkyldimethylmonoalkoxy- and alkylmethyldialkoxy-silanes were also used as the structural units, implying that the inorganic-organic interface can be designed at a molecular level. In these cases, co-condensation in the precursor solution plays an essential role in the formation of homogeneous and ordered films. Alkenyltriethoxysilanes with terminal C=C bonds were also employed to prepare layered hybrid films. Interlayer chains were polymerized upon UV irradiation, and the resulting films exhibited a significant increase in the hardness if compared with the films before polymerization. Hybrid films thus obtained are a new class of materials and of great interest for a wide range of materials chemistry.

• Formation of ordered silica-organic hybrids by self-assembly of hydrolyzed organoalkoxysilanes with long organic chains

  Kazuyuki Kuroda, Atsushi Shimojima

  Materials Research Society Symposium - Proceedings   703   71 - 82  2002.01

  　View Summary

  Various layered hybrid films prepared from organoalkoxysilanes with long organic chains, based on the self-assembly of the hydrolyzed species, are reviewed. Morphological control of transparent and oriented films was achieved by cohydrolysis and polycondensation with tetraalkoxysilanes, followed by dip- or spin-coating. In addition to alkyltrialkoxysilanes, alkyldimethylmonoalkoxy- and alkylmethyldialkoxy-silanes were also used as the structural units, implying that the inorganic-organic interface can be designed at a molecular level. In these cases, co-condensation in the precursor solution plays an essential role in the formation of homogeneous and ordered films. Alkenyltriethoxysilanes with terminal C=C bonds were also employed to prepare layered hybrid films. Interlayer chains were polymerized upon UV irradiation, and the resulting films exhibited a significant increase in the hardness if compared with the films before polymerization. Hybrid films thus obtained are a new class of materials and of great interest for a wide range of materials chemistry.

• Synthesis of NaLnNbC (Ln=La, Nd, Sm, Gd) an their structures and electrical properties

  Wataru Sugimolo, Masahiro Nailo, Yoshiyuki Sugahara, Kazuyuki Kuroda

  Materials Research Society Symposium - Proceedings   547   267 - 272  1999.12

  　View Summary

  Polycrystalline samples of NaiLnbO (Ln=La, Nd, Sm, Gd) were synthesized by solid-state reactions. Reduced niobates were obtained as single-phase perovskites for x=0.05 and 0.1 when Ln=La and Nd and x=0.05 when Ln=Sm. The Gd-substituted samples could not be prepared under the synthetic conditions studied. Compositional analysis of the products revealed a slight amount of sodium loss during synthesis. The structural parameters obtained from Rietveld analysis revealed an increase in unit-cell volume. All of the obtained samples showed semiconducting behavior. Similar semiconducting behavior was observed for the same x value, suggesting the weak influence of the different Ln species to the electrical properties. © 1999 Materials Research Society.

• SYNTHESIS of A(1-x)A'xNbO3 (A=Na+, K+; A'=La3+, Sr2+) and its electrical properties

  W Sugimoto, T Tahara, Y Sugahara, K Kuroda

  SOLID-STATE CHEMISTRY OF INORGANIC MATERIALS   453   361 - 366  1997

  　View Summary

  Polycrystalline samples of A(1-x)A'xNbO3 (A=Na+, K+; A'=La3+, Sr2+) were prepared by solid-state reactions and the relationship between the structure and electrical properties was examined. Single-phase products were obtained for Na1-xLaxNbO3 (x less than or equal to 0.1), K1-xLaxNbO3 (x less than or equal to 0.15), Na1-xSrxNbO3 (x less than or equal to 0.3), and K1-xSrxNbO3 (x less than or equal to 0.5). The structures of the sodium-containing compounds and potassium-containing compounds were indexed according to a pseudocubic and cubic symmetry, respectively. The resistivity measurements showed semiconductive behavior for the lanthanum-containing samples. The strontium-containing samples showed semiconducting properties for x less than or equal to 0.2, while a transition to metallic conduction at low temperature was observed for x >0.2.

• Pyrolytic preparation of gallium nitride from [Ga(NEt2)3]2 and its ammonolysis compound

  S. Koyama, Y. Sugahara, K. Kuroda

  Materials Research Society Symposium - Proceedings   468   93 - 98  1997.01

  　View Summary

  Gallium nitride (GaN) was prepared by the pyrolytic conversion of both [Ga(NEt2)3]2 and its ammonolysis product at 600°C for 4 h under Ar. The pyrolyzed residues were analyzed by X-ray powder diffraction and scanning electron microscopy, and the pyrolysis processes of the precursors under He were investigated by thermogravimetry-mass spectrometry. The XRD pattern of the pyrolyzed residue of [Ga(NEt2)3]2 showed well-resolved peaks due to a mixture of cubic and hexagonal close-packed layers of GaN. The broad XRD pattern of the pyrolyzed residue of the ammonolysis product was also attributed to the mixture of cubic and hexagonal close-packed layers of GaN. For the pyrolysis of [Ga(NEt2)3]2, the evolution of hydrocarbons was extensively observed at relatively high temperature, but a large amount of carbon (11 mass%) was still detected in the pyrolyzed residue. On the other hand, the amount of carbon was only 1.1 mass% in the pyrolyzed residue of the ammonolysis product. The pyrolysis results of the ammonolysis product under Ar were very similar to those of [Ga(NEt2)3]2 under NH3.

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Awards 【 display / non-display 】

Awards 【 display / non-display 】

• IMMA Lifetime Achievement Award

  2015.08   International Mesostructured Materials Association  

  Winner： KURODA, Kazuyuki

• 第67回日本化学会賞

  2015.01   日本化学会   メソポーラスシリカ類の創製と展開

  Winner： 黒田 一幸

• 平成25年度錯体化学会貢献賞

  2013.11   錯体化学会   ナノ空間を有する無機固体化学に関する研究

  Winner： 黒田 一幸

• 平成25年度科学技術分野 文部科学大臣賞表彰

  2013.04   文部科学省   メソ多孔体合成の先駆的研究

  Winner： 黒田 一幸

Research Projects 【 display / non-display 】

Research Projects 【 display / non-display 】

• 無機ナノ構造体の精密合成とその熱電変換特性

  基盤研究(A)

• バイオイメージングへの応用に向けたコロイド状メソポーラスシリカ粒子の外表面被覆

  挑戦的萌芽研究

• ホウ酸有機誘導体からの窒化物,炭化物の合成

  一般研究(C)

• The Study on the Intercalation Chemistry of Layered Oxides for the Potential Use of the Resultant Intercalation Compounds as Functional Materials

• Development of Synthetic Methods for New Porous Materials by the Conversion of Inorganic Layred Compounds into Three-dimensional Networks

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Specific Research 【 display / non-display 】

Specific Research 【 display / non-display 】

• 新規熱電変換材料創製に資する無機材料合成技術の開発

  2018  

  　View Summary

  物質中の規則性ナノ空間と熱電性能との相関を実証することを目指し、ナノ空間のサイズや形状、配列を精密に制御した金属酸化物作製手法の確立を目的とした。優れた熱電特性が期待されているものの、従来手法では作製が困難とされていたN,Nb共ドープTiO2の規則性細孔配列を有するナノ多孔体を作製することに成功した。NbドープTiO2ナノ多孔体を作製後、細孔形状を保持しつつNをドープする多段階的な反応により作製が可能となることを明らかにした。層状LiCoO2ついても多段階合成の有効性も示した。この作製手法の確立は無機材料合成技術の開拓や新規熱電変換材料の創製に貢献しうる非常に重要な成果である。

• 水素結合を利用したかご型シロキサンの配列制御による結晶性多孔体合成法の開発

  2017  

  　View Summary

  ゼオライトなどの結晶性シロキサン構造体は種々応用されており、これらをビルディングブロックアプローチで合理的に構築することが期待されているが、それらの規則的集積法が従来存在しなかった。昨年度までにシラノール基を修飾した二重四員環型シロキサンの分子結晶の作製に成功しており、本年度はクロロシランを用いて結晶のシラノール基をシロキサン結合に変換した。これにより、細孔の構造を保持したままシロキサン結合形成が進行し、分子結晶の結晶構造を反映した結晶性多孔体の作製を達成した。

• 多孔性金属酸化物の精密合成に基づく物性制御

  2017  

  　View Summary

  多孔性金属酸化物結晶の構造と骨格密度を制御する手法を確立するとともに、空隙率をシームレスに制御することで、細孔径・細孔形状・細孔配列・空隙率が物性に与える影響を解明することを目的とし、本年度は、ナノ細孔が規則集積した無機ナノ構造体を鋳型に用い、その転写によって作製した多孔性金属酸化物結晶の熱物性を測定した。本研究では、ナノ細孔の形状・サイズ・配列が精密制御されたNドープTiO2を作製した。作製した多孔体試料と無孔質試料の熱伝導率を比較し、熱伝導率は密度から予想される値よりも大幅に低減したことを明らかにした。

• ケイ素アルコキシドのオリゴマー合成に向けた置換基交換反応の開発

  2016  

  　View Summary

  本研究課題では、アルコキシシロキサンオリゴマーの新規合成手法の開発を目的に、(1) トリメチルシリル(TMS)基のアルコキシシリル基への置換反応の反応条件、(2)ケイ酸塩からのシロキサン骨格の抽出条件、(3) 上記置換反応を用いたアルコキシシロキサンオリゴマーの合成の三つを検討した。(1)では、上記置換反応において、高い変換率(98%)を示す反応条件を見出した。(2)では、直鎖状のシロキサン骨格を有するケイ酸塩のTMS化において、反応条件を検討したが、シロキサン骨格の崩壊の抑制は困難であった。(3)では、TMS基の置換反応を用いてアルコキシシロキサンオリゴマーの合成に成功し、TMS基の変換率は原料のシロキサン骨格の構造により変化した。

• シリコン基板をシリカ源とするメソポーラスシリカ薄膜の作製

  2015  

  　View Summary

  Techniques of single nanometer-scalepatterning are required for fabrication of higher-density integrated circuitsand memories. However, single nanometer-scale patterning remains challengingeven today because such an extremely short pitch cannot be fabricated by the conventionalnanopatterning techniques such as photolithography. Expensive mask and photosensitivepolymer are also required for photolithography processes. We have succeeded in fabricating silica-based materials with nanogroove structures at the interfacesbetween Si substrates and lyotropic liquid crystals using soluble silicatespecies generated from Si substrates under basic conditions. Cationicsurfactants were coated on Si substrates. The substrates were exposed to aqueousammonia vapor and they were washed to remove the surfactants. A thin layer on Sisubstrates with an ordered semicircle groove structure, the periodicity anddepth of which are around 5 nm and 2 nm, respectively, was observed.

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