研究者詳細 - 吉野　正人

論文 - 吉野　正人

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Study on photoluminescence properties of Er2O3 materials as irradiation damage and temperature sensors 査読有り

38 巻頁： 101614 2024年3月

Novel Route for Enhancing Piezoelectricity of Ferroelectric Films: Controlling Nontrivial Polarization States in Pb(Zr, Ti)O3 Monodomain Superlattice Structure 査読有り

J. Song, Y. Ebihara, P. Yudin, O. Sakata, H. Morioka, T. Kiguchi, S. Kondo, X. Yuan, S. Okamura, M. Yoshino, T. Nagasaki, and T. Yamada

ACS Applied Materials & Interfaces 16 巻 ( 13 ) 頁： 16145 - 16151 2024年3月

Extraordinarily Large Contribution Ratio of Ferroelastic Domain Switching to Piezoresponse in Monoclinic (K, Na)NbO3 Films 査読有り

Yuan, XY; Okamoto, K; Kawano, M; Yoshino, M; Nagasaki, T; Imai, Y; Sakata, O; Yamada, T

ADVANCED ELECTRONIC MATERIALS 10 巻 ( 1 ) 2024年1月

Effect of Ni doping on the electro-optic property in K(Ta0.6Nb0.4)O3 films 査読有り

Yuan, X; Sakurai, Y; Kondo, S; Yoshino, M; Nagasaki, T; Yamada, T

JAPANESE JOURNAL OF APPLIED PHYSICS 61 巻 ( SN ) 2022年11月

Dynamic electrical response of vortex polarization in (Pb0.9Sr0.1)TiO3/SrTiO3 artificial superlattice thin films 査読有り

Song, JD; Iguchi, Y; Okamoto, K; Sakata, O; Yoshino, M; Nagasaki, T; Yamada, T

APPLIED PHYSICS LETTERS 121 巻 ( 17 ) 2022年10月

ガーネット構造酸化物に添加したNd3+の発光・吸収スペクトルに及ぼすホスト組成の影響に対する構造研究査読有り

長井仁史, 吉野正人, 渡邊真太, 宇留賀朋哉, 加藤和男, 新田清文

SPring-8/SACLA利用研究成果集 10 巻 ( 4 ) 頁： 336 - 338 2022年8月

担当区分：筆頭著者記述言語：日本語掲載種別：研究論文（研究会，シンポジウム資料等）出版者・発行元：公益財団法人高輝度光科学研究センター

固相反応法により作製した Nd,Sc 共添加 Y3Al5O12、Nd,Ga 共添加 Y3Al5O12、Nd,Gd 共添加 Y3Al5O12、について、Ｘ線吸収微細構造(XAFS)測定を行った。Sc および Ga の添加量増加に伴って Nd-O 間平均距離が大きくなり、また、Sc 添加量によって Nd 周りの局所構造の静的ゆらぎが異なることがわかった。これらと、試料のＸ線回折データのリートベルト解析および理論計算の結果から、吸収スペクトルの変化について考察した。

DOI： 10.18957/rr.10.4.336

CiNii Research

Optimizing the growth of K(Ta0.6Nb0.4)O3 films using pulsed laser deposition and their electro-optic property

Sakurai, Y; Yuan, XY; Kondo, S; Yoshino, M; Nagasaki, T; Yamada, T

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 130 巻 ( 7 ) 頁： 424 - 428 2022年7月

Unraveling the reasons behind lead phthalocyanine acting as a good absorber for near-infrared sensitive devices 査読有り

Kato, M; Yoshizawa, H; Nakaya, M; Kitagawa, Y; Okamoto, K; Yamada, T; Yoshino, M; Tanaka, K; Onoe, J

SCIENTIFIC REPORTS 12 巻 ( 1 ) 2022年5月

Revealing intrinsic electro-optic effect in single domain Pb(Zr, Ti)O3 thin films 査読有り

Kondo, S; Yamada, T; Yoshino, M; Teranishi, T; Kishimoto, A; Nagasaki, T

APPLIED PHYSICS LETTERS 119 巻 ( 10 ) 2021年9月

Enhanced figure of merit in Pb(Zr,Ti)O3 nanorods for piezoelectric energy harvesting 査読有り国際誌

Song, J; Yamada, T; Okamoto, K; Yoshino, M; Nagasaki, T

AIP ADVANCES 10 巻 ( 10 ) 2020年10月

Fabrication of (Pb0.9Sr0.1)TiO3/SrTiO3 artificial superlattice thin films and their electromechanical response

Iguchi, Y; Yamada, T; Sakata, O; Yoshino, M; Nagasaki, T

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 128 巻 ( 8 ) 頁： 431 - 435 2020年8月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人日本セラミックス協会

Artificial superlattice thin films of (Pb0.9Sr0.1)TiO3 (PST)n/SrTiO3 (STO)m were grown on SrRuO3-electroded DyScO3 (001)pc substrates by pulsed laser deposition. X-ray diffraction (XRD) showed that the fabricated superlattice thin films have a good periodicity in the out-of-plane direction, indicating the sharp interfaces regardless of the difference in layer thickness. Synchrotron XRD indicated that the film with n/m = 14/20 had a weak periodicity in the in-plane direction, which may had arisen from the ordered polar vortex arrays existing in the PST layers. All the fabricated superlattice thin films showed the electric field-induced strain, though its magnitude was smaller than that for typical ferroelectric materials.

DOI： 10.2109/jcersj2.20022

Web of Science

CiNii Research

Enhanced intrinsic piezoelectric response in (001)-epitaxial single c-domain Pb(Zr,Ti)O3 nanorods 査読有り国際誌

Okamoto, K; Yamada, T; Nakamura, K; Takana, H; Sakata, O; Phillips, M; Kiguchi, T; Yoshino, M; Funakubo, H; Nagasaki, T

APPLIED PHYSICS LETTERS 117 巻 ( 4 ) 2020年7月

エピタキシャル菱面体晶Pb(Zr, Ti)O3薄膜のドメインスイッチングが電気光学特性に与える影響

近藤真矢, 山田智明, 坂田修身, 吉野正人, 長崎正雅

応用物理学会学術講演会講演予稿集 2020.1 巻 ( 0 ) 頁： 1232 - 1232 2020年2月

Large impact of strain on the electro-optic effect in (Ba, Sr)TiO3 thin films: Experiment and theoretical comparison 査読有り国際誌

Kondo, S; Yamada, T; Tagantsev, AK; Ma, P; Leuthold, J; Martelli, P; Boffi, P; Martinelli, M; Yoshino, M; Nagasaki, T

APPLIED PHYSICS LETTERS 115 巻 ( 9 ) 2019年8月

Theoretical estimation of the linear electro-optic effect in compressively strained c-domain (Ba, Sr)TiO3 thin films using a phenomenological thermodynamic model

Kondo, S; Yamada, T; Tagantsev, A; Setter, N; Yoshino, M; Nagasaki, T

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 127 巻 ( 6 ) 頁： 348 - 352 2019年6月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人日本セラミックス協会

The influence of compressive strain on the linear electro-optic (EO) effect in c-domain (BaxSr1−x)TiO3 (BST) thin films was theoretically investigated using a phenomenological thermodynamic model. We considered that the c-domain BST thin films were grown on cubic substrates and an electric field was applied parallel to the direction of spontaneous polarization. To estimate the EO coefficients, we considered not only the intrinsic EO effect but also the elasto-optic effect by converse piezoelectric response. We found that the EO response is mostly determined by the difference in temperature from the ferroelectric-to-paraelectric phase transition boundary modified by the strain, and the elasto-optic effect appreciably affects the overall EO coefficient when the intrinsic EO effect is weak.

DOI： 10.2109/jcersj2.19011

Web of Science

CiNii Research

Examination of Transmutation Effect on Responses of K-Type and N-Type Thermocouples at Fusion Blanket 査読有り国際誌

Tanaka, T; Noto, H; Sato, F; Hishinuma, Y; Sakaue, HA; Yoshino, M

FUSION SCIENCE AND TECHNOLOGY 75 巻 ( 8 ) 頁： 1076 - 1083 2019年

Theoretical Analysis of Nanogenerators with Aligned Nanorods for Piezoelectric Energy Harvesting 査読有り国際誌

Song, J; Yamada, T; Yoshino, M; Nagasaki, T

SENSORS AND MATERIALS 31 巻 ( 11 ) 頁： 3669 - 3679 2019年

Significant effect of Mg-pressure-controlled annealing: non-stoichiometry and thermoelectric properties of Mg2-Si1-xSbx 査読有り

Kato, D; Iwasaki, K; Yoshino, M; Yamada, T; Nagasaki, T

PHYSICAL CHEMISTRY CHEMICAL PHYSICS 20 巻 ( 40 ) 頁： 25939 - 25950 2018年10月

Strong impact of SrTiO3/TiO2 buffer layer on epitaxial growth and dielectric response of Ba0.7Sr0.3TiO3 thin films on MgO 査読有り

Kondo, S; Yamada, T; Yoshino, M; Nagasaki, T

JAPANESE JOURNAL OF APPLIED PHYSICS 57 巻 ( 9 ) 2018年9月

Influence of deposition conditions on self-assembled growth of Pb(Zr,Ti)O3 nanorods by pulsed laser deposition at elevated oxygen pressure

Okamoto, K; Yamada, T; Yasumoto, J; Nakamura, K; Yoshino, M; Nagasaki, T

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 126 巻 ( 5 ) 頁： 276 - 280 2018年5月

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人日本セラミックス協会

Self-assembled Pb(Zr,Ti)O3 (PZT) nanorods were grown by pulsed laser deposition (PLD) at an elevated oxygen pressure. PZT grew as a film in the initial growth stage and formed nanorods upon further deposition. The influence of the substrate temperature, target-substrate distance, and Pb composition of the targets on nanorod growth was investigated. It was found that the average radius of the PZT nanorods was larger at higher substrate temperatures and longer target-substrate distances, which can be explained respectively by the enhanced surface diffusion and shadowing effect of the PLD species. The results of this study can contribute to controlling the sizes of PZT nanorods to tune their piezoelectric response.

DOI： 10.2109/jcersj2.17255

Web of Science

CiNii Research

Spectroscopic and first-principles calculation studies of the chemical forms of palladium ion in nitric acid solution for development of disposal of high-level radioactive nuclear wastes 査読有り

Watanabe, S; Sato, T; Yoshida, T; Nakaya, M; Yoshino, M; Nagasaki, T; Inaba, Y; Takeshita, K; Onoe, J

AIP ADVANCES 8 巻 ( 4 ) 2018年4月

Crystallographic orientation dependence of the sputtering yields of nickel and copper for 4-keV argon ions determined using polycrystalline targets 査読有り

Nagasaki, T; Hirai, H; Yoshino, M; Yamada, T

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS 418 巻頁： 34 - 40 2018年3月

Control of Mg content and carrier concentration via post annealing under different Mg partial pressures for Sb-doped Mg2Si thermoelectric material 査読有り

Kato, D; Iwasaki, K; Yoshino, M; Yamada, T; Nagasaki, T

JOURNAL OF SOLID STATE CHEMISTRY 258 巻頁： 93 - 98 2018年2月

Experimental study of effect of strain on electrocaloric effect in (001)-epitaxial (Ba, Sr)TiO3 thin films 査読有り

Yamada, T; Matsuo, S; Kamo, T; Funakubo, H; Yoshino, M; Nagasaki, T

JAPANESE JOURNAL OF APPLIED PHYSICS 56 巻 ( 10 ) 2017年10月

Charge screening strategy for domain pattern control in nano-scale ferroelectric systems 査読有り

Yamada, T; Ito, D; Sluka, T; Sakata, O; Tanaka, H; Funakubo, H; Namazu, T; Wakiya, N; Yoshino, M; Nagasaki, T; Setter, N

SCIENTIFIC REPORTS 7 巻 2017年7月

High carrier concentration in Mg2Si1-xSbx (0 ≤ x ≤ 0.10) prepared by a combination of liquid-solid reaction, ball milling, and spark plasma sintering 査読有り

Kato, D; Iwasaki, K; Yoshino, M; Yamada, T; Nagasaki, T

INTERMETALLICS 81 巻頁： 47 - 51 2017年2月

Indirect measurements of electrocaloric effect in ferroelectric thin films by positive-up-negative-down method

Matsuo, S; Yamada, T; Kamo, T; Funakubo, H; Yoshino, M; Nagasaki, T

JOURNAL OF THE CERAMIC SOCIETY OF JAPAN 125 巻 ( 6 ) 頁： 441 - 444 2017年

記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：公益社団法人日本セラミックス協会

Positive-up-negative-down (PUND) polarization measurement was employed to indirectly estimate the electrocaloric (EC) effect in ferroelectric films. By subtracting the conductive component from the observed charge profile, the polarization values at various electric fields and temperatures were precisely determined. The estimated EC effect for an epitaxial Ba0.3Sr0.7O3 thin film fabricated on SrRuO3/SrTiO3 (001) substrate showed the largest temperature change at around the ferroelectric-paraelectric phase transition temperature, which agrees with the theoretical prediction. On the other hand, the EC effect estimated by the conventional hysteresis loop measurement showed different peaking temperature from the theoretical prediction. The deviation became larger with lowering the measurement frequency. The observed results indicate the importance of precise evaluation of polarization for the examined temperature-electric field space.

DOI： 10.2109/jcersj2.16283

Web of Science

CiNii Research

Nonlinear electric field dependence of electrocaloric effect in (001)-epitaxial (Ba, Sr) TiO3 thin films 査読有り

Matsuo, S; Yamada, T; Yoshino, M; Nagasaki, T; Kamo, T; Funakubo, H

2017 JOINT IEEE INTERNATIONAL SYMPOSIUM ON THE APPLICATIONS OF FERROELECTRIC (ISAF)/INTERNATIONAL WORKSHOP ON ACOUSTIC TRANSDUCTION MATERIALS AND DEVICES (IWATMD)/PIEZORESPONSE FORCE MICROSCOPY WORKSHOP (PFM) 頁： 68 - 70 2017年

Intra- and inter-atomic optical transitions of Fe, Co, and Ni ferrocyanides studied using first-principles many-electron calculations 査読有り

Shinta Watanabe, Yuki Sawada, Masato Nakaya, Masahito Yoshino, Takanori Nagasaki, Tatsuya Kameyama, Tsukasa Torimoto, Yusuke Inaba, Hideharu Takahashi, Kenji Takeshita, Jun Onoe

Journal of Applied Physics 119 巻頁： 235102 2016年6月

Ab initio Study on Face Azimuth Dependency of Surface Energy and Structure in PbTiO3 査読有り

Yosuke Takagi, Tomoaki Yamada, Masahito Yoshino, Takanori Nagasaki

Ferroelectrics 490 巻頁： 167-173 2016年1月

Domain Structure of Tetragonal Pb(Zr,Ti)O3 Nanorods and its Size Dependence 査読有り

T. Yamada, D. Ito, O. Sakata, J. Kuroishi, T. Namazu, Y. Imai, T. Shiraishi, T. Shimizu, H. Funakubo, M. Yoshino, and T. Nagasaki

Japanese Journal of Applied Physics 54 巻頁： 10NA07 2015年9月

Negligible Substrate Clamping Effect on Piezoelectric Response in (111)-Epitaxial Tetragonal Pb(Ti, Zr)O3 Films 査読有り

T. Yamada, J. Yasumoto, D. Ito, O. Sakata, Y. Imai, T. Kiguchi, T. Shiraishi, T. Shimizu, H. Funakubo, M. Yoshino, T. Nagasaki

Journal of Applied Physics 118 巻 ( 7 ) 頁： 072012 2015年8月

Fabrication of Tetragonal Pb(Zr,Ti)O3 Nanorods by Focused Ion Beam and Characterization of the Domain Structure 査読有り

D. Ito, T. Yamada, M. Yoshino, T. Nagasaki, O. Sakata, J. Kuroishi, T. Namazu, T. Shiraishi, T. Shimizu, and H. Funakubo

Proc. IEEE ISAF-ISIF-PFM 2015 頁： 175-177 2015年

Bi4Ti3O12 Nanowall Growth Driven by Anisotropic Growth Rate and Size Control 査読有り

Tomoaki Yamada, Takaaki Shibata, Koji Ishii, Junichi Kimura, Hiroshi Funakubo, Masahito Yoshino, Takanori Nagasaki

Japanese Journal of Applied Physics 52 巻頁： 09Ka09 2013年9月

Influence of Ba/Sr ratio in compressively-strained (Ba,Sr)TiO3(001) films on the ferroelectric phase transition 査読有り

Tomoaki YAMADA, Itaru TAKUWA, Takafumi KAMO, Takashi IIJIMA, Masahito YOSHINO, Takanori NAGASAKI, Hiroshi FUNAKUBO

Journal of the Ceramic Society of Japan 121 巻 ( 8 ) 頁： 690-692 2013年8月

原子化エネルギーから見た3d遷移金属フッ化物の化学結合

森永正彦、斉藤由樹、伊藤和樹、吉野正人、湯川宏、中井浩巳

DV-Xα研究協会会報 26 巻 ( 1&2 ) 頁： 58-61 2013年

Characterization of Er2O3 ceramic coatings by luminescence measurements 査読有り

T. Tanaka, M. Yoshino, Y. Hishinuma, D. Zhang, W. Kada, F. Sato, T. Iida, T. Nagasaki, T. Muroga

Journal of Nuclear Materials 417 巻 ( 1-3 ) 頁： 794-797 2011年10月

Energy expression of the chemical bond between atoms in metal oxides 査読有り

Yoshifumi Shinzato, Yuki Saito, Masahito Yoshino, Hiroshi Yukawa, Masahiko Morinaga, Takeshi Baba and Hiromi Nakai

Journal of Physics and Chemistry of Solids 72 巻 ( 7 ) 頁： 853-861 2011年7月

Analysis of 4f-5d excitation spectra of Pr3+-doped SrY2O4

S. Watanabe, Y. Ichikawa, M. Yoshino, T. Yamada, T. Nagasaki

UVSOR Activity Report 10 頁： 84 2011年

First-principles and Experimental Analysis of f n-f n-1d 1 Absorption Spectra and Multiplet Energy Levels of Pr3+, Nd3+, and U3+ in LiYF4 査読有り

S. Watanabe, K. Ogasawara, M. Yoshino, T. Nagasaki

Physical Review B 81 巻 ( 12 ) 頁： 125128 2010年

Excitation and Emission Spectra for Nd3+ in SrY2O4

M. Yoshino, Y. Ichikawa, S. Watanabe

UVSOR Activity Report 09 頁： 131 2010年

Analysis of 4f-5d excitation spectra of Pr3+-doped SrY2O4

S. Watanabe, Y. Ichikawa, M. Yoshino, T. Yamada, T. Nagasaki

UVSOR Activity Report 10 巻頁： 84 2010年

Excitation Spectra for Ce3+ in SrY2O4

M. Yoshino, S. Watanabe, Y. Ichikawa

UVSOR Activity Report 08 頁： 122 2009年

Crystal structure of an oxygen deficient strontium cobaltate, Sr6Co5O14.3 査読有り

K. Iwasaki, H. Yamane, T. Murase, M. Yoshino, T. Ito, T. Nagasaki, Y. Arita, T. Matsui

Journal of the Ceramic Society of Japan 117 巻頁： 89-93 2009年

Neutron powder diffraction and difference maximum entropy methodanalysis of protium- and deuterium-dissolved BaSn0.5In0.5O2.75+α 査読有り

T. Nagasaki, S. Shiotani, N. Igawa, M. Yoshino, K. Iwasaki, H. Fukazawa, W.Utsumi

Journal of Solid State Chemistry 182 巻頁： 2632-2639 2009年

Measurement of f-d absorption spectrum for heavy lanthanides in LiYF4 by using the synchrotron light source and its analysis based on the first-principles calculation

Shinta Watanabe, Kazuyoshi Ogasawara, Masahito Yoshino

Open Research Center for Coordination Molecule-based Devices2008 Symposium on Coordination Compounds as Inorganic-organic Composite Materials abstract 頁： 31 2008年4月

Temperature dependence of the D–H replacement rates in rates in D-implanted oxide ceramics exposed to H2O vapor 査読有り

K. Morita, B. Tsuchiya S. Nagata, K. Katahira, M. Yoshino, Y. Arita, T. Ishijima, H. Sugai

Nuclear Instruments and Methods in Physics Research B 258 巻 ( 1 ) 頁： 282-286 2008年

A water splitting model of Coulomb interactions of its dipole with surface defects of hydrogen implanted perovskite oxide 査読有り

K. Morita, B. Tsuchiya S. Nagata, K. Katahira, M. Yoshino, J. Yuhara, Y. Arita, T. Ishijima, H. Sugai

Solid State Ionics (Proceedings of the 16th International Conference on Solid State Ionics (SSI-16)) 179 巻 ( 21-26 ) 頁： 793-796 2008年

*Location of deuterium atoms in BaZr0.5In0.5O2.75+α at 10 K by neutron powder diffraction 査読有り

Takanori Nagasaki, Tsuyoshi Ito, Masahito Yoshino, Kouta Iwasaki, Shinya Shiotani, Hiroshi Fukazawa, Naoki Igawa, Yoshinobu Ishii

J. Nucl. Sci. Technol. Supplement 巻 ( 6 ) 頁： 122-127 2008年

Thermoelectric Properties of Polycrystalline La1-xSrxCoO3 査読有り

Kouta Iwasaki, Tsuyoshi Ito, Takanori Nagasaki, Yuji Arita, Masahito Yoshino, and Tsuneo Matsui

J. Solid State Chem. 頁： in press 2008年

Excitation Spectra for Lanthanides in YAG and its First-Principles Analysis

M. Yoshino, S. Watanabe, H. Yoshida and K. Ogasawara

UVSOR Activity Report 07 頁： 86 2008年

The Temperature dependence of Absorption Spectra for Heavy Lanthanides in LiYF4 and its First-Principles Analysis

S. Watanabe, K. Ogasawara, and M. Yoshino

UVSOR Activity Report 07 頁： 85 2008年

Power factor of La1-xSrxFeO3 and LaFe1-yNiyO3 査読有り

Iwasaki, Kouta; Ito, Tsuyoshi; Yoshino, Masahito; Matsui, Tsuneo; Nagasaki, Takanori; Arita, Yuji

J. Alloy. Compd. 430 巻 ( 1-2 ) 頁： 297-301 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

The electrical conductivity (sigma), Seebeck coefficient (S), and power factor (sigma S-2) of perovskite-type LaFeO3, La1-xSrxFeO3 [0.1 <= x <= 0.4] and LaFe1-yNiyO3 [0.1 <= y <= 0.6] were investigated in the temperature range of 300-1100 K to explore their possibility as thermoelectric materials. The electrical conductivity of LaFeO3 showed semiconducting behavior, and its Seebeck coefficient changed from positive to negative around 650 K with increasing temperature. The electrical conductivity of LaFeO3 increased with the substitutions of Sr and Ni atoms, while its Seebeck coefficient decreased. The Seebeck coefficient of La1-xSrxFeO3 was positive, whereas that of LaFe1-yNiyO3 changed from positive to negative with increasing Ni content. The substitutions of Sr and Ni were effective in increasing the power factor of LaFeO3; 0.0053 x 10(-4) Wm(-1) K-2 for LaFeO3 (1050K), 1.1 x 10(-4) Wm(-1) K-2 for La1-xSrxFeO3 (x = 0.1 at 1100K) and 0.63 x 10(-4) Wm(-1) K-2 for LaFe1-yNiyO3 (y = 0.1 at 1100K).

Thermoelectric properties of (La,Ca)CrO3 査読有り

Kouta Iwasaki, Hiroshi Kawashima, Takanori Nagasaki, Yuji Arita, Masahito Yoshino, Tsuneo Matsui

Proceeding of the International Symposium on EcoTopia Science 2007 頁： 58-60 2007年

Thermoelectric properties of Fe3-xCoxSi Heusler alloys 査読有り

Kohei Ishii, Kouta Iwasaki, Yuji Arita, Masahito Yoshino, Takanori Nagasaki, Tsuneo Matsui

Proceeding of the International Symposium on EcoTopia Science 2007 頁： 142-144 2007年

Electrical conductivity and Seebek coefficient of Ba-Co-C-O single crystal 査読有り

Teruhisa Yamamoto, Kouta Iwasaki, Yuji Arita, Hisanori Yamane, Takashi Takeda, Masahito Yoshino, Takanori Nagasaki, Tsuneo Matsui

Proceeding of the International Symposium on EcoTopia Science 2007 頁： 145-147 2007年

Location of Deuterium Atoms in BaSn0.5In0.5O2.75+ at 77-473 K by Neutron Powder Diffraction 査読有り

Tsuyoshi Ito, Takanori Nagasaki, Kouta Iwasaki, Masahito Yoshino, Tsuneo Matsui, Hiroshi Fukazawa, Naoki Igawa, and Yoshinobu Ishii

Solid State Ionics 178 巻頁： 607-613 2007年

*Photoluminescence of Er-containing metal oxide in U-band 査読有り

Takaaki Ito, Masahito Yoshino, Kouta Iwasaki, Tsuneo Matsui, Takanori Nagasaki

Proceedings of International Symposium on EcoTopia Science 2007 頁： 128-130 2007年

*1.5 μm Luminescence and Electronic Structures in Er-containing Compounds

Yoshino, M

Bulletin of the Society for Discrete Variational Xalpha 19 巻頁： 31 2007年

Electrical conductivity and seebeck coefficient of Sr6Co5O14.3 single crystal 査読有り

Iwasaki, Kouta; Murase, Tamotsu; Ito, Tsuyoshi; Yoshino, Masahito; Matsui, Tsuneo; Nagasaki, Takanori; Arita, Yuji

Jpn. J. Appl. Phys. Part 1 - Regul. Pap. Brief Commun. Rev. Pap. 46 巻 ( 1 ) 頁： 256-260 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

Rod-like single crystals of Sr6Co5O14.3 Were grown by the flux method, and the electrical conductivity (sigma), Seebeck coefficient (S) and power factor (sigma S-2) were investigated in the temperature range of 300-900 K in air to explore the potential as thermoelectric materials. Sr6Co5O14.3 is an oxygen-nonstoichiometric phase of Sr6Co5O15, which is a member of the homologous (A(3)Co(2)O(6))(m)(A(3)Co(3)O(9))(n) [A = Ca, Sr, Ba] series including Ca3Co2O6 (m = 1, n = 0) and BaCoO3 (m = 0, n = 1) as the end members. The rod-like single crystals mainly grew along Co-O one-dimensional chains (c-axis) consisting of face-sharing CoO6 octahedra and CoO6 triangular prisms. The electrical conductivity along the Co-O chains showed semiconducting behavior (260-9600 S m(-1) in the temperature range of 300-900 K). The Seebeck coefficient was positive, and decreased with increasing temperature (280-140 mu V K-1). The power factor increased with increasing temperature (0.20 x 10(-4)-1.9 x 10(-4) W m(-1) K-2), which was about one order of magnitude larger than that of polycrystalline Sr6Co5O15.

Location of deuterium atoms in BaSn0.5In0.5O2.75+alpha by neutron powder diffraction at 10 K 査読有り

Ito, Tsuyoshi; Nagasaki, Takanori; Iwasaki, Kouta; Yoshino, Masahito; Matsui, Tsuneo; Igawa, Naoki; Ishii, Yoshinobu

Solid State Ion. 178 巻 ( 1-2 ) 頁： 13-17 2007年

記述言語：英語掲載種別：研究論文（学術雑誌）

This paper describes a neutron diffraction study that has located hydrogen atoms in a proton-conducting perovskite oxide more definitely than ever. The neutron diffraction data were collected on BaSn0.5In0.5O2.75 with and without dissolved D2O at 10 K. Data analysis by the Rietveld method and the maximum entropy method revealed that deuterium atoms were located at or very close to the 12h site of the cubic perovskite structure (space group Pm3m) with an O-D distance of 1.0 angstrom. This hydrogen position is similar to those suggested by the previous computational studies for proton-conducting perovskite oxides. (c) 2006 Elsevier B.V All rights reserved.

The determination of deuteron site in SrZr0.95Sc0.05O3-alpha by neutron powder diffraction 査読有り

Ito, Tsuyoshi; Nagasaki, Takanori; Iwasaki, Kouta; Yoshino, Masahito; Matsui, Tsuneo; Igawa, Naoki; Ishii, Yoshinobu

Solid State Ion. 177 巻 ( 26-32 ) 頁： 2353-2356 2006年

記述言語：英語

High-resolution, powder, neutron diffraction data have been collected on the protonic conductors SrZr0.95Sc0.05O3-alpha with and without dissolved heavy water at a temperature of 10K. Diffraction data have been analyzed by the Rietveld and maximum entropy methods (MEM). The crystal structure of these samples at 10K is successfully refined assuming a perovskite-type structure with the space group Pnma. The deuterons are located outside the ZrO6/ScO6 octahedra near oxygen atoms. (c) 2006 Elsevier B.V. All rights reserved.

Sr6Co5O15-δの熱電特性に及ぼす酸素量の影響査読有り

岩崎航太、伊藤剛、吉野正人、松井恒雄、長崎正雅、有田裕二

第3回日本熱電学会学術講演会論文集頁： 132-133 2006年

Local geometry and energetics of hydrogen in orthorhombic SrZrO3 査読有り

Liu, Y; Yoshino, M; Tatsumi, K; Tanaka, I; Morinaga, M; Adachi, H

Mater. Trans. 46 巻 ( 6 ) 頁： 1106-1111 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）

The local geometry around hydrogen and activation energies for hydrogen transfer in undoped, Y-and Al-doped SrZO(4), have been studied using the density functional theory under the generalized gradient approximation. It is shown that strong, O-H bond is formed and orientated towards the outside of the ZrO6 octahedron in SrZrO3. The hydrogen tends to approach the dopant ion in the doped oxides. It is found that large local distortion is induced around hydrogen and dopant ion, and affects the activation energy of hydrogen transfer largely. The calculated activation energies are in agreement with the experimental values in the doped oxides.

Water uptake and infrared absorption in SrZr0.95M0.05O3-alpha (M=Ga, Sc, Y and Nd) 査読有り

Ito, T; Nagasaki, T; Iwasaki, K; Yoshino, M; Matsui, T

J. Therm. Anal. Calorim. 81 巻 ( 3 ) 頁： 545-548 2005年

記述言語：英語

Proton concentration in SrZr0.95M0.05O3-alpha (M=Ga, Sc, Y and Nd) was measured with a thermobalance at different temperatures (T=673-973 K) and water vapor pressures (P-H2O=0.9-12.8 kPa). At all the pressures and temperatures examined, the amount of proton concentration in these samples is in the order of Sc>Y>Ga>Nd. By an equilibrium evaluation, we estimated the maximum possible proton concentration about 2.0 mol% in these samples. Infrared (IR) absorption spectra are measured in these samples. The absorption bands can be fitted by four (M=Ga, Y, Nd) or three (M=Sc) Gaussian bands.

Enhanced 1.54 mu m photoluminescence from Er-containing ZnO through nitrogen doping 査読有り

Zhou, Z; Komori, T; Yoshino, M; Morinaga, M; Matsunami, N; Koizumi, A; Takeda, Y

Appl. Phys. Lett. 86 巻 ( 4 ) 頁： 041107 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）

Nitrogen doping into an erbium (Er)-containing ZnO specimen through the N+ irradiation and the subsequent annealing in air was found to increase the photoluminescence (PL) intensity around 1.54 mum by about 40 times. The existence of nitrogen in the specimen was proved firmly by means of the N-14(d,alpha)C-12 nuclear reaction analysis. Further, the Ne+ irradiation was conducted instead of the N+ irradiation, but no effect was observed in the PL spectra. So, it was concluded that the substitution of N for O could modify the local structure around Er3+, resulting in the surprisingly large enhancement of the PL intensity. (C) 2005 American Institute of Physics.

First-principles study of protonic conduction in In-doped AZrO(3) (A=Ca, Sr, Ba) 査読有り

Shi, CS; Yoshino, M; Morinaga, M

Solid State Ionics 176 巻 ( 11-12 ) 頁： 1091-1096 2005年

記述言語：英語掲載種別：研究論文（学術雑誌）

The first-principles calculations based on the density functional theory were carried out to investigate the effects of A-cations on the protonic conductivity of AZrO(3) (A=Ca, Sr, Ba). The local geometries around proton and dopant ion, formation energies of interstitial proton and activation energies for proton transfer were simulated in the In-doped CaZrO3, SrZrO3 and BaZrO3. The results showed that the crystallographic feature of AZrO(3) (A=Ca, Sr, Ba) is an important factor to control the protonic conduction. In the In-doped CaZrO3 or SrZrO3 with the orthorhombic structure, there is a unique stabilized proton site located between two adjacent octahedra. But in the In-doped BaZrO3 with the cubic structure, there exists a certain region of stable sites between them. As the ionic radii of A-cations decrease, the crystal symmetry changes from cubic to orthorhombic, resulting in the rotation of ZrO6 (or InO6) octahedra, which causes the increase of activation energies for proton transfer in the oxides.

*Nature of the chemical bond in complex hydrides, NaAlH4, LiAlH4, LiBH4 and LiNH2 査読有り

Yoshino, M; Komiya, K; Takahashi, Y; Shinzato, Y; Yukawa, H; Morinaga, M

J. Alloy. Compd. 404 巻頁： 185-190 2005年

担当区分：筆頭著者記述言語：英語

The most stable crystal structures of complex hydrides, MXHn (NaAlH4, LiAlH4, LiBH4 and LiNH2) were simulated by the plane-wave pseudopotential method. The local chemical bonds between constituent ions were simulated using the DV-X alpha molecular orbital method. As a result, it was found that the covalent interaction is operating between X and H ions to form a XHn ion in MXHn. In addition, the ionic interaction is operating between M and XHn ions through the charge transfer from M to XHn ions. On the basis of this understanding of the nature of the chemical bond between ions, a phase stability diagram of complex hydrides was proposed using two parameters. One is the bond energy of XH diatomic molecules and the other is electronegativity difference, Delta Phi(X-M), between M and X ions. The calculated stability change by doping into NaAlH4 could by explained qualitatively following this diagram. This diagram will provide us a clue to the modification of hydrides to lower the hydrogen decomposition temperature.

エルビウムをドープしたペロブスカイト型酸化物の1.5μm帯の発光と電子状態

吉野正人、伊藤孝明、伊藤剛、岩崎航太、小泉淳、小森敏敬、鮎川達也、周震、豊島広朗、小笠原一禎、竹田美和、森永正彦、松井恒雄、長崎正雅

DV-Xa研究協会会報 18 巻 ( 1 ) 頁： 56-61 2005年

*Local electronic structure and protonic conductivity in perovskite-type oxide, SrZrO3 査読有り

Yoshino, M; Kato, K; Mutiara, E; Yukawa, H; Morinaga, M

Mater. Trans. 46 巻 ( 6 ) 頁： 1131-1139 2005年

担当区分：筆頭著者記述言語：英語掲載種別：研究論文（学術雑誌）

Local electronic states around hydrogen and acceptor ions in SrZrO3 are simulated by the DV-X alpha molecular orbital method to examine their effects on protonic conductivity. The calculated ioncities of the acceptor dopant ion, M. and the surrounding six oxygen ions, O-(i) (i = 1-6) are found to change largely with M in the doped oxide, where M's are Yb, Y, In, Al and Ga. There is a clear tendency that the protonic conductivity decreases as these ionocities around the dopant ion. M, deviate further from the ones around the Zr ion in un-doped oxide. Also, in a geometrical viewpoint, the bond order between M and O-(i) (i = 1-6) ions is another indication to control the protonic conductivity. The presence of the slightly weaker M-O-(i) bond than the Zr-O bond causes small expansion of the MO6 octahedron, and then gives a nearly symmetrical position for proton to move readily to the neighboring oxygen sites. These results are also found in the other oxides, BaZrO3 and CaZrO3. Both the ionicity and the bond order are indeed useful parameters for the design of perovskite-type oxides with high protonic conductivity.

Effects of nitrogen irradiation on photoluminescence around 1.54 mu m from Er-containing ZnO 査読有り

Zhou, Z; Komaki, T; Komori, T; Koizumi, A; Yoshino, M; Matsunami, N; Takeda, Y; Morinaga, M

Mater. Trans. 45 巻 ( 9 ) 頁： 2906-2908 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）

The Er-containing ZnO specimens were treated through the N+ irradiation and the subsequent annealing, and the effect was investigated on the photoluminescence (PL) spectra around 1.54 mum. When the specimens were annealed at 1273 K in air after the N+ irradiation, the PL spectra changed remarkably. The PL intensity increased by about 35 times after the N+ irradiation and the subsequent annealing, and there was the attendant shift in the wavelength of the strongest peak from 1.534 to 1.539 mum. Thus, the N+ irradiation and the subsequent annealing could modify the local structure around Er3+ ions in ZnO, resulting in the surprisingly large enhancement of the PL intensity.

錯体系水素化物(NaAlH4, LiAlH4, LiBH4, LiNH2)の化学結合

吉野正人、小宮健嗣、新里喜文、高橋義孝、湯川宏、森永正彦

DV-Xa研究協会会報 17 巻 ( 1 ) 頁： 78-83 2004年

Er2O3からの吸収スペクトルの計算

下出晃広、吉野正人、周震、豊島広朗、小笠原一禎、森永正彦

DV-Xa研究協会会報 17 巻 ( 2 ) 頁： 226-228 2004年

Effects of dopants and hydrogen on the electrical conductivity of ZnO 査読有り

Zhou, Z; Kato, K; Komaki, T; Yoshino, M; Yukawa, H; Morinaga, M; Morita, K

J. European Ceram. Soc. 24 巻 ( 1 ) 頁： 139-146 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）

The effects of dopants on the electrical conductivity of ZnO were investigated through the ac impedance spectroscopy. The doping of Al increased the electrical conductivity of ZnO greatly, whereas the doping of Li decreased it both in the grain and in the grain boundary. The doping of the 3d transition metals (Co, Mn, and Cu) made the grain boundary more resistive, but the doping effect on the electrical conductivity inside the grain was varied depending on the doping elements. The doping of Co had no significant effects on the electrical conductivity of the grain, and the doping of Mn made the grain a little more resistive. The doping of Cu made the grain much more resistive. In addition, hydrogen was introduced into ZnO by the ion implantation method. The electrical conductivity in the hydrogen-implanted ZnO layer increased by four orders of magnitude. The mechanisms for the doping effects were discussed in this investigation.

Effects of hydrogen doping through ion implantation on the electrical conductivity of ZnO 査読有り

Zhou, Z; Kato, K; Komaki, T; Yoshino, M; Yukawa, H; Morinaga, M

Int. J. Hydrog. Energy 29 巻 ( 3 ) 頁： 323-327 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）

Hydrogen ion implantation technique was applied to introduce hydrogen into ZnO. ZnO specimens with different electrical conductivity were prepared by the addition of some dopants. The elastic recoil detection analysis was used to measure the content of hydrogen in ZnO before and after the hydrogen ion implantation. The electrical conductivity of ZnO was increased greatly by the hydrogen ion implantation. The increase of the electrical conductivity varied with the dopants. The greatest increase was about 9 orders of magnitude in the highly resistive Cu-doped ZnO. The mechanism for such a hydrogen effect was discussed. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

First-principles Study of Protonic Conduction in Acceptor-doped SrZrO3 査読有り

Shi, CS; Yoshino, M; Morinaga, M

Journal of the Ceramics Society of Japan (Proceedings of the 5th International Meeting of Pacific Rim Ceramic Societies (PACRIM-5)) (Nagoya, October 2003) 112 巻 ( 4 ) 頁： S742-S746 2004年

Changes in Electrical Conductivity of ZnO with Hydrogen Implantation 査読有り

Zhou, Z; Kato, K; Komaki, T; Yoshino, M; Yukawa, H; Morinaga, M

Journal of the Ceramics Society of Japan (Proceedings of the 5th International Meeting of Pacific Rim Ceramic Societies (PACRIM-5)) (Nagoya, October 2003) 112 巻 ( 4 ) 頁： S668-S671 2004年

Energetics of native defects in Al2O3 and SiO2 査読有り

Yoshino, M; Shinzato, Y; Morinaga, M

Materials Science Forum 449-4 巻頁： 713-716 2004年

記述言語：英語

Formation energies of various defects in Al2O3 and SiO2 are calculated by using the plane-wave pseudopotential method. Also, the formation energies of Schottky defects and Frenkel defects are evaluated on the basis of these calculations. It is shown that formation energies of these defects are higher in SiO2 than in Al2O3. In other words, less defects are formed in SiO2 than in Al2O3. It is also found that the principal defect is the cation Frenkel defect in Al2O3 but the anion Frenkel defect in SiO2. These results agree with the experimental results that Al ions diffuse preferably in Al2O3 but oxygen ions diffuse in SiO2 at high temperatures.

Characteristics of electron density distributions in metal oxides 査読有り

Morinaga, M; Yoshino, M; Shimode, A; Okabayashi, K; Nakamatsu, F; Sekine, R

Materials Science Forum 449-4 巻頁： 77-80 2004年

記述言語：英語

The electron density distributions in a series of metal oxides are calculated using the DV-Xalpha molecular orbital method. It is found that the logarithm of the electron density, logrho(r), decreases with the distance, r, from the oxygen nucleus, while keeping a constant slope relevant to oxygen atom. The magnitude of the slope is about 15.75 for O-1s electrons, and about 6.61 for O-2s, 2p electrons being nearly close to the respective values of 16 and 8, expected from the radial distribution functions of hydrogen-like atom containing only one electron. The extent of the region for the O-2s, 2p electrons changes with metal species in the oxides, but the slope remains unchanged. Furthermore, it is shown that the nature of the chemical bonding is well represented in 109 (rho(min)Z(-3)) VS. 2(Z/n) r(min) in plots, where rho(min) is the minimum electron density, r(min) is the distance r at rho(min), Z is the atomic number, and n is the principal quantum number.

Modification of local electronic structures due to phase transition in perovskite-type oxides, SrBO3 (B=Zr, Ru, Hf) 査読有り

Yoshino, M; Yukawa, H; Morinaga, M

Mater. Trans. 45 巻 ( 7 ) 頁： 2056-2061 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）

The local electronic structures are simulated for a perovskite-type oxide with four polymorphous phases, SrZrO3, using the DV-Xalpha molecular orbital method. It is found that a series of phase transitions occurs at certain temperatures so as to retain not only the Zr-O bond strength, but also the Sr-O bond strength, by the tilting of ZrO6 octahedra and the attendant accommodation to the Zr-O and the Sr-O interionic distances. The occurrence of such smart phase transitions is observed in other perovskite-type oxides, SrRuO3 and SrHfO3. Another type of phase transition occurs by the cooperative ionic displacements along the [100] direction in BaTiO3. The differences in the local chemical bond are discussed between the two types of phase transitions.

Photoluminescence around 1.54 mu m from Er-containing ZnO at room temperature 査読有り

Zhou, Z; Komaki, T; Koizumi, A; Komori, T; Yoshino, M; Morinaga, M; Fujiwara, Y; Takeda, Y

Mater. Trans. 45 巻 ( 7 ) 頁： 2003-2007 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）

The photoluminescence (PL) around the wavelength of 1.54 mum from the Er-containing ZnO specimens was measured at room temperature by the indirect excitation of the He-Cd laser (325 nm). The PL intensity varied greatly with the Er concentration and the specimen preparation conditions as well. The specimens with the Er content of about 2.6 at%, sintered at 1623 K, and cooled quickly to room temperature in air showed the highest PL intensity at 1.534 mum. The local structure of the optically active Er centers in ZnO was also discussed, and the appropriate optically active center might be the Er ions existing in the grain boundaries.

A universal relation between electron density minima and ionic radii in ceramics 査読有り

Yoshino, M; Morinaga, M; Shimode, A; Okabayashi, K; Nakamatsu, H; Sekine, R

Mater. Trans. 45 巻 ( 7 ) 頁： 1968-1972 2004年

記述言語：英語掲載種別：研究論文（学術雑誌）

A universal relation between electron density minima and ionic radii, was discovered from the first principles calculations of electronic structures in ceramics over 60 species, including oxides, borides, carbides, nitride and fluorides. Every ceramic falls on a curve Of log(rho(min)Z(-3)) vs. 2(Z/n)r(min), where rho(min) is the minimum electron density in the line linking the first-nearest-neighbor nuclei, r(min) is the distance r at rho(min) is the atomic number, and n is the principal quantum number.

Electrical conductivity of Cu-doped ZnO and its change with hydrogen implantation 査読有り

Zhou, Z; Kato, K; Komaki, T; Yoshino, M; Yukawa, H; Morinaga, M; Morita, K

J. Electroceram. 11 巻 ( 1-2 ) 頁： 73-79 2003年

記述言語：英語掲載種別：研究論文（学術雑誌）

The doping effects of Cu on the electrical conductivity of ZnO were studied in the simple binary system through the ac impedance spectroscopy. The Cu doping decreased the electrical conductivity of ZnO by several orders of magnitude. The Cu doping decreased the electrical conductivity of ZnO both in the grain and in the grain boundary. Hydrogen was introduced into the Cu-doped ZnO specimens by the ion implantation technique. The electrical conductivity of the hydrogen-implanted layer increased by about 9 orders of magnitude at most. The mechanism for such a hydrogen effect was also discussed.

電子密度分布に見られるユニバーサルな関係

吉野正人、岡林功介、下出晃広、森永正彦、中松博英、関根理香

DV-Xa研究協会会報 16 巻 ( 1 ) 頁： 46-48 2003年

Local geometries and energetics of hydrogen in acceptor-doped SrZrO3 査読有り

Yoshino, M; Liu, Y; Tatsumi, K; Tanaka, I; Morinaga, M; Adachi, H

Solid State Ion. 162 巻頁： 127-133 2003年

記述言語：英語掲載種別：研究論文（学術雑誌）

The local geometry and chemical bonding around proton and acceptor dopant in perovskite-type oxide SrZrO3 have been investigated by the pseudopotential method and the DV-Xalpha molecular orbital method. Special attention is directed towards the MO6 octahedron in the perovskite-type structure, where Ms are acceptor dopants (e.g., Y and Al) substituted for Zr ions in the oxide. It is shown that local electronic state of the constituent ions in the MO6 octahedron is a good measure of the local geometrical change of the octahedron with doping. For example, there is a strong resemblance in the local ionic state and hence the local geometry of the octahedron between the undoped and Y-doped oxides. However, there is little resemblance between the undoped and Al-doped oxides. The calculated activation energy for protonic conduction is higher in the Al-doped oxide than that in the Y-doped oxide, in agreement with experimental results. From these results, it is found that such an acceptor dopant that does not change local electronic state or local geometry of the octahedron is a preferable element for enhancing protonic conductivity in perovskite-type oxides.

Energetics of hydrogen states in SrZrO3 査読有り

Yoshino, M; Liu, Y; Tatsumi, K; Tanaka, I; Morinaga, M; Adachi, H

Mater. Trans. 43 巻 ( 7 ) 頁： 1444-1450 2002年

記述言語：英語掲載種別：研究論文（学術雑誌）

The optimized geometries and formation energies of hydrogen in the perovskite-type oxide, SrZrO3, have been calculated using the density functional theory under the generalized gradient approximation (GGA). The stable hydrogen sites in the oxide are examined with special interests. It is shown that the hydrogen is tightly bound to an oxygen ion and located slightly outside the ZrO6 octahedron in SrZrO3. The O-H bond orientates towards the second-nearest-neighbor oxygen ion, which induces large local displacements of adjacent oxygen ions. For example, the nearest-neighbor oxygen ions tend to approach the hydrogen. The addition of an acceptor dopant, yttrium, modifies such local distortion of oxygen ions around the hydrogen as to increase protonic conductivity. In addition, the calculated hydrogen formation energy shows that the hydrogen behaves as a shallow donor in SrZrO3. The fundamental principles of doping and atmosphere control in proton conducting oxides are also given in view of energetics.

水素修飾されたペロブスカイト型酸化物の局在量子構造査読有り

吉野正人、劉軼、森永正彦

セラミックス 37 巻 ( 6 ) 頁： 457-462 2002年

化合物中の原子の周りの電子密度分布と化学結合

吉野正人、湯川宏、森永正彦

DV-Xa研究協会会報 15 巻 ( 1 ) 頁： 40-42 2002年

DV-Xα法による材料設計-水素と材料-

森永正彦、湯川宏、吉野正人

DV-Xa研究協会会報 15 巻 ( 1 ) 頁： 17-24 2002年

Local Electronic Structures and Chemical Bonding in Proton Conducting Perovskite-type Oxides 査読有り

Yoshino, M; Mutiara, E; Kato, K; Yukawa, H; Morinaga, M

Proceedings of Fourth Pacific Rim International Conference on Advanced Materials and Processing (PRICM4) 頁： 563-566 2001年

ペロブスカイト型酸化物SrZrO3中のアクセプタイオンの周りの局所電子状態とプロトン伝導性

吉野正人、加藤勝也、Etty Mutiara、湯川宏、森永正彦

DV-Xa研究協会会報 14 巻 ( 1 ) 頁： 70-73 2001年

Theoretical Study of Oxygen-vacancy Defects in Ferroelectric BaTiO3

14 巻 ( 1 ) 頁： 114-117 2001年

Local electronic structures around hydrogen and acceptor ions in perovskite-type oxide, SrZrO3 査読有り

Yoshino, M; Nakatsuka, K; Yukawa, H; Morinaga, M

Solid State Ion. 127 巻 ( 1-2 ) 頁： 109-123 2000年

記述言語：英語掲載種別：研究論文（学術雑誌）

Local electronic structures around hydrogen and acceptor ions in SrZrO3 are simulated by the DV-X alpha molecular orbital method. In pure SrZrO3, there is a band gap of about 6 eV between the O-2p valence band and the Zr-4d conduction band, in agreement with experiments. When Y or Sc is doped into SrZrO3, an acceptor level appears just above the valence band. When hydrogen is introduced into SrZrO3, a donor level appears below the conduction band. Also, an oxygen ion vacancy makes the defect level below the conduction band. It is shown that charge compensation takes place among these acceptor, donor and defect levels. In addition, local electronic structure around hydrogen is found to change largely with the acceptor dopants, Sc and Y. For example, the metal-oxygen bond strength changes in the order, Y-O < Zr-O < Sc-O, which probably modifies the thermal vibrational amplitude of oxygen ions near hydrogen, and affects protonic conductivity in the doped SrZrO3.

プロトン伝導性ペロブスカイト型酸化物BaZrO3の電子状態

吉野正人、加藤勝也、湯川宏、森永正彦

DV-Xa研究協会会報 13 巻 ( 1 ) 頁： 27-31 2000年

Roles of the hydride forming and non-forming elements in hydrogen storage alloys 査読有り

Nakatsuka, K; Yoshino, M; Yukawa, H; Morinaga, M

J. Alloy. Compd. 295 巻頁： 222-226 1999年

記述言語：英語掲載種別：研究論文（学術雑誌）

The electronic structures of small octahedral model clusters containing hydrogen, 3d, 4d, 5d transition and non-transition elements are investigated by the DV-X alpha molecular orbital method. It is found that hydrogen makes a strong chemical bond with the hydride non-forming elements, B, as long as the hydride forming elements, A, exist in the neighborhood. This is a reason why hydrogen is located preferentially near the hydride non-forming elements in many hydrides. Also it is suggested that the ratio of the A-B bond strength to the A-A bond strength lies in a certain range for conventional hydrogen storage A-B alloys. (C) 1999 Elsevier Science S.A. All rights reserved.

ペロブスカイト型酸化物SrRuO3の電子状態と構造相転移の機構

吉野正人、川口光晴、湯川宏、森永正彦

DV-Xa研究協会会報 12 巻 ( 1 ) 頁： 118-122 1999年

Modification of Electronic Structure Due to Phase Transition in Perovskite-type Oxide, SrZrO3 査読有り

Yoshino, M; Yukawa, H; Morinaga, M

Proceedings of an International Conference on Solid - Solid Phase Transformations (PTM'99) (Kyoto, May 1999) 頁： 645-648 1999年

Molecular Orbital Calculation of the Electronic Structures of Hydrogen in Perovskite-type Oxide, SrZrO3 査読有り

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