Updated on 2021/06/28

写真a

 
ASAHI Ryoji
 
Organization
Institutes of Innovation for Future Society Professor
Graduate School
Graduate School of Engineering
Title
Professor
Contact information
メールアドレス

Degree 1

  1. Ph.D. ( 1999.6   Northwestern University ) 

Research Interests 1

  1. ab-initio calculation, materials design, materials informatics

Research Areas 1

  1. Informatics / Computational science  / ab-initio calculation, materials design, materials informatics

Current Research Project and SDGs 1

  1. data-driven materials design

Research History 2

  1. Nagoya University   Institutes of Innovation for Future Society   Professor

    2021.1

  2. Toyota Central R&D Labs., Inc.

    1987.4 - 2020.12

Education 2

  1. Northwestern University   Department of Physics and Astronomy, Graduate School

    1995.9 - 1999.6

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    Notes: Ph.D.

  2. Kanazawa University

    1983.4 - 1987.3

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    Country: Japan

Professional Memberships 1

  1. 応用物理学会

Committee Memberships 8

  1.   産総研自己評価検証委員会材料・化学領域分科会専門委員  

    2021.3   

  2.   計算物質科学協議会運営委員  

    2020   

  3.   SACLA選定委員  

    2017.4 - 2021.3   

  4.   industry advisory board member of NCCR MARVEL  

    2017   

  5.   応用物理学会アドバイザリー会議メンバ  

    2016.4   

  6.   日本熱電学会 評議員  

    2013.4 - 2019.3   

  7.   三重大学極限ナノエレクトロニクスセンターリサーチアドバイザー  

    2010.4 - 2014.3   

  8.   日本熱電学会 理事  

    2004.4 - 2013.3   

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Awards 5

  1. 日本化学会化学技術賞

    2007  

  2. 日本熱電学会欧文論文賞

    2017  

  3. 中日産業技術賞

    2010  

  4. The American Ceramic Society Corporate Environmental Achievement Award

    2006   American Ceramic Society  

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    Country:United States

  5. 日本ファインセラミックス協会 技術振興賞

    2003  

 

Papers 197

  1. Transfer learning for materials informatics using crystal graph convolutional neural network

    Lee Joohwi, Asahi Ryoji

    COMPUTATIONAL MATERIALS SCIENCE   Vol. 190   2021.4

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    Publishing type:Research paper (other academic)   Publisher:Computational Materials Science  

    DOI: 10.1016/j.commatsci.2021.110314

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  2. Molecular dynamics simulations of lithium superionic conductor Li<inf>10</inf>GeP<inf>2</inf>S<inf>12</inf> using a machine learning potential

    Miwa K.

    Solid State Ionics   Vol. 361   2021.3

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    Publishing type:Research paper (other academic)   Publisher:Solid State Ionics  

    DOI: 10.1016/j.ssi.2021.115567

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  3. Characterization of AE(TM)(2)Bi2O9 (AE: Ca, Sr, Ba; TM: Nb, Ta) as oxide ion conductors

    Tajima Shin, Ohba Nobuko, Suzumura Akitoshi, Masuoka Yumi, Asahi Ryoji

    JOURNAL OF THE EUROPEAN CERAMIC SOCIETY   Vol. 41 ( 2 ) page: 1352 - 1359   2021.2

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    Publishing type:Research paper (other academic)   Publisher:Journal of the European Ceramic Society  

    DOI: 10.1016/j.jeurceramsoc.2020.10.028

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  4. Stationary interatomic force constant matrix method with ultrasoft pseudopotentials

    Miwa Kazutoshi, Asahi Ryoji

    PHYSICAL REVIEW B   Vol. 102 ( 17 )   2020.11

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B  

    DOI: 10.1103/PhysRevB.102.174313

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  5. On-the-Fly Active Learning of Interatomic Potentials for Large-Scale Atomistic Simulations

    Jinnouchi Ryosuke, Miwa Kazutoshi, Karsai Ferenc, Kresse Georg, Asahi Ryoji

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   Vol. 11 ( 17 ) page: 6946 - 6955   2020.9

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    Publishing type:Research paper (other academic)   Publisher:Journal of Physical Chemistry Letters  

    DOI: 10.1021/acs.jpclett.0c01061

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  6. Charge Trapping Process in Photoexcited Nitrogen-Doped Titanium Oxides

    Sato Kosuke, Yamanaka Ken-ichi, Nozawa Shunsuke, Fukuzawa Hironobu, Katayama Tetsuo, Morikawa Takeshi, Nonaka Takamasa, Dohmae Kazuhiko, Ueda Kiyoshi, Yabashi Makina, Asahi Ryoji

    INORGANIC CHEMISTRY   Vol. 59 ( 15 ) page: 10439 - 10449   2020.8

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    Publishing type:Research paper (other academic)   Publisher:Inorganic Chemistry  

    DOI: 10.1021/acs.inorgchem.0c00696

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  7. Descriptors representing two- and three-body atomic distributions and their effects on the accuracy of machine-learned inter-atomic potentials

    Jinnouchi Ryosuke, Karsai Ferenc, Verdi Carla, Asahi Ryoji, Kresse Georg

    JOURNAL OF CHEMICAL PHYSICS   Vol. 152 ( 23 ) page: 234102   2020.6

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    Publishing type:Research paper (other academic)   Publisher:Journal of Chemical Physics  

    DOI: 10.1063/5.0009491

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  8. Discovery of superionic conductors by ensemble-scope descriptor

    Kajita Seiji, Ohba Nobuko, Suzumura Akitoshi, Tajima Shin, Asahi Ryoji

    NPG ASIA MATERIALS   Vol. 12 ( 1 )   2020.4

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    Publishing type:Research paper (other academic)   Publisher:NPG Asia Materials  

    DOI: 10.1038/s41427-020-0211-1

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  9. Design Rules for High Oxygen-Ion Conductivity in Garnet-Type Oxides

    Lee Joohwi, Ohba Nobuko, Asahi Ryoji

    CHEMISTRY OF MATERIALS   Vol. 32 ( 4 ) page: 1358 - 1370   2020.2

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    Publishing type:Research paper (other academic)   Publisher:Chemistry of Materials  

    DOI: 10.1021/acs.chemmater.9b02044

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  10. Identifying superionic conductors by materials informatics and high-throughput synthesis

    Matsubara Masato, Suzumura Akitoshi, Ohba Nobuko, Asahi Ryoji

    COMMUNICATIONS MATERIALS   Vol. 1 ( 1 )   2020.2

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    Publishing type:Research paper (other academic)  

    DOI: 10.1038/s43246-019-0004-7

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  11. SC-CoMIcs: A superconductivity corpus for materials informatics

    Yamaguchi K.

    LREC 2020 - 12th International Conference on Language Resources and Evaluation, Conference Proceedings     page: 6753 - 6760   2020

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    Publishing type:Research paper (other academic)   Publisher:LREC 2020 - 12th International Conference on Language Resources and Evaluation, Conference Proceedings  

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  12. Highly efficient evaluation of diffusion networks in Li ionic conductors using a 3D-corrugation descriptor

    France-Lanord Arthur, Asahi Ryoji, Leblanc Benoit, Lee Joohwi, Wimmer Erich

    SCIENTIFIC REPORTS   Vol. 9 ( 1 ) page: 15123   2019.10

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    Publishing type:Research paper (other academic)   Publisher:Scientific Reports  

    DOI: 10.1038/s41598-019-51585-z

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  13. y Path integral study on C15-type Laves TiCr2 hydride

    Miwa Kazutoshi, Asahi Ryoji

    INTERNATIONAL JOURNAL OF HYDROGEN ENERGY   Vol. 44 ( 42 ) page: 23708 - 23715   2019.9

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    Publishing type:Research paper (other academic)   Publisher:International Journal of Hydrogen Energy  

    DOI: 10.1016/j.ijhydene.2019.07.086

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  14. Phosphorescent Material Search Using a Combination of High-Throughput Evaluation and Machine Learning

    Hazama Hirofumi, Sobue Susumu, Tajima Shin, Asahi Ryoji

    INORGANIC CHEMISTRY   Vol. 58 ( 16 ) page: 10936 - 10943   2019.8

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    Publishing type:Research paper (other academic)   Publisher:Inorganic Chemistry  

    DOI: 10.1021/acs.inorgchem.9b01370

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  15. Development of a High-Throughput Screening Method for Oxide-Ion Conductors and Its Application to Bismuth-Based Oxide Library Thin Films

    Matsubara Masato, Suzumura Akitoshi, Tajima Shin, Asahi Ryoji

    ACS COMBINATORIAL SCIENCE   Vol. 21 ( 5 ) page: 400 - 407   2019.5

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    Publishing type:Research paper (other academic)   Publisher:ACS Combinatorial Science  

    DOI: 10.1021/acscombsci.8b00193

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  16. Water Facilitated Electrochemical Reduction of CO2 on Cobalt-Porphyrin Catalysts

    Miyamoto Kaito, Asahi Ryoji

    JOURNAL OF PHYSICAL CHEMISTRY C   Vol. 123 ( 15 ) page: 9944 - 9948   2019.4

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    Publishing type:Research paper (other academic)   Publisher:Journal of Physical Chemistry C  

    DOI: 10.1021/acs.jpcc.9b01195

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  17. Hybrid Quantum-Classical Simulation of Li Ion Dynamics and the Decomposition Reaction of Electrolyte Liquid at a Negative-Electrode/Electrolyte Interface

    Ohba Nobuko, Ogata Shuji, Asahi Ryoji

    JOURNAL OF PHYSICAL CHEMISTRY C   Vol. 123 ( 15 ) page: 9673 - 9679   2019.4

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    Publishing type:Research paper (other academic)   Publisher:Journal of Physical Chemistry C  

    DOI: 10.1021/acs.jpcc.8b11737

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  18. Collaborative effects of Zn and Sb Co-doping in magnesium silicide for thermoelectric applications

    Masuoka Yumi, Mito Youhiko, Ogino Atsushi, Nakamura Takashi, Amano Kumi, Asahi Ryoji

    JOURNAL OF ALLOYS AND COMPOUNDS   Vol. 781   page: 606 - 612   2019.4

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    Publishing type:Research paper (other academic)   Publisher:Journal of Alloys and Compounds  

    DOI: 10.1016/j.jallcom.2018.12.103

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  19. First-principles prediction of high oxygen-ion conductivity in trilanthanide gallates Ln(3)GaO(6)

    Lee Joohwi, Ohba Nobuko, Asahi Ryoji

    SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS   Vol. 20 ( 1 ) page: 144 - 159   2019.3

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    Publishing type:Research paper (other academic)   Publisher:Science and Technology of Advanced Materials  

    DOI: 10.1080/14686996.2019.1578183

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  20. Correlation between thermal-vibration-induced large displacement of Cu atoms and phase transition in Cu4SnS4: First-principles investigation

    Nagasako Naoyuki, Suzumura Akitoshi, Asahi Ryoji

    ACTA MATERIALIA   Vol. 166   page: 37 - 46   2019.3

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    Publishing type:Research paper (other academic)   Publisher:Acta Materialia  

    DOI: 10.1016/j.actamat.2018.11.058

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  21. Oxygen conduction mechanism in Ca3Fe2Ge3O12 garnet-type oxide

    Lee Joohwi, Ohba Nobuko, Asahi Ryoji

    SCIENTIFIC REPORTS   Vol. 9 ( 1 ) page: 2593   2019.2

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    Publishing type:Research paper (other academic)   Publisher:Scientific Reports  

    DOI: 10.1038/s41598-019-39288-x

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  22. Effects of doping IIIB elements (Al, Ga, In) on thermoelectric properties of nanostructured n-type filled skutterudite compounds

    Matsubara M., Masuoka Y., Asahi R.

    JOURNAL OF ALLOYS AND COMPOUNDS   Vol. 774   page: 731 - 738   2019.2

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    Publishing type:Research paper (other academic)   Publisher:Journal of Alloys and Compounds  

    DOI: 10.1016/j.jallcom.2018.10.003

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  23. Solar Thermal Cogeneration System Using a Cylindrical Thermoelectric Module

    Suzumura Akitoshi, Hazama Hirofumi, Matsubara Masato, Asahi Ryoji

    JOURNAL OF ELECTRONIC MATERIALS   Vol. 48 ( 1 ) page: 467 - 474   2019.1

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    Publishing type:Research paper (other academic)   Publisher:Journal of Electronic Materials  

    DOI: 10.1007/s11664-018-6725-4

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  24. Molecular dynamics simulations with machine learning potential for Nb-doped lithium garnet-type oxide Li7-xLa3(Zr2-xNbx)O-12

    Miwa Kazutoshi, Asahi Ryoji

    PHYSICAL REVIEW MATERIALS   Vol. 2 ( 10 )   2018.10

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    Publishing type:Research paper (other academic)   Publisher:Physical Review Materials  

    DOI: 10.1103/PhysRevMaterials.2.105404

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  25. Charge transfer dynamics at the boron subphthalocyanine chloride/C-60 interface: non-adiabatic dynamics study with Libra-X

    Sato Kosuke, Pradhan Ekadashi, Asahi Ryoji, Akimov Alexey V.

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   Vol. 20 ( 39 ) page: 25275 - 25294   2018.10

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    Publishing type:Research paper (other academic)   Publisher:Physical Chemistry Chemical Physics  

    DOI: 10.1039/c8cp03841d

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  26. Cylindrical thermoelectric generator with water heating system for high solar energy conversion efficiency

    Hazama Hirofumi, Masuoka Yumi, Suzumura Akitoshi, Matsubara Masato, Tajima Shin, Asahi Ryoji

    APPLIED ENERGY   Vol. 226   page: 381 - 388   2018.9

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    Publishing type:Research paper (other academic)   Publisher:Applied Energy  

    DOI: 10.1016/j.apenergy.2018.06.015

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  27. Phase-field modeling of stress generation in polycrystalline LiCoO2

    Yamakawa Shunsuke, Nagasako Naoyuki, Yarnasaki Hisatsugu, Koyama Toshiyuki, Asahi Ryoji

    SOLID STATE IONICS   Vol. 319   page: 209 - 217   2018.6

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    Publishing type:Research paper (other academic)   Publisher:Solid State Ionics  

    DOI: 10.1016/j.ssi.2018.02.013

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  28. Band bending and dipole effect at interface of metal-nanoparticles and TiO2 directly observed by angular-resolved hard X-ray photoemission spectroscopy

    Sato Shunsuke, Kataoka Keita, Jinnouchi Ryosuke, Takahashi Naoko, Sekizawa Keita, Kitazumi Kousuke, Ikenaga Eiji, Asahi Ryoji, Morikawa Takeshi

    PHYSICAL CHEMISTRY CHEMICAL PHYSICS   Vol. 20 ( 16 ) page: 11342 - 11346   2018.4

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    Publishing type:Research paper (other academic)   Publisher:Physical Chemistry Chemical Physics  

    DOI: 10.1039/c8cp00551f

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  29. Effects of Ta2O5 Surface Modification by NH3 on the Electronic Structure of a Ru-Complex/N Ta2O5 Hybrid Photocatalyst for Selective CO2 Reduction

    Shirai Soichi, Sato Shunsuke, Suzuki Tomiko M., Jinnouchi Ryosuke, Ohba Nobuko, Asahi Ryoji, Morikawa Takeshi

    JOURNAL OF PHYSICAL CHEMISTRY C   Vol. 122 ( 4 ) page: 1921 - 1929   2018.2

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    Publishing type:Research paper (other academic)   Publisher:Journal of Physical Chemistry C  

    DOI: 10.1021/acs.jpcc.7b09670

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  30. Discovery of zirconium dioxides for the design of better oxygen-ion conductors using efficient algorithms beyond data mining

    Lee Joohwi, Ohba Nobuko, Asahi Ryoji

    RSC ADVANCES   Vol. 8 ( 45 ) page: 25534 - 25545   2018

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    Publishing type:Research paper (other academic)   Publisher:RSC Advances  

    DOI: 10.1039/c8ra02958j

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  31. A universal 3D voxel descriptor for solid-state materials informatics with convolutional neural networks

    KAJITA Seiji, OHBA Nobuko, ASAHI Ryoji

    Proceedings of the Annual Conference of JSAI   Vol. 2018 ( 0 ) page: 3Z102 - 3Z102   2018

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    Publishing type:Research paper (other academic)   Publisher:The Japanese Society for Artificial Intelligence  

    <p>Materials informatics (MI) is a promising approach to liberate us from the time-consuming trial and error process for material discoveries. Contrary to molecular systems, however, practical successes of the solid-state MI are very scarce because existing descriptors insufficiently describe 3D features of eld quantities (e.g., electron distributions and local potentials). We develop a simple, generic 3D voxel descriptor that compacts any field quantities, in such a suitable way to implement convolutional neural networks. We examine the reciprocal-lattice 3D voxel space descriptor encoded from the electron distribution by a regression task with 680 oxides data. The present scheme outperforms other descriptors in the prediction of Hartree energies that are signicantly relevant to the long-wavelength distribution of the valence electrons.</p>

    DOI: 10.11517/pjsai.JSAI2018.0_3Z102

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  32. Visualization of SEM/EBSD Features of Ionic Conductivity with Convolutional Neural Networks

    KONDO Ruho, YAMAKAWA Shunsuke, MASUOKA Yumi, TAJIMA Shin, ASAHI Ryoji

    Proceedings of the Annual Conference of JSAI   Vol. 2018 ( 0 ) page: 3Z103 - 3Z103   2018

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    Publishing type:Research paper (other academic)   Publisher:The Japanese Society for Artificial Intelligence  

    <p>To automatically extract the features required to predict the material properties from microstructure, we utilized convolutional newral networks (CNNs). Training of CNNs was carried out by using experimentally obtained scanning electron microscope images and ionic conductivities. After training, the nodes, which placed after global average pooling (GAP), specically activated by passing through the images with high/low ionic conductivities were searched. Then, the corresponding feature maps just before GAP operations were shown. We found that the CNNs focused on the reagion containing large voids and on the area without any crystal defects for the specic features for the material with high ionic conductivities while on the small voids for low ionic conductivities. Such observations agree with knowledge of materials engineering.</p>

    DOI: 10.11517/pjsai.JSAI2018.0_3Z103

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  33. Linear independent non-negative matrix factorization for automatic decomposition of experimental spectra

    KIKKAWA Nobuaki, SUZUMURA Akitoshi, TAJIMA Shin, YAMAKAWA Shunsuke, ASAHI Ryoji

    Proceedings of the Annual Conference of JSAI   Vol. 2018 ( 0 ) page: 3Z101 - 3Z101   2018

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    Publishing type:Research paper (other academic)   Publisher:The Japanese Society for Artificial Intelligence  

    DOI: 10.11517/pjsai.JSAI2018.0_3Z101

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  34. A Universal 3D Voxel Descriptor for Solid-State Material Informatics with Deep Convolutional Neural Networks

    Kajita Seiji, Ohba Nobuko, Jinnouchi Ryosuke, Asahi Ryoji

    SCIENTIFIC REPORTS   Vol. 7 ( 1 ) page: 16991   2017.12

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    Publishing type:Research paper (other academic)   Publisher:Scientific Reports  

    DOI: 10.1038/s41598-017-17299-w

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  35. Improvement of power factor of n-type Bi2Te3 by dispersed nanosized Ga2Te3 precipitates

    Hazama Hirofumi, Masuoka Yumi, Yamamoto Hidenari, Suto Hiroyuki, Kinoshita Yohei, Ishikiriyama Mamoru, Asahi Ryoji

    JOURNAL OF ALLOYS AND COMPOUNDS   Vol. 726   page: 578 - 586   2017.12

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    Publishing type:Research paper (other academic)   Publisher:Journal of Alloys and Compounds  

    DOI: 10.1016/j.jallcom.2017.07.272

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  36. Microstructure recognition using convolutional neural networks for prediction of ionic conductivity in ceramics

    Kondo Ruho, Yamakawa Shunsuke, Masuoka Yumi, Tajima Shin, Asahi Ryoji

    ACTA MATERIALIA   Vol. 141   page: 29 - 38   2017.12

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    Publishing type:Research paper (other academic)   Publisher:Acta Materialia  

    DOI: 10.1016/j.actamat.2017.09.004

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  37. Extrapolating Energetics on Clusters and Single-Crystal Surfaces to Nanoparticles by Machine-Learning Scheme

    Jinnouchi Ryosuke, Hirata Hirohito, Asahi Ryoji

    JOURNAL OF PHYSICAL CHEMISTRY C   Vol. 121 ( 47 ) page: 26397 - 26405   2017.11

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    Publishing type:Research paper (other academic)   Publisher:Journal of Physical Chemistry C  

    DOI: 10.1021/acs.jpcc.7b08686

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  38. Study of the conformation of polyelectrolyte aggregates using coarse-grained molecular dynamics simulations

    Mima Toshiki, Kinjo Tomoyuki, Yamakawa Shunsuke, Asahi Ryoji

    SOFT MATTER   Vol. 13 ( 35 ) page: 5991 - 5999   2017.9

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    Publishing type:Research paper (other academic)   Publisher:Soft Matter  

    DOI: 10.1039/c7sm01196b

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  39. Predicting Catalytic Activity of Nanoparticles by a DFT-Aided Machine-Learning Algorithm

    Jinnouchi Ryosuke, Asahi Ryoji

    JOURNAL OF PHYSICAL CHEMISTRY LETTERS   Vol. 8 ( 17 ) page: 4279 - 4283   2017.9

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    Publishing type:Research paper (other academic)   Publisher:Journal of Physical Chemistry Letters  

    DOI: 10.1021/acs.jpclett.7b02010

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  40. Measurement and ab initio calculation of the structural parameters and physical properties of 3d transition intermetallics TiMP (M = Cr, Mn, Fe, Co, or Ni)

    Suzuki Nobuaki, Asahi Ryoji, Kishida Yoshihiro, Masuoka Yumi, Sugiyama Jun

    MATERIALS RESEARCH EXPRESS   Vol. 4 ( 4 )   2017.4

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    Publishing type:Research paper (other academic)   Publisher:Materials Research Express  

    DOI: 10.1088/2053-1591/aa6ac4

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  41. Prediction of Ionic Conductivity from Ceramics Microstructure via Convolutional Neural Networks

    Kondo Ruho, Yamakawa Shunsuke, Masuoka Yumi, Tajima Shin, Asahi Ryoji

    The Proceedings of The Computational Mechanics Conference   Vol. 2017 ( 0 )   2017

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    Publishing type:Research paper (other academic)   Publisher:The Japan Society of Mechanical Engineers  

    DOI: 10.1299/jsmecmd.2017.30.023

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  42. What makes the photocatalytic CO2 reduction on n-doped Ta2O5 efficient: insights from nonadiabatic molecular dynamics

    Akimov Alexey, Jinnouchi Ryosuke, Asahi Ryoji, Prezhdo Oleg

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   Vol. 251   2016.3

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  43. Optimization of Filler Elements in CoSb3-Based Skutterudites for High-Performance n-Type Thermoelectric Materials

    Matsubara M., Asahi R.

    JOURNAL OF ELECTRONIC MATERIALS   Vol. 45 ( 3 ) page: 1669 - 1678   2016.3

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    Publishing type:Research paper (other academic)   Publisher:Journal of Electronic Materials  

    DOI: 10.1007/s11664-015-4155-0

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  44. Microscopic study of gum-metal alloys: A role of trace oxygen for dislocation-free deformation

    Nagasako Naoyuki, Asahi Ryoji, Isheim Dieter, Seidman David N., Kuramoto Shigeru, Furuta Tadahiko

    ACTA MATERIALIA   Vol. 105   page: 347 - 354   2016.2

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    Publishing type:Research paper (other academic)   Publisher:Acta Materialia  

    DOI: 10.1016/j.actamat.2015.12.011

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  45. Transport properties of the Cu2ZnSnS4 bulk systems: Effects of nonstoichiometry and defect formation

    Hazama Hirofumi, Tajima Shin, Masuoka Yumi, Asahi Ryoji

    JOURNAL OF ALLOYS AND COMPOUNDS   Vol. 657   page: 179 - 183   2016.2

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    Publishing type:Research paper (other academic)   Publisher:Journal of Alloys and Compounds  

    DOI: 10.1016/j.jallcom.2015.10.032

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  46. 22aPS-59 Structural and physical properties of 3d transition metal phosphides TiMP (M = Cr, Mn, Fe, Co, Ni)

    Suzuki N., Asahi R., Kishida Y., Masuoka Y., Sugiyama J.

    Meeting Abstracts of the Physical Society of Japan   Vol. 71 ( 0 )   2016

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    Publishing type:Research paper (other academic)   Publisher:The Physical Society of Japan  

    DOI: 10.11316/jpsgaiyo.71.1.0_2448

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  47. Upward Shift in Conduction Band of Ta2O5 Due to Surface Dipoles Induced by N-Doping

    Jinnouchi Ryosuke, Akimov Alexey V., Shirai Soichi, Asahi Ryoji, Prezhdo Oleg V.

    JOURNAL OF PHYSICAL CHEMISTRY C   Vol. 119 ( 48 ) page: 26925 - 26936   2015.12

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    Publishing type:Research paper (other academic)   Publisher:Journal of Physical Chemistry C  

    DOI: 10.1021/acs.jpcc.5b06932

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  48. Sodium distribution in solar-grade Cu2ZnSnS4 layers using atom-probe tomographic technique

    Tajima Shin, Asahi Ryoji, Isheim Dieter, Seidman David N., Itoh Tadayoshi, Ohishi Kei-ichiro

    JAPANESE JOURNAL OF APPLIED PHYSICS   Vol. 54 ( 11 )   2015.11

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    Publishing type:Research paper (other academic)   Publisher:Japanese Journal of Applied Physics  

    DOI: 10.7567/JJAP.54.112302

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  49. Thermal diffusion of correlated Li-ions in graphite: A hybrid quantum-classical simulation study

    Ohba Nobuko, Ogata Shuji, Kouno Takahisa, Asahi Ryoji

    COMPUTATIONAL MATERIALS SCIENCE   Vol. 108   page: 250 - 257   2015.10

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    Publishing type:Research paper (other academic)   Publisher:Computational Materials Science  

    DOI: 10.1016/j.commatsci.2015.06.018

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  50. What Makes the Photocatalytic CO2 Reduction on N-Doped Ta2O5 Efficient: Insights from Nonadiabatic Molecular Dynamics

    Akimov Alexey V., Asahi Ryoji, Jinnouchi Ryosuke, Prezhdo Oleg V.

    JOURNAL OF THE AMERICAN CHEMICAL SOCIETY   Vol. 137 ( 35 ) page: 11517 - 11525   2015.9

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    DOI: 10.1021/jacs.5b07454

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  51. Improvement of the open-circuit voltage of Cu2ZnSnS4 solar cells using a two-layer structure

    Tajima Shin, Itoh Tadayoshi, Hazama Hirofumi, Ohishi Keiichiro, Asahi Ryoji

    APPLIED PHYSICS EXPRESS   Vol. 8 ( 8 )   2015.8

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    DOI: 10.7567/APEX.8.082302

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  52. Theoretical Insights into the Impact of Ru Catalyst Anchors on the Efficiency of Photocatalytic CO2 Reduction on Ta2O5

    Akimov Alexey V., Jinnouchi R., Shirai S., Asahi R., Prezhdo Oleg V.

    JOURNAL OF PHYSICAL CHEMISTRY B   Vol. 119 ( 24 ) page: 7186 - 7197   2015.6

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    DOI: 10.1021/jp5080658

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  53. Highly luminescent flexible amino-functionalized graphene quantum dots@cellulose nanofiber-clay hybrids for white-light emitting diodes

    Tetsuka H., Nagoya A., Asahi R.

    JOURNAL OF MATERIALS CHEMISTRY C   Vol. 3 ( 15 ) page: 3536 - 3541   2015

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    DOI: 10.1039/c5tc00250h

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  54. Presence of a Doubly-Splitting Site and Its Effect on Thermoelectric Properties of Cu4SnS4

    Suzumura Akitoshi, Nagasako Naoyuki, Kinoshita Youhei, Watanabe Masaki, Kita Takuji, Asahi Ryoji

    MATERIALS TRANSACTIONS   Vol. 56 ( 6 ) page: 858 - 863   2015

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    Thermoelectric properties of Cu<sub>4</sub>SnS<sub>4</sub> significantly change around 230 K along with a phase transition between a high temperature phase (HT-phase) and a low temperature phase (LT-phase). Here we particularly focus on a very low thermal conductivity of Cu<sub>4</sub>SnS<sub>4</sub>, which is even lower in HT-phase. The crystal structures of Cu<sub>4</sub>SnS<sub>4</sub> are analyzed using synchrotron radiation. HT-phase is determined to be orthorhombic structure with the space group <i>Pnma</i>, as previously reported; however, the results of Rietveld refinement of HT-phase suggest that there are some Cu sites around saddle points of the double well potential. Phonon dispersion calculated by first-principles calculations indeed exhibits soft phonon modes of the Cu sites, consistent with the Rietveld analysis. The detailed analysis leads to a conclusion that the lower thermal conductivity in HT-phase results from an additional phonon scattering resonated with an anharmonic Cu vibration in the double well potential.

    DOI: 10.2320/matertrans.E-M2015804

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  55. 059 Phase-field modeling of stress generation in a delithiated positive electrode

    Yamakawa Shunsuke, Nagasako Naoyuki, Yamasaki Hisatsugu, Asahi Ryoji, Koyama Toshiyuki

    The Proceedings of The Computational Mechanics Conference   Vol. 2015 ( 0 ) page: _059 - 1_-_059-2_   2015

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    DOI: 10.1299/jsmecmd.2015.28._059-1_

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  56. Improvement of the open-circuit voltage of Cu<inf>2</inf>ZnSnS<inf>4</inf> cells using a two-layered process

    Tajima S.

    2014 IEEE 40th Photovoltaic Specialist Conference, PVSC 2014     page: 431 - 434   2014.10

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    DOI: 10.1109/PVSC.2014.6924951

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  57. Nitrogen-Doped Titanium Dioxide as Visible-Light-Sensitive Photocatalyst: Designs, Developments, and Prospects

    Asahi Ryoji, Morikawa Takeshi, Irie Hiroshi, Ohwaki Takeshi

    CHEMICAL REVIEWS   Vol. 114 ( 19 ) page: 9824 - 9852   2014.10

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    DOI: 10.1021/cr5000738

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  58. Thermal expansion, diffusion and melting of Li2O using a compact forcefield derived from ab initio molecular dynamics

    Asahi Ryoji, Freeman Clive M., Saxe Paul, Wimmer Erich

    MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING   Vol. 22 ( 7 )   2014.10

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    Publishing type:Research paper (other academic)   Publisher:Modelling and Simulation in Materials Science and Engineering  

    DOI: 10.1088/0965-0393/22/7/075009

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  59. Atom-probe tomographic study of interfaces of Cu2ZnSnS4 photovoltaic cells

    Tajima S., Asahi R., Isheim D., Seidman D. N., Itoh T., Hasegawa M., Ohishi K.

    APPLIED PHYSICS LETTERS   Vol. 105 ( 9 )   2014.9

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    DOI: 10.1063/1.4894858

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  60. Effect of microstructure on discharge properties of polycrystalline LiCoO2

    Yamakawa Shunsuke, Yamasaki Hisatsugu, Koyama Toshiyuki, Asahi Ryoji

    SOLID STATE IONICS   Vol. 262   page: 56 - 60   2014.9

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    DOI: 10.1016/j.ssi.2013.10.011

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  61. Improvement in Thermoelectric Properties of Se-Free Cu3SbS4 Compound

    Suzumura Akitoshi, Watanabe Masaki, Nagasako Naoyuki, Asahi Ryoji

    JOURNAL OF ELECTRONIC MATERIALS   Vol. 43 ( 6 ) page: 2356 - 2361   2014.6

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    DOI: 10.1007/s11664-014-3064-y

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  62. Surface segregations in platinum-based alloy nanoparticles

    Yamakawa Shunsuke, Asahi Ryoji, Koyama Toshiyuki

    SURFACE SCIENCE   Vol. 622   page: 65 - 70   2014.4

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    DOI: 10.1016/j.susc.2013.12.008

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  63. A metathesis reaction route to obtain fine Mg2Si particles

    Itahara H., Yamada T., Oh S. -Y., Asahi R., Imagawa H., Yamane H.

    CHEMICAL COMMUNICATIONS   Vol. 50 ( 33 ) page: 4315 - 4318   2014

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    Publishing type:Research paper (other academic)   Publisher:Chemical Communications  

    DOI: 10.1039/c4cc01330a

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  64. Improvement of the open-circuit voltage of CU2ZnSnS4 cells using a two-layered process

    Tajima Shin, Itoh Tadayoshi, Hazama Hirofumi, Ohishi Keiichiro, Asahi Ryoji

    2014 IEEE 40TH PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC)     page: 431 - 434   2014

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  65. 27aAL-4 A hybrid quantum-classical simulation study on the negative electrode/electrolyte interface of Li-ion battery

    Ohba Nobuko, Ogata Shuji, Kouno Takahisa, Kobayashi Ryo, Tamura Tomoyuki, Asahi Ryoji

    Meeting Abstracts of the Physical Society of Japan   Vol. 69 ( 0 )   2014

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    DOI: 10.11316/jpsgaiyo.69.1.4.0_911_2

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  66. 8pAE-8 A hybrid quantum-classical simulation study of migration of Li-ions and charge transfer at the negative electrode/electrolyte interface of Li-ion battery

    Ohba Nobuko, Ogata Shuji, Kouno Takahisa, Kobayashi Ryo, Tamura Tomoyuki, Asahi Ryoji

    Meeting Abstracts of the Physical Society of Japan   Vol. 69 ( 0 )   2014

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    DOI: 10.11316/jpsgaiyo.69.2.4.0_695_3

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  67. Effects of viscosity, surface tension, and evaporation rate of solvent on dry colloidal structures: A lattice Boltzmann study

    Munekata Toshihisa, Suzuki Takahisa, Yamakawa Shunsuke, Asahi Ryoji

    PHYSICAL REVIEW E   Vol. 88 ( 5 ) page: 052314   2013.11

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    DOI: 10.1103/PhysRevE.88.052314

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  68. Design and development of photocatalytic and photovoltaic materials

    Asahi Ryoji

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   Vol. 246   2013.9

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  69. Phase-Field Modeling of Phase Transformations in Platinum-Based Alloy Nanoparticles

    Yamakawa Shunsuke, Asahi Ryoji, Koyama Toshiyuki

    MATERIALS TRANSACTIONS   Vol. 54 ( 8 ) page: 1242 - 1249   2013.8

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    A phase-field model that describes the phase decomposition and phase transformations inside platinum-based alloy nanoparticles is developed to elucidate the effects of particle size, alloy composition, and heat-treatment temperature on the microstructure formation. FePt, CoPt, NiPt, CuPt and IrPt binary alloy nanoparticles with diameters of less than 10 nm are investigated. The calculation results clearly show that surface segregation and atomic ordering are sensitive to the alloy components and particle size, and that the equilibrium nanostructure obtained varies according to the balance between the surface energy and chemical interaction between atomic components. Platinum-based alloy nanoparticles are expected to find applications as electrocatalysts in polymer electrolyte fuel cells. Thus, the proposed phase-field approach demonstrates its usefulness for the control of the radial distributions of each alloying component within a nanoparticle, leading to improvements in the activity and durability of the catalyst and reducing the required amount of platinum loading.

    DOI: 10.2320/matertrans.ME201304

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  70. Numerical study of Li diffusion in polycrystalline LiCoO2

    Yamakawa Shunsuke, Yamasaki Hisatsugu, Koyama Toshiyuki, Asahi Ryoji

    JOURNAL OF POWER SOURCES   Vol. 223   page: 199 - 205   2013.2

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    DOI: 10.1016/j.jpowsour.2012.09.055

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  71. 1611 Effect of Microstructure on Li Diffusivity of Polycrystalline LiCoC_2

    Yamakawa Shunsuke, Yamasaki Hisatsugu, Ide Kazuto, Asahi Ryoji, Koyama Toshiyuki

    The Proceedings of The Computational Mechanics Conference   Vol. 2013 ( 0 ) page: _1611 - 1_-_1611-2_   2013

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    DOI: 10.1299/jsmecmd.2013.26._1611-1_

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  72. 28pXZB-8 A hybrid quantum-classical simulation study on the diffusion of multiple Li's in graphite

    Ohba Nobuko, Ogata Shuji, Kouno Takahisa, Kobayashi Ryo, Tamura Tomoyuki, Asahi Ryoji

    Meeting Abstracts of the Physical Society of Japan   Vol. 68 ( 0 )   2013

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    DOI: 10.11316/jpsgaiyo.68.1.4.0_1046_2

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  73. A hybrid quantum-classical simulation study on the interaction effects between Li-ions for those diffusion in graphite

    Ohba Nobuko, Ogata Shuji, Kouno Takahisa, Kobayashi Ryo, Tamura Tomoyuki, Asahi Ryoji

    Meeting Abstracts of the Physical Society of Japan   Vol. 68 ( 0 )   2013

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    DOI: 10.11316/jpsgaiyo.68.2.4.0_838_3

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  74. 2415 A hybrid quantum-classical simulation study on the interaction effects between Li-ions for those diffusion in graphite

    OHBA Nobuko, OGATA Shuji, KOUNO Takahisa, KOBAYASHI Ryo, TAMURA Tomoyuki, ASAHI Ryoji

    The Proceedings of The Computational Mechanics Conference   Vol. 2013 ( 0 ) page: _2415 - 1_-_2415-2_   2013

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    DOI: 10.1299/jsmecmd.2013.26._2415-1_

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  75. Model GW study of the late transition metal monoxides

    Ye Lin-Hui, Asahi Ryoji, Peng Lian-Mao, Freeman Arthur J.

    JOURNAL OF CHEMICAL PHYSICS   Vol. 137 ( 15 ) page: 154110   2012.10

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    DOI: 10.1063/1.4758986

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  76. Optically Tunable Amino-Functionalized Graphene Quantum Dots

    Tetsuka Hiroyuki, Asahi Ryoji, Nagoya Akihiro, Okamoto Kazuo, Tajima Ichiro, Ohta Riichiro, Okamoto Atsuto

    ADVANCED MATERIALS   Vol. 24 ( 39 ) page: 5333 - 5338   2012.10

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    DOI: 10.1002/adma.201201930

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  77. Thermoelectric Properties of Off-Stoichiometric Ti-Ni-Sn Half-Heusler Systems

    Hazama Hirofumi, Matsubara Masato, Asahi Ryoji

    JOURNAL OF ELECTRONIC MATERIALS   Vol. 41 ( 6 ) page: 1730 - 1734   2012.6

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    DOI: 10.1007/s11664-012-2048-z

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  78. Enhanced Thermal Diffusion of Li in Graphite by Alternating Vertical Electric Field: A Hybrid Quantum-Classical Simulation Study

    Ohba Nobuko, Ogata Shuji, Tamura Tomoyuki, Kobayashi Ryo, Yamakawa Shunsuke, Asahi Ryoji

    Journal of the Physical Society of Japan   Vol. 81 ( 2 ) page: 23601 - 23601   2012.2

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  79. Enhanced Thermal Diffusion of Li in Graphite by Alternating Vertical Electric Field: A Hybrid Quantum-Classical Simulation Study

    Ohba Nobuko, Ogata Shuji, Tamura Tomoyuki, Kobayashi Ryo, Yamakawa Shunsuke, Asahi Ryoji

    JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN   Vol. 81 ( 2 )   2012.2

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    DOI: 10.1143/JPSJ.81.023601

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  80. Ideal tensile and shear strength of a gum metal approximant: Ab initio density functional calculations

    Nagasako Naoyuki, Asahi Ryoji, Hafner Juergen

    PHYSICAL REVIEW B   Vol. 85 ( 2 )   2012.1

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    DOI: 10.1103/PhysRevB.85.024122

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  81. 1111 Phase-Field Study of Compositional Variation within Bimetallic Nanoparticle

    Yamakawa Shunsuke, Sakurai Shogo, Asahi Ryoji, Koyama Toshiyuki

    The Proceedings of The Computational Mechanics Conference   Vol. 2012 ( 0 ) page: 68 - 69   2012

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    DOI: 10.1299/jsmecmd.2012.25.68

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  82. 25aCD-7 Enhanced thermal diffusion of Li in graphite by alternating vertical electric Field : A hybrid quantum-classical simulation study

    Ohba Nobuko, Ogata Shuji, Kobayashi Ryo, Tamura Tomoyuki, Yamakawa Shunsuke, Asahi Ryoji

    Meeting Abstracts of the Physical Society of Japan   Vol. 67 ( 0 )   2012

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    DOI: 10.11316/jpsgaiyo.67.1.4.0_993_1

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  83. 2110 Hybrid quantum-classical simulation with DC-RGDFT on thermal diffusion of Li in Graphite

    OHBA Nobuko, OGATA Shuji, KOUNO Takahisa, KOBAYASHI Ryo, TAMURA Tomoyuki, ASAHI Ryoji

    The Proceedings of The Computational Mechanics Conference   Vol. 2012 ( 0 ) page: 191 - 192   2012

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    DOI: 10.1299/jsmecmd.2012.25.191

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  84. First-principles study of Cu2ZnSnS4 and the related band offsets for photovoltaic applications

    Nagoya A., Asahi R., Kresse G.

    JOURNAL OF PHYSICS-CONDENSED MATTER   Vol. 23 ( 40 )   2011.10

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    DOI: 10.1088/0953-8984/23/40/404203

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  85. A hybrid quantum-classical simulation study on stress-dependence of li diffusivity in graphite

    Ohba N.

    CMES - Computer Modeling in Engineering and Sciences   Vol. 75 ( 3-4 ) page: 247 - 264   2011.9

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  86. Improvement of thermoelectric properties for half-Heusler TiNiSn by interstitial Ni defects

    Hazama Hirofumi, Matsubara Masato, Asahi Ryoji, Takeuchi Tsunehiro

    JOURNAL OF APPLIED PHYSICS   Vol. 110 ( 6 )   2011.9

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    DOI: 10.1063/1.3633518

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  87. First-principles materials design for photocatalysis and photovoltaic applications

    Asahi Ryoji

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   Vol. 242   2011.8

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  88. Temperature-induced martensitic phase transitions in gum-metal approximants: First-principles investigations for Ti3Nb

    Lazar Petr, Jahnatek Michal, Hafner Juergen, Nagasako Naoyuki, Asahi Ryoji, Blaas-Schenner Claudia, Stoehr Markus, Podloucky Raimund

    PHYSICAL REVIEW B   Vol. 84 ( 5 )   2011.8

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    DOI: 10.1103/PhysRevB.84.054202

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  89. Computational Materials Design for High-performance Thermoelectrics

    ASAHI Ryoji, HAZAMA Hirofumi, NAGASAKO Naoyuki, MATSUBARA Masato

    Ceramics Japan   Vol. 46 ( 6 ) page: 505 - 509   2011.6

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  90. Fabrication of Nanocomposite Thermoelectric Materials by a Pulsed Laser Deposition Method

    Matsubara Masato, Azuma Hirozumi, Asahi Ryoji

    JOURNAL OF ELECTRONIC MATERIALS   Vol. 40 ( 5 ) page: 1176 - 1180   2011.5

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    DOI: 10.1007/s11664-011-1575-3

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  91. Thermoelectric Properties of Si2Ti-Type Al-(Mn,Cr,Fe)-Si Alloys

    Toyama Yasuhiro, Hazama Hirofumi, Asahi Ryoji, Takeuchi Tsunehiro

    JOURNAL OF ELECTRONIC MATERIALS   Vol. 40 ( 5 ) page: 1052 - 1056   2011.5

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    DOI: 10.1007/s11664-011-1531-2

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  92. A Hybrid Quantum-Classical Simulation Study on Stress-Dependence of Li Diffusivity in Graphite

    Ohba N., Ogata S., Tamura T., Yamakawa S., Asahi R.

    CMES-COMPUTER MODELING IN ENGINEERING & SCIENCES   Vol. 75 ( 3-4 ) page: 247 - 265   2011.5

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  93. 1506 Hybrid quantum-classical simulation : development of O(N)-real-space DFT method and application to the Li-graphite intercalation compound

    Ohba Nobuko, Ogata Shuji, Kobayashi Ryo, Tamura Tomoyuki, Asahi Ryoji

    The Proceedings of The Computational Mechanics Conference   Vol. 2011 ( 0 ) page: 481 - 482   2011

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    DOI: 10.1299/jsmecmd.2011.24.481

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  94. 906 Phase-field Modeling of Lithium Intercalation in Polycrystalline Oxide

    Yamakawa Shunsuke, Yamasaki Hisatsugu, Koyama Toshiyuki, Asahi Ryoji

    The Proceedings of The Computational Mechanics Conference   Vol. 2011 ( 0 ) page: 296 - 297   2011

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    DOI: 10.1299/jsmecmd.2011.24.296

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  95. 21pGT-15 Hybrid quantum-classical simulation using the divide-&-conquer type real-space DFT code

    Ohba Nobuko, Ogata Shuji, Kobayashi Ryo, Tamura Tomoyuki, Asahi Ryoji

    Meeting Abstracts of the Physical Society of Japan   Vol. 66 ( 0 )   2011

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    DOI: 10.11316/jpsgaiyo.66.2.2.0_211_1

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  96. Selected contributions from the 3rd Theory Meets Industry International Workshop, TMI2009 (Nagoya, Japan, 11-13 November 2009) PREFACE

    Tanaka Isao, Hafner Juergen, Wimmer Erich, Asahi Ryoji

    JOURNAL OF PHYSICS-CONDENSED MATTER   Vol. 22 ( 38 ) page: 380301   2010.9

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    DOI: 10.1088/0953-8984/22/38/380301

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  97. Electronic Structure and Thermoelectric Properties of Al-Mn-Fe-Si Alloys

    Takeuchi T., Toyama Y., Hazama H., Asahi R.

    JOURNAL OF ELECTRONIC MATERIALS   Vol. 39 ( 9 ) page: 1433 - 1438   2010.9

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    DOI: 10.1007/s11664-010-1240-2

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  98. Electronic Structure and Thermoelectric Properties of Si_2Ti-Type Al-(Mn, X)-Si (X=Cr, Fe) Alloys

    TOYAMA Yasuhiro, HAZAMA Hirofumi, ASAHI Ryoji, TAKEUCHI Tsunehiro

    Journal of the Japan Institute of Metals and Materials   Vol. 74 ( 9 ) page: 605 - 609   2010.9

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    &nbsp;&nbsp;In order to make variation in thermoelectric properties of Si<sub>2</sub>Ti-type Al<sub>32</sub>Mn<sub>34</sub>Si<sub>34</sub>, which possesses a large magnitude of Seebeck coefficient exceeding 300 &mu;V/K, we partially substituted Fe and Cr for Mn, and succeeded in decreasing the number of valence electrons by the latter. The large, positive Seebeck coefficient up to 330 &mu;V/K was observed for Al<sub>32</sub>Cr<sub><i>x</i></sub>Mn<sub>34&minus;<i>x</i></sub>Si<sub>34</sub> (1&le;<i>x</i>&le;2.5), which consists almost solely of the phase of Si<sub>2</sub>Ti-type structure. The increase of hole concentration with increasing Cr concentration was confirmed by the fact that the electrical resistivity was decreased with Cr concentration. The positive sign and the decrease of Seebeck coefficient with increasing Cr concentration also lend a support on this scenario. The largest <i>ZT</i>-value with the positive sign of Seebeck coefficient (<i>p</i>-type behavior) was obtained at Al<sub>32</sub>Cr<sub>2.5</sub>Mn<sub>31.5</sub>Si<sub>34</sub>, and the resulting <i>ZT</i>-value was twice as large as the largest <i>ZT</i>-value of the ternary compound Al<sub>33</sub>Mn<sub>34</sub>Si<sub>33</sub> that possesses a <i>p</i>-type behavior.<br>

    DOI: 10.2320/jinstmet.74.605

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  99. Electronic Structure and Thermoelectric Properties of Si2Ti-Type Al-(Mn, X)-Si (X = Cr, Fe) Alloys

    Toyama Yasuhiro, Hazama Hirofumi, Asahi Ryoji, Takeuchi Tsunehiro

    JOURNAL OF THE JAPAN INSTITUTE OF METALS   Vol. 74 ( 9 ) page: 605 - 609   2010.9

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  100. Study of Electronic Structure and Defect Formation in Ti1-x Ni1+x Sn Half-Heusler Alloys

    Hazama Hirofumi, Asahi Ryoji, Matsubara Masato, Takeuchi Tsunehiro

    JOURNAL OF ELECTRONIC MATERIALS   Vol. 39 ( 9 ) page: 1549 - 1553   2010.9

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    DOI: 10.1007/s11664-010-1283-4

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  101. Thermoelectric Properties of Si2Ti-Type Al-Mn-Si Alloys

    Takeuchi Tsunehiro, Toyama Yasuhiro, Yamamoto Akio, Hazama Hirofumi, Asahi Ryoji

    MATERIALS TRANSACTIONS   Vol. 51 ( 6 ) page: 1127 - 1135   2010.6

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    By using the first principle band calculations, we identified that Si<SUB>2</SUB>Ti-type Al-Mn-Si <I>C</I>54-phase possesses an electronic structure suitable for the thermoelectric materials. The formation range of the Al-Mn-Si <I>C</I>54-phase was determined by preparing samples at a number of different compositions, and the samples solely consisting of the <I>C</I>54-phase were successfully obtained around Al:Mn:Si=1:1:1. The carrier concentration of the Al-Mn-Si <I>C</I>54-phase was controlled by the partial substitution of the constituent elements, and behaviors in electrical properties characteristic to <I>n</I>-type and <I>p</I>-type thermoelectric materials were alternatively observed for the samples of a larger electron concentration and a smaller electron concentration, respectively. The absolute value of the Seebeck coefficient |<I>S</I>| was found to exceed 300 &mu;V/K for both <I>n</I>-type and <I>p</I>-type samples.

    DOI: 10.2320/matertrans.M2010022

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  102. Anomalies in the response of V, Nb, and Ta to tensile and shear loading: Ab initio density functional theory calculations

    Nagasako Naoyuki, Jahnatek Michal, Asahi Ryoji, Hafner Juergen

    PHYSICAL REVIEW B   Vol. 81 ( 9 )   2010.3

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    DOI: 10.1103/PhysRevB.81.094108

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  103. Defect formation and phase stability of Cu2ZnSnS4 photovoltaic material

    Nagoya Akihiro, Asahi Ryoji, Wahl Roman, Kresse Georg

    PHYSICAL REVIEW B   Vol. 81 ( 11 )   2010.3

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    DOI: 10.1103/PhysRevB.81.113202

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  104. Field-modulated thermopower in SrTiO3-based field-effect transistors with amorphous 12CaO center dot 7Al(2)O(3) glass gate insulator

    Ohta Hiromichi, Masuoka Yumi, Asahi Ryoji, Kato Takeharu, Ikuhara Yuichi, Nomura Kenji, Hosono Hideo

    APPLIED PHYSICS LETTERS   Vol. 95 ( 11 )   2009.9

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    DOI: 10.1063/1.3231873

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  105. Preparation of Conducting Polyaniline-Bismuth Nanoparticle Composites by Planetary Ball Milling

    Anno H., Fukamoto M., Heta Y., Koga K., Itahara H., Asahi R., Satomura R., Sannomiya M., Toshima N.

    JOURNAL OF ELECTRONIC MATERIALS   Vol. 38 ( 7 ) page: 1443 - 1449   2009.7

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    DOI: 10.1007/s11664-009-0786-3

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  106. Thermoelectric Properties of Organic Charge-Transfer Compounds

    Itahara H., Maesato M., Asahi R., Yamochi H., Saito G.

    JOURNAL OF ELECTRONIC MATERIALS   Vol. 38 ( 7 ) page: 1171 - 1175   2009.7

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    DOI: 10.1007/s11664-009-0791-6

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  107. Cu2ZnSnS4 as a potential photovoltaic material: A hybrid Hartree-Fock density functional theory study

    Paier Joachim, Asahi Ryoji, Nagoya Akihiro, Kresse Georg

    PHYSICAL REVIEW B   Vol. 79 ( 11 )   2009.3

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    DOI: 10.1103/PhysRevB.79.115126

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  108. e/a Determination for the transition metal element TM in Al-Cu-TM-Si (TM = Fe and Ru) approximants and B2-compounds by means of the FLAPW-Fourier method

    Mizutani Uichiro, Asahi Ryoji, Takeuchi Tsunehiro, Sato Hirokazu, Kontsevoi Oleg Y., Freeman Arthur J.

    ZEITSCHRIFT FUR KRISTALLOGRAPHIE   Vol. 224 ( 1-2 ) page: 17 - 20   2009

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    DOI: 10.1524/zkri.2009.1078

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  109. 26aYB-9 Electronic structure and thermoelectric properties of Al-based Si_2Ti type compounds

    Toyama Y., Yamamoto A., Hazama H., Asahi R., Ikuta H., Takeuchi T.

    Meeting Abstracts of the Physical Society of Japan   Vol. 64 ( 0 )   2009

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    DOI: 10.11316/jpsgaiyo.64.2.4.0_700_2

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  110. 27pYK-9 Electronic structure and thermoelectric properties of Al-Mn-Fe-Si alloys

    Toyama Y., Hazama H., Asahi R., Takeuchi T.

    Meeting Abstracts of the Physical Society of Japan   Vol. 64 ( 0 )   2009

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    DOI: 10.11316/jpsgaiyo.64.1.4.0_775_2

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  111. Visualization of SrTiO<SUB>3</SUB>-based Field Effect Transistor by Thermopower Measurements

    Ohta Hiromichi, Masuoka Yumi, Asahi Ryoji, Kato Takeharu, Ikuhara Yuichi, Nomura Kenji, Hosono Hideo

    Preprints of Annual Meeting of The Ceramic Society of Japan<br>Preprints of Fall Meeting of The Ceramic Society of Japan   Vol. 2009 ( 0 ) page: 2L08 - 2L08   2009

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    Here we report visualization of carrier concentration (n<SUB>2D</SUB>, n<SUB>3D</SUB>) & effective thickness (t<SUB>eff.</SUB>) of two-dimensional-electron layer for a SrTiO<SUB>3</SUB>-based FET during the gate electric field application. The n<SUB>3D</SUB> values were estimated from thermopower (=Seebeck coefficient) measurements of 2D-electron layer in the FETs, which exhibit excellent transistor characteristics (on-to-off current ratio ~10<SUP>6</SUP>, threshold gate voltage +0.3 V, sub-threshold swing ~0.5 Vdecade<SUP>-1</SUP>, effective mobility ~3 cm<SUP>2</SUP>V<SUP>-1</SUP>s<SUP>-1</SUP>). At lower electric field (E <100 kVcm<SUP>-1</SUP>), dramatic reduction of t<SUB>eff</SUB>. from ~10 um to ~50 nm originates n<SUB>3D</SUB> increase, while n<SUB>3D</SUB> increases almost proportionally to E when E is higher than 100 kVcm<SUP>-1</SUP>.

    DOI: 10.14853/pcersj.2009F.0.2L08.0

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  112. Failure of the Hume-Rothery stabilization mechanism in the Ag5Li8 gamma-brass studied by first-principles FLAPW electronic structure calculations

    Mizutani U., Asahi R., Sato H., Noritake T., Takeuchi T.

    JOURNAL OF PHYSICS-CONDENSED MATTER   Vol. 20 ( 27 )   2008.7

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    DOI: 10.1088/0953-8984/20/27/275228

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  113. Materials design and development of functional materials for industry

    Asahi Ryoji, Morikawa Takeshi, Hazama Hirofumi, Matsubara Masato

    JOURNAL OF PHYSICS-CONDENSED MATTER   Vol. 20 ( 6 ) page: 064227   2008.2

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    DOI: 10.1088/0953-8984/20/6/064227

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  114. Nanostructural characterization of TiNiSn-based half-Heusler compounds

    Matsubara M., Asahi R., Nakagaki T., Isheim D., Seidman D. N.

    PROCEEDINGS ICT 07: TWENTY-SIXTH INTERNATIONAL CONFERENCE ON THERMOELECTRICS     page: 268 - 271   2008

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  115. 21aYG-12 Defect states of Ti_<1+x>Ni_<1-x>Sn identified by soft x-ray photoemission

    Hazama H., Asahi R., Matsubara M., Nakagaki T., Takeuchi T.

    Meeting Abstracts of the Physical Society of Japan   Vol. 63 ( 0 )   2008

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    DOI: 10.11316/jpsgaiyo.63.2.4.0_640_2

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  116. Nanostructural characterization of TiNiSn-based half-Heusler compounds

    Matsubara M.

    International Conference on Thermoelectrics, ICT, Proceedings     page: 263 - 266   2007.12

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    DOI: 10.1109/ICT.2007.4569475

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  117. Nitrogen complex species and its chemical nature in TiO2 for visible-light sensitized photocatalysis

    Asahi Ryoji, Morikawa Takeshi

    CHEMICAL PHYSICS   Vol. 339 ( 1-3 ) page: 57 - 63   2007.10

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    DOI: 10.1016/j.chemphys.2007.07.041

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  118. Crystallographic orientation analysis on calcium cobaltite ceramic grains textured by reactive-templated grain growth

    Tani T.

    International Journal of Applied Ceramic Technology   Vol. 4 ( 4 ) page: 318 - 325   2007.8

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    DOI: 10.1111/j.1744-7402.2007.02146.x

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  119. Properties of the gold oxides Au2O3 and Au2O: First-principles investigation

    Shi Hongqing, Asahi Ryoji, Stampfl Catherine

    PHYSICAL REVIEW B   Vol. 75 ( 20 )   2007.5

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    DOI: 10.1103/PhysRevB.75.205125

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  120. Crystallographic orientation analysis on calcium cobaltite ceramic grains textured by reactive-templated grain growth

    Tani Toshihiko, Itahara Hiroshi, Kadoura Hiroaki, Asahi Ryoji

    INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY   Vol. 4 ( 4 ) page: 318 - 325   2007

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  121. Mediated resonance effect of the vanadium 3d states on phase stability in the Al8V5 gamma-brass studied by first-principles FLAPW and LMTO-ASA electronic structure calculations

    Mizutani U., Asahi R., Sato H., Takeuchi T.

    PHYSICAL REVIEW B   Vol. 74 ( 23 )   2006.12

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    DOI: 10.1103/PhysRevB.74.235119

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  122. Analysis of crystallographic orientation on textured Ca-doped (ZnO) <inf>m</inf>in<inf>2</inf>O<inf>3</inf> ceramics by electron back scattering diffraction pattern

    Kaga H.

    Journal of the Ceramic Society of Japan   Vol. 114 ( 1335 ) page: 1022 - 1028   2006.11

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    Crystallographic orientation and phase identification on textured Ca-doped (ZnO)<sub><i>m</i></sub>In<sub>2</sub>O<sub>3</sub> (<i>m</i>=3 and 4, denoted as Z<sub><i>m</i></sub>IO) ceramics were investigated for better understanding and further improvement of the high-efficiency <i>n</i>-type thermoelectric oxide materials. Textured ceramics were prepared by the reactive-templated grain growth (RTGG) method, in which plate-like reactive seeds were exploited. A combination of electron backscatter diffraction pattern (EBSP) and energy dispersive X-ray spectrometry (EDS) techniques was utilized for analyzing the textured specimen parallel and perpendicular to the original sheet plane in detail. We revealed that in the specimen plate-like grains were aligned parallel to the sheet plane with the thickness direction parallel to the <i>c</i>-axis of each grain. Parallel aligned trigonal Z<sub>3</sub>IO domains with a 60&deg; misorientation angle were observed in a single grain. Coexisting trigonal Z<sub>3</sub>IO and hexagonal Z<sub>4</sub>IO phases were also observed in a single grain. These axis-sharing crystallites must be formed by the in situ topotactic conversion from a common hexagonal template crystal.<br>

    DOI: 10.2109/jcersj.114.1022

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  123. Analysis of crystallographic orientation on textured ca-doped (ZnO) mIn2O3 ceramics by electron back scattering diffraction pattern

    Kaga Hisashi, Tani Toshihiko, Kadoura Hiroaki, Seki Juntaro, Asahi Ryoji

    JOURNAL OF THE CERAMIC SOCIETY OF JAPAN   Vol. 114 ( 1335 ) page: 1022 - 1028   2006.11

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  124. Extremely small thermal conductivity of the Al-based Mackay-type 1/1-cubic approximants

    Takeuchi Tsunehiro, Nagasako Naoyuki, Asahi Ryoji, Mizutani Uichiro

    PHYSICAL REVIEW B   Vol. 74 ( 5 )   2006.8

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    DOI: 10.1103/PhysRevB.74.054206

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  125. First-principles calculations of Ag-Sb nanodot formation in thermoelectric AgPbmSbTe2+m (m=6,14,30)

    Hazama H, Mizutani U, Asahi R

    PHYSICAL REVIEW B   Vol. 73 ( 11 )   2006.3

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    DOI: 10.1103/PhysRevB.73.115108

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  126. The Hume-Rothery electron concentration rule for a series of gamma-brasses studied by full-potential linearized augmented plane wave (FLAPW) band calculations

    Mizutani U, Asahi R, Sato H, Takeuchi T

    PHILOSOPHICAL MAGAZINE   Vol. 86 ( 3-5 ) page: 645 - 654   2006

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    DOI: 10.1080/14786430500274899

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  127. Thermoelectric properties of Al-doped ZnO prepared by electrical field-assist sintering

    Kaga H.

    Key Engineering Materials   Vol. 317-318   page: 811 - 814   2006

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    DOI: 10.4028/www.scientific.net/kem.317-318.811

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  128. Thermoelectric properties of Al-doped ZnO prepared by electrical field-assist sintering

    Kaga Hisashi, Asahi Ryoji

    SCIENCE OF ENGINEERING CERAMICS III   Vol. 317-318   page: 811 - 814   2006

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  129. 28aXE-2 Interpretation of the Hume-Rothery rule and evaluation of average electron concentration for Al-Cu-TM-Si (TM=Fe and Ru) approximants by using the first-principles FLAPW band calculations

    Mizutani U., Asahi R., Kontsevoi O.Y., Takeuchi T., Freeman A.J.

    Meeting Abstracts of the Physical Society of Japan   Vol. 61 ( 0 )   2006

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    DOI: 10.11316/jpsgaiyo.61.1.4.0_774_1

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  130. High-temperature thermoelectric power generation module of layered oxides improved by multistage structure with Bi-Te module

    Asahi R.

    International Conference on Thermoelectrics, ICT, Proceedings   Vol. 2005   page: 358 - 361   2005.12

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    DOI: 10.1109/ICT.2005.1519960

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  131. Interpretation of the Hume-Rothery electron concentration rule in the T2Zn11 (T=Ni, Pd, Co, and Fe) gamma brasses based on first-principles FLAPW calculations

    Asahi R, Sato H, Takeuchi T, Mizutani U

    PHYSICAL REVIEW B   Vol. 72 ( 12 )   2005.9

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    DOI: 10.1103/PhysRevB.72.125102

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  132. Thermoelectric properties of Ca-doped (ZnO)<inf>m</inf>in<inf>2</inf>O <inf>3</inf> ceramics and their improvement upon texture

    Kaga H.

    Ceramic Transactions   Vol. 167   page: 127 - 136   2005.8

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  133. Verification of Hume-Rothery electron concentration rule in Cu5Zn8 and Cu9Al4 gamma brasses by ab initio FLAPW band calculations

    Asahi R, Sato H, Takeuchi T, Mizutani U

    PHYSICAL REVIEW B   Vol. 71 ( 16 )   2005.4

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    DOI: 10.1103/PhysRevB.71.165103

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  134. Fully first-principles screened-exchange LDA calculations of excited states and optical properties of III-V semiconductors

    Rhim SH, Kim M, Freeman AJ, Asahi R

    PHYSICAL REVIEW B   Vol. 71 ( 4 )   2005.1

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    DOI: 10.1103/PhysRevB.71.045202

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  135. High-temperature thermoelectric power generation module of layered oxides improved by multistage structure with Bi-Te module

    Asahi R, Tani T, Itahara H, Kaga H, Okuda K

    ICT: 2005 24TH INTERNATIONAL CONFERENCE ON THERMOELECTRICS     page: 358 - 361   2005

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  136. Thermoelectric properties of Ca-doped (ZnO)(m)In2O3 ceramics and their improvement upon texture

    Kaga H, Asahi R, Tani T

    DEVELOPMENTS IN DIELECTRIC MATERIALS AND ELECTRONIC DEVICES   Vol. 167   page: 127 - 136   2005

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  137. Thermoelectric Properties of Highly Textured Ca-Doped (ZnO)_mIn_2O_3 Ceramics

    Kaga Hisashi, Asahi Ryoji, Tani Toshihiko

    Japanese journal of applied physics. Pt. 1, Regular papers & short notes   Vol. 43 ( 10 ) page: 7133 - 7136   2004.10

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  138. Thermoelectric properties of highly textured Ca-doped (ZnO)(m)In2O3 ceramics

    Kaga H, Asahi R, Tani T

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS   Vol. 43 ( 10 ) page: 7133 - 7136   2004.10

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    Publishing type:Research paper (other academic)   Publisher:Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers  

    Highly textured Ca-doped (ZnO)<I><SUB>m</SUB></I>In<SUB>2</SUB>O<SUB>3</SUB> (<I>m</I> is an integer) ceramics were fabricated by the reactive templated grain growth (RTGG) method and their thermoelectric properties were examined. Platelike ZnSO<SUB>4</SUB>&middot;3Zn(OH)<SUB>2</SUB> particles were used as reactive templates and mixed with In<SUB>2</SUB>O<SUB>3</SUB> and CaCO<SUB>3</SUB> powders into a stack of tapes. <I>In situ</I> formation and subsequent sintering resulted in textured Ca-doped (ZnO)<I><SUB>m</SUB></I>In<SUB>2</SUB>O<SUB>3</SUB> ceramics. The electrical conductivity of the textured specimen along the <I>ab</I>-plane was almost two times larger than that of the textured specimen along the <I>c</I>-axis and about 30% larger than that of a nontextured specimen. On the other hand, the Seebeck coefficients of the textured specimen exhibited a small anisotropy. The thermal conductivity of the RTGG specimen along the <I>ab</I>-plane was higher than that of the RTGG specimen along the <I>c</I>-axis. However, both specimens showed similar values at high temperatures. As a result, the Ca-doped specimen along the <I>ab</I>-plane with a composite phase of (ZnO)<SUB>3</SUB>In<SUB>2</SUB>O<SUB>3</SUB> and (ZnO)<SUB>4</SUB>In<SUB>2</SUB>O<SUB>3</SUB> showed a <I>ZT</I> value of 0.31 (at 1053 K), compared with 0.23 (at 1053 K) for the nontextured specimen.

    DOI: 10.1143/JJAP.43.7133

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  139. Thermoelectric Properties of Doped (ZnO)_mIn_2O_3

    Kaga Hisashi, Asahi Ryoji, Tani Toshihiko

    Japanese journal of applied physics. Pt. 1, Regular papers & short notes   Vol. 43 ( 6 ) page: 3540 - 3543   2004.6

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  140. Thermoelectric properties of doped (ZnO)(m)In2O3

    Kaga H, Asahi R, Tani T

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS SHORT NOTES & REVIEW PAPERS   Vol. 43 ( 6A ) page: 3540 - 3543   2004.6

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    The thermoelectric properties of layer-structured homologous compounds of (ZnO)<I><SUB>m</SUB></I>In<SUB>2</SUB>O<SUB>3</SUB> (<I>m</I> is an integer) were investigated in terms of the detailed dependence of the molar ratio of ZnO to In<SUB>2</SUB>O<SUB>3</SUB>, <I>n</I> (=ZnO/In<SUB>2</SUB>O<SUB>3</SUB>), and of doping, such as with Ba<SUP>2+</SUP>, Ca<SUP>2+</SUP>, Sr<SUP>2+</SUP>, and Sn<SUP>4+</SUP>, for an In site. Except for the Ba and Sr dopings, all sintered specimens with <I>n</I>&ge;3 were found to be in the phases of (ZnO)<I><SUB>m</SUB></I>In<SUB>2</SUB>O<SUB>3</SUB>. The highest power factor apparently existed around <I>n</I>=3 while the thermal conductivity was minimum at the range from <I>n</I>=3.5 to 5. The Ca doping effectively reduced the thermal conductivity, resulting in a dimensionless figure of merit of 0.23 (at 1053 K) for <I>n</I>=3.5, which was relatively high among n-type oxides.

    DOI: 10.1143/JJAP.43.3540

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  141. 15aWA-11 Studies of Atomic and Electronic Structures of γ-phase Zn-X (X=Cu, Ni, Co, Fe and Pd) Electron Compounds

    Mizutani U., Takahashi H., Takeuchi T., Sato H., Asahi R.

    日本物理学会講演概要集   Vol. 59 ( 0 )   2004

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    Publishing type:Research paper (other academic)   Publisher:一般社団法人 日本物理学会  

    DOI: 10.11316/jpsgaiyo.59.2.4.0_731_3

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  142. First Principles Calculations of Auger Recombination and Impact Ionization Rates in Semiconductors

    Picozzi S.

    Journal of Computational Electronics   Vol. 2 ( 2-4 ) page: 197 - 202   2003.12

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    DOI: 10.1023/B:JCEL.0000011424.07265.d5

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  143. First Principles Calculations of Auger Recombination and Impact Ionization Rates in Semiconductors

    Picozzi S., Asahi R., Freeman A. J.

    JOURNAL OF COMPUTATIONAL ELECTRONICS   Vol. 2 ( 2-4 ) page: 197 - 202   2003.12

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  144. Growth of In2O3(ZnO)(5) platelet micro-crystals by flux methods

    Xia CT, Asahi R, Tani T

    JOURNAL OF CRYSTAL GROWTH   Vol. 254 ( 1-2 ) page: 144 - 150   2003.6

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    Publishing type:Research paper (other academic)   Publisher:Journal of Crystal Growth  

    DOI: 10.1016/S0022-0248(03)01180-1

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  145. Characterization of Nitrogen-doped Titanium Oxide Photocatalyst Activated by Visible-light

    OHWAKI Takeshi, MORIKAWA Takeshi, AOKI Koyu, ASAHI Ryoji, TAGA Yasunori, ISOMURA Noritake

    Hyomen Kagaku   Vol. 24 ( 1 ) page: 25 - 30   2003.1

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    Publishing type:Research paper (other academic)   Publisher:The Surface Science Society of Japan  

    N-doped titanium oxide photocatalyst is found to be activated by visible light irradiation as well as ultraviolet irradiation. We evaluated its crystal structure, N states in the lattice, composition, and surface morphology using X-ray diffiraction (XRD), X-ray photoemission spectroscopy (XPS), and scanning probe microscopy (SPM). As a result, it is found that the materials have rutile or anatase crystal structure with nitrogen doped into substitutional sites of oxygen in TiO<Sub>2</Sub>, which contributes band gap narrowing. It is also confirmed that XPS measurement was influenced by surface treatment such as Ar ion bombardment.

    DOI: 10.1380/jsssj.24.25

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  146. Thermoelectric Properties of (ZnO)<SUB>m</SUB>In<SUB>2</SUB>O<SUB>3</SUB>-Dependence of m(=1-19) and Effects of Doping (Ba, Ca, Sr, Sn, and Al)-

    KAGA Hisashi, ASAHI Ryoji, TANI Toshihiko

    日本セラミックス協会 年会・秋季シンポジウム 講演予稿集   Vol. 2003 ( 0 ) page: 427 - 427   2003

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    Publishing type:Research paper (other academic)   Publisher:公益社団法人 日本セラミックス協会  

    Layered-structured homologous compounds (ZnO)<SUB><I>m</I></SUB>In<SUB>2</SUB>O<SUB>3</SUB> (Z<SUB><I>m</I></SUB>IO, <I>m</I>=integer) have been extensively studied for a candidate of n-type thermoelectric oxide material. Most of the studies focused on m=5, 7, and 9, and trivalent-ion doping for In site. In this study, we investigate the detailed dependence of m(=1-19) and doping effects of Ba<SUP>2</SUP><SUP>+</SUP>, Ca<SUP>2</SUP><SUP>+</SUP>, Sr<SUP>2</SUP><SUP>+</SUP>, and Sn<SUP>4</SUP><SUP>+</SUP> for In site and of Al<SUP>3</SUP><SUP>+</SUP> for Zn site. The sintered specimens were formed in a single phase of Z<SUB><I>m</I></SUB>IO (m=3-19) except Ba- and Sr-doped specimens and the densities reached more than 95% of TD. The thermal conductivity showed a minimum at m=5 and that of Ca-doped Z<SUB><I>m</I></SUB>IO was about 10% smaller than that of pure Z<SUB><I>m</I></SUB>IO. Carrier concentrations were changed by Ca- or Sn-doping, which, however, did not improve the power factor. The highest power factor, 5.18 x 10<SUP>-</SUP><SUP>4</SUP> W/K<SUP>2</SUP>m (@780 &deg;C), was obtained in pure Z<SUB>3</SUB>IO.

    DOI: 10.14853/pcersj.2003F.0.427.0

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  147. Accurate first-principles detailed-balance determination of Auger recombination and impact ionization rates in semiconductors

    Picozzi S, Asahi R, Geller CB, Freeman AJ

    PHYSICAL REVIEW LETTERS   Vol. 89 ( 19 )   2002.11

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    Publishing type:Research paper (other academic)   Publisher:Physical Review Letters  

    DOI: 10.1103/PhysRevLett.89.197601

    Web of Science

    Scopus

  148. Impact Ionization in GaAs within A Screened Exchange Density Functional Formalism

    Picozzi S.

    Journal of Computational Electronics   Vol. 1 ( 3 ) page: 421 - 424   2002.10

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    DOI: 10.1023/A:1020728414482

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  149. First-principles calculations for understanding high conductivity and optical transparency in InxCd1-x films

    Asahi R, Wang A, Babcock JR, Edleman NL, Metz AW, Lane MA, Dravid VP, Kannewurf CR, Freeman AJ, Marks TJ

    THIN SOLID FILMS   Vol. 411 ( 1 ) page: 101 - 105   2002.5

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  150. First-principles calculations for understanding high conductivity and optical transparency in In<inf>x</inf>Cd<inf>1-x</inf>O films

    Asahi R.

    Thin Solid Films   Vol. 411 ( 1 ) page: 101 - 105   2002.5

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    Publishing type:Research paper (other academic)   Publisher:Thin Solid Films  

    DOI: 10.1016/S0040-6090(02)00196-7

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  151. Surface properties of the refractory metal-nitride semiconductor ScN: Screened-exchange LDA-FLAPW investigations

    Stampfl C, Asahi R, Freeman AJ

    PHYSICAL REVIEW B   Vol. 65 ( 16 ) page: 1 - 4   2002.4

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B - Condensed Matter and Materials Physics  

    DOI: 10.1103/PhysRevB.65.161204

    Web of Science

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  152. Surface properties of the refractory metal-nitride semiconductor ScN: Screened-exchange LDA-FLAPW investigations

    Stampfl C.

    Physical Review B - Condensed Matter and Materials Physics   Vol. 65 ( 16 ) page: 1612041 - 1612044   2002.4

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  153. Impact ionization in GaAs: A screened exchange density-functional approach

    Picozzi S, Asahi R, Geller CB, Continenza A, Freeman AJ

    PHYSICAL REVIEW B   Vol. 65 ( 11 ) page: 1 - 4   2002.3

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B - Condensed Matter and Materials Physics  

    DOI: 10.1103/PhysRevB.65.113206

    Web of Science

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  154. Impact ionization in GaAs: A screened exchange density-functional approach

    Picozzi S.

    Physical Review B - Condensed Matter and Materials Physics   Vol. 65 ( 11 ) page: 1132061 - 1132064   2002.3

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  155. Photocatalysts sensitive to visible light - Response

    Asahi R, Morikawa T, Ohwaki T, Aoki K, Taga Y

    SCIENCE   Vol. 295 ( 5555 ) page: 627 - 627   2002.1

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  156. Electronic structure of misfit-layered calcium cobaltite

    Asahi R, Sugiyama J, Tani T, Xia CT

    XXI INTERNATIONAL CONFERENCE ON THERMOELECTRICS, PROCEEDINGS ICT '02     page: 203 - 206   2002

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  157. Excited states and optical properties entirely from first principles: Extended FLAPW method and its graphical user interface

    Kim MY, Asahi R, Freeman AJ

    JOURNAL OF COMPUTER-AIDED MATERIALS DESIGN   Vol. 9 ( 3 ) page: 173 - 201   2002

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  158. Electronic structure of misfit-layered calcium cobaltite

    Asahi R.

    Physical Review B - Condensed Matter and Materials Physics   Vol. 66 ( 15 ) page: 1 - 7   2002

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B - Condensed Matter and Materials Physics  

    DOI: 10.1103/PhysRevB.66.155103

    Web of Science

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  159. Electronic structure of misfit-layered calcium cobaltite

    Asahi R.

    International Conference on Thermoelectrics, ICT, Proceedings   Vol. 2002-January   page: 203 - 206   2002

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    Publishing type:Research paper (other academic)   Publisher:International Conference on Thermoelectrics, ICT, Proceedings  

    DOI: 10.1109/ICT.2002.1190300

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  160. Excited states and optical properties entirely from first principles: Extended FLAPW method and its graphical user interface

    Kim M.

    Journal of Computer-Aided Materials Design   Vol. 9 ( 3 ) page: 173 - 201   2002

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    Publishing type:Research paper (other academic)   Publisher:Journal of Computer-Aided Materials Design  

    DOI: 10.1023/A:1026079901670

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  161. Effect of GGA on the half-metallicity of the itinerant ferromagnet CoS2

    Shishidou T, Freeman AJ, Asahi R

    PHYSICAL REVIEW B   Vol. 64 ( 18 )   2001.11

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  162. Effect of GGA on the half-metallicity of the itinerant ferromagnet CoS<inf>2</inf>

    Shishidou T.

    Physical Review B - Condensed Matter and Materials Physics   Vol. 64 ( 18 ) page: 1804011 - 1804014   2001.11

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B - Condensed Matter and Materials Physics  

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  163. Electronic structure and small polaron hole transport of copper aluminate

    Ingram BJ, Mason TO, Asahi R, Park KT, Freeman AJ

    PHYSICAL REVIEW B   Vol. 64 ( 15 )   2001.10

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  164. Electronic structure and small polaron hole transport of copper aluminate

    Ingram B.

    Physical Review B - Condensed Matter and Materials Physics   Vol. 64 ( 15 ) page: 1551141 - 1551147   2001.10

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B - Condensed Matter and Materials Physics  

    DOI: 10.1103/PhysRevB.64.155114

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  165. Visible-light photocatalysis in doped titanium oxides.

    Asahi R, Morikawa T, Taga Y

    ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY   Vol. 222   page: U633 - U633   2001.8

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  166. Computational band-structure engineering of III-V semiconductor alloys

    Geller CB, Wolf W, Picozzi S, Continenza A, Asahi R, Mannstadt W, Freeman AJ, Wimmer E

    APPLIED PHYSICS LETTERS   Vol. 79 ( 3 ) page: 368 - 370   2001.7

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  167. Computational band-structure engineering of III-V semiconductor alloys

    Geller C.

    Applied Physics Letters   Vol. 79 ( 3 ) page: 368 - 370   2001.7

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    Publishing type:Research paper (other academic)   Publisher:Applied Physics Letters  

    DOI: 10.1063/1.1383282

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  168. Visible-light photocatalysis in nitrogen-doped titanium oxides

    Asahi R, Morikawa T, Ohwaki T, Aoki K, Taga Y

    SCIENCE   Vol. 293 ( 5528 ) page: 269 - 271   2001.7

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  169. Visible-light photocatalysis in nitrogen-doped titanium oxides

    Asahi R.

    Science   Vol. 293 ( 5528 ) page: 269 - 271   2001.7

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    Publishing type:Research paper (other academic)   Publisher:Science  

    DOI: 10.1126/science.1061051

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  170. Indium-cadmium-oxide films having exceptional electrical conductivity and optical transparency: Clues for optimizing transparent conductors

    Wang A, Babcock JR, Edleman NL, Metz AW, Lane MA, Asahi R, Dravid VP, Kannewurf CR, Freeman AJ, Marks TJ

    PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA   Vol. 98 ( 13 ) page: 7113 - 7116   2001.6

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  171. Indium-cadmium-oxide films having exceptional electrical conductivity and optical transparency: Clues for optimizing transparent conductors

    Wang A.

    Proceedings of the National Academy of Sciences of the United States of America   Vol. 98 ( 13 ) page: 7113 - 7116   2001.6

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    Publishing type:Research paper (other academic)   Publisher:Proceedings of the National Academy of Sciences of the United States of America  

    DOI: 10.1073/pnas.121188298

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  172. Band-gap narrowing of titanium dioxide by nitrogen doping

    Morikawa T, Asahi R, Ohwaki T, Aoki K, Taga Y

    JAPANESE JOURNAL OF APPLIED PHYSICS PART 2-LETTERS   Vol. 40 ( 6A ) page: L561 - L563   2001.6

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  173. Band-Gap Narrowing of Titanium Dioxide by Nitrogen Doping

    Morikawa Takeshi, Asahi Ryoji, Ohwaki Takeshi, AOKI Koyu, TAGA Yasunori

    Japanese journal of applied physics. Pt. 2, Letters   Vol. 40 ( 6 ) page: L561 - L563   2001.6

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    Publishing type:Research paper (other academic)   Publisher:社団法人応用物理学会  

    DOI: 10.1143/JJAP.40.L561

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  174. Band-gap narrowing of titanium dioxide by nitrogen doping

    Morikawa T.

    Japanese Journal of Applied Physics, Part 2: Letters   Vol. 40 ( 6 A )   2001.6

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    Publishing type:Research paper (other academic)   Publisher:Japanese Journal of Applied Physics, Part 2: Letters  

    DOI: 10.1143/jjap.40.l561

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  175. Electronic structure and physical properties of early transition metal mononitrides: Density-functional theory LDA, GGA, and screened-exchange LDA FLAPW calculations

    Stampfl C, Mannstadt W, Asahi R, Freeman AJ

    PHYSICAL REVIEW B   Vol. 63 ( 15 )   2001.4

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  176. Electronic structure and physical properties of early transition metal mononitrides: Density-functional theory LDA, GGA, and screened-exchange LDA FLAPW calculations

    Stampfl C.

    Physical Review B - Condensed Matter and Materials Physics   Vol. 63 ( 15 )   2001.3

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B - Condensed Matter and Materials Physics  

    DOI: 10.1103/PhysRevB.63.155106

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  177. Band-Gap Narrowing of Titanium Dioxide by Nitrogen Doping.

    Morikawa Takeshi, Asahi Ryoji, Ohwaki Takeshi, Aoki Koyu, Taga Yasunori

    Japanese Journal of Applied Physics   Vol. 40 ( 6 ) page: L561 - L563   2001

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    Publishing type:Research paper (other academic)   Publisher:The Japan Society of Applied Physics  

    TiO<FONT SIZE="-1"><SUB>2</SUB></FONT>-based powder, including 0.1 at% of N doped in the rutile lattice, has been synthesized by oxidation of TiN. As a result, a significant shift of the absorption edge to a lower energy in the visible-light region has been observed. The substitutional doping of N into the TiO<FONT SIZE="-1"><SUB>2</SUB></FONT> lattice is found to be effective; its 2p states contribute to the band-gap narrowing by mixing with O 2p as shown in <I>ab initio</I> electronic structure calculations.

    DOI: 10.1143/JJAP.40.L561

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  178. Effect of GGA on the half-metallicity of the itinerant ferromagnet (formula presented)

    Shishidou T.

    Physical Review B - Condensed Matter and Materials Physics   Vol. 64 ( 18 )   2001

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B - Condensed Matter and Materials Physics  

    DOI: 10.1103/PhysRevB.64.180401

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  179. Screened-exchange LDA methods for films and superlattices with applications to the Si(100)2X1 surface and InAs/InSb superlattices

    Asahi R, Mannstadt W, Freeman AJ

    PHYSICAL REVIEW B   Vol. 62 ( 4 ) page: 2552 - 2561   2000.7

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  180. Electronic and optical properties of anatase TiO2

    Asahi R, Taga Y, Mannstadt W, Freeman AJ

    PHYSICAL REVIEW B   Vol. 61 ( 11 ) page: 7459 - 7465   2000.3

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  181. Volume and composition dependence of direct and indirect band gaps in ordered ternary III-V semiconductor compounds: A screened-exchange LDA study

    Picozzi S, Continenza A, Asahi R, Mannstadt W, Freeman AJ, Wolf W, Wimmer E, Geller CB

    PHYSICAL REVIEW B   Vol. 61 ( 7 ) page: 4677 - 4684   2000.2

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  182. Electronic and optical properties of anatase

    Asahi R.

    Physical Review B - Condensed Matter and Materials Physics   Vol. 61 ( 11 ) page: 7459 - 7465   2000

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B - Condensed Matter and Materials Physics  

    DOI: 10.1103/PhysRevB.61.7459

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  183. Volume and composition dependence of direct and indirect band gaps in ordered ternary III-V semiconductor compounds: A screened-exchange LDA study

    Picozzi S.

    Physical Review B - Condensed Matter and Materials Physics   Vol. 61 ( 7 ) page: 4677 - 4684   2000

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B - Condensed Matter and Materials Physics  

    DOI: 10.1103/PhysRevB.61.4677

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  184. Moss-Burstein and plasma reflection characteristics of heavily doped n-type InxGa1-xAs and InPyAs1-y

    Charache GW, DePoy DM, Raynolds JE, Baldasaro PF, Miyano KE, Holden T, Pollak FH, Sharps PR, Timmons ML, Geller CB, Mannstadt W, Asahi R, Freeman AJ, Wolf W

    JOURNAL OF APPLIED PHYSICS   Vol. 86 ( 1 ) page: 452 - 458   1999.7

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  185. Moss-Burstein and plasma reflection characteristics of heavily doped n-type In<inf>x</inf>Ga<inf>1-x</inf>As and InP<inf>x</inf>As<inf>1-y</inf>

    Charache G.W.

    Journal of Applied Physics   Vol. 86 ( 1 ) page: 452 - 458   1999.7

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    Publishing type:Research paper (other academic)   Publisher:Journal of Applied Physics  

    DOI: 10.1063/1.370751

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  186. Optical properties and electronic structures of semiconductors with screened-exchange LDA

    Asahi R, Mannstadt W, Freeman AJ

    PHYSICAL REVIEW B   Vol. 59 ( 11 ) page: 7486 - 7492   1999.3

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  187. Optical properties and electronic structures of semiconductors with screened-exchange lda

    Asahi R.

    Physical Review B - Condensed Matter and Materials Physics   Vol. 59 ( 11 ) page: 7486 - 7492   1999

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    Publishing type:Research paper (other academic)   Publisher:Physical Review B - Condensed Matter and Materials Physics  

    DOI: 10.1103/PhysRevB.59.7486

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  188. Micromachined sensors using polysilicon sacrificial layer etching technology

    Tabata O.

    Sensors and Materials   Vol. 8 ( 1 ) page: 057 - 067   1996.12

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    Publishing type:Research paper (other academic)   Publisher:Sensors and Materials  

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  189. Micromachined sensors using polysilicon sacrificial layer etching technology

    Tabata O, Shimaoka K, Asahi R, Sugiyama S

    SENSORS AND MATERIALS   Vol. 8 ( 1 ) page: 57 - 67   1996

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  190. STM observation of laser-exposed Fe/GaAs by STM

    Arisawa Y., Hazama Y., Hosoyama N., Sueoka K., Asahi R., Taga Y., Hayakawa K., Mukasa K.

    Meeting Abstracts of the Physical Society of Japan   Vol. 1996 ( 0 )   1996

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    Publishing type:Research paper (other academic)   Publisher:The Physical Society of Japan  

    DOI: 10.11316/jpsgaiyoj.1996.2.0_639_1

    CiNii Article

  191. 3p-YA-4 Magneto-Optic Kerr Effect of Ultrathin Fe Films on (2x1)S/GaAs(001)

    Asahi R, Taga Y

    Meeting Abstracts of the Physical Society of Japan   Vol. 1994 ( 0 )   1994

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    Publishing type:Research paper (other academic)   Publisher:The Physical Society of Japan  

    DOI: 10.11316/jpsgaiyoj.1994.3.0_83_1

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  192. MICROMACHINED SENSORS USING POLYSILICON SACRIFICIAL LAYER ETCHING TECHNOLOGY

    SUGIYAMA S, TABATA O, SHIMAOKA K, ASAHI R

    INTERNATIONAL ELECTRON DEVICES MEETING 1994 - IEDM TECHNICAL DIGEST     page: 127 - 130   1994

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  193. ANISOTROPIC ETCHING OF SILICON IN TMAH SOLUTIONS

    TABATA O, ASAHI R, FUNABASHI H, SHIMAOKA K, SUGIYAMA S

    SENSORS AND ACTUATORS A-PHYSICAL   Vol. 34 ( 1 ) page: 51 - 57   1992.7

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  194. Anisotropic etching of silicon in TMAH solutions

    Tabata O.

    Sensors and Actuators: A. Physical   Vol. 34 ( 1 ) page: 51 - 57   1992.7

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    Publishing type:Research paper (other academic)   Publisher:Sensors and Actuators: A. Physical  

    DOI: 10.1016/0924-4247(92)80139-T

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  195. INTEGRATED PYROELECTRIC INFRARED-SENSOR USING PVDF THIN-FILM DEPOSITED BY ELECTRO-SPRAY METHOD

    ASAHI R, SAKATA J, TABATA O, MOCHIZUKI M, SUGIYAMA S, TAGA Y

    FERROELECTRIC THIN FILMS III   Vol. 310   page: 79 - 84   1992

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  196. Infrared linear image sensor using a poly-Si pn junction diode array

    Tanaka A.

    Infrared Physics   Vol. 33 ( 4 ) page: 229 - 236   1992

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    Publishing type:Research paper (other academic)   Publisher:Infrared Physics  

    DOI: 10.1016/0020-0891(92)90019-P

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  197. INFRARED LINEAR IMAGE SENSOR USING A POLY-SI PN JUNCTION DIODE-ARRAY

    TANAKA A, SUZUKI M, ASAHI R, TABATA O, SUGIYAMA S

    INFRARED PHYSICS   Vol. 33 ( 4 ) page: 229 - 236   1992

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    Publishing type:Research paper (other academic)  

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Books 7

  1. Multiscale Simulations for Electrochemical Devices

    ( Role: Edit)

    Jenny Stanford  2020  ( ISBN:978-981-4800-71-6

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    Total pages:330   Language:English Book type:Scholarly book

  2. Multiscale Simulations for Electrochemical Devices

    R. Asahi, R. Jinnouchi( Role: Joint author ,  Atomistic Modeling of Photoelectric Cells for Artificial Photosynthesis)

    Jenny Stanford  2020  ( ISBN:978-981-4800-71-6

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    Total pages:330   Responsible for pages:107-146   Language:English Book type:Scholarly book

  3. 可視光応答型光触媒の実用化技術

    ( Role: Joint author ,  可視光応答型光触媒の設計)

    シーエムシー出版  2010 

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    Responsible for pages:18-26   Language:Japanese Book type:Scholarly book

  4. Diffuse Scattering and the Fundamental Properties of Materials

    U. Mizutani, R. Asahi, H. Sato, and T. Takeuchi( Role: Joint author ,  Ab Initio Test of the Hume-Rothery Electron Concentration Rule for Gamma-Brasses)

    Momentum Press  2009 

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    Responsible for pages:283-302   Language:English Book type:Scholarly book

  5. 可視光応答型光触媒-材料設計から実用化までのすべて-

    ( Role: Joint author ,  バンドギャップ狭窄法による可視光応答化)

    シーエムシー出版  2005.9 

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    Responsible for pages:18-25   Language:Japanese Book type:Scholarly book

  6. Solid-State Photoemission and Related Methods International journal

    A.J. Freeman, R. Asahi, A. Continenza, and R. Wu( Role: Joint author ,  Electronic Structure Theory for Ground and Excited State Properties of Materials)

    Wiley-VCH  2003 

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    Responsible for pages:1-49   Book type:Scholarly book

  7. Sci. Rep. Kanazawa Univ.

    Y. Ohno, R. Asahi( Role: Joint author ,  Theory of a Quasi-One Dimensional Organic Ferromagnet, m-Polydiphenylcarbene)

    1986 

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    Responsible for pages:5-29   Language:English

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KAKENHI (Grants-in-Aid for Scientific Research) 1

  1. Development of hybrid quantum-classical simulation scheme for chemical reaction in nano-scale liquid-solid interface under electric field

    Grant number:23310074  2011.4 - 2014.3

    OGATA Shuji

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    Authorship:Collaborating Investigator(s) (not designated on Grant-in-Aid) 

    We have developed the divide-and-conquer-type, order-N real-space density-functional-theory (DC-RGDFT) code. Using the DC-RGDFT, we have performed the first-principles molecular dynamics simulation about the Li-ion transfer through the interface between the solid-electrolyte-interface and liquid electrolyte in the Li-ion battery to find the enhancement mechanism of the Li-ion transfer rate by the salt. Installing the DC-RGDFT to the hybrid quantum-classical code, a large-scale hybrid simulation is performed for the thermal diffusion of Li-ions in graphite with or without external electric field in the Li-ion battery.