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2次元伝導を示す六方晶化合物のファンホーベ特異点を利用した高性能熱電材料の創製

Research Project

Project/Area Number 19656160
Research Category

Grant-in-Aid for Exploratory Research

Allocation TypeSingle-year Grants
Research Field Physical properties of metals
Research InstitutionNagoya University

Principal Investigator

竹内 恒博  Nagoya University, エコトピア科学研究所, 准教授 (00293655)

Project Period (FY) 2007 – 2008
Project Status Completed (Fiscal Year 2008)
Budget Amount *help
¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2008: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2007: ¥2,500,000 (Direct Cost: ¥2,500,000)
Keywords熱電材料 / 角度分解光電子分光 / 熱電能 / 電子構造 / 電気伝導度 / 線形応答理論 / van Hove特異点
Research Abstract

2次元3角格子で特徴づけられるNa_xCoO_2は,巨大なゼーベック係数と金属的な電気伝導を示す.Na_xCoO_2で観測されるこれらの特徴的な熱電物性の起源は明らかではなく,その起源を解明することができれば,新しい熱電材料の材料設計指針の構築に大きく寄与できるはずである.我々は,2次元3角格子が生み出す電子構造に熱電物性の特徴を生み出す起源があると考え,高分解能角度分解光電子分光を用いてNa_xCoO_2の電子構造を明らかに,その熱電物性への影響を解明する研究を実施した.
測定した角度分解光電子分光スペクトルにおいて,波数kとともにエネルギー固有値が変化するスペクトル強度と,波数kに依存しないスペクトル強度が共存することを確認した.前者は,波として振る舞うコヒーレントな電子であり,後者は局在したインコヒーレントな電子である.電子状態がコヒーレントパートとインコヒーレントパートに分離する現象は,強い電子相関に影響を受けた典型的なフェルミ流体が示す特徴であり,Na_xCoO_2の電子状態が電子相関により強く影響を受けていることを示唆している.
角度分解光電子分光から得られた電子構造と線形応答理論から得られる熱電能の評価式を用いてゼーベック係数を計算したところ,ゼーベック係数の温度依存性及び組成依存性を定量的に再現することに成功した.その結果,Na_xCoO_2の熱電能は低温ではコヒーレントパートにより,また,高温ではインコヒーレントパートにより支配されていることがわかった.さらに,コヒーレントパートから生み出される熱電能が大きくなる原因として,2次元3角格子のファンホーベ特異点が重要な役割を果たしていることを解明した.

Report

(2 results)
  • 2008 Annual Research Report
  • 2007 Annual Research Report
  • Research Products

    (30 results)

All 2009 2008 2007

All Journal Article (7 results) (of which Peer Reviewed: 7 results) Presentation (23 results)

  • [Journal Article] Unusual increase of electron thermal conductivity caused by pseudogap at the Fermi level2009

    • Author(s)
      Tsunehiro Takeuchi
    • Journal Title

      Journal of Electronic Materials Published online : 28 January 2009

    • Related Report
      2008 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Thermal Conductivity of The Al-based Quasicrystals and Approximants2009

    • Author(s)
      Tsunehiro Takeuchi
    • Journal Title

      Zeitschrift fuer Kristallographie 224

      Pages: 35-38

    • Related Report
      2008 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Large thermoelectric power of La_<2-x>Sr_xCuO_4 possessing two-dimensional electronic structure2009

    • Author(s)
      Haduki Komoto, Tsunehiro Takeuchi
    • Journal Title

      Journal of Electronic Materials Published online : 4 April 2009

    • Related Report
      2008 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Electronic structure and thermoelectric properties of the layered cobalt oxide NaxCoO_2(05<x<0.8) investigated by angle-resolved photoemission spectroscopy2007

    • Author(s)
      S. Kuno, T. Takeuch, H. Ikuta, T. Kondo, A. Kaminski, Y. Saito, S. Fujimori
    • Journal Title

      Proceedings of International Conference on Thermoelectrics (CDROM出版)

    • Related Report
      2007 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Large thermoelectric power generated by the van Hove singularity in NaxCoO_22007

    • Author(s)
      T. Takeuch, S. Kuno
    • Journal Title

      hermoelectric Power Generation, edited by T.P. Hogan, J. Yang, R. Funahashi, and T. Tritt (Mater. Res. Soc. Symp. Proc. Volume 1044, Warrendale, PA, 2007) 1044

    • Related Report
      2007 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Evidence for two energy scales in the superconducting state of optimally doped (Bi, Pb)_2(Sr, La)_2CuO_<6+δ>2007

    • Author(s)
      T. Kondo, T. Takeuchi, A. Kaminski, S. Tsuda, S. Shin
    • Journal Title

      Physical Review Letters 98

    • Related Report
      2007 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Quantitative evaluation of the thermoelectric power of (Bi, Pb)_2Sr_2CaCu_2O_<8+d> from the experimentally determined electronic structure2007

    • Author(s)
      T. Takeuchi, H. Kaga, Y. Okada, H. Ikuta, T. Baba, S. Tsuda, S. Shin
    • Journal Title

      Journal of Electron Spectroscopy and Related Phenomena 156-158

      Pages: 452-456

    • Related Report
      2007 Annual Research Report
    • Peer Reviewed
  • [Presentation] 高性能熱電材料を得る為の電子構造の条件2009

    • Author(s)
      竹内恒博
    • Organizer
      日本金属学会2009年春期大会
    • Place of Presentation
      東京工業大学大岡山キャンパス
    • Year and Date
      2009-03-29
    • Related Report
      2008 Annual Research Report
  • [Presentation] Na_xCoO_2(0.6≦x≦0.8)の電子輸送現象におけるコヒーレント-インコヒーレント転移2009

    • Author(s)
      有田正吾, 竹内恒博
    • Organizer
      日本物理学会
    • Place of Presentation
      立教大学池袋キャンパス
    • Year and Date
      2009-03-28
    • Related Report
      2008 Annual Research Report
  • [Presentation] Al-Mn-Fe-Si合金の電子構造と熱電物性2009

    • Author(s)
      外山泰弘, 間広文, 旭良司, 竹内恒博
    • Organizer
      日本物理学会
    • Place of Presentation
      立教大学池袋キャンパス
    • Year and Date
      2009-03-27
    • Related Report
      2008 Annual Research Report
  • [Presentation] Quantitative evaluation of electron transport properties for noble materials2009

    • Author(s)
      Tsunehiro Takeuchi
    • Organizer
      Synchrotron Radiation center. Quantum lunch seminar
    • Place of Presentation
      Synchrotron Radiation Center Stoughton, Wisconsin, United states
    • Year and Date
      2009-02-04
    • Related Report
      2008 Annual Research Report
  • [Presentation] Na_xCoO_2(0.5≦x≦0.8)の電子構造と熱電物性2009

    • Author(s)
      有田正吾, 近藤猛, 竹内恒博
    • Organizer
      2009年日本放射光学会年会・放射光科学合同シンポジウム
    • Place of Presentation
      東京大学本郷キャンパス
    • Year and Date
      2009-01-12
    • Related Report
      2008 Annual Research Report
  • [Presentation] 電子構造の詳細解析に基づく電子輸送現象(熱電物性)の定量評価2009

    • Author(s)
      竹内恒博
    • Organizer
      2009年日本放射光学会年会・放射光科学合同シンポジウム
    • Place of Presentation
      東京大学本郷キャンパス
    • Year and Date
      2009-01-11
    • Related Report
      2008 Annual Research Report
  • [Presentation] Electronic structure and thermoelectric property of layered cobalt oxides Na_xCoO_22008

    • Author(s)
      Syogo Arita, Syuhei Kuno, Tsunehiro Takeuchi
    • Organizer
      The IUMRS international conference in Asia 2008
    • Place of Presentation
      Nagoya Congress Center, Nagova, Japan
    • Year and Date
      2008-12-11
    • Related Report
      2008 Annual Research Report
  • [Presentation] Large thermoelectric power and metallic electrical conduction in the La_<2-x>Sr_xCuO_4 and Nd_<2x>Ce_xCuO_4 of two-dimensional electronic structure2008

    • Author(s)
      Haduki Komoto, Tsunehiro Takeuchi
    • Organizer
      The IUMRS international conference in Asia 2008
    • Place of Presentation
      Nagoya Congress Center, Nagoya. Japan
    • Year and Date
      2008-12-11
    • Related Report
      2008 Annual Research Report
  • [Presentation] The conditions of spectral conductivity to optimize thermoelectric properties for developing practical thermoelectric materials2008

    • Author(s)
      Tsunehiro Takeuchi
    • Organizer
      The IUMRS international conference in Asia 2008
    • Place of Presentation
      Nagoya Congress Center, Nagoya, Japan
    • Year and Date
      2008-12-10
    • Related Report
      2008 Annual Research Report
  • [Presentation] NaxCoO2(0.5〓x〓0.8)の電子構造と熱電物性2008

    • Author(s)
      有田正吾, 久野修平, 竹内恒博
    • Organizer
      日本熱電学会学術講演会(TSJ2008)
    • Place of Presentation
      早稲田大学大久保キャンパス
    • Year and Date
      2008-08-22
    • Related Report
      2008 Annual Research Report
  • [Presentation] Large thermoelectric power of La_<2-x>Sr_xCuO_4 possessing two-dimensional electronic structure2008

    • Author(s)
      Haduki Komoto, Tsunehiro Takeuchi
    • Organizer
      International Conference on Thermoelectrics 2008(ICT2008)
    • Place of Presentation
      Oregon state University Corvallis, Oregon, United states
    • Year and Date
      2008-08-06
    • Related Report
      2008 Annual Research Report
  • [Presentation] Unusual increase of electron thermal conductivity caused by pseudogap at the Fermi level2008

    • Author(s)
      Tsunehiro Takeuchi
    • Organizer
      International Conference on Thermoelectrics 2008(ICT2008)
    • Place of Presentation
      Oregon state University Corvallis, Oregon, United states
    • Year and Date
      2008-08-04
    • Related Report
      2008 Annual Research Report
  • [Presentation] Development of thermoelectric materials with precisely determined electronic structure and phonon dispersion2008

    • Author(s)
      Tsunehiro Takeuchi
    • Organizer
      NIMS Conference 2008
    • Place of Presentation
      Tsukuba International Congress Center, EPOCHALT SUKUBA, Tsukuba, Japan
    • Year and Date
      2008-07-15
    • Related Report
      2008 Annual Research Report
  • [Presentation] Thermal Conductivity of The Al-based Quasicrystals and Approximants2008

    • Author(s)
      Tsunehiro Takeuchi, Masatoshi Shinmei
    • Organizer
      10th International Conference on Quasicrystals (ICQ10)
    • Place of Presentation
      ETH Zurich Zurich, Switzerland
    • Year and Date
      2008-07-10
    • Related Report
      2008 Annual Research Report
  • [Presentation] La_<2-x>SrxCuO_4の熱電特性2008

    • Author(s)
      河本葉月, 竹内恒博
    • Organizer
      第142回日本金属学会春期講演大会
    • Place of Presentation
      武蔵工業大学世田谷キャンパス
    • Year and Date
      2008-03-27
    • Related Report
      2007 Annual Research Report
  • [Presentation] 層状Co酸化物NaxCoO_2の軟X線角度分解光電子分光2008

    • Author(s)
      久野修平, 竹内恒博, 生田博志, 斎藤祐児, 大河内拓雄
    • Organizer
      日本物理学会 第62回年次大会
    • Place of Presentation
      近畿大学大学本部キャンパス
    • Year and Date
      2008-03-23
    • Related Report
      2007 Annual Research Report
  • [Presentation] 光電子分光法を用いた電子輸送現象の定量評価(物性研究と材料開発への応用2008

    • Author(s)
      竹内 恒博
    • Organizer
      第3回JAEA放射光科学研究シンポジウム
    • Place of Presentation
      SPring-8 放射光普及棟
    • Year and Date
      2008-02-29
    • Related Report
      2007 Annual Research Report
  • [Presentation] Large thermoelectric power generaed by the van Hove singularity of two-dimensional triangular lattice2007

    • Author(s)
      Tsunehiro Takeuchi
    • Organizer
      Materials Research Society, 2007 Fall Meeting(米国)
    • Place of Presentation
      ハインスコンベンションセンターボストン,米国
    • Year and Date
      2007-11-26
    • Related Report
      2007 Annual Research Report
  • [Presentation] 層状Co酸化物鞍NaxCoO_2の熱電特性のキャリア濃度依存性2007

    • Author(s)
      久野 修平, 生田 博志, 近藤 猛, A. Kaminski, 伊藤 孝寛, 竹内 恒博
    • Organizer
      日本物理学会 第62回年次大会
    • Place of Presentation
      北海道大学札幌キャンパス
    • Year and Date
      2007-09-23
    • Related Report
      2007 Annual Research Report
  • [Presentation] 層状Co酸化物鞍NaxCoO_2の熱電特性のキャリア濃度依存性2007

    • Author(s)
      久野 修平, 生田 博志, 近藤 猛, A. Kaminski, 竹内 恒博
    • Organizer
      第4回 日本熱電学会学術講演会
    • Place of Presentation
      大阪大学吹田キャンパス
    • Year and Date
      2007-08-30
    • Related Report
      2007 Annual Research Report
  • [Presentation] Electronic structure and thermoelectric properties of NaxCoO_2(x=0.6,0.8)2007

    • Author(s)
      T. Takeuchi, S. Kuno, T. Kitao, H. Ikuta, T. Kondo, A. Kaminski, Y. Saito, S. Fujimori, T. Ohkochi
    • Organizer
      15th international conference on vacuum ultraviolet radiation physics (VUV15)
    • Place of Presentation
      コンツエルトハウスベルリン,ドイツ
    • Year and Date
      2007-07-30
    • Related Report
      2007 Annual Research Report
  • [Presentation] 電子構造とフォノン分散の詳細解析による熱電材料設計指針の構築2007

    • Author(s)
      竹内恒博(招待講演)
    • Organizer
      日本熱電学会第5回研究会
    • Place of Presentation
      湘南工科大学東京キャンパス
    • Year and Date
      2007-06-22
    • Related Report
      2007 Annual Research Report
  • [Presentation] Electronic structure and thermoelectric properties of the layered cobalt oxide NaxCoO_2(0.5<x<0.8) investigated by angle-resolved photoemission spectroscopy2007

    • Author(s)
      S. Kuno, T. Takeuchi, H. Ikuta, T. Kondo, A. Kaminski, Y. Saito, S. Fujimori
    • Organizer
      26th International conference on thermoelectrics
    • Place of Presentation
      済州島,大韓民国
    • Year and Date
      2007-06-06
    • Related Report
      2007 Annual Research Report

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Published: 2007-04-01   Modified: 2016-04-21  

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