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Thermoelectric calculation at finite temperature: towards environmentally benign thermoelectric materials

Research Project

Project/Area Number 17K14922
Research Category

Grant-in-Aid for Young Scientists (B)

Allocation TypeMulti-year Fund
Research Field Energy engineering
Research InstitutionThe University of Tokyo (2019)
Osaka University (2017-2018)

Principal Investigator

Hirayama Naomi  東京大学, 物性研究所, 特任研究員 (70581750)

Project Period (FY) 2017-04-01 – 2020-03-31
Project Status Completed (Fiscal Year 2019)
Budget Amount *help
¥4,420,000 (Direct Cost: ¥3,400,000、Indirect Cost: ¥1,020,000)
Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2018: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2017: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Keywords第一原理計算 / 熱電材料 / シリサイド / 不純物効果 / 熱電輸送現象 / 熱電効果 / ゼーベック係数 / 化学圧力 / 全電子計算 / FLAPW法 / 有効質量 / 熱電発電 / 物性理論 / 不純物ドーピング / マグネシウムシリサイド / カーボンナノチューブ / 不純物ドープ / 不純物サイト / 格子欠陥 / 半導体物性 / 再生可能エネルギー
Outline of Final Research Achievements

First, we theoretically investigated Mg2Si with various p-type dopants and found that they exhibit comparable formation energies for different impurity sites, which may explain the experimental instability of their p-type conductivity. Furthermore, our calculation predicted new acceptors (Cl and F). We also revealed that the enhancement of power factor by increasing the lattice constant originates from a larger effective mass of bottom conduction bands.
Next, we investigated the fluorine doping in LaOBiS2-type layered compounds and found that the structural phase is closely related to the doping―monoclinic distortion of the mother compound decreases the capability of Fluorine doping.
Finally, our analysis of semiconducting carbon nanotubes showed that their thermoelectric performance depends on the distribution of vacancies, which suggests the possibility of thermoelectric performance improvement by controlling the structural properties including defects.

Academic Significance and Societal Importance of the Research Achievements

近年,エネルギー資源の枯渇と環境汚染の問題が加速するなか,熱エネルギーを電気エネルギーに直接変換する熱電変換技術の本格的な普及が望まれる.しかし,既存の主要な熱電材料の多くは,毒性や資源希少性の問題があり,実用化には限界があった.本研究では,環境低負荷型熱電材料の性能向上にむけて,第一原理計算に基づく材料設計指針の提案を行った.キャリア密度制御のため,安定な不純物ドーピングを実現する方法を検討したほか,結晶の構造特性が熱電性能に及ぼす影響を,電子状態計算に基づき考察した.本研究から得られた知見は,熱電材料の高性能化にむけた重要な示唆を与えるものである.

Report

(4 results)
  • 2019 Annual Research Report   Final Research Report ( PDF )
  • 2018 Research-status Report
  • 2017 Research-status Report
  • Research Products

    (11 results)

All 2020 2019 2018 2017

All Journal Article (5 results) (of which Peer Reviewed: 5 results,  Open Access: 2 results) Presentation (5 results) (of which Int'l Joint Research: 1 results) Book (1 results)

  • [Journal Article] Conduction band engineering of Mg2Si by isotropic strain for enhancement of thermoelectric performance: a first-principles study2020

    • Author(s)
      N. Hirayama, Y. Imai, and N. Hamada
    • Journal Title

      Journal of Applied Physics

      Volume: 127 Issue: 20 Pages: 205107-205107

    • DOI

      10.1063/5.0001857

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Change of the band structure of Mg2Si induced by interstitial doping with nonmetallic elements2020

    • Author(s)
      Y. Imai, N. Hirayama, A. Yamamoto, and K. Takarabe
    • Journal Title

      Japanese Journal of Applied Physics

      Volume: 59 Issue: SF Pages: SFFC04-SFFC04

    • DOI

      10.7567/1347-4065/ab6567

    • NAID

      210000157894

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Theoretical study of fluorine doping in layered LaOBiS2-type compounds2019

    • Author(s)
      N. Hirayama, M. Ochi, and K. Kuroki
    • Journal Title

      Physical Review B

      Volume: 100 Issue: 12

    • DOI

      10.1103/physrevb.100.125201

    • Related Report
      2019 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Substitutional and interstitial impurity p-type doping of thermoelectric Mg2Si: a theoretical study2019

    • Author(s)
      Hirayama Naomi、Iida Tsutomu、Sakamoto Mariko、Nishio Keishi、Hamada Noriaki
    • Journal Title

      Science and Technology of Advanced Materials

      Volume: 20 Issue: 1 Pages: 160-172

    • DOI

      10.1080/14686996.2019.1580537

    • Related Report
      2018 Research-status Report
    • Peer Reviewed / Open Access
  • [Journal Article] Influence of native defects on structural and electronic properties of magnesium silicide2017

    • Author(s)
      N. Hirayama, T. Iida, K. Nishio, Y. Kogo, K. Takarabe, and N. Hamada
    • Journal Title

      Japanese Journal of Applied Physics

      Volume: 57 Issue: 5S1 Pages: 05DC05-05DC05

    • DOI

      10.7567/jjap.56.05dc05

    • NAID

      210000147765

    • Related Report
      2017 Research-status Report
    • Peer Reviewed
  • [Presentation] Effects of Electron-phonon Scattering on Temperature Dependence of Half-metallicity of Co2MnSi2019

    • Author(s)
      N. Hirayama and H. Akai
    • Organizer
      Materials Research Meeting 2019
    • Related Report
      2019 Annual Research Report
  • [Presentation] Enhancement of Thermoelectric Performance of N-type Mg2Si by Chemical Pressure of Impurity Dopants2019

    • Author(s)
      N. Hirayama, Y. Imai, and N. Hamada
    • Organizer
      17th European Conference on Thermoelectrics
    • Related Report
      2019 Annual Research Report
  • [Presentation] 第一原理計算によるLaOBiS2およびLaOSbSe2におけるフッ素ドープと結晶構造の関係2018

    • Author(s)
      平山 尚美
    • Organizer
      日本物理学会2018年秋季大会
    • Related Report
      2018 Research-status Report
  • [Presentation] 第一原理計算によるLaOBiS2およびLaOSbSe2におけるフッ素ドープと結晶構造の関係2018

    • Author(s)
      平山 尚美
    • Organizer
      第15回日本熱電学会学術講演会
    • Related Report
      2018 Research-status Report
  • [Presentation] Theoretical Study on the Fluorine Doping for Layered Thermoelectric Materials with LaOBiS2-type Structures2018

    • Author(s)
      Naomi Hirayama
    • Organizer
      XVI INTERSTATE CONFERENCE Thermoelectrics and their applications 2018 (ISCTA 2018)
    • Related Report
      2018 Research-status Report
    • Int'l Joint Research
  • [Book] Thermoelectric Energy Conversion -Theory, New Phenomena, Materials Design, Modules, and Applications-2020

    • Author(s)
      R. Funahashi et al.
    • Publisher
      Elsevier
    • Related Report
      2019 Annual Research Report

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Published: 2017-04-28   Modified: 2021-02-19  

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