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2005 Fiscal Year Final Research Report Summary

Development of next generation Peltier materials by means of misfit-layered sulfides

Research Project

Project/Area Number 15560582
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Inorganic materials/Physical properties
Research InstitutionTohoku University

Principal Investigator

MIYAZAKI Yuzuru  Tohoku University, Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (40261606)

Project Period (FY) 2003 – 2005
KeywordsThermoelectric conversion / Peltier materials / Misfit / Sulfides / Composite crystals / Thermoelectric power / Thermoelectric properties / Structure analyses
Research Abstract

We have focused on preparing misfit-layered sulfides [Ln_2S_2]_pTS_2 (Ln:lanthanide ions, T:transition metal ions), in which a large thermoelectric power factor and a low lattice thermal conductivity can be simultaneously realized, to design novel Peltier materials. First of all, a T=Nb system has been explored to prepare new p-type materials. Except for Ln=Eu and Lu, all the lanthanides ions including Y are found to form [Ln_2S_2]_pNbS_2 phases. Three-types of structure with different superspace group are discovered depending on their ionic radii. Larger ions with Ln=La,Ce and Pr form orthorhombic Fm2m(p00)00s, while the samples with Ln=Nd and Sm form Fm2m(p00)000. For smaller ions with Ln=Gd,Tb,Dy,Ho,Er,Tm,Yb and Y, monoclinic F2(p0q) phases are obtained. The sample with Ln=Yb exhibits the highest thermoelectric figure-of-merit Z=3.2 x 10^<-4> K^<-1>, with the Seebeck coefficient S=60μVK^<-1>, resistivity ρ=1.4 mΩcm and κ=0.80 WK^<-1>m^<-1>, at around 300 K, yielding the dimensionles … More s figure-of-merit ZT〜0.1. The Z value still increases with increasing temperature, but the maximum value of Z as well as the highest limit temperature to be utilized are not determined in detail. Next, we have fabricated a thermoelectric pn junction (1 pair) using a Yb-Nb-S compound as a p-type leg and a Sn-Ti-S compound as an n-type leg. The pn uncouple was attached to an Al sheet on its top with silver paste and then was subjected to the Peltier property measurements. At the beginning, a small temperature difference with several kelvin was in fact observed but the difference became small and reached zero with further applying an electric current. This behavior can be ascribed to the fact that the Seebeck coefficient of the both legs was not enough (〜70μVK^<-1>) to keep generating temperature difference because the generated Joule heat easily overcame the temperature difference. Hence, further study is necessary to design sulfide thermoelectric materials which have larger figure-of-merit. Less

  • Research Products

    (18 results)

All 2006 2005 2004 2003

All Journal Article (16 results) Book (2 results)

  • [Journal Article] Compounds and subsolidus phase relations in the CaO-Co_3O_4-CuO system2005

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Journal of Solid State Chemistry 178

      Pages: 2973-2979

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Preparation and thermoelectric properties of misfit layered sulfides [Ln_2S_2]_pNbS_22005

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Proceedings of the 23^<rd> International Conference on Thermoelectrics

      Pages: 081(3 pages)

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Bismuth substitution effect on the structure and thermoelectric properties of [Ca_2CoO_3]_pCoO_22005

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Transactions of the Materials Research Society of Japan 30

      Pages: 499-502

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Preparation and thermoelectric properties of oxygen-deficient misfit layered cobaltite [Ca_2CoO_<3-δ>]_pCoO_22005

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Proceedings of the 23^<rd> International Conference on Thermoelectrics

      Pages: 129(3 pages)

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Compounds and subsolidus phase relations in the CaO-Co_3O_4-CuO System2005

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Journal of Solid State Chemistry 178

      Pages: 2973-2979

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Preparation and thermoelectric properties of misfit layered sulfides [Ln_2S_2]_pNbS_22005

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Proceedings of the 23^<rd> International Conference on Thermoelectrics 081

      Pages: 3

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Preparation and thermoelectric properties of oxygen-deficient misfit layered cobaltite [Ca_2CoO_<3-δ>}_pCoO_22005

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Proceedings of the 23^<rd> International Conference on Thermoelectrics 129

      Pages: 3

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Preparation and thermoelectric properties of misfit layered sulfide [Yb_<1.90>S_2]_<0.62>NbS_22004

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Japanese Journal of Applied Physics 43

      Pages: L1202-L1204

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Crystal structure and thermoelectric properties of the misfit-layered cobalt oxides2004

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Solid State Ionics 172

      Pages: 463-467

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] 大きな熱電能を持つミスフィット層状化合物(Ca_2CoO_3)_pCoO_2の結晶構造2004

    • Author(s)
      宮崎 譲
    • Journal Title

      日本結晶学会誌 46

      Pages: 21-26

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Modulated structure of misfit-layered cobalt oxide [(Ca_<0.90>Bi_<0.10>)_2(Co_<0.95>Bi_<0.05>)O_3]_pCoO_22004

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Japanese Journal of Applied Physics 43

      Pages: 6252-6258

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Effect of 3d-transition metal substitution on the thermoelectric properties of the misfit-layered cobalt oxide [Ca_2CoO_3]_pCoO_22004

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Proceedings of the 22^<nd> International Conference on Thermoelectrics

      Pages: 203-206

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Modulated structure of the misfit layer thermoelectric compound (Ca_2CoO_3)_pCoO_22004

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Journal of the Crystallographic Society of Japan 46

      Pages: 21-26

    • Description
      「研究成果報告書概要(欧文)」より
  • [Journal Article] Modulated structure of misfit-layered cobalt oxide [Ca_2(Co_<0.6>5Cu_<0.35>)_2O_4]_<0.63>CoO_22003

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Japanese Journal of Applied Physics 42

      Pages: 7467-7473

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] 複合結晶[(Ca_<1-x>Sr_x)_2CoO_3]_pCoO_2 の結晶構造と熱電特性2003

    • Author(s)
      宮崎 譲
    • Journal Title

      粉体および粉末冶金 50

      Pages: 475-479

    • Description
      「研究成果報告書概要(和文)」より
  • [Journal Article] Crystal structure and thermoelectric properties of the composite crystal [(Ca_<1-x>Sr_x)_2CoO_3]_pCoO_22003

    • Author(s)
      Yuzuru Miyazaki
    • Journal Title

      Journal of the Japan Society of Powder and Powder Metallurgy 50

      Pages: 475-479

    • Description
      「研究成果報告書概要(欧文)」より
  • [Book] 環境調和型新材料シリーズ「熱電変換材料」2.2章2006

    • Author(s)
      宮崎 譲
    • Total Pages
      7
    • Publisher
      日刊工業新聞社
    • Description
      「研究成果報告書概要(和文)」より
  • [Book] Environment Friendly New Materials Series, "Thermoelectric materials", Section 2.22006

    • Author(s)
      Yuzuru Miyazaki
    • Total Pages
      7
    • Publisher
      The Nikkan Kogyo Shimbun Ltd.
    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2007-12-13  

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