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Correlation between pseudo-gap electronic structures and thermoelectric properties in Fe_2 VAl intermetallic compounds

Research Project

Project/Area Number 13450258
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Physical properties of metals
Research InstitutionNagoya University

Principal Investigator

SODA Kazuo  Nagoya University, Graduate School of Engineering, Professor, 工学研究科, 教授 (70154705)

Co-Investigator(Kenkyū-buntansha) YUHARA Junji  Nagoya University, Graduate School of Engineering, Research Associate, 工学研究科, 助手 (10273294)
KATO Masahiko  Nagoya University, Graduate School of Engineering, Assistant Professor, 工学研究科, 助手 (70222429)
YAGI Shinya  Nagoya University, Graduate School of Engineering, Associate Professor, 工学研究科, 助教授 (20284226)
Project Period (FY) 2001 – 2002
Project Status Completed (Fiscal Year 2002)
Budget Amount *help
¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2002: ¥1,400,000 (Direct Cost: ¥1,400,000)
KeywordsFe-based Heusler-type Alloys / thermoelectric properties / mid-pseudo-gap electronic states / photoelectron spectroscopy / invese photoelectron spectroscopy / Fe_2VAl系金属間化合物 / 擬ギャップ / 電子状態
Research Abstract

The Heusler-type Fe_2VAl compound has been theoretically predicted to have a pronounced pseudo-gap across the Fermi level and experimentally proved to show the drastic change in the electronic transport properties and the large enhancement of the thermoelectric power on the deviation of the composition from its stoichiometry. The purpose of this research is to experimentally clarify the relation between their electronic structures and thermoelectric properties of the Heusler-type Fe_2VAl-related alloys with use of the normal and inverse photoelectron spectroscopy, and thus to obtain a new guideline for developing thermoelectric materials.
In this study, the electronic structures have been investigated for the stoichiometric Fe_2VAl, off-stoichiometric (Fe_<2/3>V_<1/3>)_<100-y>Al_y and Fe_<2-x>V_<1+x>Al, and substituted Fe_2VAl_<1-z>Si_z. It is experimentally shown for the first time that the existence of the pseudo-gap and the relative position of the Fermi level in the pseudo-gap are strongly related to their thermoelectric properties. The change in the electronic structure near the Fermi level and thermoelectric properties with the composition is explained qualitatively by a rigid band model for (Fe_<2/3>V_<1/3>)_<100-y>Al_y and Fe_2VAl_<1-z>Si_z but not for Fe_<2-x>V_<1+x>Al. This arises from the large modification of the electronic structure near the Fermi level due to the transition metal d states in contrast to the sp valence states of Al and Si. These mid-gap d states are responsible for the unusual transport properties at low temperatures. Thus it is important to control the d states near the Fermi level for the further development of these Heusler-type alloys as thermoelectric materials. We suggest that the substitution of the forth element for the Fermi level positioning and the microscopic structural control for the low thermal conductivity are effective for the development.

Report

(3 results)
  • 2002 Annual Research Report   Final Research Report Summary
  • 2001 Annual Research Report
  • Research Products

    (10 results)

All Other

All Publications (10 results)

  • [Publications] K.Soda et al.: "High-resolution photoelectron spectroscopy of Heasler-type Fe_2VAl alloy"J.Synchrotron Rad.. 9. 233-236 (2002)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] K.Soda et al.: "Magnetic circular dichroism at transition metal L_<2,3> edges in DO_3-type (Fe_<1-x>Mn_x)_3Al alloys"J.Synchrotron Rad.. 8. 455-456 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] O.Yoshimoto et al.: "Magnetic circular dichroism at transition metal L_<2,3> edges in DO_3-type (Fe_<1-x>Mn_x)_3Al alloys"J.Synchrotron Rad.. 8. 457-459 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Y.Saitoh et al.: "Soft X-ray beamline for spectroscopy of solids at Spring-8"Nucl.Instrum. Methods A. 467-468. 553-556 (2001)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] K.Soda et al.: "High-resolution photoelectron spectroscopy of Heusler-type Fe_2VAl alloy"J.Synchrotron Rad.. 9. 233-236 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] K.Soda et al.: "Magnetic circular dichroism at transition metal L_<2,3> edges in D0_3-type(Fe_<1-x>Mn_x)_3Al alloys"J.Synchrotron Rad.. 8. 455-456 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] O.Yoshimoto et al.: "Magnetic circular dichroism at transition metal L_<2,3> edges in D0_3-type(Fe_<1-x>V_x)_3Al alloys"J.Synchrotron Rad.. 8. 457-459 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] Y.Saitoh et al.: "Soft X-ray beamline for spectroscopy of solids at SPring-8"Nucl.Instrum.Methods. A467-A468. 553-556 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2002 Final Research Report Summary
  • [Publications] K.Soda et al.: "High-resolution Photoelectron Spectroscopy of Heusler-type Fe_2 VAl Alloy"J. Synchrotron Rad.. 9. 233-236 (2002)

    • Related Report
      2002 Annual Research Report
  • [Publications] O.Yoshimoto, K.Kato, K.Soda 他: "Magnetic Circular Drchroism at Transition Metal L_<2,3> Edges in DO_3-type (Fe_<1-x>Vx)_3Al"J.Synchrotron Rad.. 8. 457-459 (2001)

    • Related Report
      2001 Annual Research Report

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Published: 2002-04-01   Modified: 2016-04-21  

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