Solid-state synthesis of Mg2Si1-xYx(Y=Ge and Sn) thermoelectric materials via bulk mechanical alloying

R. B. Song, T. Aizawa, A. Yamamoto, T. Obara

Research output: Contribution to journalArticle

6 Citations (Scopus)

Abstract

Magnesium base compounds and their solid solution have a promising potential as a thermoelectric material to be working in the middle-temperature range of 500 to 800K. In the present study, intrinsic Mg2Si 1-xYx(Y=Ge and Sn; x=0, 0.2, 0.4, 0.6, 0.8 and 1.0) semi-conductive materials are successfully synthesized by the bulk mechanical alloying (BMA) at room temperature, starting from the elemental powder mixture. XRD and DTA techniques are used to describe the solid reaction process during BMA. The BMA specimens were further consolidated by the hot pressing (HP) at 773K by 1 GPa for 3.6ks for direct measurement of thermoelectric properties. Temperature dependence of the electrical conductivity, the Seebeck coefficient and thermal conductivity for both Mg2Si1-xGex and Mg2Si1-xSnx were measured from the room temperature up to 700K. With increasing temperature, the electrical conductivity increased, the Seebeck coefficient and thermal conductivity decreased. The changes of the thermoelectric properties were also investigated for various Ge and Sn concentration. The thermoelectric properties were sensitive to the Ge and Sn concentration. The p-n conversion takes place at the vicinity of x=0.35 for Mg2Si1- xGex and x=0.2 for Mg 2Si1-xSnx. The figure of merit of Mg 2Si0.6Ge0.4 in Mg-Si-Ge system reached 0.34 × 10-3K-1 at 610K and Mg2Si 0-4Sn0.6 in Mg-Si-Sn system reached 0.19 × 10 -3K-1 at 653K.

Original languageEnglish
Pages (from-to)347-350
Number of pages4
JournalJournal of Metastable and Nanocrystalline Materials
Volume24-25
DOIs
Publication statusPublished - 2005
Externally publishedYes

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Keywords

  • Bulk mechanical alloying
  • Hot pressing
  • Solid-state synthesis
  • Thermoelectricity

ASJC Scopus subject areas

  • Materials Science(all)
  • Physical and Theoretical Chemistry
  • Condensed Matter Physics

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