Thermoelectric Hexagonal A-Mg-Si with A = Sr and Ba Zintl Phases

T. Kajitani, K. Takahashi, M. Saito, H. Suzuki, S. Kikuchi, M. Kubouchi, K. Hayashi

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Hexagonal A-Mg-Si with A = Sr and Ba Zintl phases are promising candidates for p-type magnesium silicides usable with n-Mg2Si under 900 K. We synthesized p-type A-Mg-Si Zintl phases by the spark plasma synthesis procedure. Mg2Si and Mg2A powders were mixed at the ratio of 1−x/x with x = 0.3–0.4. Two-step synthesis was performed at 850 K for 20 min and 1100 K for 20 min under uniaxial pressure at 30 MPa. Sintered pellets exhibited a stable p-type thermoelectric property. These pellets consisted of several unknown phases. We found two semiconductor phases, namely A2Mg4Si3 and A2Mg12Si7. The crystal structures of the 2/4/3- and 2/12/7-phases were P6 ¯ 2 m (No. 189)- and P6 3/ m (No. 176)-types, respectively. Sr0.70Mg2Si, Ba3Mg10Si7 and Sr3Mg10Si7 phases are newly found and characterized by a single crystal diffraction study. Previously found Sr2Mg4Si3 single phase polycrystalline 30φ × 10 mm pellets were successfully synthesized. The thermoelectric performance of the Sr2Mg4Si3 single phase sample was tested. The pellets exhibit p-type behavior from room temperature to 700 K. The thermal conductivity, κ, was almost constant at 1.1 W/mK from 350 K to 700 K.

Original languageEnglish
Pages (from-to)5238-5245
Number of pages8
JournalJournal of Electronic Materials
Volume45
Issue number10
DOIs
Publication statusPublished - 2016 Oct 1

Keywords

  • Alkaline earth metal
  • Zintl phase
  • p-type magnesium silicon semiconductor
  • structure refinement

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering
  • Materials Chemistry

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