Formation of Sb2Te3 Widmanstätten precipitates in thermoelectric PbTe

Teruyuki Ikeda, Vilupanur A. Ravi, G. Jeffrey Snyder*

*Corresponding author for this work

Research output: Contribution to journalArticle

55 Scopus citations

Abstract

Unidirectional solidification experiments have been performed with a thermoelectric alloy with a starting composition of Pb10.5Sb31.6Te57.9 in the pseudobinary PbTe-Sb2Te3 system. The bottom of the resulting rod consists of PbTe phase with Widmanstätten precipitates of Sb2Te3. The precipitation is due to a decrease in the solubility of Sb2Te3 with temperature: the solubility at 450 °C was determined to be 2.1 ± 0.2 at.% Sb. The average thickness of plates was estimated to be ∼100 nm. The spacings between neighboring plates has a distribution in the 200-3000 nm range, peaking around 900 nm. The habit planes of precipitation are of the {1 1 1}PbTe family. An orientation relationship of (0 0 0 1)Sb2Te3//{1 1 1}PbTe and <1 1over(2, -) 0>Sb2Te3//<1 1 0>PbTe was found with a maximum misorientation of 15°. The Seebeck coefficient after annealing at 450 °C was -50 ± 10 μV °C-1 at room temperature. To improve the thermoelectric properties, tuning of the carrier concentration would be necessary.

Original languageEnglish (US)
Pages (from-to)666-672
Number of pages7
JournalActa Materialia
Volume57
Issue number3
DOIs
StatePublished - Feb 1 2009

Keywords

  • Bridgman technique
  • Precipitation
  • Solidification microstructure
  • Thermoelectric materials

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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