Size control of Sb2Te3 Widmanstätten precipitates in thermoelectric PbTe

Teruyuki Ikeda*, Nathan J. Marolf, Kristin Bergum, Marcus B. Toussaint, Nicholas A. Heinz, Vilupanur A. Ravi, G. Jeffrey Snyder

*Corresponding author for this work

Research output: Contribution to journalArticle

22 Scopus citations

Abstract

The number density and area per unit volume of Sb2Te3 Widmanstätten plates in thermoelectric PbTe were controlled through two types of heat treatments of (PbTe)1-x-(Sb 2Te3)x, where x = 0.04 and 0.06: isothermal annealing at various temperatures and cooling from a solid-solution regime to a two-phase region with various rates. The microstructure was quantified by image analysis of scanning electron micrographs and Rietveld refinements of X-ray diffraction profiles. Isothermal annealing of (PbTe)0.94-(Sb 2Te3)0.06, results in increasing number density and area per volume of precipitates with decreasing temperature. In controlled cooling rate experiments, faster cooling rates or smaller x result in higher number density and area per volume. These trends are discussed using phase transformation theories. Overall the number density and area per volume of precipitates were controlled in the ranges from 0.4 to 44 μm-3 and from 0.5 to 1.8 μm-1, respectively. Isothermal annealing was performed for time periods from 10 to 166 h at 723 K to check the stability of the microstructure at the (PbTe)0.94-(Sb2Te 3)0.06 composition. While the Boyd and Nicholson model of the Greenwood-Lifshitz-Slyozov-Wagner theory for the average diameter of plates gives a reasonable value for peripheral interfacial energy, the time dependence was found to decelerate more than the t1/3 rule. It has also been found that the coarsening mechanism involves the elongation of plates.

Original languageEnglish (US)
Pages (from-to)2679-2692
Number of pages14
JournalActa Materialia
Volume59
Issue number7
DOIs
StatePublished - Apr 1 2011

Keywords

  • Image analysis
  • Nanostructured materials
  • Precipitation kinetics
  • Scanning electron microscopy
  • Thermoelectric materials

ASJC Scopus subject areas

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

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    Ikeda, T., Marolf, N. J., Bergum, K., Toussaint, M. B., Heinz, N. A., Ravi, V. A., & Jeffrey Snyder, G. (2011). Size control of Sb2Te3 Widmanstätten precipitates in thermoelectric PbTe. Acta Materialia, 59(7), 2679-2692. https://doi.org/10.1016/j.actamat.2011.01.006