Precipitate morphologies of pseudobinary Sb2Te3-PbTe thermoelectric compounds

Nanostructured thermoelectric materials offer promising levels of conversion efficiency due to enhanced phonon scattering at interfaces, and a good understanding of the formation and evolution of their microstructure is important. In this paper, we analyze precipitate morphologies of pseudobinary Sb2Te3-PbTe thermoelectric compounds using energetics analysis, combining the equivalent inclusion method and phase-field simulations. It is found that Sb2Te3 precipitates embedded in PbTe matrix tend to be lamellar, ribbon-like or needle-like in shape to minimize the potential energy, and tend to lie on a crystallographical cone around the body diagonal of the PbTe lattice. Furthermore, phase-field simulations reveal that interfacial energy plays an important role in precipitate morphology, with low interfacial energy favoring needle-like precipitates, while intermediate interfacial energy favors ribbon-like ones. Good agreements with experimental data and compatibility analysis are observed. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.