Precipitate morphologies of pseudobinary Sb2Te3Sb2Te3–PbTePbTe 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 Sb2Te3Sb2Te3–PbTePbTe thermoelectric compounds using energetics analysis, combining the equivalent inclusion method and phase-field simulations. It is found that Sb2Te3Sb2Te3 precipitates embedded in PbTePbTe 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 PbTePbTe 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.