Eutectic microstructures and thermoelectric properties of MnTe-rich precipitates hardened PbTe

Eutectic microcosmic characteristics, mechanical and thermoelectric properties are studied in Pb1-xMnxTe beyond the Mn solubility limit. Particle-like MnTe2 and lamellar MnTe precipitates are spontaneously formed, presumably due to the precipitate-matrix lattice misfit. MnTe-rich precipitates in PbTe can improve the mechanical properties without significant impact on the thermoelectric performance. Band degeneracy effect and additional phonon scattering by discontinued particle-like precipitates prompt a high figure of merit ZT of 1.5 in Pb0.94Mn0.06Te. Though continuum ordered lamellar precipitates lead to larger electrical resistivity and anomalous increase of lattice thermal conductivity, the average ZT (approximate to 0.8) in Pb1-xMnxTe (0.12 <= x <= 0.36) is still comparable with PbTe (all doped by 2% Na). Such precipitation hardening by eutectic microstructures without strongly influencing the thermoelectric performance can be promising for thermoelectric applications. (C) 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.