Approaching the Minimum Lattice Thermal Conductivity of P-Type SnTe Thermoelectric Materials by Sb and Mg Alloying

SnTe, as the nontoxic analogue to high-performance PbTe thermoelectric material, has captured the worldwide interest recently. Many triumphant instances focus on the strategies of band convergence, resonant doping, and nano-precipitates phonon scattering. Herein, the p-type SnTe-based materials Sn-0.85 xSb0.15MgxTe (x = 0-0.10) are fabricated and a combined effect of Sb and Mg is investigated. Sb alloying tunes the hole carrier concentration of SnTe and decreases the lattice thermal conductivity. Mg alloying leads to a nearly hundredfold rise of disorder parameter due to the large mass and strain fluctuations, and as a consequence the lattice thermal conductivity decreases further down to similar to 0.64 W m(-1) K-1 at 773 K, close to the theoretical minimum of the lattice thermal conductivity (similar to 0.50 W m(-1) K-1) of SnTe. In conjunction with the enhancement of the Seebeck coefficient caused by band convergence due to Mg alloying, the maximum zT(max) reaches similar to 1.02 and the device zT(device) of similar to 0.50 at 773 K for Sn0.79Sb0.15Mg0.06Te, suggesting this SnTe-based composition has a promising potential in intermediate temperature thermoelectric applications. (C) 2019 Science China Press. Published by Elsevier B.V. and Science China Press. All rights reserved.