Investigation on native defects of α-MgAgSb and its effects on thermoelectric properties using first principles calculations

Abstract

α-MgAgSb is a promising thermoelectric materials having good performance at medium temperature. Native defects in α-MgAgSb are frequently reported experimentally and are tightly involved in the thermoelectric properties of α-MgAgSb. In this paper, all possible native defects in α-MgAgSb are calculated as well as detailed results are given and discussed. The concentrations of several dominant native defects, for example, VAg and AgSb, could reach up to 10−4 cm−3 at 540 K. Furthermore, the electronic structure and transport properties of α-MgAgSb with dominant native defects are investigated. Results show that the introduction of AgMg and VAg contributes to a much lower inertial mass and slight decrease in Seebeck coefficient. The lattice thermal conductivity is greatly reduced with the introduction of native defects. For α-MgAgSb with VAg, the peak ZT could reach up to 1.84 at 420 K. Our calculation demonstrates that defect engineering is an effective strategy to enhance thermoelectric performance of the materials.