Enhanced electrical transport performance through cation site doping in Y-doped Mg3.2Sb2

Abstract

Mg3Sb2-based alloys are promising thermoelectric materials through n-type doping in Mg-rich growth conditions to overcome their intrinsic p-type behavior. First principle calculations are employed to investigate the dopant formation energy and electronic structures of Y-doped Mg3Sb2. Results indicate that the Y atom is more favorable for substitution at the cation site. Simultaneously, the flattened band structure and increased density of state near the Fermi level of Y-doped Mg3Sb2 indicate an enhanced electronic transport performance. The carrier concentration rises to 5.31 × 1019 cm−3 at room temperature, resulting in a significant increased power factor for Mg3.17Y0.03Sb2. The available optimization of electrical transport contributes to excellent thermoelectric performance, and a peak ZT ∼0.83 at 773 K was achieved for Y concentration x = 0.03 in Mg3.2-xYxSb2. This work provides an alternative measure for optimizing the thermoelectric performance of n-type Mg3Sb2 alloys by cation site doping. Keywords: First principle calculations, n-type Mg3Sb2, Y doping, Thermoelectric performance