Anomalous electrical conductivity of n-type Te-doped Mg3.2Sb1.5Bi0.5

Defects, which can scatter the carriers as well as alter the carrier concentration, could greatly impact the material's electrical conductivity. Here we report the anomalous temperature dependences of electrical conductivity observed in n-type Te-doped Mg3Sb2-based materials. These anomalies are induced by the variations of Hall carrier concentration and mobility, both of which are influenced by the defects that closely relate to the Te dopant. Our results demonstrate that Te concentration plays a critical role in manipulating the defect chemistry of n-type Mg3Sb2-based materials. The intricate relationship among the defects, composition, Fermi level, and temperature significantly complicates our understanding on the thermoelectric properties of n-type Mg3Sb2-based materials. Our work indicates that further enhancement in thermoelectric performance of this material is possible if the defects can be effectively controlled. (c) 2017 Elsevier Ltd. All rights reserved.