2022/06/09 by Juan Li, K. L. Han, Kai Han +4
Materials Science · #Advanced Thermoelectric Materials and Devices #Thermal properties of materials #Thermal Expansion and Ionic Conductivity
paper · doi:10.1016/j.vacuum.2022.111239
Numerous efforts have been paid on n-type Mg 3 Sb 2 -based Zintl compounds with exceptional thermoelectric performance, but seldom on p-type sample with poor electrical transports. In this work, we investigate the electronic structure and transport properties of p-type Mg 3 Sb 2 by using first-principles method and Boltzmann transport theory. Firstly, the slightly higher low-temperature electrical conductivity for theoretical calculations than experimental results suggest that different from n-type sample, the contribution of eliminating grain boundary scattering to electrical transports is weak in p-type Mg 3 Sb 2 . Secondly, the calculated higher Seebeck coefficient along x -axis and higher electrical conductivity along z -axis reveal the anisotropy of electrical transports, and this phenomenon may be ascribed to the anisotropic carrier's effective masses. Because the gradual leading role of Seebeck coefficient as temperature increasing, the peak power factor along x -axis exceeds that along z -axis at temperature above ∼500 K, which indicates that further improvement of the electrical performance can be expected through anisotropic transports. Thirdly, the effect of the adsorption of oxygen atom on Mg 3 Sb 2 (001) surface on the electronic structure are investigated. This work aims to provide new insight into the optimization of p-type electrical transport property, thereby closing the gap with n-type property for developing Mg 3 Sb 2 -based thermoelectric devices.