Sb Substitution Effect on Thermoelectric Properties of Mg2Si

The effects of Sb dopant on electronic and thermoelectric properties of Mg2Si (Mg2Si1-x Sb (x) , 0.125 ae 0.5) have been studied using density functional theory and semiclassical Boltzmann transport theory. Classical kinetic theory was employed to calculate the lattice thermal conductivity. The calculations show that the Sb-doped Mg2Si system exhibits metallic nature and Sb enhances the thermoelectric efficiency of Mg2Si. Increase in the concentration of Sb leads to decrease in the Seebeck coefficient and increase in the electrical and electronic thermal conductivity as well as reduction in the lattice thermal conductivity. We found that the lattice thermal conductivity decreases with increase in temperature. There is little effect on the lattice thermal conductivity as the doping concentration is increased, but the overall thermal conductivity increases with increasing concentration due to increased electronic thermal conductivity. High ZT value of 0.47 is obtained at 1200 K for x = 0.125.