Effects of Ga substitution on electronic and thermoelectric properties of gapless semiconductor V3Al

Abstract

Thermoelectric properties of the antiferromagnetic (AF) gapless semiconductor (GS) V₃Al were optimized by substituting Al with the isoelectric element Ga in the D0₃ structure. Structural and mechanical stability, electronic structure and transport properties of V₃Al_1−xGa_x (x = 0.25, 0.5, 0.75 and 1) compounds have been studied based on first-principles calculations with the combination of the semi-classical Boltzmann theory and deformation potential theory. All the compounds are structurally and mechanically stable gapless semiconductors. The Ga substitution for Al leads to an appreciably decreased thermal conductivity and an undesirable decrease in power factor, but contributes more to the decreased thermal conductivity. Consequently, the figure of merit (zT) is effectively improved in V₃Al_0.75Ga_0.25 and V₃Ga compounds with respect to V₃Al.