Effects of Ga substitution on electronic and thermoelectric properties of gapless semiconductor V 3 Al.

Thermoelectric properties of the antiferromagnetic (AF) gapless semiconductor (GS) V 3 Al were optimized by substituting Al with the isoelectric element Ga in the D0 3 structure. Structural and mechanical stability, electronic structure and transport properties of V 3 Al 1- x Ga 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 V 3 Al 0.75 Ga 0.25 and V 3 Ga compounds with respect to V 3 Al.