Enhanced figure of merit of TaIrGe Half-Heusler alloy for thermoelectric applications under the effect of isotropic strain

Abstract

The structural, electronic and transport properties of the Half-Heusler TaIrGe compound have been reported at different values of tensile and compressive strain using density functional theory (DFT) in conjunction with Boltzmann transport theory. The mechanical and thermodynamical stability of TaIrGe at different values of isotropic strain is confirmed by the calculated value of elastic constants and the phonon dispersion curve, respectively. The electronic structure calculations reveals that the energy bandgap changes significantly on applying tensile and compressive strain. The calculated low value of lattice thermal conductivity (kl) and high value of power factor are key factors in enhancing the performance of resultant thermoelectric material. The calculated value of figure of merit (ZT) for pristine TaIrGe compound is 0.69 and it attains a maximum value (0.82) for 4% tensile strain at T ​= ​1200 ​K, which shows that it can be used as an efficient thermoelectric material under the effect of isotropic strain for high temperature applications.