Intrinsically high thermoelectric figure of merit of half-Heusler ZrRuTe

Abstract

The electronic structure and thermoelectric properties of ZrRuTe-based Half-Heusler compounds are studied using density functional theory (DFT) and Boltzmann transport formalism. Based on rigorous computations of electron relaxation time $\tau$ considering electron-phonon interactions and lattice thermal conductivity $\kappa_l$ considering phonon-phonon interactions, we find ZrRuTe to be an intrinsically good thermoelectric material. It has a high power factor of $\sim 2\times 10^{-3}$ W/m-K$^{2}$ and low $\kappa_l\sim 10$ W/m-K at 800 K. The thermoelectric figure of merit $ZT \sim 0.13$ at 800 K is higher than similar other compounds. We have also studied the properties of the material as a function of doping and find the thermoelectric properties to be substantially enhanced for $p$-doped ZrRuTe with the $ZT$ value raised to $\sim 0.2$ at this temperature. The electronic, thermodynamic, and transport properties of the material are thoroughly studied and discussed