Thermoelectric properties of hexagonal WN6 from first-principles calculations
Abstract
Recent research demonstrated high thermoelectric figure of merit in CrN, implying that the transition metal nitrides could be promising thermoelectric materials. Herein, we investigate the thermoelectric properties of a newly predicted superhard material WN6 by using first-principles calculations and Boltzmann transport theory. Results indicate that WN6 has a small band gap of 0.76 eV, a relatively low lattice thermal conductivity of around 10.7 W/mk at 700 K, and a large Seeback coefficient of 1330 μV/K at 300 K. Its low lattice thermal conductivity and large Seeback coefficient lead to an excellent thermoelectric response, with the maximum thermoelectric figure of merit being 0.78 for n-type. The mode Grüneisen parameters and phonon mean free path are exhibited to analyze the anharmonic properties and the size effects. These results shed light on the thermoelectric performance of WN6.