Promising thermoelectric performance of full-Heusler compound Sr2AuBi

Abstract

Heusler alloys are important class of materials having remarkable electronic, magnetic, spintronic, and topological properties. Due to their larger power factors, full-Heusler compounds could be promising candidates for thermoelectric applications if the systems have smaller lattice thermal conductivity. Here, we demonstrate by first-principles and Boltzmann transport theory that the Sr2AuBi compound is a good choice, which is thermodynamically stable up to 500 K. It is found that the system exhibits weak phonon dispersion and strong anharmonicity, leading to ultrasmall lattice thermal conductivity of 0.64 W/mK at room temperature. As a consequence, a maximum p-type ZT of 2.1 can be reached at 300 K. If the temperature is further increased to 450 K, it is interesting to find that a comparable ZT of 1.7 can be realized for both n- and p-type systems.