High Thermoelectric Figure of Merit of Full‐Heusler Ba2AuX (X = As, Sb, and Bi)

Abstract

Herein, an unprecedentedly high thermoelectric figure of merit (ZT) in full‐Heusler compounds of Ba2AuX (X = As, Sb, and Bi) is predicted by performing first‐principles calculations combined with parameter‐free Boltzmann transport equations. It is found that the ZT can reach up to 5 and 3 at 800 K in n‐ and p‐type systems, respectively, and can be as high as 1.7 and 1.0 at room temperature. The high ZT is attributed to the high power factor coupled with low thermal conductivity. The spin–orbit coupling (SOC) is necessarily considered because the exclusion of SOC significantly overestimates the electron mobility but underestimates the hole mobility of Ba2AuBi. The Lorenz number is found to exhibit an expected monotonical increase with carrier concentration, in contrast to the reported literature results.