Low lattice thermal conductivity and high figure of merit in n-type doped full-Heusler compounds X2YAu (X = Sr, Ba; Y = as, Sb).

As a new type of thermoelectric (TE) material, full-Heusler compounds have aroused widespread interest, for its ultralow lattice thermal conductivity. The first-principles calculations and Boltzmann transport theory are used to study the TE transport properties of n-type doped full-Heusler compounds X2YAu (X = Sr, Ba; Y = As, Sb). At room-temperature, the calculated lattice thermal conductivities are 1.02, 0.89, 0.79, and 0.53 W/mK for Sr2AsAu, Ba2AsAu, Sr2SbAu, and Ba2SbAu, respectively. The ultralow κL is mainly by the extremely low uq and relatively high 1=q. By combining the calculated TE transport coefficients, we get the excellent dimensionless TE figure of merit zT of X2YAu (X = Sr, Ba; Y = As, Sb). The calculated zT of Sr2AsAu, Ba2AsAu, Sr2SbAu, and Ba2SbAu are 0.89, 0.59, 1.55, 0.87 at 300K and 3.35, 2.15, 4.45, 2.91 at 700 K, which indicate that X2YAu (X = Sr, Ba; Y = As, Sb) are potential and excellent TE materials. [ABSTRACT FROM AUTHOR]