The Thermoelectric Properties of KSc(Si, Ge, Sn, Pb) Half-Heusler Alloys

The ground state properties and thermoelectric efficiency of KScX (X = Si, Ge, Sn, and Pb) half-Heusler alloys are investigated using the density functional theory and Boltzmann transport equation. For all compounds under study, the low values of lattice thermal conductivity κlat, which are below 3.5 W m–1 K–1 over the whole temperature range, are obtained. The room temperature values of κlat are calculated to be 2.31, 1.20, 1.19, and 0.40 W m–1 K–1 for KScX (X = Si, Ge, Sn, and Pb), respectively. It is shown that at room temperature, the thermoelectric figure of merit zT is predicted to be 0.70, 0.80, 0.74, and 0.91 and 0.42, 0.58, 0.61, and 0.82 for KScX (X = Si, Ge, Sn, and Pb) under appropriate p-type (hole) doping and n-type (electron) doping, respectively. Large values of zT make these alloys promising materials for thermoelectric applications at room temperature.