Electronic thermoelectric properties of MgXY$_2$Z$_2$ double half-Heusler alloys (X = Zr/Hf, Y = Pd/Pt, Z = Bi/Sb)

Double half-Heusler alloys represent a novel promising class of materials for applications, e.g., in thermoelectric energy converters. In this work, the electronic thermoelectric properties of five MgXY$_2$Z$_2$ (X = Zr/Hf, Y = Pd/Pt, Z = Bi/Sb) compounds of this alloy class with the previously predicted low lattice thermal conductivity have been investigated for the first time. It has been shown that the Seebeck coefficients of MgHfPd$_2$Sb$_2$ and MgTiPd$_2$Sb$_2$ are among the highest in double half-Heusler alloys. The dependences of the Seebeck coefficient and power factor on the chemical potential at different temperatures and carrier densities have been analyzed, and the relationship between these dependences and the peculiarities of the electronic structure of the considered compounds has been revealed.