First-principles investigations on phase stability and electronic structures of Yb1−xMxAl3 (M = Ho, Er and Tm) alloys

YbAl3 is a promising thermoelectric (TE) material to be used at near room temperature in TE power generator by waste heat sources. This work systematically investigated the alloying behavior of M in Yb1−xMxAl3 (M = Ho, Er and Tm) and their electronic structures by first-principles calculations. The solubility of alloying elements M and phase stability of Yb1−xMxAl3 were studied by analyzing the elastic constants, energies of formation and cohesive energies. The variation of shear modulus c44 with composition was discussed in terms of valence electron concentration. The results show that Ho, Er and Tm can continuously substitute Yb in YbAl3 and form completely miscible Yb1−xMxAl3 solid solutions, which are helpful for improving the TE properties of YbAl3.