Electronic structure, elastic and transport properties of new Palladium-based Half-Heusler materials for thermoelectric applications

Electronic structure with reference to bandgap energies play a significant role in deciding the dimensionless figure of merit (ZT), which in turn is used to identify the thermoelectric performance of a material. Slater Pauling arrangement of valence electrons and band orientations along k-space decide the effective mass of electrons/ holes in the corresponding band valleys of PdMX (M= Sc, Y, and X = P, As, Sb) semiconductors. A detailed picture of the electronic structure and transport properties is rigorously established in this report. Calculations of elastic constant, phonon dispersion and formation (cohesive) energy reveal that these alloys are mechanically, dynamically, and chemically stable materials. Substantially, low lattice thermal conductivity is observed in the range 4.57 W/mK for PdScAs and 11.51 W/mK for PdYSb alloy. The relaxation time and effective mass are calculated with Deformation potential theory. The maximum calculated ZT value for PdScP, PdScAs, PdScSb, PdYP, PdYAs and PdYSb are 0.28, 0.33, 0.19, 0.43, 0.44 and 0.27 respectively.