Quasi-harmonic approximation of lattice dynamics and thermodynamic properties of half Heusler ScXSb (x = Ni, Pd, Pt) from first principles

Abstract

We report the lattice dynamics and thermodynamic properties of ScXSb (X = Ni, Pd, Pt) half Heusler compounds. Calculations for the structural and electronic properties were performed based on the Perdew–Burke–Ernzerhof–generalized gradient approximation density functional theory. We used the linear response density functional perturbation theory for computations addressing the elastic property, lattice dynamics, and thermodynamic properties. Results for the equilibrium lattice parameter are in reasonable agreement with reports in the existing literature. The electronic band structure behavior and bandgap agree with relevant results in research. The elastic parameters and phonon dispersions establish the mechanical stability of the compounds. Deductions from the tone of the mode-Grüneisen parameter, specific heat capacity at constant pressure and volume, and thermal expansion favor ScNiSb as the most promising material for thermal conductivity at high temperatures in the three compounds studied. The three compounds obey the Dulong–Petit law at high temperatures. Results for the Dulong–Petit limit is consistent with expectations for solid materials at high temperatures.