Lattice Dynamics and Thermal Properties of TixZr1-xNiSn Half-Heusler Alloys

Half-Heusler alloys are promising materials for thermoelectric applications, yet the impact of the compositional disorder on their lattice dynamics remains incompletely understood. This study investigates the effect of systematic Zr substitution on the lattice dynamics and thermal properties of TixZr1-xNiSn half-Heusler alloys using first-principles calculations. Through careful analysis of phonon dispersions, density of states, and thermodynamic properties, it is revealed that Zr substitution (25%, 50%, and 75%) introduces minimal structural distortion while enhancing system stability. It is shown that increasing Zr content systematically modifies the phonons, particularly affecting the high-frequency optical modes above 5 THz. Notably, with Zr content, these findings provide valuable insights for tailoring the thermal properties of half-Heusler alloys for high-temperature applications in thermoelectric devices and components.