Electronic, optical, elastic, and thermal properties of the half-Heusler-derived Ti2FeNiSb2: A DFT study

The electronic, optical, elastic, and thermal transport properties of half-Heusler-derived (HHD) Ti2FeNiSb2 are comprehensively characterized via density functional theory. The stability of HHD Ti2FeNiSb2 is evaluated by the phonon dispersion, formation energy, and phase separation, and its elastic constants meet the mechanically stable conditions. HHD Ti2FeNiSb2 is predicted to be an indirect nonmagnetic semiconductor with a bandgap of 0.94 (PBE) eV and 1.75 (HSE06) eV. To further understand the electronic structures, the atomic orbital projection of the electronic band structure is systematically studied and discussed. The band structures and bandgap can be sensitively tuned by the strain. The calculated elastic and optical properties indicate that Ti2FeNiSb2 has good ductility and hardness, and the optical property calculations reveal its excellent potential for harvesting solar energy. Using the elastic properties, the minimum lattice thermal conductivity is evaluated by the Slack, Clarke, and Cahill models. Based on the Slack model, the lattice thermal conductivity is 5.93 W/mK at 300 K; this value is consistent with the experimental value.