Influence of metalloid antimony on the physical properties of palladium-based half-Heusler compared to the metallic bismuth: A first-principle study

Abstract

In this study, a comparative analysis of structural, elastic, mechanical, electronic, thermal and optical behaviors of LuPdBi and LuPdSb have been explored to understand the effect of replacement of metallic Bismuth (Bi) by metalloid Antimony (Sb) on the physical properties of Palladium (Pd)-based half-Heusler compound. We have noticed that the replacing of Bi by Sb affects the lattice parameters, mechanical stability, electronic band gap, Debye temperature, melting temperature as well as minimum thermal conductivity significantly. We have observed a customary decrease in lattice parameters whereas a noteworthy increase in mechanical stability against deformation with the replacement of Bi by Sb. Equally important, the anisotropy in elastic moduli as well as in Poisson’s ratio is more prominent in LuPdSb compared to LuPdBi. We have predicted that the band gap of Pd-based half-Heusler significantly depends on the p-block element and can be tuned by replacing them properly. We have seen that the band gap for LuPdBi is zero whereas, for LuPdSb, it is nearly ∼0.1 eV. The Debye temperature and the melting temperature have a positive correlation with minimum thermal conductivity and all these thermodynamic parameters increase with the shifting from metallic Bi to metalloid Sb. Apart from this, the calculated minimum thermal conductivity (κmin) indicates that this pair of half-Heusler can be used more efficiently for the thermal barrier coatings (TBC) in high-temperature applications, compared to the other species. At the same time, these compounds can be used in absorbing UV-radiation and may be applied to reduce solar heating as coating materials.