Comprehensive ab-initio calculations of AlNiX (X = P, As and Sb) half-Heusler compounds: Stabilities and applications as green energy resources

The objective of this work is to explore structural, mechanical and thermal stability including electronic, optical and thermoelectric properties of state-of-the-art AlNiX (X = P, As and Sb) half-Heusler compounds having 18 valence electron count (VEC). Calculations have been carried out in the framework of density functional theory (DFT) implemented in WIEN2k code followed by the solution of the Boltzmann transport equation with constant relaxation time approximation. In the most energetically favorable structure, their lattice constants lie in the range of 5.501 angstrom - 5.983 angstrom and band gaps have been found to be 0 eV, which confirm the metallic behavior of these compounds. The different elastic and thermodynamic parameters confirm their mechanical and thermal stability with a mechanically anisotropic and ductile nature. Specific heat and entropy of these materials increase as the atomic number of X atom increases. The calculated optical parameters prove their candidature for promising photovoltaic devices and shields for UV radiation. The thermal conductivity has been computed using Slack's model. This detailed study shows that these compounds are promising for materials scientists due to their very high lattice thermal conductivity and low figure of merit. We deny recommending them as good thermoelectric applications.

Automated summary

The study investigates the structural, mechanical, thermal stability, electronic, optical, and thermoelectric properties of AlNiX half-Heusler compounds. The compounds exhibit metallic behavior with good mechanical and thermal stability, making them suitable for applications in photovoltaic devices and UV radiation shields.