Iridium's influence on the structural, electronic and mechanical characteristics of ZrCo1-xIrxSb half-heusler alloys

Structural, electronic and mechanical properties of ZrCo1,IrxSb Half-Heusler alloys with varying x concentrations (x = 0, 0.125, 0.25, 0.375, 0.5, 0.625, 0.75, 0.875, and 1) were studied by performing the exchange-correlation (XC) energy evaluated using the local density (LDA) and generalized gradient (GGA) approximations. The calculated lattice constant, bulk modulus, and band gap energy of the ternary alloy show good agreement with previous theoretical predictions. The results indicate that an increase in Ir atom concentration in the alloy leads to an enlargement of the lattice constant (from 6.10 to 6.36 & Aring;) and bulk modulus (from 138.09 to 149.70 GPa), resulting in increased volume and hardness of the compound. Moreover, the Engel-Vosko generalized gradient approximation (EVGGA) and modified Becke-Johnson (mBJ) schemes were employed to improve the calculations of the band structure and density of states. The studied alloys exhibit semiconductor characteristics, with a direct band gap for both x = 0.75 and x = 0.875 concentrations and an indirect band gap for the rest of the concentrations. The computed elastic constants for ZrCo1_ xIrxSb alloys satisfy the requirements for mechanical stability. The VRH approximations have been used to determine the bulk modulus, shear modulus, Young's modulus, Poisson's ratio and Hardness. In addition, we also determined the anisotropy factor, sound velocities and Debye temperature.