Optical response functions and thermodynamic stability of BSb1-xNx ternary alloys in zinc blende structure

Abstract

Optical properties and thermodynamic stability of BSb1-xNx ternary alloys in zinc blende structure are investigated by employing the first-principles calculations based on the density functional theory. We have evaluated BSb1-xNx ternary alloys for 0 ≤ x ≤ 1 using special quasi-random structures with 16 atoms. The generalized gradient approximation of Perdew et al. (PBEsol-GGA) was used as the exchange correlation potential to calculate the structural properties at different nitrogen concentrations x (0 ≤ x ≤ 1). The lattice parameter (a), bulk modulus (B) and pressure derivative of bulk modulus (B′) have been evaluated and analyzed for ternary alloys. Our obtained results show that the lattice parameter of BSb1-xNx decreases with nitrogen concentration (x) while its bulk modulus increases.The enthalpy of mixing (ΔHm) is calculated in the whole composition range. The obtained phase diagrams indicate a significant phase miscibility gap. The calculated critical temperature is found to be 246.6 K. The electronic properties of these ternary alloys were predicted using the Tran–Blaha-modified Becke–Johnson (TB-mBJ) scheme. The band gap of BSb1-xNx positively deviate from Vegard's law. The optical response functions such as dielectric function and, complex refractive index are determined for BSb1-xNx in the zinc-blende structure. In general, our results are in agreement with the available experimental and theoretical data reported in the literature. The investigation of the optical response functions for BSb1-xNx ternary alloys is reported for the first time. The calculation endorses that the BSb1-xNx ternary is a promising candidate for optoelectronics.