Ab initio investigations of structural, elastic and electronic properties of ZnSiP2: Pressure effect

In this work, we present ab initio investigations of the pressure effect on the structural, elastic and electronic properties of ZnSiP2 by employing the plane wave pseudo-potential method (PP-PW) within the generalized gradient approximation (GGA-PW91). The calculated equilibrium structural parameters are in excellent agreement with available experimental and theoretical results. We have found that ZnSiP2 undergoes a structural phase transition under pressure from chalcopyrite to rocksalt type structure at 35 GPa. Single-crystal and polycrystalline elastic constants and some related properties under pressure effect in both chalcopyrite and rocksalt phases have been predicted. The analysis of the bulk modulus to shear modulus (B/G) ratio shows that ZnSiP2 must be classified as brittle material. Electronic properties and chemical bonding nature have been studied throughout the band structure, density of states and charge distribution analyses. It is found that the studied compound is a direct band gap (Γ−Γ) semiconductor (Eg = 1.34 eV) in chalcopyrite structure, and is a conductor in the rock-salt structure. The chemical bonding of ZnSiP2 has a mixture of ionic–covalent and ionic–covalent–metallic character, respectively in chalcopyrite and rocksalt type structure.

► Based on DFT calculations, ZnSiP2 compound have been studied under pressure effect.
► It is shown that ZnSiP2 undergoes a structural phase transition from chalcopyrite to rocksalt at 35 GPa.
► ZnSiP2 behaves as direct band gap semiconductor in chalcopyrite phase and as conductor in rocksalt phase.
► The bonding of chalcopyrite and rocksalt phases characterized by a mixture of covalent–ionic and ionic–covalent–metallic.
► Based on the empirical rule of Pugh, we have found that ZnSiP2 may be classified as brittle material.