Ab-initio study on the stability, electronic and mechanical properties of transition metal nitrides under external pressure

Abstract

Structures of transition metal nitrides (TMNs) are optimized using the plane-wave pseudopotential method based on density functional theory. Energy as a function of volume curves are calculated to predict the phase transition pressures. Density of states (DOS), charge density difference, and charge transfers are calculated. The elastic constant (C11) and modulus (G) as a function of pressure are computed. Results show that TMNs in the WC structure is most stable at normal pressure. All TMNs exhibit metallic, covalent and ionic property. Metallic character increase and covalent property reduce with increasing atomic number of TM atom. The elastic constant (C11) and modulus (G) increase linearly with increasing pressure due to stronger hybridization, bonding and covalent property. Thus, mechanical property enhance under external pressure.