Mechanical, electronic and thermodynamic properties of Mg2Ca Laves phase under high pressure: A first-principles calculation

Abstract

The mechanical, electronic and thermodynamic properties of C14-type Mg2Ca Laves phase under various pressure were investigated by means of first-principles calculations based on density functional theory with the generalized gradient approximation. The calculated results of lattice constants were in good agreement with the experimental and other theoretical values. The five independent elastic constants of Mg2Ca structure were calculated and the mechanical parameters, such as bulk modulus, shear modulus, Young’s modulus and Poisson’s ratio were determined by using the Voigt–Reuss–Hill (VRH) averaging scheme. The Cauchy pressure and elastic anisotropy of Mg2Ca were also investigated. The calculated result showed that Mg2Ca was a ductile phase according to the calculation results of Cauchy pressure and G/B values under different pressures. In addition, the electronic density of states (DOSs) as a function of pressure was analyzed. The Debye temperature obtained by elastic constants showed that the variation trend of Debye temperature was the same as shear modulus. The dependences of thermodynamic properties on temperature and pressure were also discussed by using the quasi-harmonic approximation.