First-principles Study of Electronic Structural and Mechanical Properties of Mg _xLa(x=1, 2, 3) Compounds under Pressure

Abstract

The effects of pressure on structural, elastic and electronic properties of Mg _xLa (x=1, 2, 3) compounds are investigated by using CASTEP program based on the density functional theory. The calculated equilibrium lattice parameters at zero pressure agree well with available experimental and theoretical values. The calculated DOS show that the structure of these compounds remains mechanically stable and structural phase transformation is not induced with increasing pressure from 0 to 30 GPa, and their structural stability increases with pressure. The ductility of MgLa can be improved by increasing pressure, which is the same as Mg₂La in 0–20 GPa, while brittle behavior turns into ductile behavior in 0–5 GPa for Mg₃La. The resistance to volume deformation of Mg _xLa (x=1, 2, 3) compounds can be improved as the pressure increases. The shear deformation resistance and elastic stiffness of Mg₃La can be enhanced by rising pressure, but MgLa and Mg₂La increase first and then decrease when pressure is up to 25 GPa. In addition, the three compounds exhibit the elastic anisotropy with pressure.

Keywords

Mg−La alloys / elastic properties / electronic structure / first-principles