First-principles calculations of mechanical and thermodynamic properties of the Laves C15-Mg2RE (RE=La, Ce, Pr, Nd, Pm, Sm, Gd)

We present a study of the energetics, elastic properties and electronic structures of the Laves C15-Mg2RE (RE = La, Ce, Pr, Nd, Pm, Sm, and Gd) through density functional theory (DFT). The calculated lattice constants are in good agreement with available experimental data and previously theoretical predictions. The formation enthalpies, elastic constants, bulk moduli, and pressure derivatives of the C15-type Mg2RE are predicted. Young's moduli, shear moduli, and anisotropic ratios of the C15-type Mg2RE are further estimated from the calculated single-crystal elastic constants. The present results indicate that the Young's modulus and anisotropic ratio of C15-Mg2RE are all less than those of B2-MgRE and D03-Mg3RE. The electronic densities of states and bonding charge densities have been discussed in details. The characteristic of mechanical properties has been explained from the point view of electronic structure. The present calculation indicates that C15-Mg2RE might be more ductile than B2-MgRE and D03-Mg3RE.