First-principles investigation on vibrational, anisotropic elastic and thermodynamic properties for L12 structure of Al3Er and Al3Yb under high pressure

Abstract

To better clarify the physical properties for Al3RE precipitates, first-principles calculations are performed to investigate the vibrational, anisotropic elastic and thermodynamic properties of Al3Er and Al3Yb. The calculated results agree well with available experimental and theoretical ones. The vibrational properties indicate that Al3Er and Al3Yb will keep their dynamical stabilities with L12 structure up to 100 GPa. The elastic constants are satisfied with mechanical stability criteria up to the external pressure of 100 GPa. The mechanical anisotropy is predicted by anisotropic constants AG, AU, AZ and 3D curved surface of Young’s modulus. The calculated results show that both Al3Er and Al3Yb are isotropic at zero pressure and obviously anisotropic under high pressure. Further, we systematically investigate the thermodynamic properties and provide the relationships between thermal parameters and pressure. Finally, the pressure-dependent behaviours of density of states, Mulliken charge and bond length are discussed.