Structural, electronic, elastic and thermodynamic properties of AlSi _2RE (RE = La, Ce, Pr and Nd) from first-principle calculations

摘要

It is of academic interest to study the ternary intermetallic compounds of the Al-Si-RE system for the development of both structural and functional materials. In this work, the structural, electronic, elastic and thermodynamic properties of the AlSi_2RE (RE = La, Ce, Pr and Nd) compounds was investigated using first-principle calculations based on density functional theory. The calculated structural parameters of AlSi_2RE compounds are consistent with the experimental data. Due to the fact that there is strong Coulomb correlation among the partially filled 4f electron for RE atoms, we present a combination of the GGA and the LSDA + U approaches to investigate the electronic structures of Al_3RE compounds in order to obtain the appropriate results. The elastic constants were determined from a linear fit of the calculated stress-strain function according to Hooke's law. The bulk modulus B, shear modulus G, Young's modulus E, and Poisson's ratio ν of polycrystalline AlSi_2RE compounds were determined using the Voigt-Reuss-Hill (VRH) averaging scheme. The Debye temperature of AlSi _2RE compounds can be obtained from elastic constants. The temperature dependence of the internal energy, free energy, entropy and heat capacity for AlSi_2RE compounds were also calculated by using the quasi-harmonic approximation.