First-Principles Calculations on Structure, Elastic and Thermodynamic Properties of Al2X (X=Sc, Y) under Pressure

Abstract

To understand deeply the structural, elastic and thermodynamic characteristics of Al 2 X ( X = Sc, Y) compounds in C15 type (space number 227) Cu 2 Mg structure, we have performed ab-initio density functional theory within the local density approximation (LDA) and the generalized gradient approximation (GGA). The thermodynamic properties of the considered structures are obtained through the quasi-harmonic Debye model. We have presented the results on the basic physical parameters, such as the lattice constant, bulk modulus, pressure derivative of bulk modulus, second-order elastic constants, Zener anisotropy factor, Poisson's ratio, Young's modulus, and isotropic shear modulus. In order to gain further information, the pressure- and temperature-dependent behaviour of the volume, bulk modulus, thermal expansion coefficient, heat capacity, entropy, Debye temperature and Gruneisen parameter were also evaluated over a pressure range of 0–20 GPa for Al 2 Sc and 0–17 GPa for Al 2 Y compound and a wide temperature range of 0–2000 K for both compounds. The obtained results were compared with the other reported values.