High pressure structural, elastic, mechanical and thermal behavior of LaX3 (X = In, Sn, Tl and Pb) compounds: A FP-LAPW study

Abstract

A theoretical study of structural, electronic, elastic and mechanical properties of nonmagnetic rare-earth intermetallics LaX3 (X=In, Sn, Tl and Pb), which crystallize in AuCu3-type structure, has been performed using first principles density functional theory based on full potential linearized augmented plane wave (FP-LAPW) method. The calculations are carried out within the generalized gradient approximation (GGA) for the exchange correlation potential. Ground state properties such as lattice constant (a0), bulk modulus (B) and its pressure derivative (B′) are calculated. The present results are in good agreement with the experimental and other available theoretical results. We first time predict the elastic constants for these compounds. All these LaX3 compounds are found to be ductile in nature in accordance with Pugh’s criteria. The computed electronic band structures show metallic character of these compounds. The charge density plot and density of states (DOS) of these compounds reveals that the chemical bond between La and X is mainly ionic. Poisson’s ratio (σ), Young’s modulus (E), shear modulus (GH), anisotropy factor (A), average sound velocities (vm), density (ρ) and Debye temperature (θD) of these LaX3 compounds are also estimated for the first time. Variation of elastic constants, elastic moduli and Debye temperatures of these compounds as a function of pressure is also reported.