Theoretical study of phase stability, structural, magnetic, mechanical and thermal behavior of gadolinium-based intermetallic compounds in cubic AuCu3 structure

The phase stability, structural, magnetic, electronic, mechanical and thermal properties of cubic GdX3 (X = In, Sn, Tl and Pb) rare earth intermetallics, which crystallize in AuCu3-type structure, have been investigated using first-principles density functional theory based on full-potential linearized augmented plane wave method. The calculations are carried out within local spin approximation and local spin approximation along with Hubbard term for the exchange correlation potential in order to obtain the appropriate results. The computed lattice parameters using local spin approximation along with Hubbard term are in good agreement with the experimental results. It is lucid from the magnetic stability curves that all these studied compounds are magnetic in nature. The electronic band structures as well as density of states reveal that the studied compounds show metallic behavior under ambient conditions. The results of cohesive energy indicate that these compounds are stable in AuCu3 phase at ambient conditions and that the stability of GdSn3 is the strongest among the investigated cubic GdX3 compounds. We, for the first time, predict the second-order elastic constants for these compounds. All these GdX3 compounds, except GdIn3, are found to be ductile in nature in accordance with Pugh's criteria. Poisson's ratio, Young's modulus, shear modulus, anisotropy factor, average sound velocities, density and Debye temperature of these GdX3 compounds are also estimated for the first time.