A comparative ab initio study on mechanical and thermal properties of rare-earth scandate LnScO₃ (Ln = La, Pr, Nd, Sm, Eu and Tb) compounds

Abstract

To comparatively examine the mechanical and thermal properties of rare-earth scandate LnScO3 (Ln = La, Pr, Nd, Sm, Eu and Tb) compounds, ab initio calculation based on density functional theory was used within the framework of the generalized gradient approximation. The elastic moduli, Pugh's criterion, Poisson's ratio, Vickers hardness, linear compressibility, Debye temperature, Grüneisen parameter, elastic wave velocities, minimum thermal conductivities of LnScO3 were successfully obtained from independent single crystal elastic coefficients. The computed elastic constants indicate that these compounds have mechanical stability. The ductile and brittle properties of LnScO3 compounds were investigated using the BH/GH, Poisson’s ratio and Cauchy pressure. The mechanical anisotropic properties of LnScO3 compounds were discussed using universal anisotropic index, shear anisotropy factors, percentage shear (compressible) anisotropy index. Minimum thermal conductivities of LnScO3 were determined using Cahill’s and Clark's model. Except for the elastic coefficients of NdScO3, SmScO3 and TbScO3 compounds, many physical properties of LnScO3 compounds were calculated for the first time in this study. We compared our calculation results with experimental and other theoretical data available in the literature.