Physical Insights of BaNiSn3-Type Compounds SrXGe3 (X = Ni, Rh): DFT Calculations

Abstract

Employing first-principles computation depending on the density functional theory (DFT), we have investigated the structural, mechanical, electronic, bonding and optical properties of the newly discovered bulk superconductors SrRhGe3 (Tc = 0.71 K) and SrNiGe3 (Tc = 0.46 K). The optimized lattice parameters show good agreement with the experimental results. The positive elastic constants revealed that both the superconductors are stable in nature. The calculated values of Pugh's ratio and Poisson's ratio refer the brittle nature of SrNiGe3 and ductility behavior of SrRhGe3 and show anisotropic behavior. The analysis of the electronic band structures and density of states (TDOS and PDOS) revealed the metallic nature for both the compounds, and the major contribution comes from the Ge-4d states for both the phases. The calculations of the chemical bonding specify that a mixture of covalent, ionic and metallic bonds exist in both superconductors. The negative value of the real part of the dielectric constant of SrXGe3 (X = Ni, Rh) also ensured that these compounds exhibit metallic behavior. The large reflectivity in the low energy region indicates that both the compounds might be useful as coating materials for reducing solar heating. By using the elastic constants information, the calculated Debye temperatures of SrNiGe3 and SrRhGe3 superconductors are 313.62 K and 285.96 K, respectively which are in good accord with the experimental data.