The impact of Si substitution on Ge sites in full heusler compound Ru₂VGe: stability analysis

This study presents a comprehensive analysis of the stability of Ru₂VGe_1-xSi_x for x = [0, 0.25, 0.5, 0.75, 1] compounds using a first-principle full-potential linearized augmented plane wave method implemented in a computational code based on WIEN2k. The article sheds light on the behavior of different concentrations of Si and their impact on the magneto-structural, thermodynamic, and mechanical stability, resulting in the prediction of five compounds with varying magnetism based on their compositions, including Fm-3 m cubic for Ru₂VGe and Ru₂VSi, Pm-3 m cubic structure for x = 0.25, 0.75, and P4/mmm tetragonal structure for x = 0.5. A tiny energy difference between phases may lead to a low magnetic transition temperature T^MFA for all compounds except the tetragonal one, which keeps the antiferromagnetic phase above room temperature. Their formation and cohesive energies prove their stability. A regular solution model was used to investigate the thermodynamic stability of the alloys, revealing a miscibility gap at a composition range of 0.537 ≤ x ≤ 1, with the critical temperature of T_c = 986.24 K at a specific composition of x_C = 0.801. The elastic properties showed the compounds are stable against external stresses and deformations with ductility and good thermal conductivity, hardness, and machinability. The anisotropy behavior moves from anisotropic in Ru₂VGe to semi-isotropic by Si substitution.