Structural, Elastic, and Thermodynamic Properties of <scp> MgSc ₂ X ₄ </scp> X = S, Se Under High Pressure From First Principles

ABSTRACT We investigate the structural, elastic, and thermodynamic properties of spinel compounds MgSc 2 X 4 X = S, Se under high pressure using first‐principles calculations. The obtained equilibrium structures at zero pressure show good agreement with previous theoretical and experimental results. The elastic constants, bulk modulus, shear modulus, Young's modulus, Poisson's ratio, B / G ratio, sound velocity, and Debye temperature were calculated under zero pressure and high pressure conditions. The B / G ratio reveals that both materials exhibit ductility under high pressure. Based on the Born stability criteria for cubic crystals under pressure, MgSc 2 S 4 and MgSc 2 Se 4 demonstrate structural stability within the investigated pressure ranges (up to 14.5 GPa for MgSc 2 S 4 and 11.5 GPa for MgSc 2 Se 4 ), and are predicted to lose stability at 33.43 and 25.81 GPa, respectively. Calculated anisotropy factors indicate elastic anisotropy in these compounds. Furthermore, thermodynamic properties of MgSc 2 X 4 X = S, Se under high temperature and pressure were investigated through the quasi‐harmonic Debye model. This study provides theoretical foundations for potential high‐pressure applications of MgSc 2 X 4 X = S, Se.