Ab Initio Modeling of MgXIr2 (X = Al, Ga, In, Si): A Multifaceted Study on Physical Properties

Abstract We present a comprehensive ab initio investigation of the structural, electronic, mechanical, thermodynamic, and vibrational properties of Mg X Ir 2 ( X = Al, Ga, In, Si) full-Heusler compounds using density functional theory (DFT). Structural optimization reveals that all four compounds stabilize in the cubic Fm3m phase, with lattice parameters showing a monotonic increase from X = Si to In. Electronic band structure calculations demonstrate metallic behavior, characterized by Ir- d orbital dominance near the Fermi level. Mechanical properties, including elastic constants (C 11 , C 12 , C 44 ), confirm thermodynamic stability and ductile behavior, with MgSiIr 2 exhibiting the highest bulk modulus (218 GPa). Phonon dispersion spectra show no imaginary frequencies, verifying dynamic stability across all compositions. Thermodynamic analysis via quasi-harmonic approximation predicts Debye temperatures ranging from 420 K (MgInIr 2 ) to 580 K (MgSiIr 2 ), correlating with bond stiffness trends. Vibrational modes indicate distinct optical phonon splitting is the highest in MgSiIr 2 owing to mass contrast. The Grüneisen parameters suggest anharmonic effects are most pronounced in MgInIr 2 . Comparative analysis highlights MgSiIr 2 as the most promising candidate for high-temperature applications, balancing mechanical strength and thermal stability. This work provides foundational insights into experimental synthesis and targeted applications in catalysis or spintronics. Given magnesium’s osteogenic properties, these alloys also hold significant potential in regenerative medicine, particularly for repairing osseous defects triggered by degenerative disorders or bone cancer.