Compositional tuning and property evolution in cubic Mg-based perovskite and anti-perovskite compounds (MgBO3 and Mg3BO; B = Si, Ge, Sn, Pb): a comparative first-principles study for multifunctional device applications

Abstract

This study presents a comprehensive and comparative first-principles analysis of cubic-phase perovskite (MgBO₃) and anti-perovskite (Mg₃BO) compounds, where B = Si, Ge, Sn, Pb, with a focus on their structural, electronic, mechanical, thermodynamical and optical properties. Structural optimization confirms phase stability through tolerance factor evaluation and Birch–Murnaghan equation of state, revealing a systematic increase in lattice constants from Si to Pb due to cationic radius expansion. Formation energy calculations reveal that anti-perovskite compounds exhibit greater thermodynamic stability than their perovskite counterparts, with values decreasing systematically from Si to Pb. The dynamic and thermodynamic stability of MgBO₃ perovskites and (Mg₃BO) anti-perovskites investigated via phonon dispersion analysis and thermodynamic potential calculations, reveal that anti-perovskites exhibit superior dynamic stability, higher entropy, and enhanced heat capacity making them promising candidates for thermoelectric and high-temperature applications. All compounds satisfy mechanical stability criteria, with elastic moduli decreasing across the series, indicating reduced stiffness. Perovskites exhibit superior ductility and mechanical robustness compared to anti-perovskites, as supported by Cauchy pressure, anisotropy, and Kleinman parameter analyses. Electronic band structure calculations using GGA-PBE, GGA-PBEsol and HSE06 functionals reveal indirect band gaps in perovskites, transitioning from semiconducting to metallic behavior with heavier B-site cations while anti-perovskites display narrow direct band gaps (<0.5 eV). Density of states analysis highlights dominant O-p and B-p orbital contributions near the Fermi level, with most compounds classified as p-type semiconductors, except MgPbO₃, which exhibits metallicity. Thermal evaluations identified MgGeO₃ and MgSnO₃ as the most stable, with Debye parameters and phonon conductivity decreasing with heavier cation substitution. Optical investigations including dielectric function, reflectivity, refractive index, and optical conductivity demonstrate strong tunability across the series. Perovskites show enhanced UV conductivity and low reflectivity, ideal for photodetectors and antireflective coatings, while anti-perovskites excel in visible-light absorption, positioning them as promising candidates for photovoltaics and energy storage. These findings underscore the multifunctional potential and compositional flexibility of Mg-based perovskite and anti-perovskite systems for next-generation optoelectronic, photonic, and memory device applications.