Regarding the structural, thermodynamic, mechanical, thermoelectric, and optoelectronic properties of anti-perovskite Mg3XN (X = As, Sb, and Bi) through a DFT approach

Abstract

In this work, we comprehensively analyzed the structure, thermodynamics, mechanical, thermoelectric, and photoelectric properties of antiperovskite Mg3XN (X = As, Sb, and Bi) using first-principles calculations and semi-classical Boltzmann transport theory. Our calculations of phonon spectra and elastic constants suggest that Mg3XN (X = As, Sb, and Bi) exhibit excellent dynamic and mechanical stability, characterized as brittle materials with Vickers hardness (HV) values exceeding 10 GPa. Electronic structure analysis reveals that Mg3AsN is a direct bandgap semiconductor with a 2.25 eV gap, whereas Mg3SbN and Mg3BiN are indirect bandgap semiconductors with gaps of 1.58 eV and 1.41 eV, respectively. At room temperature, the lattice thermal conductivities (κL) for Mg3AsN, Mg3SbN, and Mg3BiN are 13.63, 9.93, and 7.26 Wm−1K−1, respectively, with ZT values of 0.32, 0.08, and 0.10 at optimal doping concentrations. At 1000 K, κL values decrease to 3.19, 2.29, and 1.65 Wm−1K−1, respectively, with ZT values reaching 2.12, 0.98, and 0.92. Our analysis of optical properties demonstrates that these materials exhibit absorbance in the visible and ultraviolet spectra, with negligible energy loss in the respective energy ranges, thereby rendering them suitable for photovoltaic applications.