First-principles calculations to investigate photovoltaic, photocatalytic, and spintronic properties of Fe-doped and alloyed MgSiO3 perovskite

Abstract

The structural, electronic, optical, and photocatalytic properties of pure and iron (Fe)-doped and alloyed MgSiO₃ at silicon (Si) site have been explored using the first-principles calculations based on density functional theory. The results reveal a band gap of 9.10 eV for pure MgSiO₃, obtained using the PBE-GGA approximation combined with the mBJ potential. The results show that the doped compounds (MgSi${}_{1-x}$Fe${}_x$O${}_3$ where x = 0.16 and 0.33) behave as p-type semiconductors with a direct band gap. However, when MgSiO₃ compound is heavily doped, with concentrations reaching between x = 0.83 and x = 1, it exhibits as a semiconductor with an indirect band gap. Moreover, the total substitution (x = 1) of Si by Fe in MgSiO₃ leads to a significant reduction in the band gap value, from 9.10 eV for pure MgSiO₃ (x = 0) to 1.36 eV for MgFeO${}_3$ (x = 1). This decrease leads to the increase of the absorption coefficient in the visible region, reaching more than $10^5{\mathrm{cm}}^{-1}$. According to thermodynamic analysis based on the enthalpy of formation, every structure under study is stable. Furthermore, the compounds also showed promise in splitting water to generate hydrogen especially at x = 0.16 and x = 0.33 concentrations. The magnetic characteristics calculations prove a useful use of the doped compounds in the spintronics applications. These results suggest that the Fe doped-MgSiO₃ compounds can be used in photovoltaic, photocatalytic, and, spintronic devices, opening up promising prospects for various technological applications.