A study of structural phase transitions and optoelectronic properties of perovskite-type hydride MgFeH 3 : ab initio calculations

In this study, the structural phase transition and optoelectronic properties of perovskite-hydride MgFeH under high pressure have been performed by ab initio calculations based on GGA-PBE functional. The phase transitions were observed from the cubic structure ([Formula: see text]) to the orthorhombic [Formula: see text] and [Formula: see text] structure. During the phase transition, the [Formula: see text] and [Formula: see text] intermediate phases were predicted. The energy-volume (E-V) relationships show that the most stable phase is [Formula: see text]. The lattice parameters and volume increased as based on the phase transforms. From the electronic band analysis, the MgFeH shows a metallic character from the cubic to orthorhombic structure. The MgFeH indicates the peaks at 2.67 eV (464 nm) for [Formula: see text] phase, 5.21 eV (238 nm) for [Formula: see text] phase and 2.63 eV (471 nm) for [Formula: see text] phase. [Formula: see text] and [Formula: see text] phases correspond to the visible region. The absorption peaks are getting wider and have higher magnitude from [Formula: see text] to [Formula: see text] phase. The optical conductivity for the cubic structure with [Formula: see text] phase was found to be higher than orthorhombic structures with [Formula: see text], and [Formula: see text] phases. The reflectivity maxima decrease from [Formula: see text] to [Formula: see text].