A DFT study of structural, electronic, mechanical, phonon, thermodynamic, and H2 storage properties of lead-free perovskite hydride MgXH3(X=Cr, Fe, Mn)

Perovskite hydride materials have gained significant attention for their potential in hydrogen storage, a key component of renewable energy systems. In this study, we used density functional theory (DFT) to investigate the structural, vibrational, electronic, mechanical, thermodynamic, and hydrogen storage properties of MgXH3 (X = Cr, Fe, Mn) hydrides. The energy volume curves were used to determine optimized lattice parameters of MgCrH3(3.4590 Å), MgFeH3(3.0284 Å), and MgMnH3(3.3485 Å). The Born criteria for elastic constant (Cij) showed that the hydrides are mechanically stable, whereas the phonon dispersion curves showed their dynamic stability. The calculated electronic properties revealed the metallic nature of hydrides under investigation. The Cauchy pressure (Cp) revealed the brittle and ductile behavior. The calculated gravimetric hydrogen storage capacity of MgCrH3, MgFeH3, and MgMnH3 hydrides was 3.771, 3.606, and 3.643 wt% respectively. The electronic and thermodynamic properties suggest that MgXH3 hydrides can conduct electrical as well as thermal energy. Our results provide insight into the potential of MgXH3(X = Cr, Fe, Mn) perovskite hydride material for hydrogen storage application.