Insight into the mechanical, electronic, kinetic, thermodynamic, and hydrogen storage properties of XFeH3 (X=Ca, Sr, Ba) perovskites for hydrogen storage applications: First-principle calculations

Abstract

Based on the first-principle calculations, the XFeH3 (X=Ca, Sr, Ba) hydrides have been systematically investigated. The lattice constant, elastic constants, bulk modulus, Poisson's ratio, and Young's modulus of XFeH3 hydrides are calculated. According to the B/G and Poisson's ratio, CaFeH3 and SrFeH3 exhibit brittleness, while BaFeH3 exhibits ductility. The electronic properties demonstrate that CaFeH3 and SrFeH3 exhibit half-metallic ferromagnetism, while BaFeH3 exhibits metallic ferromagnetism. We analyze the Bader partial net charges to better understand the charge transport in XFeH3 hydrides. In addition, the formation energy, Born stability criterion, and phonon dispersion curves of XFeH3 were investigated, which confirmed that XFeH3 perovskites are simultaneously thermodynamic, mechanical, and kinetic stable. The gravimetric hydrogen storage capacities of CaFeH3, SrFeH3, and BaFeH3 are 3.06, 2.06, and 1.54 wt%, respectively, revealing that CaFeH3 hydride can be a better material for hydrogen storage applications compared to SrFeH3 and BaFeH3. Our results would provide a new candidate for hydrogen storage materials.