Structural, electronic, elastic and thermodynamic properties of Zr2Fe and Zr2FeH5: A comprehensive study using first principles approach

The structural, electronic, elastic and thermodynamic properties of Laves phase alloy Zr2Fe and its hydride Zr2FeH5 were investigated employing the state of the art first principles calculation. The equilibrium structures of both Zr2Fe and Zr2FeH5 were found to be within ±1% from the experimental values. The charge distribution and bonding between the constituent atoms of Zr2Fe and Zr2FeH5 were examined through electronic density of state spectra, charge density contour, and electron localization function analysis. The density of states showed significant contribution of 4d and 3d orbitals of Zr and Fe to the Fermi energy level, respectively and signatures of two types of hydrogen atoms occupying the lattice of Zr2FeH5. Investigation of elastic properties showed that two compounds were mechanically stable and anisotropic. The formation energy (ΔfH) of Zr2Fe and Zr2FeH5 at 0 K, after zero point energy correction, was estimated to be −40.04 kJ/mol and −147.40 kJ/mol H2, respectively. A van't Hoff plot was constructed using computed thermodynamic functions of Zr2Fe and Zr2FeH5.