Structural, electronic, elastic, vibrational and thermodynamic properties of ZrNi and ZrNiH3: A comprehensive study through first principles approach

Zirconium based alloys have potential applications in automobile, energy and spacecraft industries. The structural, electronic, elastic, vibrational and thermodynamic properties of orthorhombic ZrNi and ZrNiH3 are studied in detail using the projector augmented wave method and the generalized gradient approximation based on density functional theory. The optimized lattice parameters of both ZrNi and ZrNiH3 agree well within +/- 1% from the experimental values. The electronic structure analysis shows significant contribution of 4d and 3d orbitals of Zr and Ni to the fermi energy level, respectively and along with signatures of two types of hydrogen atoms occupying the lattice of ZrNiH3. Elastic property calculation of these two compounds showed mechanical stability and anisotropy at ambient pressure. In addition, the phonon calculation of both the compounds showed that ZrNi is dynamically stable but ZrNiH3 is dynamically unstable. The formation energies (Delta H-f) of ZrNi and ZrNiH3 at 0 K, after zero point energy correction, have been estimated to be -41.87 kJ/mol and -78.25 kJ/mol H-2, respectively. The temperature dependent thermodynamic functions of ZrNi and ZrNiH3 have also been calculated from the Debye-Gru-neisen quasi-harmonic approximation. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.