Eur. Phys. J. B 79, 283-288 (2011)
https://doi.org/10.1140/epjb/e2010-10653-3

Structural, vibrational and thermodynamic properties of Mg₂ FeH₆ complex hydride

Institute of Atomic and Molecular Physics, Sichuan University, Chengdu, 610065, P.R. China

Corresponding author: ^a gaotao@scu.edu.cn

Received: 27 August 2010
Revised: 10 November 2010
Published online: 14 January 2011

Abstract

Mg₂FeH₆, which has one of the highest hydrogen storage capacities among Mg based 3d-transitional metal hydrides, is considered as an attractive material for hydrogen storage. Within density-functional perturbation theory (DFPT), we have investigated the structural, vibrational and thermodynamic properties of Mg₂FeH₆. The band structure calculation shows that this compound is a semiconductor with a direct X-X energy gap of 1.96 eV. The calculated phonon frequencies for the Raman-active and the infrared-active modes are assigned. The phonon dispersion curves together with the corresponding phonon density of states and longitudinal-transverse optical (LO-TO) splitting are also calculated. Findings are also presented for the temperature-dependent behaviors of some thermodynamic properties such as free energy, internal energy, entropy and heat capacity within the quasi-harmonic approximation based on the calculated phonon density of states.