Structural destabilisation of MgH2 obtained by heavy ion irradiation

MgH2 powder samples have been irradiated with 120 keV Ar+8 ions with different ion fluencies ranging from 10(12) to 10(16) ions/cm(2). irradiation effects are estimated by SRIM calculations, and investigated experimentally using Raman spectroscopy and X-ray diffraction (XRD) analysis. The observed changes of structure and vibrational spectra are elaborated, their consequences on hydrogen bonding in MgH2 discussed, and influence on H-desorption properties investigated by Temperature Programmed Desorption (TPD) and Differential Scanning Calorimetry (DSC) techniques. it has been established that near-surface defects have a predominant influence on decreasing the H-desorption temperature. Variations of Raman, TPD and DSC spectra with irradiation conditions suggest that there are several mechanisms of dehydriding, and that they depend on defect concentration, interaction and ordering. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.