Formation of a High Pressure Form of Magnesium Hydride γ-MgH2 by Mechanical Grinding under Low Hydrogen Pressure

Abstract

In order to investigate the formation of a high pressure form of magnesium hydride, γ-MgH2, X-ray diffraction patterns before and after the hydriding reaction were obtained for samples of MgH2, MgH2 after reactive mechanical grinding (RMG), and 94 wt% MgH2-6 wt% Ni after reactive mechanical grinding. In addition, absorbed hydrogen quantity versus time curves at the first cycle were examined. The MgH2 sample did not contain γ-MgH2. However, the MgH2 after RMG and the 94 wt% MgH2-6 wt% Ni after RMG contained γ-MgH2. All these results prove that after reactive mechanical grinding, γ-MgH2, one of the high pressure forms of MgH2, was formed in the MgH2 and 94 wt% MgH2-6 wt% Ni samples under low hydrogen pressures.