2014 Volume 55 Issue 8 Pages 1175-1178
We propose the microstructural change model of magnesium hydride catalyzed by Nb2O5 during hydrogenation. The ball-milled composites, MgH2 and 1 mol% Nb2O5, were dehydrogenated and then rehydrogenated for varied time at room temperature under 0.1 MPa H2 atmosphere. The crystallite size of Mg and MgH2 was evaluated by powder X-ray diffraction (XRD) measurement and confirmed by transmission electron microscopy (TEM) observation. The crystallite size of generated MgH2 was smaller than that of Mg and did not change significantly with increasing time of hydrogenation. It is suggested that the number density of MgH2 crystallites increases during the hydrogenation process.