Cooperative hydriding properties in a nanostructured Mg₂Ni-H system

A nanostructured Mg₂Ni-H system was prepared by reactive mechanical grinding (RMG) of Mg₂Ni under a H₂ gas pressure of 1 MPa during various time periods from 5 to 4800 min. The structural and hydriding properties of the products obtained were examined by X-ray diffraction, thermal analysis, SEM and TEM. The experimental results showed the existence of cooperative dehydriding phenomena in intra- and inter-grain regions which have about the same volume fractions. Dehydrogenation from distorted inter-grain regions in nanostructured Mg₂Ni-H prepared by RMG for 60 min occurs at the same temperature as hydrogen leaves the intra-grain region of crystalline Mg₂NiH_0.3. Elastic interactions in nanostructured materials are important for the understanding of such cooperative dehydriding phenomena.