Materials science of Mg-Ni-based new hydrides

One of the advantageous functional properties of ME alloys (or compounds) i s to exhibit the reversible hydriding reaction. In this paper, we present o ur systematic studies regarding the relationship between nanometer- or atom istic-scale structures and the specific hydriding properties of the Mg-Ni b inary system, such as (1) nanostructured (n)-Mg2Ni, (2) a mixture of n-Mg2N i and amorphous (a)-MgNi, (3) pure a-MgNi, and (4) n-MgNi2. Further studies on (5) an a-MgNi based system for clarifying the effect of the short-range ordering on the structural and hydriding properties and (6) a MgNi2-based system for synthesizing the new Laves phase structure are also presented. T he materials science of MgNi-based new hydrides will provide indispensable knowledge for practically developing the Mg alloys as hydrogen-storage mate rials.