Microstructure of hydrogenated Mg₂Ni studied by SANS

X-ray powder diffraction (XRD) and small-angle neutron scattering (SANS) experiments were carried out for the hydrogenated and duterated Mg ₂Ni, respectively. According to the results of XRD experiments, both of them coexisted with unhydrogenated (or undeuterated) Mg₂Ni in the hydrogen absorbing cycle. Furthermore, in the SANS experiments, a slope of SANS curve, I(Q), was roughly evaluated by using the following power law: I(Q) Q ^-m, where Q is the magnitude of the scattering vector, and m can be equated with a fractal dimensionality, D_S (= 6 - m). In conclusion, the hydrogenated and duterated Mg₂Ni showed D_S∼ 3 and ∼ 2, respectively. The significant difference between D_S's can be understood by considering the scattering length densities, ρ, of Mg ₂Ni, Mg₂NiH₄, and Mg₂NiD ₄.