H-1 NMR and magnetization measurements of a nanostructured composite material of the Mg2Ni-H system synthesized by reactive mechanical grinding

H-1 NMR spectra and magnetization have been measured for a nanostructured Mg2Ni-H system.H-1 MAS NMR spectra indicate the presence of four phases; alpha-Mg2NiHx, beta-Mg2NIH4, alpha-MgHx and beta-MgH2. Most of the hydrogens are contained in the disordered beta-Mg2NiH4 phase. Magnetization consists of superparamagnetic and paramagnetic ones. The former has its origin in Ni particles formed during the hydrogenation. The latter is greater than the values of crystalline alpha-Mg2NiH4 and beta-Mg2NiH4. H-1 NMR line width increases with the decrease in temperature linearly, most of which is of dipolar origin. The hydrogen is more mobile in the disordered beta-Mg2NiH4 phase than in the crystalline counterpart. (C) 1997 Elsevier Science S.A.