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 nanostructu red Mg2Ni-H system.H-1 MAS NMR spectra indicate the presence of four p hases; alpha-Mg2NiHx, beta-Mg2NIH4, alpha-MgHx and beta-MgH2. Most of the hydrogens are contained in the disordered beta-Mg2NiH4 phase. Magn etization consists of superparamagnetic and paramagnetic ones. The for mer has its origin in Ni particles formed during the hydrogenation. Th e latter is greater than the values of crystalline alpha-Mg2NiH4 and b eta-Mg2NiH4. H-1 NMR line width increases with the decrease in tempera ture linearly, most of which is of dipolar origin. The hydrogen is mor e mobile in the disordered beta-Mg2NiH4 phase than in the crystalline counterpart. (C) 1997 Elsevier Science S.A.