Mechanically alloyed mixtures were hydrided, under pressure, at temperatures of between 543 and 623K. The proton magnetic resonance was measured at 30MHz, and at temperatures ranging from 250 to 423K. Three hydrides, MgH0.03, MgH2 and Mg2NiH4, were identified. Proton diffusion was studied in monoclinic Mg2NiH4. By monitoring the thermal evolution of the proton line-width, the diffusivity was deduced for temperatures of between 250 and 331K. The results could be described by:

D (cm2/s) = 1.1 x 10-9 exp[-2440/T]

A plateau was observed in the motional narrowing at temperatures above 331K. Competition between the trapping and diffusion of H was used to explain this behavior.

Phase Characterization and Hydrogen Diffusion Study in the Mg-Ni-H System. J.Senegas, M.Y.Song, M.Pezat, B.Darriet: Journal of the Less-Common Metals, 1987, 129, 317-26