The diffusion mechanisms of H in metallic and nanostructured materials were studied systematically by using various nuclear magnetic resonance techniques, and 3 examples of recent work were reviewed here. These were firstly the H-stabilized Laves-phase compound, C15-HfTi2H4, with rather complex mechanisms of H diffusion. Long-range diffusion and localized motion coexisted on different time scales in this compound. Secondly, nano-structured vanadium-hydrides n-VHx, in which the dynamic properties of H were fundamentally changed compared to that in a crystalline compound. The diffusionparameters of H in the grain-boundary regions could be determined independently of H motion within the crystalline grains. Thirdly, the H in nano-structured H-graphite-systems n-CHx, where the nuclear magnetic resonance spectra revealed 2 types of H coordinations. The relaxation data indicated high H mobilities at ambient temperatures.

Hydrogen Diffusion in Metallic and Nanostructured Materials. G.Majer, U.Eberle, F.Kimmerle, E.Stanik, S.Orimo: Physica B, 2003, 328[1-2], 81-9