In order to determine the parameters of H motion in the cubic C15-type Laves phase. Quasi-elastic neutron-scattering measurements and nuclear magnetic resonance measurements of the proton spin-lattice relaxation rate of Mo2ZrHx (where x was between 0.3 and 1) were carried out at temperatures ranging from 10 to 430K. The diffusive motion of H could be described in terms of 2 jump processes. These were a fast localized motion of H within the hexagons formed by interstitial g-sites, and a slower hopping from one hexagon to another. The hopping rate of the faster process was found to be of the order of 1010/s at 300K. The characteristic frequency of the slower process, at the same temperature, was about 6 x 107/s. A comparison of the motional parameters of H in the present material, with those in related C15-type systems (V2TaHx, Cr2ZrHx), showed that the ratio of the frequencies of the slow and fast processes was between the corresponding ratios for V2TaHx and Cr2ZrHx. This was consistent with changes in the g-g distances within hexagons and between different hexagons.

Hydrogen Motion in C15-Type ZrMo2Hx: Quasielastic Neutron Scattering and Nuclear Magnetic Resonance Studies. A.V.Skripov, J.C.Cook, C.Karmonik, V.N.Kozhanov: Physical Review B, 1999, 60[10], 7238-44