Effect of substitutional Mo on diffusion and site occupation of hydrogen in the BCT monohydride phase of V-H system studied by 1H NMR

The diffusion and site occupation of hydrogen in the monohydride phase of V1-xMox-H (0 <= x <= 0.1) were studied by means of H-1 nuclear magnetic resonance (NMR). Hydrogen atoms in VH0.68 occupied the octahedral (O) sites in a body centered tetragonal (BCT) structure. The addition of Mo to V reduced the activation energy for hydrogen diffusion, E-H, for the O sites. In V0.9Mo0.1H0.68 hydrogen atoms occupied both the O and tetrahedral (T) sites, which was demonstrated by two components observed in the temperature dependence of the H-1 spin-lattice relaxation time. The value of E-H for the T sites was lower than that for the O sites. Hydrogen atoms in V0.9Mo0.1H0.68 diffused faster than those in VH0.68. (C) 2010 Elsevier B.V. All rights reserved.