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

Abstract

The diffusion and site occupation of hydrogen in the monohydride phase of V 1− x Mo x –H (0 ≤ x ≤ 0.1) were studied by means of 1H nuclear magnetic resonance (NMR). Hydrogen atoms in VH 0.68 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 V 0.9Mo 0.1H 0.68 hydrogen atoms occupied both the O and tetrahedral ( T) sites, which was demonstrated by two components observed in the temperature dependence of the 1H spin-lattice relaxation time. The value of E H for the T sites was lower than that for the O sites. Hydrogen atoms in V 0.9Mo 0.1H 0.68 diffused faster than those in VH 0.68.