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 1H 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, EH, 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 1H spin-lattice relaxation time. The value of EH 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.

Research highlights▶ Site occupation of hydrogen in the monohydride phase of V1−xMoxH0.68 (0 ≤ x ≤ 0.1). ▶ Temperature dependence of the 1H spin-lattice relaxation time in V1−xMoxH0.68 (0 ≤ x ≤ 0.1). ▶ Activation energy for hydrogen diffusion for the octahedral and tetrahedral sites.