Direct evidence of stress-induced site change of H in V observed by the channeling method

The effect of external stress on the lattice location of H in α-${\mathrm{VH}}_{0.010–0.015}$ was investigated at room temperature by the channeling method using the reaction ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ ${(}^{11}$B, α)αα. A drastic site change of H from T sites to the displaced-T or 4T configuration was observed when a compressive stress of 7 kg/${\mathrm{mm}}^2$ (below the elastic limit) was applied along the 〈100〉 direction. With the release of the stress, the H atoms returned to the T sites. The observed stress-induced configuration is believed to be closely connected to the occurrence of an enormous enhancement of diffusivity of H in V under stress.