Stress-induced site change of H in V observed by channeling experiments

The lattice location of H in α-${\mathrm{VH}}_{0.1}$ was determined at 150 °C with the channeling method using the nuclear reaction ${}_{}{}^1{}_{}{}^{}\mathrm{H}$ ${(}^{11}$B, α)αα. A drastic change from T sites for the H to a displaced-T or 4T configuration was observed when internal stress was introduced by thermal cycling, i.e., by precipitation and redissolution of the β phase. As the internal stress estimated by x-ray diffraction was comparable to the external stress which induces enormous diffusion enhancement (superdiffusion), it is suggested that the observed stress-induced site change underlies the occurrence of superdiffusion of H in V.