NMR studies of hydrogen diffusion in β-LaNi5−yAly hydrides

Proton relaxation times have been measured in β-phase LaNi_5?yAl_yH_x, where 0<y<1.2, to determine the role of Al on hydrogen diffusion. Al substitution significantly increases the observed activation energy with a corresponding 100-fold decrease in the room temperature (300K) diffusion constant between y=0 and y=1.2. Comparisons are also made with previous studies of β-LaNi₅H_x and possible diffusion mechanisms are suggested.