The lattice defect behavior of LaNi4.97Sn0.27 during hydrogenation cycles was investigated by means of in situ positron lifetime measurements. It was found that the mean positron lifetime was increased and decreased by each hydrogenation and dehydrogenation step, respectively, regardless of the hydrogenation cycle. It was suggested that lattice defects were introduced by the hydrogenation, and removed from the lattice by the dehydrogenation; even at temperatures which were below the migration temperature of vacancies in LaNi5. Furthermore, the dislocation density and the vacancy concentration remained almost constant at values of around 6 x 109/cm2 and 10ppm throughout at least 8 hydrogenation/dehydrogenation cycles.

Lattice Defect Behavior of LaNi4.97Sn0.27 during Hydrogenation Cycles. K.Sakaki, Y.Nakamura, Y.Shirai, R.C.Bowman, E.Akiba: Materials Transactions, 2006, 47[8], 1875-7