Lattice Defect Behavior of LaNi_4.97Sn_0.27 during Hydrogenation Cycles

Abstract

Lattice defect behavior of LaNi_4.97Sn_0.27 during the hydrogenation cycles has been investigated by in-situ positron lifetime measurement. Mean positron lifetime increased and decreased by each hydrogenation and dehydrogenation, respectively, independently of the hydrogenation cycles. It suggests that lattice defects are introduced by the hydrogenation and removed from the lattice by the dehydrogenation even at below the migration temperature of vacancy in LaNi₅. Furthermore, dislocation density and vacancy concentration kept almost constant at the value of around 6×10⁹ cm⁻² and 10 ppm through at least eight hydrogenation/dehydrogenation cycles.