Compounds of AB5 and AB2 type, for H storage, were characterized by using positron annihilation lifetime spectroscopy. It was shown that they contained no constitutional vacancies, and that deviations from the stoichiometric compositions were all compensated by antistructure atoms. Surprising numbers of vacancies and dislocations were found to be generated during the first H absorption step.

Positron Annihilation Study of Lattice Defects Induced by Hydrogen Absorption in Some Hydrogen Storage Materials. Y.Shirai, H.Araki, T.Mori, W.Nakamura, K.Sakaki: Journal of Alloys and Compounds, 2002, 330-332, 125-31