TDPAC STUDY OF THE HF-DOPED LANI5-HYDROGEN SYSTEM

The dependence of the electric field gradients (EFGs) in the Hf-doped LaNi5-hydrogen system, as a function of hydrogen composition ratio (X) , has been investigated in the range 0 less than or equal to X less th an or equal to 5.7 using the Time Differential Perturbed Angular Corre lation (TDPAC) technique. The TDPAC spectrum of LaNi5 was fitted with a single EFG, while two EFGs were needed to fit the LaNi5HX spectra. T he first EFG was similar to the one found in metallic LaNi, and the se cond one was interpreted as related to those probe atoms located in th e basal plane next to hydrogen interstitial sites located in the same plane. The relative fraction of the probe atoms experiencing these EFG s is dependent on the relative occupation of hydrogen in these sites. (C) 1997 Elsevier Science S.A.