Diffusible and residual hydrogen in amorphous Ni(Cu)–Zr–H alloys

The partition of hydrogen into diffusible and residual parts was realized by pulse NMR spectroscopy, by gas chromatography and by prompt gamma activation analysis (PGAA). The total hydrogen content was determined by the two non-NMR methods and the diffusible (mobile) component by CPMG NMR pulse sequence. Results on amorphous Ni(Cu)–Zr–H systems of different compositions are shown. Partially crystallized samples were also studied as an extension. A method proposed by us directly gives the fractional population of hydrogen atoms in the free (mobile) state on the spin–spin relaxation time scale. On the other hand the least values of the residual hydrogen content correlate surprisingly well with the numbers of filled four Zr-type H-sites calculated by Batalla et al. [NATO ASI Ser. 136 (1985) 203] for 0.21-nm exclusion distance.