STRUCTURE OF HYDROGENATED AMORPHOUS NI56DY44

The structure of amorphous Ni56Dy44, loaded with 32 at% and 60 at% hyd rogen, was investigated by X-ray and neutron diffraction using the iso topic substitution method. The results are discussed on the basis of t he pair distribution functions. The incorporation of hydrogen atoms ca uses a change of the Ni-Dy matrix, i.e., an increase of the atomic dis tances and of the coordination numbers, in particular those of the Dy- Dy correlations. The H-atoms are preferentially located in a tetrahedr al Dy-coordination, but also some hydrogen-Ni coordination was found. The hydrogen-metal distances agree with the distances between tetrahed ral interstitial sites and the metal atoms in the crystalline hydrides DyH2 and Ni57H43. A distance correlation between the hydrogen atoms w as found at 2.78 Angstrom.