Anisotropy in the inelastic neutron scattering from fcc NiH

A sample of nearly stoichiometric fee nickel hydride in the form of polycry stalline plates with strong texture was studied by inelastic neutron scatte ring (INS) in two different orientations, with the [100] axis of the textur e parallel and at an angle of 45 degrees to the direction of neutron moment um transfer. The INS spectra were measured at 5 K with energy transfers ome ga ranging from 26 to 380 meV. In the region of the second and third band o f optical hydrogen vibrations. they showed a significant directional depend ence. A similar anisotropy was recently observed in the INS spectrum of fee palladium hydride, and the now available data for NiH and PdH are discusse d together.