Neutron scattering study of hydrogen vibrations in polycrystal and glassy TiCuH

Abstract

Neutron vibrational spectra have been measured for both crystalline and amorphous titanium copper hydride from 40-200 meV. A rather narrow distribution of optical (hydrogen) vibrations is observed for the crystalline alloy TiCuH_0.93 with maxima at 142 and 157 meV, very close to previous results for gamma -TiH₂. Amorphous TiCuH_1.3, however, exhibits a very broad band of hydrogen vibrations ( approximately 76 meV FWHM) peaked at about 145 meV. This density of states provides a probe of the local environments of the hydrogen atoms residing in holes in the metallic glass structure and suggests an 'average' occupation of tetrahedral holes, but considerable fluctuations in local symmetry around these sites.