NEUTRON SPECTROSCOPY OF TIH0.74 AFTER HIGH-PRESSURE TREATMENT

High resolution neutron scattering studies of vibrational spectra (2-800 meV) were carried out on the epsilon-, delta'- and delta-phases of titanium hydride, obtained after high pressure treatment. The observed splitting of the fundamental optic peak in the delta-phase spectrum can be explained by a strong H-H interaction along the c-axis. Well pronounced features are seen on the low energy side of the two- and three-phonon optic bands. These are assigned to bound bi- and tri-phonon excitations. This is the first observation of bi- and tri-phonons in metal hydrides.