Hydrogen Vibrational Excitation Spectra of CaF₂-Type Metal Hydrides Synthesized from Ti-Based BCC Solid Solution Alloys

Abstract

Hydrogen vibrational excitation was studied for CaF₂-type metal hydrides synthesized from Ti-based BCC solid solution alloys using inelastic incoherent neutron scattering (IINS). Ti_1.0V_1.1Mn_0.9H_4.5 and Ti_0.7V_1.2Cr_1.1H_4.8 showed IINS spectra similar to that reported for TiH₂. The first three peaks were isolated but the higher excitation peaks were not clear. Analysis of the spectra using curve-fitting with Gauss functions revealed that the hydrogen vibration of Ti_1.0V_1.1Mn_0.9H_4.5 is harmonic but that of the Ti_0.7V_1.2Cr_1.1H_4.8 is deviated from harmonic, which reflects a trumpet-type potential. The relation between metal-hydrogen distance and vibrational excitation energy for the above two hydrides and Ti_1.1Cr_1.4Mo_0.3H_∼5 was compared with a series of CaF₂-type binary metal hydrides. All the hydrides of the Ti-based alloys had lower vibrational excitation energies than the binary metal hydrides for the corresponding metal-hydrogen distances.