Hydrogen vibration excitation of metal hydrides up to 21 GPa by incoherent inelastic neutron scattering

Hattori, Takanori   ; Nakamura, Mitsutaka   ; Iida, Kazuki*; Machida, Akihiko*; Sano, Asami   ; Machida, Shinichi*; Arima, Hiroshi*; Oshita, Hidetoshi*; Honda, Takashi*; Ikeda, Kazutaka*; Otomo, Toshiya*

Recently, the high-pressure state of metal hydrides has attracted much attention due to the discovery of superhydrides with high- near room temperature under ultra-high pressure. The vibrational state of hydrogen is important to understand the origin of high and to search for materials with higher . Incoherent Inelastic Neutron Scattering (IINS) is a powerful tool to study the vibrational excitations of hydrogen. Therefore, vibrational excitations of various metal hydrides have been investigated, but a unified understanding is still lacking due to the differences in the lattice size and electronic states. Pressure allows us to investigate the nature of the lattice more rationally because the lattice size can be changed continuously. In the present work, we have developed an apparatus for IINS under high pressure, and succeeded in observing vibrational excitations of hydrogen in ZrH and TiH up to 21 GPa. In this talk, we will introduce the principle of IINS, the experiments, and the results obtained.