High-pressure study of YH3 by Raman and visible absorption spectroscopy

Raman and visible absorption spectra of YH3 were measured at high pressures, in order to clarify the structural and electronic phase transitions. The Raman results revealed the presence of an intermediate phase at 9-24 GPa between the low-pressure hexagonal and high-pressure fcc phases. The Y-framework structure and the position of interstitial H atoms are changed on the transition to intermediate phase. The results of the absorption measurements demonstrate that the optical band gap starts to close in response to the phase transition.