High pressure studies of terbium trihydride. X-ray, Raman and DFT investigations

Highlights: • Hexagonal to cubic phase transition has been studied by X-ray and Raman measurements. • Theoretical calculations have supported our findings. • Equations of state for both phases have been determined. - Abstract: Pressure induced phase transformation in terbium trihydride has been studied by X-ray diffraction and Raman spectroscopy up to 20 GPa. Theoretical calculations were performed using density functional theory (DFT) with the Perdew–Burke–Ernzerhof parameterizations of the generalized gradient approximation as implemented in the VASP code. X-ray diffraction analysis and Raman measurements show structural transformation from original hcp to cubic structure at pressure of ∼7.0 GPa. The result is in good agreement with the theoretical predictions. Characterization of the new phase along with equations of state of both phases is presented