High-pressure Raman-scattering study of germanium diselenide

We have measured the Raman-scattering spectra of the beta modification of GeSe2 at low temperatures and under hydrostatic pressures up to 8 GPa at room temperature. A total of 28 modes of symmetry A(g) and 29 of symmetry B-g, were resolved by polarized light-scattering measurements at 10 K. The mode frequencies harden with pressure up to 2.5 GPa. At 6.2 GPa the changes of the spectra reveal a transition to an amorphous phase. Further increase of the pressure up to 7 GPa yields strong indication of a phase transition from the disordered phase to the low-temperature modification of GeSe2. At 8 GPa, this modification transforms back to the disordered phase. All these phase transformations are reversible.