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 o f symmetry B-g, were resolved by polarized light-scattering measuremen ts at 10 K. The mode frequencies harden with pressure up to 2.5 GPa. A t 6.2 GPa the changes of the spectra reveal a transition to an amorpho us phase. Further increase of the pressure up to 7 GPa yields strong i ndication of a phase transition from the disordered phase to the low-t emperature modification of GeSe2. At 8 GPa, this modification transfor ms back to the disordered phase. All these phase transformations are r eversible.