PRESSURE-INDUCED AMORPHIZATION OF GERMANIUM DISELENIDE

We have measured the Raman scattering spectra of beta-GeSe2 single cry stal thigh-temperature modification with layered crystal structure) un der hydrostatic pressures to 12.5 GPa at room temperature. According t o the Raman spectra, the pressure increase produces transformation of the layered crystal structure into a fully disordered structure (at 6. 2 GPa). A further increase of the pressure to 7 GPa yields indications of a phase transition from the disordered phase to the alpha-GeSe2 (l ow-temperature modification of GeSe2 with three dimensional crystal st ructure), At 8 GPa, this modification transforms back to the disordere d phase. Reversibility of the phase changes, upon releasing the pressu re, depends on the maximum pressure. (C) 1998 Elsevier Science B.V. Al l rights reserved.