Brillouin scattering in densified GeO2 glasses

Brillouin and Raman scattering measurements have been applied for the inves tigation of GeO2 glasses densified under high pressures up to 9 GPa at 673 K. The density of obtained glasses increases with an increase of applied pr essure. It increases significantly around 3 GPa, however shows a peak at 6 GPa. A significant increase is also observed in hypersonic wave velocity, a nd longitudinal and shear moduli around 3 GPa. These results are well expla ined by amorphous-amorphous transition. In Raman scattering measurement, vi brational modes illustrate continuous changes of local structures with incr easing applied pressures up to 9 GPa. Boson peaks show a maximum around 3 G Pa, which indicates the minimum correlation length. These data suggest a ch ange in the intermediate-range structure.