LOW-FREQUENCY INELASTIC LIGHT-SCATTERING FROM GEO2-BASED GLASS - EARLY STEPS OF CRYSTALLIZATION

Room-temperature polarized Raman scattering spectra of germanium feldspar glass have been collected. Depolarized spectra of the very early stages of thermal treatment are found to differ significantly from the spectra of the more advanced steps of structural rearrangement. The temperature dependence and spectral distribution of the light scattering excess in the acoustic Raman modes region (the so-called boson peak) have been interpreted in terms of changes in the microstructure (phase separation) of the glass network. Changes in the acoustic Raman modes after thermal treatment were accompanied by the presence of a new weak band located on the low frequency side of the boson peak. The spectra in the low frequency (5-300 cm-1) region were compared with the spectra in the region of high frequency (to 1500 cm-1). The progress of crystallization and the phase composition were checked by infrared spectroscopy and X-ray diffraction.