Thermal and vibrational properties of silica xerogels

The structure and the dynamics of silica sol--gel samples have been studied by means of Brillouin and Raman scattering, and specific heat experiments. The results are compared with those of xerogel glasses and amorphous silica, obtained by thermal treatment and by melt quenching respectively. Increasing the treatment temperatures produces progressive densification of the xerogel systems, whose dynamics and calorimetric properties are analysed for a wide range of temperatures.