Impact of the silica glass initial state on the thermal and structural properties of metamict-like silica glass

This study investigates the structural and thermal stability of metamict-like silica glass samples prepared through different thermomechanical pathways and then subjected to the same high dose of electron irradiation (11 GGy). Specifically, we compared Suprasil F300 silica glass samples treated with high-pressure high-temperature (HPHT) conditions followed by irradiation to those solely irradiated. Additionally, Suprasil CG samples were analyzed to investigate the effect of silica impurities (e.g. OH) on the resulting state. Using Raman and FTIR spectroscopy, along with photoluminescence spectroscopy, we analyzed the vibrational structure and point defects changes. The activation energy distribution of the densification relaxation process was calculated to assess its thermal stability in a reliable manner. The results demonstrate that, despite achieving similar densities and vibrational structures in the metamict-like state, the initial structure of silica significantly influences the thermal stability and the resulting point defects population.