Irradiation induced densification and its correlation with three-membered rings in vitreous silica

• Electron irradiation causes densification and the increase of D2 peak in Silica glass.
• Densification of the glass is related to the increase of the three-membered rings.
• Topological changes in the glass structure are possible below the glass transition temperature.

Suprasil silica glass was irradiated by 50 keV electron beam with doses within the range of 3.1–191.1 kC/m2. Volume changes induced by electron irradiation were monitored by means of Atomic Force Microscopy (AFM). Raman spectra were taken from irradiated spots to observe structural changes. Irradiated glasses were annealed at temperatures 500–1000 °C. After annealing irradiated spots were again examined by AFM and Raman spectroscopy in order to observe volume and structural relaxation of radiation-induced changes. Electron beam caused volume compaction that was correlated with D2 peak area for lower doses. D2 peak evolution under irradiation and subsequent annealing showed that topological changes in glass structure are possible deeply below the glass transition temperature.