Aluminosilicate glasses structure under electron irradiation: An EPR study

To understand the complex oxide glasses behavior under irradiation, 13 simplified aluminosilicate glasses were elaborated, composed of SiO2, Al2O3, Na2O and CaO oxides, which were distributed in 3 series to investigate the influence of Na2O/CaO, Al2O3/SiO2 ratios and Al2O3 content. 2.5 MeV Electron irradiations were performed to obtain bulk irradiated samples by electronic collisions at low stopping power. The influence of dose (from 1.105 up to 4.109 Gy) and chemical composition on the formation of paramagnetic centers have been investigated by electron paramagnetic resonance (EPR) spectroscopy. It has shown that electronic collisions induce production of mainly 3 types of point defects (OHC, Al-OHC, E') in the glassy network, whose content increase up to 1 GGy. The production efficiency of Al-OHC defects is increased when the calcium cations are in charge compensator role around aluminum cations instead of sodium cations. A significant decrease of defects concentration was observed between 1 and 4 GGy for all studied glasses.