Aluminosilicate glasses behavior under irradiation

The understanding of radiation effects in oxide glasses is important in nuclear waste conditioning field and requires the evaluation of the role of the glass formers, mainly silicon, boron and aluminum, but also of the alkali and alkali-earth elements that can act either as modifier elements or charge compensators. Alumino-borosilicate glasses were highly studied and the role of boron coordination changes on structural evolution under irradiation was highlighted. However, there are only few studies on aluminosilicate glasses and almost no information about the influence of aluminum and its charge compensators on the glassy network evolution under irradiation. The goal of this work is therefore to determine the effects of aluminum content and type of charge compensators (here, Na and Ca cations) on the aluminosilicate glass structure evolution under irradiation. To understand the different phenomena in complex oxide glasses, 13 simplified glasses, composed of SiO₂, Al₂O₃, Na₂O and CaO oxides, were elaborated. Hence, the influence of Na₂O/CaO and Al₂O₃/SiO₂ ratios, and Al₂O₃ content, were investigated. To simulate alpha decays and compare electronic and ballistic damage, external irradiations at room temperature with 5 MeV He²⁺ and 7 MeV Au⁴⁺ were performed on glasses. 2.5 MeV electron irradiations were also done to obtain bulk samples irradiated by electronic collisions at low stopping power. (author)