Irradiation effects in oxide glasses doped with transition and rare-earth elements

The effect of β-irradiation on silicate and alumino-borosilicate glasses doped with transition metals (TM) and rare earth (RE) elements has been studied using Electron Paramagnetic Resonance (EPR), Raman and luminescence spectroscopy. Irradiation leads to the reduction of both Cr and Mn ions in both types of glass matrix. It is shown that even small amounts of TM dopants completely block defect production, as occurs under irradiation in non-doped glasses. As well, TM doping results in the disappearance of structural changes in the glass (densification, polymerization increase and Na migration) for doses of about 109 Gy. Unlike TM-doped matrices, incorporation of RE ions into alumino-borosilicate glass blocks neither defect production nor structural changes in glass matrices during irradiation. Simultaneously, we observe a reduction of RE ions, most clearly demonstrated for Ce4+ ions in alumino-borosilicate glasses. We propose that the relative stability of the different charge states of the RE ions is linked to the efficiency of the reduction process, and therefore to the evolution of the glass structure during irradiation. (authors)