Tuning Eu²⁺ amount and site symmetry in phosphate glasses under irradiation by electron energy and integrated dose

This paper relates the formation of Eu²⁺ under 700 keV and 2.5 MeV irradiation in meta and polyphosphate glasses. EPR and photoluminescence measurements evidenced the presence of two sites for Eu²⁺ ions corresponding to low-symmetry and high-symmetry sites. We highlighted that the glass composition and in particular the presence of ZnO favors the formation of high-symmetry sites. Moreover, we found out that 700 keV electron energy is much more efficient to produce Eu²⁺ ions compared to 2.5 MeV. This is probably linked to an enhancement of the alkaline migration generated under the charge depletion induced by the 700 keV electrons implentation. This migration depolymerizes the network structure and tends to favor the formation of Eu²⁺. The same tendency is observed at 2.5 MeV when the dose is higher than 1 GGy.