X-ray absorption study of rare earth ions in Sr2MgSi2O7:Eu2+,R3+ persistent luminescence materials
The valence of the europium dopant and selected rare earth co-dopants (Ce3+, Dy3+, and Yb3+) in the Sr2MgSi2O7:Eu2+,R3+ persistent luminescence materials were studied by room temperature XANES measurements. The results indicated the co-existence of both divalent and trivalent europium in all the studied materials. The relative amount of Eu3+ was observed to increase upon increasing exposure to X-r