Rare-Earth-Activated Fluorophosphate Glasses: Local Environment of the Activator and Capture Volume Model

摘要

Data are presented on the induced optical absorption and EPR in Ba(PO_3)_2-MgF_2 glasses activated with Tb_2O_3 and Eu_2O_3. The effect of activator concentration on the EPR spectra of the PO_4~(2-) and PO_3~(2-) centers in glasses differing in fluoride content is analyzed. The results indicate that fluorophosphate glasses can be characterized by two capture volumes which may differ several times, depending on the activator concentration. At low activator concentrations, corresponding to the largest capture volume, the activator ions seem to be in a phosphate environment. The maximum Tb~(3+) concentration is comparable to the Eu~(3+) concentration at which the luminescence spectrum points to a phosphate environment of the rare-earth ion.