Defect chemistry in CaF2:Eu3+

Site selective spectroscopy has been performed for CaF2:Eu3+ samples as a function of annealing temperature and dopant concentration. The Eu3+ lines have been classified into five sites, two of which correspond with Eu3+ clusters. High annealing temperatures dissociate the clusters and leave Eu3+ ions in cubic and tetragonal sites. The relative concentrations of these sites change anomalously as the Eu3+ concentration is raised. Absolute concentration measurements of all the sites eliminates competing equilibria as a possible explanation. These results confirm the conclusions reached in an earlier paper for a more complex system.