FLUORESCENCE LINE-NARROWING STUDY OF EU3-DOPED SOL-GEL SILICA - EFFECT OF MODIFYING CATIONS ON THE CLUSTERING OF EU3+()

Fluorescence line-narrowing spectroscopy is used to characterize the e ffect of metal cation codopants (Sr2+, La3+, Gd3+, Y3+, Lu3+, Sc3+, an d Ga3+) on the state of aggregation of Eu3+ in sol-gel silica. Signifi cant Eu3+ clustering occurs in samples doped only with Eu3+. The addit ion of codopants inhibits the clustering of Eu3+ and promotes better d ispersion of Eu3+ in the glasses. The extent of the inhibition of clus tering increases with field strength of the codopant and levels off at high field strength. The inhibition of clustering is correlated with the generation of strong crystal field bonding sites for Eu3+ in the p resence of codopants. Characteristics of these sites include the prese nce of Eu-O-M (M = codopant) linkages and stronger interactions with t he network-forming regions of the glass. Supporting luminescence decay and Raman spectroscopy measurements are also presented.