Studies of the structure of lead metaborate glasses doped with up to 15 mol% Eu2O3 are reported. Measurements of the samples using laser ionization time of flight mass spectrometry revealed an isolated role for single Eu~(+3) ions and a preference for sites near B3O6 rings. The relative isolation of the europium modifier ions was confirmed by infrared spectroscopy and UV/visible absorbance and fluorescence. The impact on the lead borate network was limited to an increase in the fraction of three-coordinated borons and an increase in lead rich units. Fluorescence measurements suggest a stable (+3) oxidation state for the europium ions, and very little change in the fluorescence emission lifetime. The stable borate sites (near rings) occupied by the Eu and its high field strength are possible explanations of these observations.
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