Dye-laser spectroscopy of commercial Y/sub 2/O/sub 3/: Eu/sup 3 +/ phosphors

Commercial Y/sub 2/O/sub 3/: Eu phosphors, formulated at constant europium content, exhibit under 254 nm excitation plaquebrightness variations of up to 10%. Several working models are proposed to explain this variation in emission brightness, and their physical implications on the spectral behavior of the Y/sub 2/O/sub 3/: Eu materials under discussion are explored by means of the techniques of low temperature, time-resolved emission and excitation spectroscopy, following dye-laser excitation. The following physical models were considered, as affecting the emission brightness of the Y/sub 2/O/sub 3/: Eu phosphors: sample-specific, nonradiative deactivation of the /sup 5/D/sub 6/ level; preferential site occupation (C/sub 2/ or C /SUB m/ ) by Eu/sup 3 -/; and the presence of secondary crystalline phases, or sites, of low emission efficiency. None of these models satisfactorily explains the variation in emission brightness for 254 nm excitation. However, a variety of spectral observations suggest that the Eu/sup 3 -/ content is lower in Y/sub 2/O/sub 3/: Eu materials of reduced brightness. This conclusion has been confirmed by high sensitivity, visible-reflectance spectroscopy on the phosphor powders.