Dye‐Laser Spectroscopy of Commercial Y 2 O 3 : Eu3 + Phosphors

Commercial phosphors, formulated at constant europium content, exhibit under 254 nm excitation plaque‐brightness 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 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 phosphors: sample‐specific, nonradiative deactivation of the level; preferential site occupation ( or ) by Eu 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 3+ content is lower in materials of reduced brightness. This conclusion has been confirmed by high sensitivity, visible‐reflectance spectroscopy on the phosphor powders.