Effect of composition on the phosphorescence from BaAl2O4: Eu2+, Dy3+ crystals

Effect of composition on the afterglow phosphorescence from BaAl2O4: Eu2+, Dy3+ crystals has been evaluated using crystals grown by the floating zone technique. Broad band emissions peaking at lambda, = 500 nm derived from excited slates of Eu2+ ions were observed for all crystals grown from various compositions. Intensity of afterglow phosphorescence was greatly influenced by the composition of the starting materials. Phosphorescence from Ba-rich crystals disappear within 30 msec, although those from AI-rich and stoichiometric crystals last for several hours. The trap depth and the trap density evaluated using thermally stimulated luminescence technique also vary with compositions. Several traps can be seen in the specimens. The trap, which shows the thermal glow peak at around 350 K? which is extremely weak in the Ba-rich specimen, is considered to be responsible for the long duration phosphorescence at room temperature. (C) 1999 Elsevier Science B.V. All rights reserved.