EFFECTS OF COMPOSITION ON THE LONG PHOSPHORESCENT SRAL2O4-EU2+, DY3+ PHOSPHOR CRYSTALS

Effects of the composition on the afterglow characteristics of SrAl2O4 :Eu2+, Dy3+ phosphors have been evaluated using crystals grown by a fl oating zone technique for the first time. Phosphorescence spectrum due to Eu2+ ions peaking at lambda = 520 nm does not vary with the compos itions. Persistent times vary greatly with different compositions. Dy concentrations added as auxiliary activators are changed dramatically with the Sr/Al molar ratio of the starting materials. The phosphoresce nce decay consists of three exponential components with different deca y times. The faster decay components play an important role for the lo ng persistent phosphorescence.