CHARACTERISTICS OF STRONTIUM ALUMINATE CRYSTALS USED FOR LONG-DURATION PHOSPHORS

Sr3Al2O6, SrAl2O4, SrAl4O7, and SrAl12O19 that have been doped with Eu 2+ and Dy3+ ions have been grown by a floating-zone technique for appl ication as long-duration phosphors. Long-duration phosphorescence with a variety of colors has been observed in SrAl2O4, SrAl4O7 and SrAl12O 19 crystals that have been doped with Eu2+ and Dy3+ ions. The peak wav elength of the phosphorescence is 520 nm for SrAl2O4, 480 nm for SrAl2 O4, and 400 nm for SrAl12O19. The phosphorescence is characterized by decay times that have been analyzed by a curve-fitting technique.