Characteristics of Strontium Aluminate Crystals Used for Long‐Duration Phosphors

Sr 3 Al 2 O 6 , SrAl 2 O 4 , SrAl 4 O 7 , and SrAl 12 O 19 that have been doped with Eu 2+ and Dy 3+ ions have been grown by a floating‐zone technique for application as long‐duration phosphors. Long‐duration phosphorescence with a variety of colors has been observed in SrA l2 O 4 , SrAl 4 O 7 , and SrAl 12 O 19 crystals that have been doped with Eu 2+ and Dy 3+ ions. The peak wavelength of the phosphorescence is 520 nm for SrAl 2 O 4 , 480 nm for SrAl 4 O 7 , and 400 nm for SrAl 12 O 19 . The phosphorescence is characterized by decay times that have been analyzed by a curve‐fitting technique.