Long afterglow of trivalent dysprosium doped strontium aluminate

Trivalent dysprosium doped strontium aluminate (SrA12O4:Dy3+) was synthesized via the sol–gel combustion method to realize green afterglow in the absence of Eu2+ luminescent centers. The morphology, crystal structure, photoluminescence and long afterglow of the SrAl2O4:Dy3+ were characterized with scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy and photoluminescence spectroscopy, respectively. The bluish-green photoluminescence of SrAl2O4:Dy3+ consists of a broad emission band centered at about 520 nm and two characteristic emissions of Dy3+ ions centered at 480 and 575 nm, respectively. The green afterglow of SrAl2O4:Dy3+ is a broad emission band centered at around 520 nm, and the lifetime extracted from afterglow decay is found to be 53 s. The mechanism on the green afterglow from SrAl2O4:Dy3+ is discussed in terms of the possible defect levels in the host.