White-light-emitting long-lasting phosphorescence in Dy3+-doped SrSiO3

We report on a luminescent phenomenon in Dy3+-doped SrSiO3 long-lasting phosphor. After irradiation by a 254-nm UV lamp for 5 min, the Dy3+-doped SrSiO3 phosphor emits white light-emitting long-lasting phosphorescence for more than 1 h even after the irradiation source has been removed. Photoluminescence, long-lasting phosphorescence and thermoluminescence (TL) spectra are used to explain this phenomenon. Photoluminescence spectra reveal that the white light-emitting long-lasting phosphorescence originated from the two mixtures of Dy3+ characteristic luminescence, the 480-nm blue emission (F-4(9/2) -> H-6(15/2)) and the 572-nm yellow emission (F-4(9/2) -> H-6(13/2)). TL spectra shows that the introduction of Dy3+ ions into the SrSiO3 host produces a highly dense trapping level at 377 K (0.59eV), which is responsible for the long-lasting phosphorescence at room temperature. A possible mechanism of the long-lasting phosphorescence based on the experimental results is proposed. It is considered that the long-lasting phosphorescence is due to persistent energy transfer from the electron traps to the Dy3+ ions, which creates the persistent luminescence of Dy3+ to produce the white light-emitting long-lasting phosphorescence. (c) 2005 Elsevier Inc. All rights reserved.