Study On The Synthesis Of Long-lasting Phosphorescence SrAl₂O₄: Eu～(2+), Dy～(3+) By Flux Method And It's Persistent Luminescence Properties

In recent years, more and more attention has been paid to the alkaline earth aluminates long lasting persistent materials. The Eu²⁺, Dy³⁺ co-doped alkaline earth aluminate SrAl₄O₄:Eu²⁺,Dy³⁺ is regarded as a useful phosphor that has very good brightness, long persistent phosphorescence and great chemical stability, in contrast to the traditional ZnS:Cu,Co. It is usually prepared by solid state reaction with a small amount B₂O₃ as a flux. Boron is not only plays the role of flux, but also enhances the luminescence properties of the aluminates. So it is significant to study the luminescence properties of the B₂O₃ effect on SrAl₂O₄:Eu²⁺,Dy³⁺ phosphor.In this paper, powder samples Sr_1-x-yAl₄O₄: Eu_x²⁺, Dy_y³⁺ ? nB₂O₃ (0. 005≤X≤0. 07, 0. 01≤y≤0. 05,0≤n≤0. 30) were synthesized successfully by flux method, and their photoluminescence were investigated. The effect of the B₂O₃ and the ratio of Al/Sr on SrAl₂O₄:Eu²⁺,Dy³⁺ were studied throught means of XRD patterns, SEM photographs, IR spectra, excitation spectra, emission spectra, decay curves, thermoluminescence, positron annihilation and EPR.The results indicate that the obtained phosphors are monocline srystal structure. B₂O₃ decreased the reaction temperature, improved the crystallinity of Sr_0.95Al₂O₄:Eu_0.02²⁺,Dy_0.03³⁺. Excitation spectrum is a broadband centered at 330nm. Under excitation, emission spectrum is also a broadband centered at 509-516nm. B³⁺ substitution of Al³⁺ significantly improved the emission intensity and persistent luminescence time. A defect complex was formed accompanied with significant hole re-trapping process in conduction band and the decay time was prolonged. When altering the ratio of Al/Sr, the afterglow intensity obtained the max in the case of Sr insufficient, this is because the vacancy which is beneficial to afterglow increases at the same time.