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

Posted on:2007-12-05Degree:MasterType:Thesis
Country:ChinaCandidate:X Y SongFull Text:PDF
GTID:2121360182494436Subject:Materials science
Abstract/Summary:PDF Full Text Request
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 Sr1-x-yAl4O4: Eux2+, Dyy3+ ? 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 Sr0.95Al2O4:Eu0.022+,Dy0.033+. 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.
Keywords/Search Tags:SrAl2O4:Eu2+,Dy3+, Persistent luminescence, flux method
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