Roles of doping ions in persistent luminescence of SrAl2O4:Eu2+, RE3+ phosphors
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The polycrystalline Eu2+ and RE3+ co-doped strontium aluminates SrAl2O4:Eu2+, RE3+ were prepared by solid state reactions. The UV-excited photoluminescence, persistent luminescence and thermo-luminescence of the SrAl2O4:Eu2+, RE3+ phosphors with different composition and doping ions were studied and compared. The results showed that the doped Eu2+ ion in SrAl2O4:Eu2+, Dy3+ phosphors works as not only the UV-excited luminescent center but also the persistent luminescent center. The doped Dy3+ ion can hardly yield any luminescence under UV-excitation, but can form a electron trap with appropriate depth and greatly enhance the persistent luminescence and thermo-luminescence of SrAl2O4:Eu2+. Different co-doping RE3+ ions showed different effects on persistent luminescence. Only the RE3+ ion (e.g. Dy3+, Nd3+), which has a suitable optical electro-negativity, can form the appropriate electron trap and greatly improve the persistent luminescence of SrAl2O4:Eu2+. Based on above observations, a persistent luminescence mechanism, electron transfer model, was proposed and illustrated.
KeywordsElectron Trap Luminescent Center Hole Trap SrAl2O4 Crystal Matrix
The financial support from the University of Jiangxi Finance and Economy as well as Jiangxi Provincial Department of Education (project 260) is gratefully acknowledged.
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