Roles of Eu²⁺, Dy³⁺ ions in persistent luminescence of strontium aluminates phosphors

Abstract

The polycrystalline Eu²⁺ and Dy³⁺ co-doped strontium aluminates SrAl₂O₄: Eu²⁺, Dy³⁺ with different compositions were prepared by solid state reactions. The UV-excited photoluminescence, persistent luminescence and thermo-luminescence were studied and compared. Results show 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 effectively enhance the persistent luminescence and thermo-luminescence of SrAl₂O₄: Eu²⁺. Dy³⁺ co-doping can help form electron traps with appropriate depth due to its suitable electro-negativity, and increase the density and depth of electron traps. Based on above observations, a persistent luminescence mechanism, electron transfer model, is proposed and illustrated.

Keywords

strontium aluminate / persistent luminescence / thermo-luminescence / rare earth ion

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