A single-phase white-emitting Ca2SrAl2O6:Ce3+,Li+,Mn2+ phosphor with energy transfer for UV-excited WLEDs

Abstract

A series of Ca₂SrAl₂O₆:Ce³⁺,Li⁺,Mn²⁺ phosphors have been synthesized by traditional solid state reactions. The structure and photoluminescence properties of the samples together with the energy transfer from Ce³⁺ to Mn²⁺ ions have been investigated in detail. The obtained phosphors can be excited efficiently by UV excitation and exhibit a broad blue-green emission band peaking at 470 nm and an orange-red emission band at 610 nm, which result from the f–d transition of the Ce³⁺ and the ⁴T₁–⁶A₁ transition of the Mn²⁺ ions, respectively. By varying the doping concentration of the Mn²⁺ ion, a series of tunable colors including white are obtained at an irradiation of 355 nm. The possible energy transfer mechanism was proposed in terms of the experimental results and analysis of photoluminescence spectra and decay curves of the phosphors. The critical distance between the Ce³⁺ and Mn²⁺ ions has been calculated by both the concentration quenching method and the spectral overlap method. Preliminary studies on the properties of the phosphor indicated that our prepared Ca₂SrAl₂O₆:Ce³⁺,Li⁺,Mn²⁺ phosphor might have potential application as a single-phase white-emitting phosphor for WLEDs.