A novel long lasting phosphor Sr5 (PO4)3FxCl1-x:Eu2+,Gd3+ prepared in air condition

A series of blue long afterglow mixed halide-phosphate phosphors Sr5 (PO4)3 FxCl1−x:Eu2+,Gd3+ were synthesized in air by traditional solid-state reaction route. The crystal structures, photoluminescence, thermoluminescence properties and afterglow properties of the phosphors were characterized systematically using X-ray diffraction (XRD), luminescence spectrophotometer, microcomputer thermoluminescence dosimeter and single photon counter, respectively. Under 280 nm excitation, the broadband emissions of Eu2+ ions were observed at 445 nm (blue) due to the 4f7→4f65d transition. It was demonstrated that there existed the self-reduction of the Eu3+ to Eu2+ ions in this special halide-phosphate matrix in air condition. The addition of Gd3+ ions obviously enhanced the afterglow properties of the single doped Eu2+ ions in the halide-phosphate phosphors. And the content of the fluoride anions also had significant influence on the afterglow properties. All results indicated that Sr5 (PO4)3 FxCl1−x:Eu2+,Gd3+ might be potential phosphors for long lasting phosphorescence (LLP) materials.