Effect of red emitting fluorescent pigment on fluorescent color of SrAl2O4:Eu2+,Dy3+ phosphors

Green-blue fluorescence emitting SrAl2O4:Eu2+,Dy3+ phosphors (SAOED) were coated by SiO2 and a coumarin type red-emitting fluorescent pigment (FP). The effects of the FP on the morphology, crystal structure, photoluminescence properties and fluorescent color of the SAOED phosphors were systematically investigated by scanning electron microscopy (SEM), FT-IR, X-ray diffraction (XRD), photoluminescence spectra and CIE-1931 chromaticity coordinates characterization. Even though the surface of the SAOED phosphors became rough after being coated with SiO2 and FP, crystal lattice of SrAl2O4 did not have any obvious lattice distortions. The photoluminescence spectra indicated that the SAOED phosphors could be used as the excitation light source to excite the FP to emit red fluorescence. The emission spectrum of the FP-coated SAOED consisted of a broad band with two emission peaks at 520 and 610 nm, and its fluorescence emission color was a mixed color of the SAOED phosphors and FP. The fluorescence color of the SAOED/SiO2/FP composites tended to transfer to red area with the increase of the FP content varying from 0.1% to 0.9%.