Preparation and luminescent properties of SiO 2 –Sr 4 A1 14 O 25 :Eu 2+ , Dy 3+ /light conversion agent phosphor for anti-counterfeiting application

To get an efficient phosphor that emit long wavelength light for anti-counterfeiting application, the phosphor SiO2–Sr4A114O25:Eu2+, Dy3+/LCA (light conversion agent) was successfully prepared by sol–gel method. The structure and morphology were studied by X-ray diffraction, scanning electron microscope and energy dispersive spectrometer. The luminescent properties were investigated by fluorescence spectrometer and afterglow spectrometer. The phenomenon of blue shift was analyzed based on fluorescence spectrum and FTIR spectrum, the blue shift caused by the chemical bonding between the LCA and silica. The results showed that there was an obvious blue shift when silica content changed in range of 0–2 wt%, and the quantum yield reached a maximum when the content of silica was 6 wt%. Because the silica coated on the composite phosphor by chemical bonds and the silica layer has an influence on both Sr4A114O25:Eu2+, Dy3+and LCA, resulted in the color changes in yellow-red range with the changing of silica content.