Nanometer Long Afterglow Luminescent Materials Sr <sub> 4 </ Sub> </ Sub> O Al <sub> 14 <sub> 25 </ Sub>: Eu ~ (2 +), Dy To (3) The Preparation And Optical Performance Study

Long persistent phosphorescence Sr₄Al₁₄O₂₅: Eu²⁺, Dy³⁺ nano-particle phosphor was synthesized by the sol-gel method (as we know now, Sr₄Al₁₄O₂₅: Eu²⁺, Dy³⁺ nano-particle phosphor through sol-gel method hasn't been reported yet). XRD, TEM, and luminescence spectrum analyzer were used to analyze and measure Sr₄Al₁₄O₂₅: Eu²⁺, Dy³⁺ microstructures, surface morphology, excitation and emission spectrums, afterglow decay time. The result showed that the emission peak is at about 486nm, the samples emit blue-green light. The first brightness is 5200mcd/m² , the afterglow time is more than 45 hours long. TEM indicated that the average size of the particles is about 50nm. Be compared with conventional solid state method, the reaction temperature can be greatly decreased, the brightness and afterglow time are enhanced markedly. The influences of different additives, the ratio of Al/Sr, synthesizing temperature, heating rates, time of constant heating, effects of H3BO3 addition on luminescence properties were studied.The results showed that the nano-particle size of long afterglow material Sr₄Al₁₄O₂₅: Eu²⁺, Dy³⁺ was strongly influenced by additives. By comparing the TEM figures of nano-particles prepared using different additives, we knew that the samples grains prepared using EDTA are round on the whole, the grain size is small and well distributed, the average size of the samples is 50 nm.The weeny change of the ratio of Al/Sr does not form new structure, but influences the luminescent properties strongly. When the ratio of Al/Sr is 3.7, the luminescent intensity and decay time of the sample are better than other samples prepared in terms of other ratios.This paper studied the samples synthesized at different temperatures under a reducing atmosphere, the result showed the sample produced at 1200℃ had better luminescent intensity and longer decay time. The luminescent intensity has no obvious change at higher temperature. Comparing with those of prepared by solid-state reaction method, the emission spectra occurs blue shift.