SrAl2O4∶Eu2+,Dy3+长余辉发光材料的喷雾热解制备及其表征

采用喷雾热解两段法制备了SrAl₂O₄∶Eu²⁺ ,Dy³⁺长余辉发光材料,并利用XRD、SEM、荧光长余辉亮度测试等方法分析了不同制备工艺条件下SrAl₂O₄∶Eu²⁺ ,Dy³⁺发光材料的结构、形貌以及发光性能的变化。结果表明:采用喷雾热解两段法可制备出球形SrAl₂O₄∶Eu²⁺ ,Dy³⁺长余辉发光材料,SrAl₂O₄∶Eu²⁺ ,Dy³⁺的晶体结构与α-SrAl₂O₄磷石英晶体结构相同。热解温度、还原温度、添加剂对产物的形貌、粒度分布、发光性能有较大影响。较之高温固相法,喷雾热解法制备的SrAl₂O₄∶Eu²⁺ ,Dy³⁺具有发光性能好、形貌好、粒度分布窄等优点。

Synthesis and Characterization of SrAl_2O_4:Eu~(2+),Dy~(3+) Long Afterglow Luminescence Materials by Spray Pyrolysis Process

The long afterglow luminescence materials of SrAl₂O₄∶Eu²⁺ ,Dy³⁺ was synthesized by a two-step spray pyrolysis process. Structure, morphology and luminous performances of SrAl₂O₄∶Eu²⁺ ,Dy³⁺ were investigated via the technologies of X-ray diffraction, field emission scanning electron microscopy, emission spectra and so on. The results showed that the higher pyrolysis temperature was conductive to formation of SrAl₂O₄∶Eu²⁺ ,Dy³⁺ spherical particle. The initial brightness, afterglow time, emission peak intensity of SrAl₂O₄∶Eu²⁺ , Dy³⁺ increased with temperature and reached the maximum at 850 ℃.The emission spectrum shape of SrAl₂O₄∶Eu²⁺ ,Dy³⁺ that prepared by different pyrolysis temperatures are similar, with wideband peaked at about 512 nm, corresponding to the emission caused by the typical Eu²⁺ 5d → 4f (4f⁶5d configuration to the ground state 4f⁷) transition, it is just difference in relative strength and the peak emission spectrum does not change. The afterglow time was prolonged by adding appropriate amount polyethylene glycol, and it was the longest when the dosage was 0.03 mol/L. Adding citric acid reduced the afterglow time of luminescent materials, and the afterglow performance declined slowly when the content changes from 0.1 g/L to 0.3 g/L. Additivesis was beneficial to formation of luminescent global particles. The liquid drop of disperse and spray showed a better effect when the polymeras can be synthesized by the esterification of polyethylene glycol and citric acid at high temperature. With increasing the reduction temperature, the afterglow properties of SrAl₂O₄∶Eu²⁺ ,Dy³⁺ prepared via spray pyrolysis method increased firstly and then decreased. The best reduction temperature was 1 250 ℃ which was distinct advantage over by solid state method. The SrAl₂O₄∶Eu²⁺ ,Dy³⁺ prepared by spray pyrolysis belongs to the ɑ-SrAl₂O₄ phosphor crystal structure and it do not affect the crystal structure of SrAl₂O₄ when a small amount of Eu and Dy introduced into the mixture. The emission spectrum shape of SrAl₂O₄∶Eu²⁺, Dy³⁺ of obtained by two methods are similar, both wideband spectrum and the peaks corresponding to the typical 4f→5d transition of Eu²⁺ were observed at 512,513,516,518 nm,respectively. With the rising of reduction temperature, the emission in the main peak all showed an obvious red shift.The results showed that the synthesis temperature used spray pyrolysis method can be significantly reduced, and the sample received more regular morphology, smaller particle size, narrower particle size distribution and more excellent luminescent properties, comparing with that prepared by solid state method.