Search

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.