Spray Pyrolysis Preparation Of Sral <sub> 2 </ Sub> The O <sub> 4 </ Sub>: Eu <sup> 2 + </ Sup>, Dy <sup> 3 + </ Sup> And Its Performance Characterization

In this paper,the development course,research status,preparation method and the emitting mechanism of rare earth ions actived alkaline aluminates salt light-storing materials,especially of SrAl₂O₄:Eu²⁺,Dy³⁺ long afterglow luminescence materials were summarized.The spherical SrAl₂O₄:Eu²⁺,Dy³⁺ was synthesized by a two-step spray pyrolysis process.The structure,morphology,luminous performances and Spectral properties of SrAl₂O₄:Eu²⁺,Dy³⁺ at different preparation technology conditions were studied.and compared with the preparation methods of solid state reaction at a high temperature.The results showed that:The SrAl₂O₄:Eu²⁺,Dy³⁺ prepared by solid state reaction at a high temperature belongs to theɑ-SrAl2O4 phosphor crystal structure . Small amount of Eu,Dy introduced into the mixture did not affect the crystal structure of SrAl2O4.The flux H3BO3 could not only reduce the synthesis temperature, but also enhance the afterlow performance. The shape of the emission spectrum of SrAl₂O₄:Eu²⁺,Dy³⁺ did not be changed by the use of flux H3BO3. Dy3+ was the best auxiliary activators for SrA12O4:Eu2+ luminescence materials, Dy3+ could enhance the afterlow performance and won't change the peak location of its emission spectrum. The best composition of the prepared material with better afterlow performance was Sr0.97Al2O4:Eu0.01,Dy0.02. The SrAl₂O₄:Eu,Dy luminescence materials with better afterlow performance could be obtained by solid state reaction method when reduction temperature was 1350℃and reduction time was 3h .The SrAl₂O₄:Eu²⁺,Dy³⁺ prepared by spray pyrolysis belongs to theɑ-SrAl2O4 phosphor crystal structure and small amount of Eu,Dy introduced into the mixture did not affect the crystal structure of SrAl2O4. The morphology,size distribution and luminous performances of the phosphors could be affected with synthesizing conditions, such as precursor concentration, sintering temperature, reduction temperature etc. As the reduction temperature rised, red shift of the main peak position in the emission spectrum had occurred (move to longer wavelengths).H3BO3 could not only reduce the synthesis temperature, but also enhance the afterlow performance.The SrAl₂O₄:Eu²⁺,Dy³⁺ with better crystals,good luminous performance and morphology was syshtesised when the adding quantity of H3BO3 was 3.5mol%.As the add amount of H3BO3 increased,(2.5mol%～5mol%),the long afterlow material inspire spectra appear "blue shift" phenomenon.Additives caould obviously improve the morphology,reinforce the initial brightness,enlarge the afterlow time (citric acid would shorten the afterlow time).Citric acid could help to obtain solid spherical particle. Ethanol was not only a good dispersant but also increased the sphericity of particle, howerve, solid spherical particles couldn't be gotten in this condition. PEG played the role of dispersant and stabilizer. The solid spherical SrAl₂O₄:Eu²⁺,Dy³⁺ particles with high initial brightness, long twilight time, good dispersion, small particle size and narrow particle size distribution (2μm⁵μm) when these additives used at the same time.Their best addition amount were citric acid of 0.3g/L, PEG of 0.03mol/L, ethanol of 40ml/L.Compared with solid state method,the SrAl₂O₄:Eu²⁺,Dy³⁺ with more regular morphology,smaller particle size, narrower particle size distribution and more excellent luminescent properties could be prepared by spray pyrolysis, and the synthesis temperature can be significantly reduced.