Studies On Preparation Of Strontium Aluminates: Europium Phosphors

SrAl2O4: Eu2+ , Dy3+ phosphor powders were prepared by solid state reaction method. The influences of raw materials and their adding ways, synthesizing temperature, the kinds and adding quantity of flux, and the ratio of Al/Sr on luminescence properties were studied. Furthermore, SrAl2O4: Eu2+, Dy3+ was synthesized by the surface diffusion method and the influences of technological parameters on luminescence performance were discussed. Based on SrAl2O4:Eu, (Sr1-xMx)Al2O4: Eu(M=Ca, Ba) were synthesized, and studied on crystal structure and luminescence performance.The results show that with soluble-salt doping way of rare earth ion, luminescence intensity can be improved because of its uniform distribution in crystal lattice of the matrix. Additionally, Al derived from Al (OH) 3 can increase the luminescence intensity, because the higher reaction activity of Al(OH)3 makes matrix phase crystallize well.Synthesizing temperature has considerable influence on the luminescence intensity. In the range of 1200C~1350C, higher luminescence intensity can be gained, and the optimum synthesizing temperature is 1200 C according with luminescence performance and energy consumption.NH4H2PO4, LiF and H3BO3 used as flux can distinctly improve the luminescence intensity .Among the flux, the best is NH4H2PO4, while AIF3 and CaF2 as flux play a little role or decrease the luminescence intensity.Chemical composition with slight Al -Rich can increase luminescence intensity and prolong afterglow time, because more Sr vacancies make rare earth ions easily and uniformly hold the Sr site in matrix to form the luminescence centers and the hole traps.In investigation of (Sr1-xMx) Al2O4: Eu (M=Ca, Ba) , the results show that Ca possesses many uses such as making composition uniform, helping Eu defusion, stabilizing hexangular phase and improving thermal degradation. Ba has little influence on crystal structure and decreases luminescence intensity and thermaldegradation.Phosphor SrAl2O4: Eu, Dy synthesized by surface diffusion method has higher luminescence intensity than that by the solid state method.