Synthesis and Luminescence Properties of Phosphor CaxSr1-xAl2O4:Eu2+

In order to improve the luminescent properties and reduce the synthesis cost, the SrAlO4∶Eu2+ phosphor doped with Ca was synthesized by high temperature solid state reaction method in reducing atmosphere for 1～3 h. The influences of the Ca content on luminescent properties and the functions of boracic acid and borax were discussed. The results indicate that Ca within 0.02 can accelerate the luminescence intensity, while weaken the afterglow characteristics with increasing Ca. The borax was introduced into the phosphor as the additive and the boric acid as the flux, which improved the luminescent properties of phosphors. The role of B2O3 in the long phosphorescence of CaxSr(1-x)Al2O4∶Eu2+ was investigated. B2O3 is just not an inert high temperature solvent (flux) to accelerate grain growth, but can gradually eliminate micropores between parts and conduce to an increase in density of the phosphors, according to SEM results. Therefore, the afterglow property is enhanced by the addition of impurities (borax), due to a increase trap energy levels in the host crystals.