Investigation on the distribution of rare earth ions in strontium aluminate phosphors

Long afterglow pigment SrAl2O4:Eu,Dy was synthesized by a solid-state reaction method, the effects of flux B2O3 on the sintering dynamic process and the distribution of the rare earth ions Eu and Dy in strontium aluminate phosphors were investigated. It is shown that most of the rare earth ions are precipitated in the grain boundary phase, which is formed by the addition of B2O3 flux, therefore the amount of rare earth activator to be added is larger than the practically necessary amount. B2O3 promotes the growth of the SrAl2O4 matrix strongly as well as decreases the synthesis temperature of SrAl2O4 remarkably. The rare earths ions diffuse into the SrAl2O4 host lattice rapidly through grain boundary diffusion, therefore, the afterglow time of SrAl2O4:Eu,Dy can be increased from 1000 min to above 6000 min.