Preparation and Optimization of Long Persistent Luminescent Sr₄Al₁₄O₂₅:(Eu,Dy) Phosphor Materials

Sr4Al14O25:(Eu,Dy) phosphor materials were prepared by solid state reaction. The dependence of long per- sistent luminescence from Sr4Al14O25:(Eu 2+ , Dy 3+ ) on the amounts of H3BO3, the solid state reaction temperature, and the contents of Eu were studied. It was found that the addition of H3BO3 as the flux agent was critical for the formation of the blue-green emitting Sr4Al14O25 phase. Sr4Al14O25 phosphors with persistent luminescence of 490 nm and after- glow time more than 24 h was obtained for the sample prepared at 1400℃ with the doping amounts of H3BO3 of 10at% and Eu/Al atomic ratio of 0.03, respectively. Furthermore, the dependence of persistent luminescence intensity on Eu content indicates that the persistent luminescence process is mainly controlled by the electron transition rate from deep traps to Eu 2+ levels.