Proton-induced fluorescence and long lasting emission of Sr ₄Al₁₄O₂₅:Eu²⁺,Dy³⁺

Fluorescence and long lasting emission properties of Sr₄Al ₁₄O₂₅:Eu²⁺,Dy³⁺ were examined under proton irradiation by varying incident energy. The fluorescence spectra have three strong peaks at 400, 480, and 570 nm. The first two peaks are attributed to the luminescence of Eu²⁺ and exhibit the long lasting property. The peak at 570 nm is attributed to the luminescence of Dy³⁺; it exhibits no luminescence after the irradiation has been stopped. The fluorescence intensity ratio of Eu²⁺/Dy³⁺ exhibits incident energy dependence, and its value increases with an increase in the proton energy. Radiation damages also exhibits incident energy dependence. And, the radiation damages show activator dependence, and Eu is more sensitive to incident particles than Dy is. Long-lasting emission is observed after the cessation of irradiation, and the decay time of the long-lasting emission is different for different irradiation fluence.