Long lasting yellow phosphorescence in Sr₃SiO₅: Eu²⁺ and Sr₃ SiO₅: Eu²⁺, Dy³⁺ phosphors

Sr₃SiO₅: Eu²⁺ and Sr₃SiO₅: Eu²⁺, Dy³⁺ phosphors have been synthesized through the solid-state reaction technique. We observed long lasting yellow phosphorescence in Sr₃SiO₅: Eu²⁺ and Sr_SiO₅: Eu²⁺, Dy³⁺ phosphors, originating from 4f⁶5d-4f⁷ transition of Eu²⁺, after UV exposure. The phosphorescence in Sr₃SiO₅: Eu²⁺ can be observed by naked eyes for more than 4 hours after the termination of excitation light. The decay patterns of phosphorescence and thermoluminescence curves demonstrate that introduction of Dy³⁺ into Sr₃SiO₅: Eu²⁺ can generate lots of shallow traps and deep traps. The generated deep traps prolong the phosphorescence up to 6 hours after UV irradiation. The depths of traps are obtained by fitting the thermoluminescence experimental data to the general order kinetics formula.