Synthesis of Sr4Al2O7:Eu2+/Dy3+ phosphors by the solid-state reaction and luminescent properties

Sr4Al2O7:Eu2+/Dy3+ phosphors are synthesized by the solid-state reaction. The obtained powders are characterized by XRD, SEM and luminescent spectrometer. The effects of the mole ratios of Dy3+/Eu2+ on luminescent properties of Sr4Al2O7:Eu2+/Dy3+ phosphors are investigated. The XRD pattern indicates that the powders have pure Sr4Al2O7 phase. The SEM micrographs reveal that Sr4Al2O7:Eu2+/Dy3+ phosphors show similar irregular morphology. Under the excitation of 360 nm, Sr4Al2O7:Eu2+/Dy3+ phosphors exhibit the characteristic emission band originating from the 4f65d1 → 4f7 transition of Eu2+ ions. The emission intensity increases with the increasing mole ratio of Dy3+/Eu2+ up to 3 and then decreases. Thermalluminescence results indicate that the persistent afterglow of Sr4Al2O7:Eu2+/Dy3+ phosphors is generated by suitable electron traps formed by the Dy3+ ions within the host.