Photoluminescence and afterglow behavior of Ce³⁺ activated Li₂Sr_0.9Mg_0.1SiO₄ phosphor

A blue emitting phosphor Li₂Sr_0.9Mg_0.1SiO₄:Ce³⁺, with long persistence, was synthesized via a high-temperature solid phase method. According to the X-ray diffraction analysis result, the introduction of Mg²⁺ and Ce³⁺ ions has no influence on the structure of the host material. Typical 5d-²F_5/2 and 5d-²F_7/2 transitions of Ce³⁺ ions were detected by PL spectra, which corresponded to the CIE chromaticity coordinates of x = 0.1584, y = 0.0338. An optimal doping concentration of Ce³⁺ was determined as of 0.4 at%. Furthermore, the Li₂Sr_0.9Mg_0.1SiO₄:Ce³⁺ phosphor showed a typical triple-exponential afterglow behavior when the UV source was switched off. The highest lifetime of the electrons within the material reached a value of 73.9 s. Thermal stimulated luminescence study indicated that the afterglow of Li₂Sr_0.9Mg_0.1SiO₄:Ce³⁺ was due to the recombination of the electrons with holes released from the traps generated by the doping of Ce³⁺ ions in the Li₂Sr_0.9Mg_0.1SiO₄ host. The afterglow mechanism of Li₂Sr_0.9Mg_0.1SiO₄:Ce³⁺ is illustrated and discussed in detail on the basis of the experimental results.