Preparation and characterization of a green emitting Li2Ca0.4Sr0.6SiO4:Tb3+ phosphor with afterglow behavior

A novel green emitting long afterglow phosphor Li2Ca0.4Sr0.6SiO4:Tb3+ was obtained via a high temperature solid-state reaction in air atmosphere. X-ray diffraction (XRD), photoluminescence spectroscope (PLS), long afterglow spectroscope (LAS) and thermal luminescence spectroscope (TLS) were performed to characterize the physical properties of the phosphors. Typical 5D4-7Fj transitions of Tb3+ ions were detected by PL spectra, corresponding to CIE chromaticity coordinates of x =0.3456, y =0.5745. An optimal concentration of Tb3+ in the substrate was determined as 0.8 at%. The Li2Ca0.4Sr0.6SiO4 phosphors showed a typical afterglow behavior when the UV source was switched off. A typical triple exponential decay behavior was confirmed after fitting the experimental data. Thermal simulated luminescence study further indicated that the afterglow behavior of Li2Ca0.4Sr0.6SiO4:Tb3+ phosphors was generated by the recombination of electrons with the holes resulted from the doping of rare-earth ions (Tb3+) in Li2Ca0.4Sr0.6SiO4 host. The long afterglow luminescence mechanism of Li2Ca0.4Sr0.6SiO4:Tb3+ is illustrated and discussed in detail on the basis of experimental results.