The effect of Ce³⁺ concentration and heat treatment on the luminescence efficiency of YAG phosphor

Y₃Al₅O₁₂ (YAG) phosphor powders doped with Ce³⁺ at different concentrations (YAG:xCe, x = 0.02, 0.04, 0.06, 0.08, 0.1 wt%) were synthesized by the solid-state reaction method with the addition of BaF₂ flux. The effects of cerium concentration and heat treatment on the luminescence efficiency of the YAG:Ce³⁺ phosphor were investigated. The introduction of Ce³⁺ ions leads to an increase in luminescent intensity of the YAG phosphor at 560 nm. The band at 530 nm is attributed to Ce³⁺ ions (optical transitions from the 4f–5d excited state). We assumed that such an increase in the luminescent intensity is due to the ability of Ce³⁺ to act as a luminescence sensitizer of intrinsic defects in YAG phosphor. The analysis of luminescence decay kinetics in the investigated samples has shown that the decay time in all samples does not differ significantly and equals τ ≈ 60 ± 3 ns. We showed experimentally that increasing the luminescence intensity has an effect observed with relatively low temperature treatment (T = 400 K). The nature of possible luminescence centers and the effect of low heat treatment on the luminescence properties of the powders are discussed.