Fabrication of high-efficiency YAG:Ce³⁺ phosphors via concurrent optimization of firing atmosphere and fluxing agent

Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce³⁺) phosphors are common components of white light-emitting diodes. However, the efficiency of the phosphor synthesis process remains inadequate. Particularly, when synthesizing YAG:Ce³⁺ samples from oxide raw materials, it is necessary to reduce CeO₂ to Ce³⁺, which is the luminescent central ion, in a reducing gas atmosphere. However, the defects that form in a Y₃Al₅O₁₂ matrix in a reducing gas atmosphere cause photoluminescence property degradation. Therefore, this study was designed for fabricating highly efficient YAG:Ce³⁺ samples with high internal quantum efficiency. We achieved an internal quantum efficiency of 99.5% by concurrently optimizing the fluxing agent and the phosphor synthesis conditions. Specifically, by optimizing the species and proportions of the fluoride and carbonate fluxing agents and sintering them with oxide materials, we could increase the percentage of Ce³⁺ that contributes to photoluminescence and suppresses defect generation, which significantly improved the internal quantum efficiency of the phosphors.