Effects of flux additives on the characteristics of Y_2.95Al ₅O₁₂:0.05Ce³⁺ phosphor: Particle growth mechanism and luminescence

The dependence of the amount of the BaF₂ flux additive on the luminescence of Y_2.95Al₅O₁₂:0.05Ce³⁺ phosphors was investigated. The integrated emission intensity of Y _2.95Al₅O₁₂:0.05Ce³⁺ prepared without the flux was enhanced by 29% with the addition of BaF₂ flux at the optimum amount of 6 wt. %. Such an enhancement can be attributed to the purer phase of Y₃Al₅O₁₂ and the morphology change from the irregular shape to spherical shape with the smoother surface due to the flux. The morphology and luminescence of Y_2.95Al₅O ₁₂:0.05Ce³⁺ prepared with the 6 wt. % BaF₂ flux additive (Sample II) were further compared with those of Y _2.95Al₅O₁₂:0.05Ce³⁺ prepared with the 7 wt. % H₃BO₃ flux additive (Sample I). The particle size, particle shape, and integrated emission intensity (λ_ex = 450 nm) of the former were found to be larger, more regular, and 6% higher than those of the latter. The difference in the morphology of Samples I and II, which led to the difference in the emission intensity and the external quantum efficiency, were well explained by the particle growth mechanism.