Effects of Flux Additives on Characteristics of Y $_{2.95}$ Al $_{5}$ O

Y_2.95Al₅O₁₂:0.05Ce³⁺ phosphors were synthesized via the solid-state reaction method using fluxes of H₃BO₃ and BaF₂. The thermal stability and luminescence of Y_2.95Al₅O 12:0.05Ce³⁺ prepared with 6 wt% BaF₂ flux additive (Sample II) were compared with those of Y_2.95Al₅O₁₂:0.05Ce³⁺ prepared with 7 wt% H₃BO₃ flux additive (Sample I). The crystallinity of Sample I was found to be better than that of Sample II. This difference in crystallinity, which led to a difference in thermal stability, is well explained by the presence of defects. Moreover, Sample I, Sample II, and commercial Y₃Al₅O₂:Ce³⁺ phosphors were coated onto 450-nm chips for the fabrication of white light-emitting diodes (WLEDs). The luminous efficacy (@350 mA) of Sample-I-based (68.98 lm/W) and commercial-Y₃Al₅O₁₂:Ce³⁺-based (70.87 lm/W) WLEDs was lower than that (77.2 lm/W) of the Sample-II-based WLED due to the powder morphology of the phosphors.