Effects of Flux Additives on Characteristics of Y$_{2.95}$ Al$_{5}$ O$_{12}$ :0.05Ce$^{3+}$ Phosphor: Thermal Stability and Application to WLEDs

Y
_2.95
Al
₅
O
₁₂
:0.05Ce
³⁺
phosphors were synthesized via the solid-state reaction method using fluxes of H
₃
BO
₃
and BaF
₂
. The thermal stability and luminescence of Y
_2.95
Al
₅
O 12:0.05Ce
³⁺
prepared with 6 wt% BaF
₂
flux additive (Sample II) were compared with those of Y
_2.95
Al
₅
O
₁₂
:0.05Ce
³⁺
prepared with 7 wt% H
₃
BO
₃
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 Y
₃
Al
₅
O
₂
:Ce
³⁺
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-Y
₃
Al
₅
O
₁₂
:Ce
³⁺
-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.