Luminescence Comparison and Enhancement of Ce-doped Yttrium Aluminum Garnet Phosphor via Cation Substitution and Adding Flux

Abstract

For (Y1−xGdx)3Al5O12:Ce and Y3Al5−2y(Mg,Si)yO12:Ce phosphors prepared by spray pyrolysis, the luminescence properties were compared with commercial YAG:Ce. When x = 0.2 and y = 0.4, the emission wavelength of each phosphor was same to the commercial YAG:Ce. In terms of realizing warm-white LEDs, the Y3Al4.2(Mg,Si)0.4O12:Ce phosphor was better than (Y0.8Gd0.2)3Al5O12:Ce and commercial YAG:Ce. However, the emission intensity and the thermal quenching temperature of Y3Al4.2(Mg,Si)0.4O12:Ce phosphor were lower than the commercial one. The addition of B(OH)3 as a flux to the spray solution improved the emission intensity as well as the quenching temperature due to the increase of crystallinity. For the Y3Al4.2(Mg,Si)0.4O12:Ce, doping the La3+ ions into the Y3+ sites made it possible to effectively improve the emission intensity without any shift on its emission peak position. From the XRD analysis, the La incorporation improved the crystallinity, which was responsible for the improvement of the emission intensity and the thermal quenching temperature. Finally, the optimized (Y0.95La0.05)3Al4.2(Mg,Si)0.4O12:Ce phosphor prepared using 3 wt % boric acid had the highest emission intensity (which was about 92% of the commercial phosphor), the quenching temperature of 224°C, and CIE color coordinates (0.462, 0528) more profitable to fabricate warm-white LEDs compared with the commercial YAG:Ce.