Study On Synthesis And Performance Of Phosphors For White LED By Blu-Ray Excitation

Because of energy sources and environment crisis, energy saving is the trend in today's society. The lighting is closely related to human life. Compared with conventional lighting sources, white LED has many merits in energy saving, compact optics designs, cold source, startup at low volt or electrical current, long life-span, rapid brightness and color changes, astigmatic, recyclable, unpolluted and so on.Yttrium aluminum garnet (YAG) has been widely used as matrix-materials of laser and luminescence because of its excellent thermal conductivity, high mechanical strength, high temperature resistance and radiation resistance. While if we doped rare-earth atoms (for example Ce) in the YAG, it will be excellent phosphor. YAG:Ce³⁺ has been found to be suitable for converting the blue light emitting diodes (LEDs) radiation into a very broad band yellow emission, and thus yellow light and blue light can be mixed to be white light.XRD, SEM, TG/DTA and PL spectra were used to characterize the as-prepared phosphors which were prepared by different methods of sol-gel method and co-precipitation method. In this study, the experiments were carried out in the air. Through testing, we could analysis YAG:Ce³⁺ phosphor luminescence properties which Sintering in the air.YAG:Ce³⁺ phosphor was prepared by sol-gel method. It was found that the synthetic temperature of pure YAG phase was 900℃. Observe the emission spectra, emission intensity was the strongest at 1000℃sintered, followed by the 1100℃sintered samples, the lowest sample sintered at 900℃. It should be that Ce3 + is oxidized to Ce4 + and loss of luminescence centers. Then we obtained YAG: Ce³⁺ phosphor emission intensity of the sample analysis at different pre-sintering temperature and found that emission intensity was improved as high as pre-sintering temperature. When we raised the pre-sintering temperature, the emission intensity was still the strongest at 1000℃sintered. If we improve sintering time, the emission intensity also could be improved.YAG:Ce³⁺ phosphor was prepared by co-precipitation method. It was found that the synthetic temperature of pure YAG phase was 1000℃. YAG:Ce³⁺ phosphor was prepared at different sintering temperature. Emission intensity was not the strongest at 1000℃sintered, the emission intensity of sample at 1100℃sintered was a little stronger than emission intensity of sample at 1000℃sintered. Because of Precursor should be washed, a part of Ce which did not dope in the YAG was lost. So we should improve Aging time. But the emission intensity of YAG:Ce³⁺ phosphor by co-precipitation method was stronger than the emission intensity of YAG:Ce³⁺ phosphor by sol-gel method.