Preparation and performance of white LED packaged YAG phosphor

In recent years, the preparation technology of the white light LED packaged YAG phosphor develops very quickly. The preparation methods include solid-phase method, sol-gel method, precipitation method, combustion method and so on. The traditional solid-phase method is still dominant in all of them, whereas this method also has shortcomings such as a high synthesis temperature, longer reaction time, bulky grains and larger hardness. So it requires a new approach to achieve the phosphor synthesis. Using metal nitrate as raw materials and citric acid as a complexing agent, we prepared Y₃A₁₅O₁₂:Ce³⁺ yellow phosphor by the sol-gel method (sol-gel). The X-ray powder diffraction (XRD) shows that it has been pure yttrium aluminum garnet phase (YAG) at 900degC. The infrared absorption spectra of the powders show that YAG phase has been formed when the calcination temperature is 900degC, because there are the characteristic vibrational peaks of metal and oxygen atoms, which are in the low-frequency area at 724 cm^-1, 792 cm^-1 peak. With scanning electron microscopy (SEM) analysis of its morphology, the result proves the grain diameter ranges from 1 to 3 mum, averaged at 2 mum. Their fluorescence spectra were studied using fluorescence spectrometer and the results show luminous intensity reach at the maximum when calcination temperature up to 1200degC.