Study Of Ce-doped YAG Phosphor Powder Prepared By Wet-chemical Method And Luminescent Properties

The wet-chemical method was used to prepare the YAG: Ce phosphor in this paper. Effects of calcining temperature, holding time, fluxes, atmosphere, precipitating agent, pH value and chelating agent on crystallization, morphology, and luminescent properties were studied by DTA-TG, XRD, SEM, fluorescence spectrophotometer. We also compared different preparation methods and analysed luminescence principle of phosphor. The main results of study are as follows:1. Effects of calcining temperature, holding time, the fluxes and atmosphere on properties of YAG:Ce³⁺ phosphor powders were studied in the polyacrylamide gel method. The results showed that calcining temperature has significant influence on crystallization, morphology, the excition and emission spectra, and the formation temperature (1000℃) of pure YAG phase is lower, compared to solid-state reaction. With the calcining temperature increasing, the intensity of excition and emission also increases steadily. Influence of the holding time on the luminescence properties isn't evident. Fluxes can improve particulate morphology and enhance the intensity of excition and emission of phosphor. Weak reduction atmosphere can contribute to improve the intensity of excition and emission of YAG: Ce phosphor powders.2. Effects of calcining temperature, holding time, precipitating agent, pH value on properties of YAG: Ce phosphor powders were studied in the co-precipitation method. The results showed that effects of calcining temperature, holding time on crystallization, morphology, the excition and emission spectra were the same as in the polyacrylamide gel method. The kind of precipitating agent and pH value have significant influence in precipitating process. The higher intensity of excition and emission were obtain as M/C=2.0, pH=2.3. Effects of the ratio of metal ions and chelating agent (M/C), pH value and calcining temperature on properties of YAG: Ce phosphor powders were studied in the sol-gel low-temperature combustion method. It is shown that the higher intensity of excition and emission were obtain as M/C=2.0, pH=2. The crystallization and the intensity of excition and emission of YAG: Ce phosphor increases steadily with increasing temperature.