Synthesis of YAG:Ce phosphor by impinging streams co-precipitation method

Ce doped yttrium aluminum garnet (YAG:Ce) spherical nanopowder was synthesized by dropping Al (NO3)3&middot9H2O, Y (NO3)3&middot6H2O and Ce (NO3)3&middot6H2O solution and ammonium hydrogen carbonate solution into the impinging streams reactor simultaneously at the same rate. The precursors and the YAG:Ce powders were characterized by XRD, FT-IR, SEM and fluorescence spectrophotometer. The factors affecting the powder characteristics, including the mother salt concentration, the dropping speeds of solutions solution, and sintering methods and temperature were analyzed and discussed. The results show that the dispersion, the composition, the morphology and luminescence intensity of the YAG phosphors are affected remarkably by these factors. The YAG powders without any interphases can be obtained at 900°C when the mother salt concentration (c0=0.055 mol/L) is relatively low; the YAG phosphors including YAM, YAP and CeO2 impurity phases were prepared at 1000°C when the mother salt concentration (c0>1.0 mol/L) is high. The crystallinity can be increased with the increasing feeding rate at corresponding scope. The pure YAG phase could be obtained by Na2CO3-S-K2CO3 mixture flux calcination method at 700°C. Compared with the direct calcination method, the YAG:Ce3+ phase transition temperature with the present method can be decreased about 300°C, and the luminescent intensity of as-prepared phosphor can be increased greatly than that prepared by direct baking method.