Low‐temperature and rapid solid‐state synthesis of YAG:Ce powders using oxides with narrow particle size distribution

Abstract

We applied a new precipitation technique to the syntheses of CeO2 and Y2O3 as starting oxides for YAG:Ce powders. This technique can be characterized by usage of NH4HCO3 as a precipitating agent and by aging of the precipitant at 80°C for 3 hours. Gibbsite (Al(OH)3) was used as an Al source. The particle size distribution of CeO2 synthesized by this process was very narrow, and was in the sub-micrometer range. Y2O3 particles, whose sizes ranged from 0.2μm to 10μm were larger and broader in distribution than CeO2 . Gibbsite, which transforms finally into Al2O3 also had a narrow particle size distribution from 0.3μm to 3μm. X-ray diffraction pattern of YAG:Ce powder synthesized from these (hydr)oxides at 1400 °C for 5 hours in air showed the material is monophasic. The best luminescent intensity, excited by blue light, was obtained in 1.5mol% Ce-doped YAG:Ce phosphor (Y2.955Ce0.045Al5O12) and is comparable to that of materials synthesized by the citric-gel method using metal nitrates as starting materials and firing at 1400 °C for 5 hours in air. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)