Preparation of Spherical Particles Containing Yttrium/Europium from Homogeneous Solution.

Abstract

The fine particles of yttrium oxide containing europium are very important for the fabrication of red phosphor. In this study, the synthesis of the fine monodispersed particles containing yttrium and europium from the homogeneous solution using urea as a precipitant generator was investigated. The obtained precipitates are considered to be amorphous basic carbonate. The ratio of yttrium to europium in the precipitate could be controlled by adjusting the concentration of the starting materials in the initial solution. The yields of metal ions were more than 99%, irrespective of the ratio of yttrium to europium. The particles of the precipitates were very spherical and dispersed, and the size distribution of the particles was narrow. The average sizes of particles changed from 100nm to 300nm continuously with increase in yttrium ratio. The dried powder converted to cubic oxide by calcination at above about 600°C, and the calcined composite powder showed specific emission at 611nm. This emission is particular to Y2O3: Eu type phosphor.