Preparation of Phosphor Fine Particles for Mercury-Free Lamps by Using Liquid-Phase Synthesis Method

Abstract

The liquid-phase synthesis method for preparing phosphor (Y2O3:Eu) fine particles, which was expected in the application for mercury-free fluorescent lamps, was investigated. The monodispersed sols as the precursor of phosphor fine particles were first synthesized by the co-precipitation method under different conditions in the aqueous-phase. The colloidal particles of precursor sols were spherical and almost uniform. The particle sizes of the sols were under 1 µm, and the size distributions were sufficiently narrow. The metal element ratio of the sol particles could be controlled by adjusting the initial concentration of the synthesis solution. The as-prepared precursor sols were converted into well crystalline phosphor particles by heat-treatment over approximately 600°C. The phosphor particles showed emission spectra with a remarkable emission line of Eu 3+ activator, and the emission intensity was sensitively influenced by the concentration of Eu 3+ in the precursor solution. A morphological feature as the monodisperse of the phosphor particles remained after the heat-treatment.