Effects of Incorporated Sodium on Photoluminescence and Particle Shapes of CaS : Ce Phosphors

Abstract

Cerium containing calcium sulfite hemihydrate, , of spherical particles was prepared as start material by precipitation using a reaction between ammonium sulfite solution containing a given concentration of cerium sulfate (III), and a calcium chloride solution. This was reduced to cerium‐activated calcium sulfide of spherical particles in a stream of hydrogen sulfide at 900°C. The relationships between the sodium (Na) content in both the starting material, , and the reduction product, , and the intensity of photoluminescence was investigated. A linear relationship between the intensity of photoluminescence and the Na content up to about 0.3–0.4 mole percent , where the intensity has its maximum, was observed. With increasing Na content in the , the surface morphology of the shows sintering, and fine particles become larger and well grown.