Abstract
Calcium sulfide phosphors exhibiting good crystallinity and smooth surfaces have been synthesized using the flux method. Calcium carbonate or calcium sulfate containing an appropriate amount of activator (Ce, Eu) were mixed with the flux and calcined between 700 and 1200°C. Morphology and grain size of phosphor powders depend on the calcium salt used, the activator concentration, the flux composition, and the calcination conditions. The luminescent efficiency is comparable to that of powders prepared by the 
method. Red phosphors show europium quenching at concentrations near 0.02%. The efficiency of green phosphors increases with Ce content up to 1% and then remains unchanged at higher concentrations.