Method of preparing halophosphate phosphor of controlled particle size

An improved method of preparing halophosphate phosphor of controlled particle size by controlling the preparation of calcium hydrogen orthosphate raw mix ingredient, said method comprising:

• a. precipitating calcium hydrogen orthophosphate di-hydrate crystals from a fluid formed by mixing a calcium chloride solution with a diammonium phosphate solution;
• b. separating said precipitated di-hydrate crystals from the remainder of said fluid;
• c. compacting said di-hydrate crystals by centrifuging, wherein said centrifuging subjects said crystals to a force of about 120-800 times the force of gravity for 5-200 seconds, said separating and compacting occurring concurrently;
• d. deagglomerating said compacted crystals, wherein said deagglomeration is performed by high shear mechanical stirring of a slurry comprising said di-hydrate crystals and water, and the weight ratio of di-hydrate crystals to water is about 0.6-1.5, and said mechanical agitation is performed for a sufficient time to provide a distinct lessening of viscosity during said agitation;
• e. converting said di-hydrate crystals into anhydrous calcium hydrogen orthophosphate crystals;
• f. preparing a raw mix comprising said anhydrous calcium hydrogen orthophosphate crystals;
• and
• g. firing said raw mix to form said halophosphate phosphor.