Calcium silicate phosphor of large particle size and process for producing same

摘要

A calcium silicate phosphor activated with manganese and lead is disclosed which has a particle size of at least about 7 microns in diameter and in which there are essentially no particles greater than about 32 microns in diameter. The process for producing the phosphor is disclosed which involves forming a relatively uniform first admixture in a dry state consisting essentially of calcium carbonate, silicic acid, a manganese containing compound in an amount sufficient to result in about .02 to 0.1 moles of manganese per mole of calcium, a lead containing compound in an amount sufficient to result in about .002 to .03 moles of lead per mole of calcium in the phosphor, firing this admixture at a temperature of at least about 1900°F, forming a second admixture of this first fired phosphor and a source of chloride in the dry state to result in a particle size distribution in the phosphor in which the particles greater than about 32 microns in diameter are eliminated, and firing this second admixture to produce the final phosphor which is deagglomerated.