Process for producing phosphors

Claim 1

THE PROCESS FOR MANUFACTURE OF AN ELECTROLUMINESCENT ZINC SULFIDE TYPE PHOSPHOR HAVING A PERDOMINANTLY HEXAGONAL CRYSTAL STRUCTURE, WHICH PROCESS COMPRISES THE STEPS OF THOROUGHLY MIXING PRECIPITATED ZINC SULFIDE AND CADMIUM SULFIDE IN PROPORTIONS TO GIVE FROM 0 TO 20 MOLE PERCENT CADMIUM SULFIDE IN THE MIXTURE WITH COPPER SULFATE IN AN AMOUNT SUCH THAT 1X10-4 UP TO 5X10-3 GRAM ATOMS OF COPPER ARE PRESENT FOR EACH MOLE OF THE MIXTURE OF ZINC AND CADMIUM SULFIDE AND FROM 3-15% OF AT LEAST ONE FLUX MATERIAL SELECTED FROM THE GROUP CONSISTING OF BROMIDES, CHLORIDES AND IODIDES OF SODIUM, BARIUM, POTASSIUM AND MAGNESIUM, FIRING SAID MIXTURE IN COVERED CRUCIBLES IN AIR AT A TEMPERATURE BETWEEN ABOUT 1000*C. AND 1300* C., COOLING THE FIRED MIXTURE RAPIDLY BY REMOVING THE CRUCIBLE FROM THE FURNACE, WASHING THE CAKE WITH WATER, ADDING BETWEEN 1X10-5 TO 5X10-3 GRAM ATOMS OF COPPER PER MOLE OF ZINC SULFIDE TO SAID CAKE, REFIRING SAID CAKE IN A COVERED CRUCIBLE IN AIR AT A TEMPERATURE BETWEEN ABOUT 700*C. AND 950*C., WASHING THE RESULTANT CAKE FIRST WITH A DILUTE AQUEOUS SOLUTION OF ACETIC ACID, THEN WITH WATER, THEN WITH A DILUTE SOLUTION OF AN ALKALI CYANIDE, AND FINALLY AGAIN WASHING WITH TO REMOVE EXCESS CYANIDE ALONG WITH DISSOLVED COPPER AND DRYING THE RESULTANT PHOSPHOR.