Lithium Carbonate → Lanthanum Cerium Terbium Gadolinium Phosphate

The following raw materials were combined in a plastic V-blender: 333 grams of lanthanum cerium terbium gadolinium oxide, 219.14 grams of boron phosphate, and 3.65 grams of lithium carbonate. The molar ratios of the raw materials were thus 1.0 mole of lanthanum cerium terbium gadolinium oxide, 1.05 moles of boron phosphate, and 0.025 mole of lithium carbonate (0.05 mole of lithium ions). The raw materials were V-blended for 15 minutes and then blended for 5 minutes with an intensifying bar, followed by 15 minutes of V-blending, to form a uniform mixture. The mixture was then fired at 1200° C. for 2 hours in a 10% hydrogen/90% nitrogen atmosphere to form the phosphor, which had the formulation La0.443 Ce0.42 Tb0.132 Gd0.005 PO4. The fired phosphor cake was broken up and washed in dilute nitric acid at 100° C. for 4 hours, followed by three washes in deionized water. The washed phosphor was finally washed in a solution of 5 % ammonium hydroxide, filtered, and washed in hot deionized water. The filtered phosphor was dried at 110° C. for 12 hours and sifted through a 378 mesh nylon screen.