| 摘要 |
A pigmented phosphor comprises a core of a phosphor particle having a light modifying layer thereon. The light modifying layer is comprised of a co-precipitated mixture of silica or pyrophosphate and a pigment which modifies the light output of the energized phosphor. The phosphor is coated by first preparing an unique pigment stock suspension containing the pigment, water, and a polyacrylamide dispersant. The stock solution is then diluted and phosphor particles are added thereto and the mixture is vigorously stirred. The pH of the mixture can be adjusted to about 5 by the addition of acetic acid and then a small amount of positively charged colloidal silica or pyrophosphate is added. After mixing, the pH is raised to about 9 by the addition of a base or a salt which causes a gel to form and the silica or pyrophosphate and the pigment to co-precipitate out upon the phosphor particles.
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