Coating material applied to improve thermostability of lanthanum-cerium-terbium phosphate green emitting phosphor and method of producing the same

Abstract

The invention discloses a coating material applied for improving the thermal stability of green fluorescent powder of (La1-x-yCexTby) PO4 and a preparation method thereof. The invention includes the following steps: 1. lanthanum chloride and diammonium phosphate are prepared into a dilute solution with equal volume and equal concentration by secondary de-ionized water and heated for maintaining the temperature between 60 and 90 DEG C; 2. lanthanum phosphate, cerium phosphate and terbium phosphate are co-settled in a container, added with the secondary de-ionized water, heated for maintaining the temperature between 60 and 90 DEG C and stirred at a constant speed of 20 to 50 r / min; 3. the two liquids are slowly dripped into a suspension liquid in step 2 at an equal speed and stirred at a constant speed; after the dropping is finished, stirring is stopped and diluted acid or weak base is used for regulating the pH value of the suspension liquid to be between 4.0 and 6.0; then the suspension liquid stands for 2 to 3h; 4. the suspension liquid in step 3 is filtered and dried; a fluxing agent is added and uniformly mixed with the suspension liquid; and high temperature iglossing is carried out in a weak reduction atmosphere; and 5. a sinter is cooled to the room temperature in the reduction atmosphere, cracked to the needed granularity and washed by pure hot water, thus obtaining the green fluorescent powder of (La1-x-yCexTby) PO4 with good thermal stability; the thermal stability of the green fluorescent powder of (La1-x-yCexTby) PO4 obtained by the preparation method is good; the brightness attenuation after a technique procedure of tube baking is small; the initial optical communication of the green fluorescent powder after being prepared into a light is high; moreover, the light decay is less and the service life is long; and the invention is an excellent green fluorescent material in the backlight cold cathode lamp of an LCD.

Description

technical field [0001] The invention belongs to the technical field of rare earth luminescent materials, in particular to a method used in (La, Ce, Tb)PO 4 The coating technology of green fluorescent powder, the invention also relates to the preparation method of the coating material. Background technique [0002] In the process of making lamps, it is necessary to go through the baking tube process to remove the organic binder in the coating tube liquid. The temperature of the baking tube is as high as 600 ° C, and the atmosphere is usually air, which requires that the phosphor must have good thermal stability. Among the rare earth three primary color phosphors, the green phosphors are most widely used in two systems: aluminate (Ce, Tb) MgAl 11 o 19 and phosphate (La, Ce, Tb)PO 4 . Phosphate (La, Ce, Tb) PO 4 Although it has higher light efficiency, its thermal stability is poor, mainly due to the Ce in the phosphate system during the tube baking process. 3+ easily oxi...

AI Technical Summary

Problems solved by technology

Phosphate (La, Ce, Tb) PO 4 Although it has higher light efficiency, its thermal stability is poor, mainly due to the Ce in the phosphate system during the tube baking process. 3+ easily oxidized to Ce 4+ , resulting in a decrease in luminous efficiency, the use of coating treatment on the phosphor is an effective way to improve the thermal stability of the phosphor

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