Claims
- 1. A process for the preparation of Ba.sub.1-y Eu.sub.y FB.sub.r where y is a number from 0.001 to 0.2 in the form of particles of a preselected diameter which process comprises:
- (a) preparing a slurry containing BaF.sub.2, BaBr.sub.2 and a curopium halide, wherein the amount of BaF.sub.2 present is at least 1.4 times that required stoichiometrically to form the phosphor;
- (b) agitating said slurry for a time sufficient to permit substantially all of said BaF.sub.2 to react with said BaBr.sub.2 to form BaFBr;
- (c) spray drying the resulting slurry of step (b) under conditions that produce porous spheroidal agglomerates having an average diameter larger than that of the preselected diameter;
- (d) firing said spheroidal agglomerates in an inert atmosphere for from about 10 to about 120 minutes at a temperature of from about 650.degree. C. to about 800.degree. C.;
- (e) cooling the fired material of step (d) to ambient temperature in an inert atmosphere;
- (f) washing the cooled material of step (e) with methanol or a 90:10 by volume mixture of water and citric acid to selectively remove excess BaBr.sub.2 ; and
- (g) drying the washed material of step (f) to produce a free flowing powder of the [BaFBr:Eu].
- 2. The process of claim 1 wherein the europium halide is selected from the group consisting of EuF.sub.2, EuF.sub.3, EuCl.sub.3, EuBr.sub.3 and mixtures thereof.
- 3. The process of claim 2 wherein the BaBr.sub.2 and BaF.sub.2 used in step (a) are in a molar ratio of from about 1.4:1 to about 5:1.
- 4. The process of claim 2 wherein the BaBr.sub.2 used in step (a) is sufficient to keep the slurry at least about 50% saturated with BaBr.sub.2.
- 5. The process of claim 4 wherein the temperature of step (d) is from about 700.degree. C. to about 800.degree. C.
- 6. The process of claim 5 wherein the time of step (d) is from about 10 to about 50 minutes.
- 7. The process of claim 6 wherein the inert atmosphere is argon or nitrogen.
Parent Case Info
This application is a continuation of application Ser. No. 07/383,333, filed on Jul. 20, 1980 now abandoned.
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254836 |
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Continuations (1)
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Number |
Date |
Country |
Parent |
383333 |
Jul 1989 |
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