Compositions – Inorganic luminescent compositions – Compositions containing halogen; e.g. – halides and oxyhalides
Patent
1983-04-22
1984-12-18
Cooper, Jack
Compositions
Inorganic luminescent compositions
Compositions containing halogen; e.g., halides and oxyhalides
2523014F, C09K 11475
Patent
active
044889836
ABSTRACT:
A process is provided for preparing lanthanum bismuth oxychloride phosphors of formula La.sub.1-x-y Bi.sub.x RE.sub.y OCl, where RE is a rare earth element, x is 0.001 to about 0.25, and y is 0 to 0.005. The process is characterized by a single firing step, and comprises (a) forming an intimate mixture of stoichiometric quantities of La.sub.2 O.sub.3, Bi.sub.2 O.sub.3, and a rare earth oxide of formula RE.sub.2 O.sub.3, together with NH.sub.4 Cl and a flux comprising BaCl.sub.2, where quantities of NH.sub.4 Cl and BaCl.sub.2, by weight, can be independently chosen from between about one-third to about one-half that of the combined weights of the oxides; (b) firing said mixture, in an inert container and in air, according to a time-temperature sequence in which the mixture is heated (1) from 1 to about 4 hours at about 275.degree. C. to 325.degree. C., followed by (2) from 2 to about 4 hours at about 275.degree. C. to 500.degree. C., and concluded by (3) from about 8 to 10 hours at about 800.degree. C. to 1000.degree. C.; and (c) recovering said phosphor from said mixture by washing the mixture with water.
REFERENCES:
patent: Re28592 (1975-10-01), Rabatin et al.
patent: 2729604 (1956-01-01), Swindels
patent: 4068129 (1978-01-01), Rabatin
patent: 4315979 (1982-02-01), Brines et al.
Simons, "J. Electrochemical Soc.", 118, p. 148, (1971).
Cooper Jack
E. I. Du Pont de Nemours and Company
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