Compositions – Inorganic luminescent compositions – Compositions containing halogen; e.g. – halides and oxyhalides
Patent
1989-06-07
1990-05-29
Cooper, Jack
Compositions
Inorganic luminescent compositions
Compositions containing halogen; e.g., halides and oxyhalides
C09K 1178
Patent
active
049293850
ABSTRACT:
A process is disclosed for preparing M' YTaO.sub.4 :Nb X-ray phosphor which comprises forming a uniform first mixture of Y.sub.2 O.sub.3, Ta.sub.2 O.sub.5, and Nb.sub.2 O.sub.5 in amounts equal to approximately the stoichiometric amounts to form the phosphor, milling with deionized water as the milling fluid, removing the water, forming a uniform second mixture of the first mixture and a flux which can be lithium sulfate, lithium chloride or a mix of lithium sulfate and potassium sulfate in a mole ratio of 80 to 20, the flux making up about 25% to 50% by weight of the second mixture, firing the second mixture in a furnace by heating to a temperature of about 1200.degree. C. to 1300.degree. C. at a heating rate of about 1.0.degree. C./minute to 1.5.degree. C./min. and maintaining the temperature for about 10 to 14 hours to react the components and produce a fired material containing luminescent material, cooling the material by turning off the heat and allowing the material to remain in the furnace until the temperature is no higher than about 300.degree. C., washing with deionized water, removing the wash water, drying, and classifying to obtain a -325 mesh particle size. The phosphor exhibits a brightness at least comparable to phosphors produced by methods absent water as the milling fluid.
REFERENCES:
patent: 3459674 (1969-08-01), Emoto et al.
patent: 4024069 (1977-05-01), Larach
patent: 4225653 (1980-09-01), Brixner
Brixner et al. "J. Electrochem. Soc.", vol. 30, No. 12, 1983, pp. 2435-2443.
Cooper Jack
GTE Products Corporation
Quatrini L. Rita
Walter Robert E.
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