Preparation of high emission efficiency alkaline earth metal thiogallate phosphors
First Claim
1. A method of making a high emission efficiency alkali metal thiogallate phosphor comprisingintimately mixing an alkali metal sulfate having a particle size below about 10 microns coated with an activator with gallium nitrate solution in an amount such that an excess of gallium is present in the final phosphor product, precipitating the activated alkali metal gallium sulfate, and firing in the presence of hydrogen sulfide.
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Abstract
A method of forming high efficiency emission alkali metal activated gallium sulfide phosphors by including an excess of 1-7% of gallium. A solution of a soluble gallium salt is added to a sulfate precipitate of an alkali metal sulfate and firing in hydrogen sulfide atmosphere at temperatures up to about 900° C.
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Citations
15 Claims
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1. A method of making a high emission efficiency alkali metal thiogallate phosphor comprising
intimately mixing an alkali metal sulfate having a particle size below about 10 microns coated with an activator with gallium nitrate solution in an amount such that an excess of gallium is present in the final phosphor product, precipitating the activated alkali metal gallium sulfate, and firing in the presence of hydrogen sulfide.
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3. A method of making high emission efficiency thiogallate phosphors comprising
a) forming an aqueous solution of a soluble alkali metal salt; -
b) adding a sulfate to precipitate an alkali metal sulfate;
c) re-suspending the sulfate in water;
d) adding 2-5 mol % of the sulfate of a soluble activator salt, e) precipitating the activator sale onto the alkali metal sulfate;
f) adding an excess of from about 0.1-7 percent by weight of a solution of a soluble gallium salt to the precipitate, g) neutralizing the solution to form a precipitate, and h) firing the precipitate in hydrogen sulfide to form the corresponding sulfide phosphor. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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- 10. A high emission efficiency rare earth activated alkaline earth metal (M) thiogallate phosphor comprising
- 13. An activated alkaline earth metal thiogallate phosphor having an excess of gallium of from 0.1 to 7 percent by weight of the alkaline earth metal.
Specification