US3927240A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Haze resistant cathode luminescent sulfide phosphors and method of preparing same
Assignee: GTE Sylvania Inc
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Filing: 1974-06-12
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Granted: 1975-12-16
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Expires: 1994-06-12
Abstract
Abstract A cathodoluminescent phosphor composition consisting essentially from about 99.6 percent to about 99.9 percent by weight of discrete particles of an activated host containing a divalent metal cation and a sulfide anion and from about 0.1 percent to about 0.4 percent by weight of a phosphate selected from the group consisting of calcium pyrophosphate and strontium pyrophosphate as a coating over the surfaces of the particles renders the cathodoluminescent phosphor haze resistant when used in cathode ray tubes. A process for preparing the cathodoluminescent phosphor comprises dispersing the sulfide phosphor in water to obtain a predetermined concentration of the phosphor, thereafter in either order a controlled amount of a water soluble pyrophosphate source sufficient to provide the desired concentration of pyrophosphate ions and a sufficient amount of a water soluble strontium or calcium salt to react with the pyrophosphate ions is added. The resulting precipitated material is separated from the water and washed to a desired purity and dried. In the case of a strontium pyrophosphate coated material, a further annealing step has additional advantageous results.
Inventors
- 👤 Michael J Hammond
- 👤 Raymond F Herner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:40
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/56; C09K11/562; C09K11/565; C09K11/02; C09K11/025; Y; Y10; Y10T; Y10T428/00; Y10T428/29; Y10T428/2982; Y10T428/2991
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
56 words
A CATHODOLUMINESCENT PHOSPHOR COMPOSITION CONSISTING ESSENTIALLY OF FROM ABOUT 99.6 PERCENT TO ABOUT 99.9 PERCENT BY WEIFHT OF DISCRETE PARTICLES OF AN ACTIVATED HOST OF A DIVALENT METAL SULFIDE AND, AS A COATING OVER THE SURFACES OF SAID PARTICLES, FROM ABOUT 0.1 PERCENT TO ABOUT 0.4 PERCENT BY GROUP CONSISTING OF CALCIUM PYROPHOSPHATE AND STRONTIUM PYROPHOSPHATE.
Claim 2
Dependent Claim
56 words
A CATHODOLUMINESCENT PHOSPHOR COMPOSITION CONSISTING ESSENTIALLY OF FROM ABOUT 99.6 PERCENT TO ABOUT 99.9 PERCENT BY WEIFHT OF DISCRETE PARTICLES OF AN ACTIVATED HOST OF A DIVALENT METAL SULFIDE AND, AS A COATING OVER THE SURFACES OF SAID PARTICLES, FROM ABOUT 0.1 PERCENT TO ABOUT 0.4 PERCENT BY GROUP CONSISTING OF CALCIUM PYROPHOSPHATE AND STRONTIUM PYROPHOSPHATE.
Claim 3
Dependent Claim
23 words
A phosphor composition according to claim 1 wherein said particles have an average particle size of from about 1 to about 20 micrometers.
Claim 4
Dependent Claim
24 words
A phosphor composition according to claim 1 wherein said host is selected from the group consisting of zinc sulfide, cadmium sulfide and zinc-cadmium sulfide.
Claim 5
Dependent Claim
13 words
A phosphor composition according to claim 3 wherein said pyrophosphate is calcium pyrophosphate.
Claim 6
Dependent Claim
13 words
A phosphor composition according to claim 3 wherein said pyrophosphate is strontium pyrophosphate.
Claim 7
Dependent Claim
29 words
A phosphor composition according to claim 3 wherein the pyrophosphate content is from about 0.10 percent to about 0.15 percent by weight of P2O7 based on the total composition.
Claim 8
Dependent Claim
111 words
A process suitable for providing a phosphate coating on the surfaces of a cathodoluminescent phosphor activated host comprising: a. dispersing a predetermined amount of a phosphor having an activated host of a divalent metal sulfide in water; b. adding to the aqueous dispersion an amount of a water-soluble pyrophosphate source to yield at least about 0.1 percent to about 0.4 percent by weight of pyrophosphate ions based on the weight of the phosphor and at least a stoichiometric amount of a reactive water-soluble strontium or calcium salt; c. separating the resulting calcium or strontium pyrophosphate-coated phosphor from the aqueous phase; and d. drying said coated phosphor to remove any residual water.
Claim 9
Dependent Claim
111 words
A process suitable for providing a phosphate coating on the surfaces of a cathodoluminescent phosphor activated host comprising: a. dispersing a predetermined amount of a phosphor having an activated host of a divalent metal sulfide in water; b. adding to the aqueous dispersion an amount of a water-soluble pyrophosphate source to yield at least about 0.1 percent to about 0.4 percent by weight of pyrophosphate ions based on the weight of the phosphor and at least a stoichiometric amount of a reactive water-soluble strontium or calcium salt; c. separating the resulting calcium or strontium pyrophosphate-coated phosphor from the aqueous phase; and d. drying said coated phosphor to remove any residual water.
Claim 10
Dependent Claim
14 words
A process according to claim 7 wherein said salt is a water-soluble strontium salt.
Claim 11
Dependent Claim
33 words
A process according to claim 8 wherein after said drying step said phosphor is heated in an inert atmosphere at about 400*C to about 450*C for from about 1 to about 3 hours.
Claim 12
Dependent Claim
20 words
A process according to claim 8 wherein said water-soluble salt is strontium nitrate and said pyrophosphate source is sodium pyrophosphate.
Claim 13
Dependent Claim
31 words
A process according to claim 7 wherein said salt is a calcium salt selected from the group consisting of calcium chloride and calcium nitrate and said pyrophosphate source is sodium pyrophosphate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-15 | 1979-06-16 | 1979-12-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-15 | 1983-06-16 | 1983-12-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-15 | 1987-06-16 | 1987-12-16 | $7700.00 | Window Closed / Lapsed |