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US4374037A
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Method for preparing divalent-europium-activated calcium sulfide phosphors
Assignee: RCA Corp
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Filing: 1982-06-23
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Granted: 1983-02-15
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Expires: 2002-06-23
Abstract
Abstract A method for preparing a divalent-europium-activated calcium sulfide phosphor comprising reacting a molten mixture consisting essentially of alkaline-earth-metal chloride and europium chloride with gaseous carbon disulfide at temperatures between 850 DEG and 1200 DEG C. for 1 to 6 hours. The molten mixture may include activator proportions of cerium and/or alkali metal cations. Minor proportions of calcium may be replaced with one or more other alkaline-earth-metal cations.
Inventors
- 👤 Tatsuo Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 11:44
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7766; C09K11/7767; C09K11/7768; C09K11/7728; C09K11/7729; C09K11/7731
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
38 words
A method for preparing a divalent-europium-activated calcium sulfide phosphor comprising reacting a molten mixture consisting essentially of calcium chloride and europium chloride with gaseous carbon disulfide at temperatures between 850° and 1200° C. for 1 to 6 hours.
Claim 2
Independent Claim
38 words
A method for preparing a divalent-europium-activated calcium sulfide phosphor comprising reacting a molten mixture consisting essentially of calcium chloride and europium chloride with gaseous carbon disulfide at temperatures between 850° and 1200° C. for 1 to 6 hours.
Claim 3
Dependent Claim
13 words
The method defined in claim 1 wherein said mixture includes a cerium chloride.
Claim 4
Dependent Claim
16 words
The method defined in claim 1 wherein said mixture includes a chloride of an alkali metal.
Claim 5
Dependent Claim
34 words
The method defined in claim 1 wherein said molten mixture is heated in a closed chamber, and a gaseous mixture of carbon disulfide vapor and a nonoxidizing carrier gas is passed through said chamber.
Claim 6
Dependent Claim
19 words
The method defined in claim 1 wherein a minor proportion of said calcium is replaced with another alkaline-earth-metal cation.
Claim 7
Dependent Claim
37 words
The method defined in claim 1 wherein said mixture is produced by dissolving said chlorides in a nonaqueous solvent, evaporating the resultant solution to dryness, and then melting the residue of said evaporation in a carbon boat.
Claim 8
Dependent Claim
32 words
The method defined in claim 6 wherein crystals of said phosphor are produced by said reaction, and said method includes washing said crystals with a solvent to dissolve away residual unreacted chlorides.
Claim 9
Dependent Claim
37 words
The method defined in claim 7 including grinding said washed crystals to a powder and then annealing said powder by heating in a reducing gaseous atmosphere for 1 to 10 hours at about 1000° to 1100° C.
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) | 1986-02-14 | 1986-08-16 | 1987-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-02-14 | 1990-08-16 | 1991-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-02-14 | 1994-08-16 | 1995-02-15 | $7700.00 | Window Closed / Lapsed |