US4272397A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of preparing flake-like ceramic particle of zinc sulfide phosphor
Assignee: Panasonic Holdings Corp
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Filing: 1979-05-31
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Granted: 1981-06-09
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Expires: 1999-05-31
Abstract
Abstract Flake-like ceramic particles of zinc sulfide phosphor and method of preparing the same including the steps of preparing flake-like particles of basic zinc sulfate crystal doped with activator, sulfurizing in the particles carbon disulfide, and heating the sulfurized particles in hydrogen sulfide. Particularly by steeping said particles in a solution of alkaline earth metal salt prior to or after sulfurizing, grain growth in ceramic particles can be improved.
Inventors
- 👤 Yoji Fukuda
- 👤 Fumio Fukushima
- 👤 Tomizo Matsuoka
- 👤 Tsuneharu Nitta
- 👤 Shigeru Hayakawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 21:08
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/56; C09K11/562; C09K11/565
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
140 words
A method of preparing flake-like ceramic particles of zinc sulfide phosphor, which comprises the steps of preparing flake-like particles of basic zinc sulfate crystal doped with activator, by precipitating said basic zinc sulfate particles from an aqueous solution containing zinc sulfate, urea and an activator metal ion component which is at least one activator metal ion selected from the group consisting of copper, silver, gold, aluminum, indium, gallium, rare earth metal and manganese, the atomic ratio of said activator metal ion component in said aqueous solution being 10 -5 to 10 -2 with respect to the zinc atom of said zinc sulfate, sulfurizing said basic zinc sulfate particles in a carbon disulfide atmosphere at a temperature from 400° to 800° C., and heating the thus sulfurized particles in a hydrogen sulfide atmosphere at a temperature from 800° to 1200° C.
Claim 2
Independent Claim
140 words
A method of preparing flake-like ceramic particles of zinc sulfide phosphor, which comprises the steps of preparing flake-like particles of basic zinc sulfate crystal doped with activator, by precipitating said basic zinc sulfate particles from an aqueous solution containing zinc sulfate, urea and an activator metal ion component which is at least one activator metal ion selected from the group consisting of copper, silver, gold, aluminum, indium, gallium, rare earth metal and manganese, the atomic ratio of said activator metal ion component in said aqueous solution being 10 -5 to 10 -2 with respect to the zinc atom of said zinc sulfate, sulfurizing said basic zinc sulfate particles in a carbon disulfide atmosphere at a temperature from 400° to 800° C., and heating the thus sulfurized particles in a hydrogen sulfide atmosphere at a temperature from 800° to 1200° C.
Claim 3
Dependent Claim
180 words
A method as claimed in claim 1, wherein said flake-like particles of basic zinc sulphate crystal doped with activator are prepared by (a) preparing an aqueous solution of 0.1 to 6 mole per liter of zinc sulfate, (b) heating said solution to a temperature from 80° to 100° C., (c) gradually adding an aqueous solution of urea to said zinc sulfate solution, the amount of urea being from 0.1 to 6 mole ratio with respect to said zinc sulfate, while stirring, whereby deposition of a precipitate of flake-like crystalline particles is caused, and (d) separating said precipitate from the resultant mixture, with the proviso that at least one of said zinc sulfate solution and said urea solution contains a metal ion component which is at least one metal ion selected from the group consisting of copper, silver, gold, aluminum, indium, gallium, rare earth metal and manganese, the atomic ratio of said metal ion component in said zinc sulfate solution and said urea solution combined being 10 -5 to 10 -2 with respect to the zinc atom of said zinc sulfate.
Claim 4
Dependent Claim
125 words
A method as claimed in claim 1, wherein said flake-like particles of basic zinc sulfate crystal doped with activator are prepared by (a) preparing an aqueous solution, of 0.1 to 6 mole per liter of zinc sulfate, 0.1 to 6 mole ratio of urea with respect to said zinc sulfate, and 10 31 5 to 10 -2 atomic ratio of at least one metal ion selected from the group consisting of copper, silver, gold, aluminum, indium, gallium, rare earth metal and, manganese with respect to the zinc atom of said zinc sulfate, (b) heating said solution to a temperature from 50° to 100° C. while stirring, whereby deposition of a precipitate of flake-like crystalline particles is caused, and (c) separating said precipitate from said solution.
Claim 5
Dependent Claim
17 words
A method as claimed in claim 1, wherein said activator is a combination of copper and aluminum.
Claim 6
Dependent Claim
17 words
A method as claimed in claim 1, wherein said activator is a combination of silver and aluminum.
Claim 7
Dependent Claim
18 words
A method as claimed in claim 1, wherein said activator is a combination of silver, gold and aluminum.
Claim 8
Independent Claim
186 words
A method of preparing flake-like ceramic particles of zinc sulfide phosphor, which comprises the steps of preparing flake-like particles of basic zinc sulfate crystal doped with activator, by precipitating said basic zinc sulfate particles from an aqueous solution containing zinc sulfate, urea and an activator metal ion component which is at least one activator metal ion selected from the group consisting of copper, silver, gold, aluminum, indium, gallium, rare earth metal and manganese, the atomic ratio of said activator metal ion component in said aqueous solution being 10 -5 to 10 -2 with respect to the zinc atom of said zinc sulfate, sulfurizing said basic zinc sulfate particles in a carbon disulfide atmosphere at a temperature from 400° to 800° C., steeping the thus sulfurized particles in an aqueous solution of 0.001 to 2.0 mole per liter of at least one alkaline earth metal salt selected from the group consisting of carbonates, sulfates and halides of calcium, magnesium, strontium and barium, filtering and drying the thus treated particles, and heating the dried particles in a hydrogen sulfide atmosphere at a temperature from 800° to 1200° C.
Claim 9
Independent Claim
186 words
A method of preparing flake-like ceramic particles of zinc sulfide phosphor, which comprises the steps of preparing flake-like particles of basic zinc sulfate crystal doped with activator, by precipitating said basic zinc sulfate particles from an aqueous solution containing zinc sulfate, urea and an activator metal ion component which is at least one activator metal ion selected from the group consisting of copper, silver, gold, aluminum, indium, gallium, rare earth metal and manganese, the atomic ratio of said activator metal ion component in said aqueous solution being 10 -5 to 10 -2 with respect to the zinc atom of said zinc sulfate, sulfurizing said basic zinc sulfate particles in a carbon disulfide atmosphere at a temperature from 400° to 800° C., steeping the thus sulfurized particles in an aqueous solution of 0.001 to 2.0 mole per liter of at least one alkaline earth metal salt selected from the group consisting of carbonates, sulfates and halides of calcium, magnesium, strontium and barium, filtering and drying the thus treated particles, and heating the dried particles in a hydrogen sulfide atmosphere at a temperature from 800° to 1200° C.
Claim 10
Dependent Claim
17 words
A method as claimed in claim 7, wherein said activator is a combination of copper and aluminum.
Claim 11
Dependent Claim
17 words
A method as claimed in claim 7, wherein said activator is a combination of silver and aluminum.
Claim 12
Dependent Claim
18 words
A method as claimed in claim 7, wherein said activator is a combination of silver, gold and aluminum.
Claim 13
Dependent Claim
16 words
A method as claimed in claim 7, wherein said alkaline earth metal salt is barium chloride.
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) | 1984-06-08 | 1984-12-08 | 1985-06-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-06-08 | 1988-12-08 | 1989-06-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-06-08 | 1992-12-08 | 1993-06-09 | $7700.00 | Window Closed / Lapsed |