US4149989A
Expired / Lapsed
US
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Process for producing phosphors
Assignee: Hitachi Ltd
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Filing: 1978-02-28
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Granted: 1979-04-17
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Expires: 1998-02-28
Abstract
Abstract Infrared-infrared phosphors having a composition represented by the general formula AB.sub.1-x-y Nd.sub.x Yb.sub.y P.sub.4 O.sub.12 wherein A is at least one element selected from the group consisting of Na, K, Rb and Cs, B is at least one element selected from the group consisting of Sc, Y, La, Ce, Gd, Lu, Ga, In, Bi and Sb, and x and y are numbers satisfying the conditions 0.05≦x≦1.0 0≦y≦0.95 x+y≦1.0 can be produced in the form of very fine particles and in a high yield by carrying out firing in the presence of a melt comprising a compound of the formula APO.sub.3 wherein A is as defined above, and in such a specific composition and such a specific temperature range as said phosphor may be crystallized out.
Inventors
- 👤 Yasutoshi Kashiwada
- 👤 Shinkichi Tanimizu
- 👤 Atsushi Suzuki
- 👤 Yoshio Furuhata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 07:56
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7709; C09K11/7766; C09K11/7777
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
172 words
A process for producing an infrared-infrared phosphor represented by the formula AB.sub.1-x-y Nd.sub.x Yb.sub.y P.sub.4 O.sub.12 wherein A is at least one element selected from the group consisting of Na, K, Rb and Cs, B is at least one element selected from the group consisting of Sc, Y, La, Ce, Gd, Lu, Ga, In, Bi and Sb, and x and y are numbers satisfying the conditions 0.05≦x≦1.0 0≦y≦0.95 x+y≦1.0 which comprises the steps of: (a) forming a mixture of starting materials; (b) firing the resulting mixture at a temperature of 520°-880° C. to effect a composition within the region β in FIG. 2 in the accompanying drawings, said composition being composed of a melt of APO 3 and said phosphor; (c) cooling the fired mixture; (d) digesting the cooled mixture with water; and (e) removing the liquid phase of the digested mixture and drying the insoluble residue wherein the residue includes particles of said phosphor, and wherein at least 30% by weight of said particles are about 5μm or less in size.
Claim 2
Dependent Claim
172 words
A process for producing an infrared-infrared phosphor represented by the formula AB.sub.1-x-y Nd.sub.x Yb.sub.y P.sub.4 O.sub.12 wherein A is at least one element selected from the group consisting of Na, K, Rb and Cs, B is at least one element selected from the group consisting of Sc, Y, La, Ce, Gd, Lu, Ga, In, Bi and Sb, and x and y are numbers satisfying the conditions 0.05≦x≦1.0 0≦y≦0.95 x+y≦1.0 which comprises the steps of: (a) forming a mixture of starting materials; (b) firing the resulting mixture at a temperature of 520°-880° C. to effect a composition within the region β in FIG. 2 in the accompanying drawings, said composition being composed of a melt of APO 3 and said phosphor; (c) cooling the fired mixture; (d) digesting the cooled mixture with water; and (e) removing the liquid phase of the digested mixture and drying the insoluble residue wherein the residue includes particles of said phosphor, and wherein at least 30% by weight of said particles are about 5μm or less in size.
Claim 3
Dependent Claim
30 words
A process according to claim 1, which further comprises the step of treating the insoluble residue obtained in said step (e) with a dilute acid to remove APO 3 .
Claim 4
Dependent Claim
32 words
A process according to claim 1, wherein the temperature for firing the resulting mixture is achieved by heating the resulting mixture at a heating rate of between 10° C./hour to 350° C./hour.
Claim 5
Dependent Claim
13 words
A process according to claim 3, wherein said heating rate is 150° C./hour.
References Cited (Backward Citations)
US4000247A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-04-16 | 1982-10-16 | 1983-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-04-16 | 1986-10-16 | 1987-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-04-16 | 1990-10-16 | 1991-04-17 | $7700.00 | Window Closed / Lapsed |