US3718600A
Expired / Lapsed
US
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Method of manufacturing a luminescent silicate activated by bivalent europium
Assignee: US Philips Corp
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Filing: 1971-06-23
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Granted: 1973-02-27
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Expires: 1991-06-23
Abstract
Abstract A luminescent silicate activated by bivalent europium defined by the formula Ba1-x-pSrxEupZrSi3O9 which O</= x </= 0.2 and 0.002</= p </= 0.10 is prepared by starting from a mixture of barium strontium disilicate, at least 1.5 mol of ZrO2 and at least 1 mol of SiO2 per mol of disilicate. The mixture, which also comprises europium, is heated at a temperature of between 1,200 DEG and 1,400 DEG C is a reducing atmosphere.
Inventors
- 👤 M Tak
- 👤 Klinken O Van
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 01:26
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7728; C09K11/77342
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
20 words
A method of claim 1, wherein the mixture comprises between 1.75 and 3.0 mol of ZrO2 per mol of disilicate.
Claim 2
Dependent Claim
20 words
A method of claim 2, wherein the mixture comprises between 1.5 and 2.5 mol of SiO2 per mol of disilicate.
Claim 3
Dependent Claim
23 words
A method of claim 3 wherein the mixture is heated for 2 to 8 hours at a temperature of between 1,300* and 1,400*C.
Claim 4
Dependent Claim
78 words
A method of claim 3, in which the barium strontium disilicate to be used is manufactured by heating a starting mixture of barium oxide, strontium oxide and silicon oxide, or of compounds which produce these oxides upon heating, wherein the starting mixture comprises at least 3 mol of SiO2 per mol of barium oxide and strontium oxide so that the barium strontium disilicate formed is already mixed with quantity of SiO2 required for obtaining the desired luminescent silicate.
Claim 5
Dependent Claim
19 words
A method of claim 3 wherein the barium strontium disilicate to be used comprises the desired quantity of europium.
Claim 6
Dependent Claim
44 words
A luminescent silicate activated by bivalent europium and defined by the formula Ba1 x pSrxEupZrSi3O9 in which O < or = x < or = 0.2 and 0.002 < or = p < or = 0.10, and manufactured by a method of claim 1.
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) | 1976-02-27 | 1976-08-28 | 1977-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-27 | 1980-08-28 | 1981-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-27 | 1984-08-28 | 1985-02-27 | $7700.00 | Window Closed / Lapsed |