US4290909A
Expired / Lapsed
US
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Process for producing a lithium borate thermoluminescent and fluorescent substance
Assignee: Panasonic Holdings Corp
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Filing: 1979-07-30
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Granted: 1981-09-22
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Expires: 1999-07-30
Abstract
Abstract A process for producing a lithium borate thermoluminescent and fluorescent substance containing lithium borate as its main component which comprises heat-treating a mixture of Li 2 B 4 O 7 powder and an activator element compound at a temperature under and neighboring the melting point of Li 2 B 4 O 7 , to provide a highly sensitive fluorescent substance which has good adherence to the substrate of a dosimeter.
Inventors
- 👤 Mutsuo Takenaga
- 👤 Osamu Yamamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:47
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/63
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
115 words
Process for producing a lithium borate (Li 2 B 4 O 7 ) thermoluminescent and fluorescent substance of substantially spherical form containing lithium borate (Li 2 B 4 O 7 ) as the main component which comprises mixing Li 2 B 4 O 7 powder with an activator element compound and heat-treating the resultant mixture in air at a temperature of about 850° C. to just below the melting point of Li 2 B 4 O 7 for a time sufficient to diffuse the activator element into the crystal interior of the Li 2 B 4 O 7 powder and effect formation of Li 2 B 4 O 7 thermoluminescent substance of substantially spherical form.
Claim 2
Dependent Claim
115 words
Process for producing a lithium borate (Li 2 B 4 O 7 ) thermoluminescent and fluorescent substance of substantially spherical form containing lithium borate (Li 2 B 4 O 7 ) as the main component which comprises mixing Li 2 B 4 O 7 powder with an activator element compound and heat-treating the resultant mixture in air at a temperature of about 850° C. to just below the melting point of Li 2 B 4 O 7 for a time sufficient to diffuse the activator element into the crystal interior of the Li 2 B 4 O 7 powder and effect formation of Li 2 B 4 O 7 thermoluminescent substance of substantially spherical form.
Claim 3
Dependent Claim
26 words
Process for producing a lithium thermoluminescent and fluorescent substance according to claim 1, wherein pre-sieved and classified Li 2 B 4 O 7 powder is used.
Claim 4
Dependent Claim
52 words
Process for producing a lithium borate thermoluminescent and fluorescent substance according to claim 1, wherein a solvent which dissolves the activator element compound and does not dissolve or swell Li 2 B 4 O 7 powder is used, to add said activator element compound to Li 2 B 4 O 7 powder.
Claim 5
Dependent Claim
27 words
Process for producing a lithium borate thermoluminescent and fluorescent substance according to claim 1 wherein the heat treated mixture is crushed to particles of a desired size.
Claim 6
Dependent Claim
17 words
A process according to claim 1, wherein the temperature is about 905° C. to about 917° C.
Claim 7
Dependent Claim
20 words
A process according to claim 1, wherein the activator element is selected from the group consisting of copper and silver.
Claim 8
Dependent Claim
30 words
A process according to claim 6, wherein the activator element compound is present in an amount of 0.001 to 1.0% by weight based on the weight of the lithium borate.
References Cited (Backward Citations)
US3573221A
Cited
US3554920A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-09-21 | 1985-03-23 | 1985-09-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-21 | 1989-03-23 | 1989-09-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-21 | 1993-03-23 | 1993-09-22 | $7700.00 | Window Closed / Lapsed |