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US3932299A
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Method for the reduction of iron in iron-doped lithium niobate crystals
Assignee: RCA Corp
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Filing: 1973-12-03
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Granted: 1976-01-13
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Expires: 1993-12-03
Abstract
Abstract Lithium niobate single crystals doped with iron can be treated to reduce trivalent iron to divalent iron without reduction of the lithium niobate host crystal, by surrounding the crystal with a high-melting salt of lithium, such as lithium carbonate, and heating in an oxygen-containing atmosphere until the desired amount of reduction is obtained.
Inventors
- 👤 William Phillips
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 19:06
CPC Classifications
G; G11; G11C; G11C13/00; G11C13/04; G11C13/042; C; C30; C30B; C30B29/00; C30B29/10; C30B29/16; C30B29/22; C30B29/30; C30B33/00; G02; G02F; G02F1/00; G02F1/35; G02F1/355; G02F1/3551
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
66 words
A method of reducing over 90 percent of the trivalent iron present in an iron-doped lithium niobate crystal to divalent iron without reducing the lithium niobate which comprises surrounding an iron-doped lithium niobate crystal in a salt of lithium and heating at a temperature of at least about 400°C up to about 1000°C but below the melting point of said lithium salt in an oxygen-containing atmosphere.
Claim 2
Independent Claim
66 words
A method of reducing over 90 percent of the trivalent iron present in an iron-doped lithium niobate crystal to divalent iron without reducing the lithium niobate which comprises surrounding an iron-doped lithium niobate crystal in a salt of lithium and heating at a temperature of at least about 400°C up to about 1000°C but below the melting point of said lithium salt in an oxygen-containing atmosphere.
Claim 3
Dependent Claim
15 words
A method according to claim 1 wherein the temperature is from about 450°to about 600°C.
Claim 4
Dependent Claim
13 words
A method according to claim 1 wherein the lithium salt is lithium carbonate.
Claim 5
Dependent Claim
31 words
A method according to claim 1 wherein the lithium niobate crystal contains up to about 0.005 mol percent of iron and the temperature of heating is from about 450°to about 550°C.
Claim 6
Dependent Claim
32 words
A method according to claim 1 wherein the lithium niobate crystal contains from about 0.005 to 0.1 mol percent of iron and the temperature of heating is from about 550°to about 1000°C.
Claim 7
Dependent Claim
37 words
A method according to claim 1 wherein the lithium niobate crystal contains from about 0.0001 to 0.005 mol percent of iron and is heated at a temperature of about 450°to about 550°C. while surrounded with lithium carbonate.
Claim 8
Dependent Claim
58 words
A crystal useful for recording and erasing phase holograms optically comprising a single crystal of lithium niobate doped with from about 0.0001 to about 0.005 mol percent of iron wherein over about 98.5 mol percent of the iron present is in the divalent state and wherein substantially all of the visible optical absorption is derived from divalent iron.
Claim 9
Dependent Claim
58 words
A crystal useful for recording and erasing phase holograms optically comprising a single crystal of lithium niobate doped with from about 0.0001 to about 0.005 mol percent of iron wherein over about 98.5 mol percent of the iron present is in the divalent state and wherein substantially all of the visible optical absorption is derived from divalent iron.
Claim 10
Dependent Claim
58 words
A crystal useful for recording and erasing phase holograms optically comprising a single crystal of lithium niobate doped with from about 0.001 to about 0.005 mol percent of iron wherein over about 90 mol percent of the iron present is in the divalent state and wherein substantially all of the visible optical absorption is derived from divalent iron.
Claim 11
Dependent Claim
58 words
A crystal useful for recording and erasing phase holograms optically comprising a single crystal of lithium niobate doped with from about 0.001 to about 0.005 mol percent of iron wherein over about 90 mol percent of the iron present is in the divalent state and wherein substantially all of the visible optical absorption is derived from divalent iron.
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) | 1979-01-12 | 1979-07-14 | 1980-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-12 | 1983-07-14 | 1984-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-12 | 1987-07-14 | 1988-01-13 | $7700.00 | Window Closed / Lapsed |