US3768983A
Expired / Lapsed
US
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Single crystal beryllium oxide growth from calcium oxide-beryllium oxide melts
Assignee: Boeing North American Inc
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Filing: 1971-11-03
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Granted: 1973-10-30
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Expires: 1991-11-03
Abstract
Abstract A process for growing large single crystals substantially free of surface inclusions within several days is disclosed. This process involves the concept of promoting further growth on seed crystals from a melt composition of suitable oxides which will form a eutectic. Growth occurs as the crystal seed is rotated and pulled slowly from the melt composition. The temperature decrease of said melt is such that the temperature can be defined by the liquidus curve of the melt composition phase diagram. Growing single crystal beryllium oxide at a temperature of about 1,980* C from a melt composition having 56 weight percent beryllium oxide and 44 weight percent calcium oxide is an example of this process.
Inventors
- 👤 P Elkins
- 👤 S Austerman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 19:13
CPC Classifications
C; C30; C30B; C30B15/00; C30B29/00; C30B29/10; C30B29/16
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
29 words
The process recited in claim 1 whereby said seed crystal is slowly rotated and slowly withdrawn from the melt during growth to form a boule about the seed crystal.
Claim 2
Dependent Claim
21 words
The process recited in claim 1 wherein the melt temperature is lowered at a rate of about 15* C per hour.
Claim 3
Dependent Claim
15 words
The process recited in claim 1 wherein said first mixture includes a third oxide compound.
Claim 4
Dependent Claim
29 words
The process recited in claim 4 wherein said third oxide compound is selected from the group consisting of barium, strontium, magnesium, aluminum, sodium, potassium and the rare earth elements.
Claim 5
Dependent Claim
22 words
The process recited in claim 1 wherein the beryllium oxide concentration in said first mixture varies from 40 to 70 weight percent.
Claim 6
Dependent Claim
49 words
The process recited in claim 1 including the step of continuously lowering the temperature of said melt while beryllium oxide from said melt grows on said seed crystal to cause the temperature of the melt to substantially follow the liquidus temperature curve of the melt towards the eutectic temperature.
Claim 7
Dependent Claim
27 words
The process recited in claim 1 wherein a thin wafer of single crystal material is formed on the surface of said melt adjacent to said seed crystal.
References Cited (Backward Citations)
US2848310A
Cited
US3234135A
Cited
US3345133A
Cited
US3341302A
Cited
US3490959A
Cited
US3595803A
Cited
US3650702A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-29 | 1977-04-30 | 1977-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-29 | 1981-04-30 | 1981-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-29 | 1985-04-30 | 1985-10-30 | $7700.00 | Window Closed / Lapsed |