US4234376A
Expired / Lapsed
US
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Growth of single crystal beryllium oxide
Assignee: Honeywell International Inc
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Filing: 1979-10-01
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Granted: 1980-11-18
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Expires: 1999-10-01
Abstract
Abstract A process for rapid growth of large single crystals of beryllium oxide of a high degree of perfection is provided. The crystals are grown by top seeding in a substantially oxygen-and water vapor-free atmosphere from molten mixtures of BeO and one or more other metal oxides. Critical parameters include seed crystal orientation, rotation and pull rates and induction heating frequency. Resultant crystals are useful as substrates and windows in electronic and laser applications.
Inventors
- 👤 Robert C. Linares
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:43
CPC Classifications
C; C30; C30B; C30B15/00; C30B29/00; C30B29/10; C30B29/16; Y; Y10; Y10S; Y10S117/00; Y10S117/901; Y10S117/902
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
179 words
A process for growing beryllium oxide single crystals comprising the steps of: (a) preparing a mixture comprising beryllium oxide and a second metal oxide wherein beryllium oxide comprises about 45 to 80 mol percent of said mixture, (b) providing over said mixture a gaseous atmosphere substantially free of oxygen and water vapor, (c) heating said mixture to a temperature at which the mixture becomes molten, (d) lowering the temperature of said molten mixture to an intermediate temperature of about 1850° C. to 2050° C., (e) placing into the surface of said molten mixture a beryllium oxide seed crystal having an orientation within about 15° C. of (0001), (f) rotating said seed crystal at about 1 to 15 rpm, (g) pulling said seed crystal from said molten mixture at a rate of about 0.005 to 0.6 mm/hr and (h) lowering the temperature at a rate of about 0.1° C./hr to 10° C./hr while heating said molten mixture using an induction heating frequency less than about 100 kHz so that beryllium oxide from said molten mixture grows on said seed crystal.
Claim 2
Dependent Claim
179 words
A process for growing beryllium oxide single crystals comprising the steps of: (a) preparing a mixture comprising beryllium oxide and a second metal oxide wherein beryllium oxide comprises about 45 to 80 mol percent of said mixture, (b) providing over said mixture a gaseous atmosphere substantially free of oxygen and water vapor, (c) heating said mixture to a temperature at which the mixture becomes molten, (d) lowering the temperature of said molten mixture to an intermediate temperature of about 1850° C. to 2050° C., (e) placing into the surface of said molten mixture a beryllium oxide seed crystal having an orientation within about 15° C. of (0001), (f) rotating said seed crystal at about 1 to 15 rpm, (g) pulling said seed crystal from said molten mixture at a rate of about 0.005 to 0.6 mm/hr and (h) lowering the temperature at a rate of about 0.1° C./hr to 10° C./hr while heating said molten mixture using an induction heating frequency less than about 100 kHz so that beryllium oxide from said molten mixture grows on said seed crystal.
Claim 3
Dependent Claim
28 words
The process of claim 1 wherein said second metal oxide is selected from the group consisting of calcium oxide, strontium oxide, magnesium oxide, zirconium oxide and mixtures thereof.
Claim 4
Dependent Claim
13 words
The process of claim 2 wherein said second metal oxide is calcium oxide.
Claim 5
Dependent Claim
19 words
The process of claim 3 wherein said beryllium oxide comprises about 70 to 80 mol percent of said mixture.
Claim 6
Dependent Claim
17 words
The process of claim 4 wherein said gaseous atmosphere contains less than about 200 ppm of oxygen.
Claim 7
Dependent Claim
26 words
The process of claim 1 wherein the intermediate temperature to which said molten mixture is lowered in step (d) is about 1900° C. to 2040° C.
Claim 8
Dependent Claim
19 words
The process of claim 1 wherein said induction heating frequency is maintained between about 5 kHz and 50 kHz.
Claim 9
Dependent Claim
19 words
The process of claim 1 wherein said induction heating frequency is maintained between about 8 kHz and 12 kHz.
Claim 10
Dependent Claim
21 words
The process of claim 1 wherein said seed crystal placed into said surface has an orientation within about 5° of (0001).
Claim 11
Dependent Claim
17 words
The process of claim 1 wherein said seed crystal is rotated at about 5 to 10 rpm.
Claim 12
Dependent Claim
23 words
The process of claim 1 wherein said seed crystal is pulled from said melt at a rate of about 0.2 to 0.3 mm/hr.
Claim 13
Dependent Claim
33 words
The process of claim 1 further comprising between steps (g) and (h) generating a signal responsive to the weight of the pulled crystal, said signal controlling the rate of heating in step (h).
References Cited (Backward Citations)
US3768983A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-11-18 | 1984-05-19 | 1984-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-11-18 | 1988-05-19 | 1988-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-11-18 | 1992-05-19 | 1992-11-18 | $7700.00 | Window Closed / Lapsed |