US3929557A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Periodically and alternately accelerating and decelerating rotation rate of a feed crystal
Assignee: United States Department of the Air Force
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Filing: 1973-06-11
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Granted: 1975-12-30
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Expires: 1993-06-11
Abstract
Abstract A method for growing a rod-like crystalline boule by placing a rotating seed crystal in contact with the surfaces of a molton solution of crystal growing materials, then withdrawing the seed crystal while simultaneously lowering the temperature of the solution and subjecting the rotating seed crystal to a periodic acceleration and deceleration of its rotation rate.
Inventors
- 👤 John W Goodrum
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:15
CPC Classifications
C; C30; C30B; C30B15/00; C30B15/30
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
114 words
IN A SYSTEM FOR GROWING SINGLE CRYSTALLINE BOULES WHICH COMPRISES THE STEPS OF PLACING A SEED CRYSTAL IN CONTACT WITH THE SURFACE OF A MOLTEN SOLUTION OF CRYSTAL GROWING MATERIAL, LOWERING THE TEMPERATURE OF THE MOLTEN SOLUTION AT A PROGRAMMED RATE TO A TEMPERATURE SUFFICIENT TO EFFECT THE FORMATION OF A ROD-LIKE CRYSTALLINE BOULE ON SAID SEED CRYSTAL WHILE SIMULTANEOUSLY ROTATING AND WITHDRAWING SAID SEED CRYSTAL DURING SAID LOWERING OF SAID TEMPERATURE, AND COOLING SAID FORMED CRYSTALLINE BOULES TO ROOM TEMPERATURE, THE IMPROVEMENT WHICH COMPRISES PERIODICALLY ALTERING THE ROTATION RATE OF SAID ROTATING SEED CRYSTAL BY ALTERNATELY ACCELERATING AND DECELERATING SAID RATE OF ROTATION AT A CONSTANT RATE FOR A PREDETERMINED PERIOD OF TIME.
Claim 2
Dependent Claim
114 words
IN A SYSTEM FOR GROWING SINGLE CRYSTALLINE BOULES WHICH COMPRISES THE STEPS OF PLACING A SEED CRYSTAL IN CONTACT WITH THE SURFACE OF A MOLTEN SOLUTION OF CRYSTAL GROWING MATERIAL, LOWERING THE TEMPERATURE OF THE MOLTEN SOLUTION AT A PROGRAMMED RATE TO A TEMPERATURE SUFFICIENT TO EFFECT THE FORMATION OF A ROD-LIKE CRYSTALLINE BOULE ON SAID SEED CRYSTAL WHILE SIMULTANEOUSLY ROTATING AND WITHDRAWING SAID SEED CRYSTAL DURING SAID LOWERING OF SAID TEMPERATURE, AND COOLING SAID FORMED CRYSTALLINE BOULES TO ROOM TEMPERATURE, THE IMPROVEMENT WHICH COMPRISES PERIODICALLY ALTERING THE ROTATION RATE OF SAID ROTATING SEED CRYSTAL BY ALTERNATELY ACCELERATING AND DECELERATING SAID RATE OF ROTATION AT A CONSTANT RATE FOR A PREDETERMINED PERIOD OF TIME.
Claim 3
Dependent Claim
32 words
A method in accordance with claim 1 wherein said rate of rotation must be less than 50 revolutions per minute when the viscosity of said molten solution is greater than 40 poise.
Claim 4
Dependent Claim
31 words
A method in accordance with claim 1 wherein rate of rotation must be greater than 50 revolutions per minute when the viscosity of said molten solution is less than 40 poise.
Claim 5
Dependent Claim
47 words
A method in accordance with claim 1 wherein the rate of rotation of said rotating seed crystal is accelerated from 0 to 50 revolutions per minute and then decelerated from 50 to 0 revolutions per minute at a constant rate for a period of about 1 minute.
Claim 6
Dependent Claim
82 words
A method in accordance with claim 1 wherein said temperature of said molten solution is lowered from 1,200*C to 975*C at a programmed rate of 2*C per hour; said rate of rotation is periodically altered by accelerating from 0 to 30 revolutions per minute and decelerating from 30 to 0 revolutions per minute at a constant rate for a period of one minute and said rotating seed crystal is withdrawn from said molten solution at a rate of 0.50 mm per hour.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |