US3976535A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Screening seeds for quartz growth
Assignee: AT&T Inc
•
Filing: 1975-05-27
•
Granted: 1976-08-24
•
Expires: 1995-05-27
Abstract
Abstract z-face quartz of good quality suitable for piezoelectric applications can be grown at rates near 35 mil/da at p-T conditions easily accessible in commercial autoclaves. The growth conditions are predictable from previous systematic studies of growth rate. Cracking of grown crystals either during growth or in crystal processing can be severe and can account for as much as 15-50% yield loss. However, much of this loss can be reduced by carefully screening seeds for strain using the new polariscopic technique of the invention. Strain (and cracking) are severe with growth on highly strained seeds and at high growth rates. Carefully choosing seeds reduces the strain in the grown material for a given growth rate.
Inventors
- 👤 Robert Leroy Barns
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 17:46
CPC Classifications
C; C30; C30B; C30B7/00; C30B29/00; C30B29/10; C30B29/16; C30B29/18; Y; Y10; Y10S; Y10S117/00; Y10S117/901; Y10S117/902; Y10T; Y10T117/00; Y10T117/10; Y10T117/1024; Y10T117/1096
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
135 words
In a method for hydrothermal growth of quartz crystals in which growth of quartz occurs on a quartz crystal seed plate immersed in a hydrothermal solution containing nutrient quartz and maintained under temperature and pressure such that the nutrient quartz dissolves and recrystallizes on the seed plate the improvement characterized in that the internal strain of the seed plate is first examined by exposing the surface of the seed plate to visible polarized light that is monochromatic within ± 200 A within a beam that is collimated to ± 2° and is directed ± 2° along the optic axis of the seed plate, then determining the approximate r value of the seed plate, r, being 0.001 waves of light retardation, and selecting those seed plates for use having an r value of 20 or less.
Claim 2
Dependent Claim
135 words
In a method for hydrothermal growth of quartz crystals in which growth of quartz occurs on a quartz crystal seed plate immersed in a hydrothermal solution containing nutrient quartz and maintained under temperature and pressure such that the nutrient quartz dissolves and recrystallizes on the seed plate the improvement characterized in that the internal strain of the seed plate is first examined by exposing the surface of the seed plate to visible polarized light that is monochromatic within ± 200 A within a beam that is collimated to ± 2° and is directed ± 2° along the optic axis of the seed plate, then determining the approximate r value of the seed plate, r, being 0.001 waves of light retardation, and selecting those seed plates for use having an r value of 20 or less.
Claim 3
Dependent Claim
16 words
The method of claim 1 in which the seed plate is a z-face (minor rhombohedral) seed.
Claim 4
Dependent Claim
12 words
The method of claim 1 in which the hydrothermal solution comprises NaOH.
Claim 5
Dependent Claim
22 words
The method of claim 1 in which the quartz recrystallizes on the seed plate at a rate in excess off 32 mils/day.
References Cited (Backward Citations)
US2558745A
Cited
US1918976A
Cited
US2423357A
Cited
US2871192A
Cited
US2907808A
Cited
US3291575A
Cited
US3607108A
Cited
US3853596A
Cited
US3917506A
Cited
US3788890A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-24 | 1980-02-23 | 1980-08-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-24 | 1984-02-23 | 1984-08-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-24 | 1988-02-23 | 1988-08-24 | $7700.00 | Window Closed / Lapsed |