US4144117A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for producing a lithium tantalate single crystal
Assignee: Toshiba Corp
•
Filing: 1977-03-10
•
Granted: 1979-03-13
•
Expires: 1997-03-10
Abstract
Abstract A method for producing a lithium tantalate single crystal comprises the steps of preparing a melt consisting essentially of lithium tantalate in a platinum-rhodium crucible including 20 to 40 weight percent of rhodium, and growing a lithium tantalate single crystal from the melt in an oxidizing atmosphere, for example, in the atmosphere.
Inventors
- 👤 Tsuguo Fukuda
- 👤 Hitoshi Hirano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 03:00
CPC Classifications
C; C30; C30B; C30B15/00; C30B29/00; C30B29/10; C30B29/16; C30B29/22; C30B29/30; Y; Y10; Y10S; Y10S117/00; Y10S117/90; Y10S117/906; Y10S117/91
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
84 words
A method for producing a lithium tantalate single crystal comprising establishing a melt under an oxidizing atmosphere consisting essentially of lithium tantalate in a platinumrhodium crucible consisting essentially of between 80% by weight and about 70% platinum and between 20% and about 30% rhodium, said melt being at a temperature of about the melting point of lithium tantalate, contacting a seed crystal of lithium tantalate with said melt, and pulling the seed crystal away from the melt to grow a lithium tantalate single crystal.
Claim 2
Independent Claim
84 words
A method for producing a lithium tantalate single crystal comprising establishing a melt under an oxidizing atmosphere consisting essentially of lithium tantalate in a platinumrhodium crucible consisting essentially of between 80% by weight and about 70% platinum and between 20% and about 30% rhodium, said melt being at a temperature of about the melting point of lithium tantalate, contacting a seed crystal of lithium tantalate with said melt, and pulling the seed crystal away from the melt to grow a lithium tantalate single crystal.
Claim 3
Dependent Claim
22 words
The method of claim 1 wherein said melt in contact with said seed crystal is at a temperature of about 1650° C.
Claim 4
Dependent Claim
16 words
The method of claim 1 wherein said single crystal contains a very small amount of rhodium.
Claim 5
Dependent Claim
39 words
The method of claim 1 wherein said single crystal has a temperature coefficient to the surface wave propogation velocity of about 18 ppm for a portion cut at an angle of 90° to the X-axis of the single crystal.
Claim 6
Dependent Claim
19 words
A method according to claim 1, in which said lithium tantalate single crystal is grown by a pullingup method.
Claim 7
Dependent Claim
19 words
A method according to claim 5, in which a lithium tantalate single crystal is grown by a Czochralski method.
Claim 8
Dependent Claim
19 words
A method according to claim 1, in which said lithium tantalate single crystal is grown by a pulling-down method.
Claim 9
Dependent Claim
20 words
A method according to claim 1, in which said lithium tantalate single crystal is grown by a laterally pulling method.
Claim 10
Dependent Claim
27 words
A method according to claim 1, in which said rhodium in said lithium tantalate single crystal is present as a crystal constituent element in a crystal site.
Claim 11
Dependent Claim
20 words
A method according to claim 1, in which said lithium tantalate single crystal contains 90 to 700 ppm of rhodium.
Claim 12
Dependent Claim
20 words
A method according to claim 10, in which said lithium tantalate single crystal contains 100 to 300 ppm of rhodium.
Claim 13
Dependent Claim
23 words
A method according to claim 1, in which said platinum-rhodium crucible consists essentially of 70% weight percent platinum and 30 weight percent rhodium.
Claim 14
Dependent Claim
28 words
A method according to claim 1, in which said lithium tantalate single crystal has a dislocation density of less than 5 × 10 2 lines /cm 2 .
Claim 15
Dependent Claim
28 words
A method according to claim 3, in which said lithium tantalate single crystal has a dislocation density of less than 5 × 10 2 lines /cm 2 .
References Cited (Backward Citations)
US2142660A
Cited
US2106527A
Cited
US2190296A
Cited
US2460547A
Cited
DE1210415B
Cited
US3393054A
Cited
US3370927A
Cited
FR1546324A
Cited
US3681033A
Cited
US3601639A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-03-12 | 1982-09-11 | 1983-03-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-12 | 1986-09-11 | 1987-03-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-12 | 1990-09-11 | 1991-03-13 | $7700.00 | Window Closed / Lapsed |