US4384989A
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Semiconductive barium titanate
Assignee: Toyota Central R&D Labs Inc
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Filing: 1982-04-30
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Granted: 1983-05-24
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Expires: 2002-04-30
Abstract
Abstract Semiconductive barium titanate having a positive temperature coefficient of resistance comprises a barium titanate semiconductor including barium titanate and a small quantity of a doping element, and at least one additive selected from among silicon nitride, titanium nitride, zirconium nitride and silicon carbide. The semiconductive barium titanate of this invention has a sharp rise in the variation of specific resistivity with temperature change and a large specific resistivity ratio in the PTC temperature region, and can be produced with high reproducibility, since a widely differing quantity of the doping element can be effectively added to barium titanate.
Inventors
- 👤 Osami Kamigaito
- 👤 Tatsumi Hioki
- 👤 Nobuyuki Yamamoto
- 👤 Yoshiharu Hirose
- 👤 Haruo Doi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 22:22
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/46; C04B35/462; C04B35/465; C04B35/468; C04B35/4682; H; H01; H01C; H01C7/00; H01C7/02; H01C7/022; H01C7/023; H01C7/025
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
91 words
Semiconductive barium titanate ceramic having a positive temperature coefficient of resistance, comprising a barium titanate semiconductor consisting essentially of barium titanate and a doping element selected from the group consisting of yttrium, lanthanum, cerium, samarium, dysprosium, antimony, niobium, tantalum and bismuth, and at least one additive selected from the group consisting of silicon nitride, titanium nitride, zirconium nitride and silicon carbide, said additive being present in an amount sufficient to effect a specific resistivity at 20° C. that is lower than the resistivity of said doped barium titanate absent the additive.
Claim 2
Dependent Claim
91 words
Semiconductive barium titanate ceramic having a positive temperature coefficient of resistance, comprising a barium titanate semiconductor consisting essentially of barium titanate and a doping element selected from the group consisting of yttrium, lanthanum, cerium, samarium, dysprosium, antimony, niobium, tantalum and bismuth, and at least one additive selected from the group consisting of silicon nitride, titanium nitride, zirconium nitride and silicon carbide, said additive being present in an amount sufficient to effect a specific resistivity at 20° C. that is lower than the resistivity of said doped barium titanate absent the additive.
Claim 3
Dependent Claim
30 words
Semiconductive barium titanate according to claim 1, wherein the amount of said silicon nitride is in the range of from 0.01 to 5.0% by weight of said barium titanate semiconductor.
Claim 4
Dependent Claim
39 words
Semiconductive barium titanate according to claim 1, wherein the amount of at least one of said titanium nitride, zirconium nitride and silicon carbide is in the range of from 0.1 to 2.0% by weight of said barium titanate semiconductor.
Claim 5
Dependent Claim
16 words
Semiconductive barium titanate according to claim 1, wherein said doping element has a valence of 3.
Claim 6
Dependent Claim
16 words
Semiconductive barium titanate according to claim 1, wherein said doping element has a valence of 5.
Claim 7
Dependent Claim
25 words
Semiconductive barium titanate according to claim 4, wherein said doping element is selected from the group consisting of yttrium, lanthanum, cerium, samarium, dysprosium and antimony.
Claim 8
Dependent Claim
22 words
Semiconductive barium titanate according to claim 5, wherein said doping element is selected from the group consisting of nobium, tantalum and bismuth.
Claim 9
Dependent Claim
19 words
Semiconductive barium tatanate according to claim 1, wherein said doping element is yttrium, and said additive is silicon nitride.
Claim 10
Dependent Claim
34 words
Semiconductive barium titanate according to claim 1, wherein said doping element is yttrium, and said additive is at least one member selected from the group consisting of titanium nitride, zirconium nitride and silicon carbide.
Claim 11
Dependent Claim
31 words
Semiconductive barium titanate according to claim 1, wherein said doping element is selected from the group consisting of lanthanum, cerium, samarium, antimony, bismuth and niobium, and said additive is silicon nitride.
Claim 12
Dependent Claim
39 words
Semiconductive barium titanate according to claim 1, wherein said doping element is selected from the group consisting of lanthanum, cerium and antimony, and said additive is selected from the group consisting of titanium nitride, zirconium nitride and silicon carbide.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-05-23 | 1986-11-22 | 1987-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-23 | 1990-11-22 | 1991-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-23 | 1994-11-22 | 1995-05-24 | $7700.00 | Window Closed / Lapsed |