US4347167A
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Fine-grain semiconducting ceramic compositions
Assignee: University of Illinois Foundation
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Filing: 1980-10-01
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Granted: 1982-08-31
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Expires: 2000-10-01
Abstract
Abstract A semiconducting internal boundary layer ceramic composition having a fine grain structure suitable for use in thin-layer multilayer capacitors is made in one step by firing a mixture comprising a major amount of finely divided strontium titanate, a minor amount of a compound containing either strontium or titanium, or an element functionally equivalent thereto, a minor amount of a semiconductor forming ingredient (dopant), the identity of which depends on whether the mixture is rich in strontium or in titanium, and a minor amount of a counterdopant selected from cuprous oxide or silver oxide. When the mixture is rich in titanium, the chemical doping agent used to produce semiconductivity is an oxide of a trivalent metal selected from bismuth, boron, iron, antimony, lanthanum and the rare earth and transition metals. When the mixture is rich in strontium, the dopant is an oxide of a pentavalent or hexavalent metal selected from tungsten (+6), niobium (+5), tantalum (+5), and molybdenum (+6).
Inventors
- 👤 David A. Payne
- 👤 Sang M. Park
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 07:15
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/46; C04B35/462; C04B35/465; C04B35/47; H; H01; H01G; H01G4/00; H01G4/002; H01G4/018; H01G4/06; H01G4/08; H01G4/12; H01G4/1272; H01G4/1281
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
182 words
A method for producing a fine-grain semiconducting internal boundary layer ceramic composition comprising the steps of: A. forming a mixture comprising: (a) about 89-99.3% by weight of finely divided strontium titanate; (b) a combination of metal oxides selected from (1) about 0.1-5% of an oxide of a tetravalent metal selected from the group consisting of Ti, Zr, Ge, Si and Sn, and about 0.5-5.0% of an oxide of a trivalent metal selected from the group consisting of Bi, B, Fe, Sb, La and the rare earth and transition metals; and (2) about 0.1-5% of an oxide of a divalent metal selected from the group consisting of Sr, Ca, Ba and Pb and about 0.5%-5% of an oxide of a pentavalent or hexavalent metal selected from the group consisting of W +6 , Nb +5 , Ta +5 and Mo +6 , and (c) about 0.1-1.0% of an oxide of a univalent metal selected from the group consisting of Cu and Ag; and B. pressing and firing the mixture of step A at a temperature of about 1200°-1400° C. for about 10-300 minutes.
Claim 2
Independent Claim
182 words
A method for producing a fine-grain semiconducting internal boundary layer ceramic composition comprising the steps of: A. forming a mixture comprising: (a) about 89-99.3% by weight of finely divided strontium titanate; (b) a combination of metal oxides selected from (1) about 0.1-5% of an oxide of a tetravalent metal selected from the group consisting of Ti, Zr, Ge, Si and Sn, and about 0.5-5.0% of an oxide of a trivalent metal selected from the group consisting of Bi, B, Fe, Sb, La and the rare earth and transition metals; and (2) about 0.1-5% of an oxide of a divalent metal selected from the group consisting of Sr, Ca, Ba and Pb and about 0.5%-5% of an oxide of a pentavalent or hexavalent metal selected from the group consisting of W +6 , Nb +5 , Ta +5 and Mo +6 , and (c) about 0.1-1.0% of an oxide of a univalent metal selected from the group consisting of Cu and Ag; and B. pressing and firing the mixture of step A at a temperature of about 1200°-1400° C. for about 10-300 minutes.
Claim 3
Dependent Claim
38 words
The method of claim 1, wherein said mixture comprises about 97-98.5% by weight of strontium titanate, about 1.0-3.0% of said tetravalent metal oxide, about 0.7-3.0% of said trivalent metal oxide, and about 0.15-0.3% of said univalent metal oxide.
Claim 4
Dependent Claim
40 words
The method of claim 1, wherein said mixture comprises about 93.7-98.15% by weight of strontium titanate, about 1.0-3.0% of said divalent metal oxide, about 0.7-3.0% of said pentavalent or hexavalent metal oxide, and about 0.15-0.3% of said univalent metal oxide.
Claim 5
Dependent Claim
22 words
The method of claim 1 wherein said tetravalent metal is titanium, said trivalent metal is bismuth, and said univalent metal is copper.
Claim 6
Dependent Claim
14 words
A fine-grain semiconducting ceramic composition produced in accordance with the method of claim 1.
Claim 7
Dependent Claim
14 words
A fine-grain semiconducting ceramic coposition produced in accordance with the method of claim 2.
Claim 8
Dependent Claim
14 words
A fine-grain semiconducting ceramic composition produced in accordance with the method of claim 3.
Claim 9
Dependent Claim
11 words
A fine grain semiconducting composition produced in accordance with claim 4.
Claim 10
Dependent Claim
92 words
A fine-grain semiconducting boundary layer ceramic composition comprising about 89-99.3% by weight of polycrystalline strontium titanate having a grain size less than about 10 microns, about 0.1-5% of an oxide of a tetravalent metal selected from the group consisting of Ti, Zr, Ge, Si and Sn, about 0.5-5.0% of an oxide of a trivalent metal selected from the group consisting of Bi, B, Fe, Sb, La and the rare earth and transition metals, and about 0.1-1.0% of an oxide of a univalent metal selected from the group consisting of Cu and Ag.
Claim 11
Dependent Claim
92 words
A fine-grain semiconducting boundary layer ceramic composition comprising about 89-99.3% by weight of polycrystalline strontium titanate having a grain size less than about 10 microns, about 0.1-5% of an oxide of a tetravalent metal selected from the group consisting of Ti, Zr, Ge, Si and Sn, about 0.5-5.0% of an oxide of a trivalent metal selected from the group consisting of Bi, B, Fe, Sb, La and the rare earth and transition metals, and about 0.1-1.0% of an oxide of a univalent metal selected from the group consisting of Cu and Ag.
Claim 12
Dependent Claim
35 words
A composition in accordance with claim 9 comprising about 93.7-98.15% of strontium titanate, about 1.0-3.0% of said tetravalent metal oxide, about 0.7-3.0% of said trivalent metal oxide, and about 0.15-0.3% of said univalent metal oxide.
Claim 13
Dependent Claim
24 words
A composition in accordance with claim 10 wherein said tetravalent metal is titanium, said trivalent metal is bismuth, and said univalent metal is copper.
Claim 14
Dependent Claim
35 words
A composition in accordance with claim 11 comprising about 97.8% by weight of strontium titanate, about 1.0% of TiO 2 , about 1% of Bi 2 O 3 and about 0.2% of Cu 2 O.
Claim 15
Dependent Claim
94 words
A fine-grain semiconducting boundary layer ceramic composition comprising about 89-99.3% by weight of polycrystalline strontium titanate having a grain size less than about 10 microns, about 0.1-5% of an oxide of a divalent metal selected from the group consisting of Sr, Ca, Ba and Pb, about 0.5-5.0% of an oxide of a pentavalent or hexavalent metal selected from the group consisting of W +6 , Nb +5 , Ta +5 , and Mo +6 , and about 0.1-1.0% of an oxide of a univalent metal selected from the group consisting of Cu and Ag.
Claim 16
Dependent Claim
94 words
A fine-grain semiconducting boundary layer ceramic composition comprising about 89-99.3% by weight of polycrystalline strontium titanate having a grain size less than about 10 microns, about 0.1-5% of an oxide of a divalent metal selected from the group consisting of Sr, Ca, Ba and Pb, about 0.5-5.0% of an oxide of a pentavalent or hexavalent metal selected from the group consisting of W +6 , Nb +5 , Ta +5 , and Mo +6 , and about 0.1-1.0% of an oxide of a univalent metal selected from the group consisting of Cu and Ag.
Claim 17
Dependent Claim
37 words
A composition in accordance with claim 13 containing about 93.7-98.15% of strontium titanate, about 1.0-3.0% of said divalent metal oxide, about 0.7-3.0% of said pentavalent or hexavalent metal oxide, and about 0.15-0.3% of said univalent metal oxide.
Claim 18
Dependent Claim
29 words
A composition in accordance with claim 14 wherein said tetravalent metal is titanium, said divalent metal is strontium, said hexavalent metal is tungsten, and said univalent metal is copper.
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) | 1985-08-30 | 1986-03-01 | 1986-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-08-30 | 1990-03-01 | 1990-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-08-30 | 1994-03-01 | 1994-08-31 | $7700.00 | Window Closed / Lapsed |