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US4477401A
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Method of manufacturing a dielectric
Assignee: US Philips Corp
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Filing: 1982-09-02
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Granted: 1984-10-16
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Expires: 2002-09-02
Abstract
Abstract A method of manufacturing a dielectric from ferroelectric ceramic material having a perovskite structure with the basic formula ABO 3 . In the method, the dielectric is sintered in a reducing atmosphere and the sintered body is aftertreated at a temperature in the range of from 500° to 900° C. in an N 2 --O 2 atmosphere. The atmosphere contains a quantity of O 2 corresponding to a partial O 2 -pressure between 10 -5 bar and 0.2 bar.
Inventors
- 👤 Hans J. Hagemann
- 👤 Siegfried Hunten
- 👤 Rolf Wernicke
- 👤 Cornelius J. Klomp
- 👤 Willem Noorlander
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:07
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/46; C04B35/462; C04B35/465; C04B35/468; C04B35/4682; C04B35/48; C04B35/49; C04B35/622; C04B35/64; H; H01; H01G; H01G4/00; H01G4/002; H01G4/018; H01G4/06; H01G4/08; H01G4/12
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
167 words
A method of manufacturing ceramic capacitors comprising the steps of: providing an unsintered capacitor body comprising a ferroelectric material having a perovskite structure and having the general formula ABO 3 ; providing an electrode paste on the capacitor body to form a composite body, said paste comprising a base or oxide of a base metal selected from the group consisting of Ni, Cr or alloys thereof; sintering the composite body in a reducing atmosphere at a temperature in the range of from 1320° to 1450° C. to form a sintered body having a metal electrode thereon; cooling the sintered body; and then aftertreating the sintered body by heating it at a temperature of from 500° to 900° C. for a period of time of from 0.5 to 4 hours in a nitrogen-oxygen atmosphere having a partial oxygen pressure of from 10 -5 bar to 0.2 bar, wherein the temperature, duration, and partial oxygen pressure are chosen such that there is substantially no oxidation of the metal electrode.
Claim 2
Independent Claim
167 words
A method of manufacturing ceramic capacitors comprising the steps of: providing an unsintered capacitor body comprising a ferroelectric material having a perovskite structure and having the general formula ABO 3 ; providing an electrode paste on the capacitor body to form a composite body, said paste comprising a base or oxide of a base metal selected from the group consisting of Ni, Cr or alloys thereof; sintering the composite body in a reducing atmosphere at a temperature in the range of from 1320° to 1450° C. to form a sintered body having a metal electrode thereon; cooling the sintered body; and then aftertreating the sintered body by heating it at a temperature of from 500° to 900° C. for a period of time of from 0.5 to 4 hours in a nitrogen-oxygen atmosphere having a partial oxygen pressure of from 10 -5 bar to 0.2 bar, wherein the temperature, duration, and partial oxygen pressure are chosen such that there is substantially no oxidation of the metal electrode.
Claim 3
Dependent Claim
44 words
A method as claimed in claim 1, wherein the aftertreatment is at a temperature of from 700° to 800° C. for a period of time of from 1 to 4 hours in a nitrogen-oxygen atmosphere having a partial oxygen pressure of 2×10 -4 bar.
Claim 4
Dependent Claim
29 words
A method as claimed in claim 2, wherein the ferroelectric material has a composition given by the formula (Ba.sub.x Ca.sub.1-x)(Ti.sub.y-z-a Zr.sub.1-y Cr.sub.z)O.sub.3-b, where 0.80≦x≦0.92 0.80≦y≦0.88 0.003≦z≦0.010 0.00≦a≦0.04, and 0.00≦b≦z/2
Claim 5
Dependent Claim
13 words
A method as claimed in claim 3, wherein x≈0.86, 0.82≦y≦0.84, 0.03≦z≦0.010, a≈0.025, 0≦b≦z/2.
Claim 6
Dependent Claim
54 words
A method as claimed in claim 4, wherein the unsintered capacitor body is formed by the steps of: providing a starting material comprising a mixture of carbonates or oxides of barium, calcium, titanium, zirconium, and chromium; and calcining the mixture in air for 15 hours at a temperature of from 1150° to 1250° C.
Claim 7
Dependent Claim
18 words
A method as claimed in claim 5, wherein the calcining step is at a temperature of 1200° C.
Claim 8
Dependent Claim
32 words
A method as claimed in claim 6, wherein the unsintered capacitor body is formed by adding from 0.2 to 2.0 mole% of Ba 2 TiSi 2 O 8 to the calcined mixture.
Claim 9
Dependent Claim
31 words
A method as claimed in claim 7, wherein the unsintered capacitor body is formed by adding from 0.5 to 1.0 mole% Ba 2 TiSi 2 O 8 to the calcined mixture.
Claim 10
Dependent Claim
19 words
A method as claimed in claim 8, wherein the electrode paste comprises NiO or CoO and an organic binder.
Claim 11
Dependent Claim
29 words
A method as claimed in claim 9, wherein the composite body is sintered in a nitrogen-hydrogen atmosphere consisting of 75 to 98 volume percent nitrogen with the remainder hydrogen.
References Cited (Backward Citations)
US3920781A
Cited
US4131444A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-10-16 | 1988-04-16 | 1988-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-10-16 | 1992-04-16 | 1992-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-10-16 | 1996-04-16 | 1996-10-16 | $7700.00 | Window Closed / Lapsed |