US4898844A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for manufacturing a ceramic body having multiple barium-titanate phases
Assignee: MRA Laboratories Inc
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Filing: 1986-07-14
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Granted: 1990-02-06
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Expires: 2006-07-14
Abstract
Abstract A ceramic includes a dielectric ceramic body that is made by mixing powders of two barium titanate compositions of widely disparate Curie temperature with a minor quantity of a borate flux and a sintering-inhibitor such as titania or bismuth oxide. A body is formed of this start powders mixture. Upon sintering to maturity at about 1100° C., the capacitor body becomes only partially co-reacted and has a dielectric constant around 2000 that varies no more than about 15% over a board operating temperature range. These properties are not a strong function of sintering conditions leading to good control at manufacturing.
Inventors
- 👤 Galeb H. Maher
- 👤 Susan E. Stefanik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 16:47
CPC Classifications
H; H01; H01G; H01G4/00; H01G4/002; H01G4/258; C; C04; C04B; C04B35/00; C04B35/01; C04B35/46; C04B35/462; C04B35/465; C04B35/468; C04B35/4682; H01G4/018; H01G4/06; H01G4/08; H01G4/12; H01G4/1209; H01G4/1218; H01G4/1227
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
114 words
A method for making a dielectric ceramic body comprising: (a) forming a start mixture by mixing a first barium titanate powder A having a Curie temperature greater than 120° C., a second barium titanate powder B having a Curie temperature less than 0° C., from 1 to 4 weight percent of a glass borate powder C and greater than zero but less than 21/2 weight percent of a powdered sintering-inhibitor agent D, said barium titanate A being present in a quantity by weight percent that is about twice that of said barium titanate B; (b) forming a body of said start mixture; and (c) sintering said body to produce a dense dielectric ceramic body.
Claim 2
Independent Claim
114 words
A method for making a dielectric ceramic body comprising: (a) forming a start mixture by mixing a first barium titanate powder A having a Curie temperature greater than 120° C., a second barium titanate powder B having a Curie temperature less than 0° C., from 1 to 4 weight percent of a glass borate powder C and greater than zero but less than 21/2 weight percent of a powdered sintering-inhibitor agent D, said barium titanate A being present in a quantity by weight percent that is about twice that of said barium titanate B; (b) forming a body of said start mixture; and (c) sintering said body to produce a dense dielectric ceramic body.
Claim 3
Dependent Claim
28 words
The method of claim 1 wherein said sintering inhibitor agent D is a powdered oxide or oxide-equivalent selected from the group consisting of titanium, bismuth and combinations thereof.
Claim 4
Dependent Claim
31 words
The method of claim 1 wherein said sintering inhibitor agent D is a powdered oxide or oxide-equivalent selected from the group consisting of zirconium, hafnium, antimony, titanium, bismuth and combinations thereof.
Claim 5
Dependent Claim
24 words
The method of claim 1 wherein said barium titanate powder A consists of pure barium titanate and has a Curie temperature at 125° C.
Claim 6
Dependent Claim
24 words
The method of claim 1 wherein said barium titanate powder A is doped with lead and has a Curie temperature greater than 125° C.
Claim 7
Dependent Claim
25 words
The method of claim 1 wherein said barium titanate powder B is doped with a cation selected from the group consisting of niobium and lanthanum.
Claim 8
Dependent Claim
37 words
The method of claim 1 wherein said barium titanate powder B is doped with a cation selected from the group consisting of niobium, tantalum, bismuth, antimony, arsenic, one of the lanthanum-series rare earth elements, and combinations thereof.
Claim 9
Dependent Claim
23 words
The method of claim 1 wherein said sintering is accomplished at a peak holding temperature within the range 1000° C. to 1150° C.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-02-05 | 1993-08-07 | 1994-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-05 | 1997-08-07 | 1998-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-05 | 2001-08-07 | 2002-02-06 | $7700.00 | Window Closed / Lapsed |