US4832939A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Barium titanate based dielectric compositions
Assignee: Cabot Corp
•
Filing: 1988-02-01
•
Granted: 1989-05-23
•
Expires: 2008-02-01
Abstract
Abstract The present invention involves a method for producing a variety of barium titanate based powder products consisting of submicron, dispersible primary particles having narrow size distributions. The method, in its broadest aspects, involves heating an aqueous slurry of PbO, or Pb(OH) 2 , and Ca(OH) 2 with a stoichiometric excess of the hydrous oxides of Ti(IV), Sn(IV), Zr(IV) and Hf(IV) to a temperature not exceeding 200° C. Thereafter, the resulting slurry temperature is adjusted to between 50° and 200° C. and a solution of Ba(OH) 2 and Sr(OH) 2 , having a temperature of 70° to 100° C. is added within a period of five minutes or less to the slurry. About 10 minutes after the addition of the Ba(OH) 2 and Sr(OH) 2 solution is completed, the slurry is heated to a temperature not exceeding 225° C. to ensure formation of a stoichiometric perovskite product. Thereafter, the slurry is cooled and the solid product is recovered.
Inventors
- 👤 Jameel Menashi
- 👤 Robert C. Reid
- 👤 Laurence P. Wagner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:33
CPC Classifications
B; B82; B82Y; B82Y30/00; C; C01; C01G; C01G23/00; C01G23/003; C01G23/006; C04; C04B; C04B35/00; C04B35/01; C04B35/46; C04B35/462; C04B35/465; C04B35/468; C04B35/4682; C04B35/4684; C01P; C01P2002/00; C01P2002/30; C01P2002/34; C01P2004/00; C01P2004/01; C01P2004/04; C01P2004/20; C01P2004/30; C01P2004/32; C01P2004/51; C01P2004/52; C01P2004/60; C01P2004/62; C01P2004/64; C01P2006/00; C01P2006/12; C01P2006/22; Y; Y10; Y10S; Y10S502/00; Y10S502/525
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
233 words
A method for producing submicron, dispersible perovskite based products having substantially the formula: Ba.sub.(1-x-x'-x") Pb.sub.x Ca.sub.x' Sr.sub.x" Ti.sub.(1-y-y'-y") Sn.sub.y Zr.sub.y' Hf.sub.y" O.sub.3 where the mole fractions x, x', x", y, y', and y" each have independent values ranging from 0 to 0.3, and the sum of either (x+x'+x") or (y+y'+y") does not exceed 0.4, comprising: (a) Heating an agitated aqueous slurry containing x moles of PbO or Pb(OH) 2 , x' moles of CaO or Ca(OH) 2 , (1-y-y'-y") moles of hydrous TiO 2 , y moles of hydrous SnO 2 , y' moles of hydrous ZrO 2 and y" moles of hydrous HfO 2 to a temperature in the range of from about 100° to 200° C., (b) Adjusting the temperature of the aqueous agitated slurry to a temperature in the range between 50° and 200° C., (c) Adding to the agitated slurry of solution, having a temperature between 70° and 110° C., containing x" moles of Sr(OH) 2 and up to a 20% excess of the stoichiometric requirement, (1-x-x'-x"), of Ba(OH) 2 over a period from about 0.1 to about 5 minutes, (d) Holding the agitated slurry at the temperature used in step (b) for a period of 10 to 30 minutes, (e) Heating the agitated slurry to a temperature not exceeding 225° C. to ensure formation of a stoichiometric perovskite product, (f) Cooling the slurry and separating the perovskite product.
Claim 2
Independent Claim
233 words
A method for producing submicron, dispersible perovskite based products having substantially the formula: Ba.sub.(1-x-x'-x") Pb.sub.x Ca.sub.x' Sr.sub.x" Ti.sub.(1-y-y'-y") Sn.sub.y Zr.sub.y' Hf.sub.y" O.sub.3 where the mole fractions x, x', x", y, y', and y" each have independent values ranging from 0 to 0.3, and the sum of either (x+x'+x") or (y+y'+y") does not exceed 0.4, comprising: (a) Heating an agitated aqueous slurry containing x moles of PbO or Pb(OH) 2 , x' moles of CaO or Ca(OH) 2 , (1-y-y'-y") moles of hydrous TiO 2 , y moles of hydrous SnO 2 , y' moles of hydrous ZrO 2 and y" moles of hydrous HfO 2 to a temperature in the range of from about 100° to 200° C., (b) Adjusting the temperature of the aqueous agitated slurry to a temperature in the range between 50° and 200° C., (c) Adding to the agitated slurry of solution, having a temperature between 70° and 110° C., containing x" moles of Sr(OH) 2 and up to a 20% excess of the stoichiometric requirement, (1-x-x'-x"), of Ba(OH) 2 over a period from about 0.1 to about 5 minutes, (d) Holding the agitated slurry at the temperature used in step (b) for a period of 10 to 30 minutes, (e) Heating the agitated slurry to a temperature not exceeding 225° C. to ensure formation of a stoichiometric perovskite product, (f) Cooling the slurry and separating the perovskite product.
Claim 3
Dependent Claim
46 words
A method as defined in claim 1 wherein at least one dopant is added in step (a) in an amount such that the molar ratio of dopant to the sum of TiO 2 , SnO 2 , ZrO 2 and HfO 2 is less than 0.05.
Claim 4
Dependent Claim
27 words
A method as defined in claim 2 wherein the dopant is selected from the group consisting of Nb, La, Y, Ni, Mn, Fe, Co and mixtures thereof.
Claim 5
Dependent Claim
23 words
A method as defined in claim 2 wherein the dopant is selected from the group consisting of Mb, Co, Mn and mixtures thereof.
Claim 6
Dependent Claim
33 words
A method as defined in claim 1 or 2 wherein the sum of the moles of the tetravalent hydrous oxides per liter in the slurry in step (a) ranges from 0.14 to 0.7.
Claim 7
Dependent Claim
27 words
A method as defined in claim 1 or 2 wherein the separated solid perovskite product in step (f) is washed with 0.005 to 0.02M Ba(OH) 2 solution.
Claim 8
Dependent Claim
28 words
A method as defined in claim 1 wherein the hydrous TiO 2 , SnO 2 , ZrO 2 , and HfO 2 used in step (a) are coprecipitated.
Claim 9
Dependent Claim
32 words
A method as defined in claim 2 wherein the hydrous TiO 2 , SnO 2 , ZrO 2 , HfO 2 and the dopant or dopants used in step (a) are coprecipitated.
Claim 10
Dependent Claim
27 words
A method as defined in claim 1 or 2 wherein the temperature of the agitated slurry in step (b) is adjusted to between 60° and 150° C.
Claim 11
Dependent Claim
23 words
A process of claim 2 wherein the dopant is added in step (a) as aqueous solutions of nitrates, formates, acetates, and/or mixtures thereof.
References Cited (Backward Citations)
US2218655A
Cited
GB715762A
Cited
US2841503A
Cited
US3490927A
Cited
US4293534A
Cited
US4520004A
Cited
EP0141551A1
Cited
US4636378A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-05-22 | 1992-11-21 | 1993-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-22 | 1996-11-21 | 1997-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-22 | 2000-11-21 | 2001-05-23 | $7700.00 | Window Closed / Lapsed |