US5288474A
Expired / Lapsed
US
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Process for the production of lead metal niobates
Assignee: H.C. Starck GmbH
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Filing: 1993-05-28
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Granted: 1994-02-22
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Expires: 2013-05-28
Abstract
Abstract Process for the production of phase-pure highly reactive lead metal niobates of perovskite structure corresponding to the general formula Pb 3 Me(II)Nb 2 O 9 or Pb 2 Me(III)NbO 6 , where Me═Mg, Fe, Co, Ni, Cr, Mn, Cd, Cu and/or Zn, in which perovskite intermediates are formed from corresponding salt solutions, separated off, dried and calcined at temperatures of 500 to 1000° C.
Inventors
- 👤 Karlheinz Reichert
- 👤 Harald Kroger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 15:47
CPC Classifications
C; C04; C04B; C04B35/00; C04B35/01; C04B35/16; C04B35/20; C04B35/495; C04B35/497; C01; C01G; C01G11/00; C01G11/006; C01G3/00; C01G3/006; C01G33/00; C01G33/006; C01G37/00; C01G37/006; C01G49/00; C01G49/009; C01P; C01P2002/00; C01P2002/30; C01P2002/34; C01P2006/00; C01P2006/80
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
111 words
A process for the production of phase-pure highly reactive lead metal niobates of perovskite structure corresponding to the general formula Pb 3 Me(II)Nb 2 O 9 or Pb 2 Me(III)NbO 6 , where Me═Mg, Fe, Co, Ni, Cr, Mn, Cd, Cu and/or Zn, in which a perovskite intermediate is obtained from a corresponding salt solution of Pb, Nb, and Me separated off, dried and calcined at temperatures of 500° to 1000° C., characterized in that said salt solution is in the form of citrates and is reacted with ammonia to effect formation of the perovskite intermediate, the phase-pure highly reactive lead metal niobates so produced having less than 5% pyrochlore content.
Claim 2
Dependent Claim
111 words
A process for the production of phase-pure highly reactive lead metal niobates of perovskite structure corresponding to the general formula Pb 3 Me(II)Nb 2 O 9 or Pb 2 Me(III)NbO 6 , where Me═Mg, Fe, Co, Ni, Cr, Mn, Cd, Cu and/or Zn, in which a perovskite intermediate is obtained from a corresponding salt solution of Pb, Nb, and Me separated off, dried and calcined at temperatures of 500° to 1000° C., characterized in that said salt solution is in the form of citrates and is reacted with ammonia to effect formation of the perovskite intermediate, the phase-pure highly reactive lead metal niobates so produced having less than 5% pyrochlore content.
Claim 3
Dependent Claim
28 words
A process as claimed in claim 1, wherein Nb is introduced into the citrate solution in the form of niobium hydroxide or niobic acid dissolved in citric acid.
Claim 4
Dependent Claim
22 words
A process as claimed in claim 2, wherein the calcination is carried out over a period of 30 minutes to 4 hours.
Claim 5
Dependent Claim
22 words
A process as claimed in claim 1, wherein the calcination is carried out over a period of 30 minutes to 4 hours.
Claim 6
Dependent Claim
19 words
A process as claimed in one of claims 1 to 4, characterized in that Me═Mg, Ni, Fe and/or Zn.
Claim 7
Dependent Claim
33 words
A process as claimed in one of claims 1 to 4, characterized in that the perovskite intermediate is obtained as a solid at a pH value in the range from 2 to 5.
Claim 8
Dependent Claim
35 words
A process as claimed in one of claims 1 to 4, characterized in that the perovskite intermediate is obtained as a gel by concentration of the reacted citrate solution at a pH value above 6.
Claim 9
Dependent Claim
31 words
A process as claimed in claim 7, characterized in that the gel is crystallized prior to calcination with the addition of one or more organic solvents selected from alcohols and ketones.
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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) | 1997-02-21 | 1997-08-23 | 1998-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-02-21 | 2001-08-23 | 2002-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-02-21 | 2005-08-23 | 2006-02-22 | $7700.00 | Window Closed / Lapsed |