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Process for preparing fine powder of perovskite-type compound

Assignee: Tayca Corp
•
Filing: 1992-03-04
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Granted: 1995-08-29
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Expires: 2012-03-04
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Abstract

Abstract A process for preparing a fine powder of perovskite-type compounds having an average particle size of at most 0.3 mu m and uniform particle sizes, which comprises subjecting to a reaction an aqueous solution of a mixture of at least one compound selected from group A element compounds comprising alkaline earth metal elements and/or bivalent metal elements with at least one compound selected from group B element compounds comprising tetravalent metal elements such as Ti, Zr, Hf and Sn and/or composite metal elements composed of a bivalent or trivalent metal element such as Zn, Ni, Co, Mg, Fe or Sb and a pentavalent metal element such as Nb or Sb in an A/B atomic ratio of more than 1, calcining the resulting powdery reaction product at a temperature which is lower than the temperature at which the growth of particles takes place and which is higher than the temperature at which the growth of particles takes place when A/B is 1, and cleaning the calcined product with an acid solution to remove the excess group A elements. The process provides fine powders of perovskite-type compounds having a good crystallinity, particularly tetragonal barium titanate, which are useful particularly as raw materials of ceramics for electronic devices.

Inventors

  • 👤 Masanori Kinugasa
  • 👤 Naoto Tsubomoto
  • 👤 Osamu Kobayashi

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-09 04:44
CPC Classifications
C; C01; C01G; C01G33/00; C01B; C01B13/00; C01B13/14; C01B13/36; C01B13/363; C01G23/00; C01G23/003; C01G23/006; C01G25/00; C01G25/006; C01G30/00; C01G30/02; C01G30/026; C01G49/00; C01G49/009; C01P; C01P2002/00; C01P2002/30; C01P2002/34; C01P2002/70; C01P2002/72; C01P2002/77; C01P2004/00; C01P2004/01; C01P2004/03; C01P2004/51; C01P2004/52; C01P2004/60; C01P2004/62; C01P2006/00; C01P2006/32; C01P2006/80

Claims Analysis

Total Claims: 13
Claim 1
Independent Claim 86 words
A process for preparing a fine powder of tetragonal crystalline barium titanate having an average particle size of at most 0.3 μm, which comprises reacting an aqueous solution of a mixture of a compound containing Ba and a compound containing Ti in a Ba/Ti atomic ratio of 1.02-1.40, obtaining a powdery reaction product of barium titanate, calcining the powder reaction product having a Ba/Ti atomic ration of 1.02-1.40 at a temperature of 1,000° to 1,100° C., and removing excess Ba element from a resulting calcined product.
Claim 2
Dependent Claim 86 words
A process for preparing a fine powder of tetragonal crystalline barium titanate having an average particle size of at most 0.3 μm, which comprises reacting an aqueous solution of a mixture of a compound containing Ba and a compound containing Ti in a Ba/Ti atomic ratio of 1.02-1.40, obtaining a powdery reaction product of barium titanate, calcining the powder reaction product having a Ba/Ti atomic ration of 1.02-1.40 at a temperature of 1,000° to 1,100° C., and removing excess Ba element from a resulting calcined product.
Claim 3
Dependent Claim 23 words
The process of claim 1, wherein the Ba compound is an hydroxide or oxide, and the Ti compound is an hydroxide or oxide.
Claim 4
Dependent Claim 22 words
The process of claim 1, wherein the Ba compound tis an hydroxide or oxide, and the Ti compound is an organometallic compound.
Claim 5
Dependent Claim 22 words
The process of claim 1, wherein the Ba compound is an organometallic compound, and the Ti compound is an hydroxide or oxide.
Claim 6
Dependent Claim 21 words
The process of claim 1, wherein the Ba compound is an organometallic compound, and the Ti compound is an organometallic compound.
Claim 7
Dependent Claim 20 words
The process of claim 1, wherein the Ba compound is barium hydroxide and the Ti compound is hydrated titanium oxide.
Claim 8
Dependent Claim 34 words
The process of claim 1, wherein the Ba compound is barium hydroxide, the Ti compound is hydrated titanium oxide, and the tetragonal barium titanate has an average particle size of 0.05 to 0.3 μm.
Claim 9
Dependent Claim 20 words
The process of claim 7, wherein the Ba/Ti atomic ratio of the powdery reaction product is from 1.02 to 1.04.
Claim 10
Dependent Claim 29 words
The process of claim 7, wherein a c/a ratio of said tetragonal barium titanate calculated from (002) and (200) peaks by X-ray diffraction pattern is not less than 1.009.
Claim 11
Dependent Claim 20 words
The process of claim 1, wherein the calcining converts the resulting powdery reaction product into a tetragonal system crystalline structure.
Claim 12
Dependent Claim 19 words
The process of claim 1, wherein the calcined product has an average particle size of at most 0.3 μm.
Claim 13
Dependent Claim 19 words
The process of claim 1, wherein tetragonal barium titanate has an average particle size of 0.05 to 0.3 μm.

References Cited (Backward Citations)

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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) 1998-08-28 1999-02-27 1999-08-29 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2002-08-28 2003-02-27 2003-08-29 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2006-08-28 2007-02-27 2007-08-29 $7700.00 Window Closed / Lapsed

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