Method of preparing ceramic powders

• US 8,853,116 B2
• Filed: 05/10/2010
• Issued: 10/07/2014
• Est. Priority Date: 08/02/2006
• Status: Active Grant

• Current Assignee: Eestor Inc. (FuelPositive Corp.)
• Original Assignee: Eestor Inc. (FuelPositive Corp.)
• Inventors: Weir, Richard D., Nelson, Carl W.
• Primary Examiner(s): Li, Jun
• Application Number:
  US12/777,251
• Publication Number:
  US 20100285947A1
• Time in Patent Office: 1,611 Days
• Field of Search: 501/134, 501/135, 501/136, 501/137, 501/138, 423/352, 423/592.1, 423/594.16, 423/598, 423/599, 423/608, 423/356, 423/71
• US Class Current: 501/138
• CPC Class Codes: C01B 13/185 Preparing mixtures of oxides
• CPC Class Codes: C01B 13/363 Mixtures of oxides or hydroxides by precipitation
• CPC Class Codes: C01G 1/02 Oxides
• CPC Class Codes: C01G 23/003 Titanates C01G23/001 takes precedence
• CPC Class Codes: C01G 23/006 Alkaline earth titanates
• CPC Class Codes: C01P 2002/34 perovskite-type (ABO3)
• CPC Class Codes: C01P 2002/72 by d-values or two theta-values, e.g. as X-ray diagram
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/51 Particles with a specific particle size distribution
• CPC Class Codes: C01P 2004/53 bimodal size distribution
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C01P 2006/80 Compositional purity
• CPC Class Codes: C01P 2006/90 Other properties not specified above
• CPC Class Codes: C04B 2235/3208 Calcium oxide or oxide-forming salts thereof, e.g. lime
• CPC Class Codes: C04B 2235/3215 Barium oxides or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3224 Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
• CPC Class Codes: C04B 2235/3225 Yttrium oxide or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3244 Zirconium oxides, zirconates, hafnium oxides, hafnates, or oxide-forming salts thereof
• CPC Class Codes: C04B 2235/3262 : Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
• CPC Class Codes: C04B 2235/441 : Alkoxides, e.g. methoxide, tert-butoxide
• CPC Class Codes: C04B 2235/449 : Organic acids, e.g. EDTA, citrate, acetate, oxalate
• CPC Class Codes: C04B 2235/5436 : micrometer sized, i.e. from 1 to 100 micron
• CPC Class Codes: C04B 2235/5445 : submicron sized, i.e. from 0,1 to 1 micron
• CPC Class Codes: C04B 2235/5472 : Bimodal, multi-modal or multi-fraction
• CPC Class Codes: C04B 2235/5481 : Monomodal
• CPC Class Codes: C04B 2235/762 : Cubic symmetry, e.g. beta-SiC
• CPC Class Codes: C04B 35/4682 : based on BaTiO3 perovskite phase
• CPC Class Codes: C04B 35/49 : containing also titanium oxides or titanates
• CPC Class Codes: C04B 35/62655 : Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• CPC Class Codes: C04B 40/0082 : making use of a rise in temperature, e.g. caused by an exothermic reaction

Abstract

A method of forming composition-modified barium titanate ceramic particulate includes mixing a plurality of precursor materials and a precipitant solution to form an aqueous suspension. The plurality of precursors include barium nitrate, titanium chelate, and a metal or oxometal chelate. The precipitant solution includes tetraalkylammonium hydroxide and tetraalkylammonium oxalate. The method further includes treating the aqueous suspension at a temperature of at least 150° C. and a pressure of at least 200 psi, and separating particulate from the aqueous suspension after treating.

Claims

1. A method for preparing a ceramic powder, the method comprising:

providing a plurality of precursor materials in solution comprises a barium source, a titanium source, and a first metal-containing source, and a second metal-containing source, and a third metal-containing source, wherein the titanium source, the first metal-containing source, the second metal-containing source, the third metal-containing source, or any combination thereof comprises a metal ion or oxometal ion and a chelate;

combining the plurality of precursor materials in solution with a precipitant solution including an oxalate compound and tetraalkylammonium hydroxide to cause co-precipitation of hydrated hydroxide-oxalate precipitates in a combined solution, wherein the hydrated hydroxide-oxalate precipitates are partly crystalline;

hydrothermally treating the hydrated hydroxide-oxalate precipitates to form a full-crystalline or near full-crystalline powder precipitate;

separating the powder precipitate from the combined solution; and

calcining the separated powder precipitate to form the ceramic powder including a cubic perovskite composition modified barium titanate having a relative permittivity of at least 18,000.

2. The method of claim 1, wherein the oxalate compound includes ammonium oxalate.

3. The method of claim 1, wherein the first, second, and third metal-containing sources comprise any combination of three selected from the group consisting of a calcium source, a neodymium source, a zirconium source, a manganese source, and a yttrium source.

4. The method of claim 3, wherein:

the barium source includes a barium nitrate;

the titanium source includes a titanium chelate;

the calcium source is a calcium nitrate;

the neodymium source is a neodymium chelate;

the zirconium source is a zirconium chelate;

the manganese source is a manganese chelate; and

the yttrium source is a yttrium chelate.

5. The method of claim 1, wherein the titanium source or the first, second, or third metal-containing source includes a metal ion or oxometal ion selected from the group consisting of Nd, Zr, Mn, La, Y, Pr, Sm, Gd, Dy, Er, Ho, Yb, Ga, Ag, Dy, Nb, Ca, Sn, Ti, and Mo.

6. The method of claim 5, wherein the barium Ba(NO₃)₂, and the calcium source includes Ca(NO₃)₂.4H₂O.

7. The method of claim 1, wherein:

the titanium source or the first, second, or third metal-containing source includes a chelate of a metal ion or oxometal ion; and

the chelate corresponds to a chelating agent that includes an alpha-hydroxycarboxylic acid.

8. The method of claim 7, wherein the alpha-hydroxycarboxylic acid is selected from the group consisting of 2-hydroxypropanoic acid, 2-hydroxyethanoic acid, 2-hydroxybutanedioic acid, 2,3-dihydroxybutanedioic acid, 2-hydroxy-1,2,3-propanetricarboxylic acid, 2-hydroxybutanoic acid, 2-hydroxypentanoic acid, and 2-hydroxyhexanoic acid.

9. The method of claim 1, wherein the combining further comprises:

mixing the plurality of precursor materials in solution and the precipitant solution in a fluid jet column.

10. The method of claim 9, further comprising:

introducing the plurality of precursor materials in solution in a first stream; and

introducing the precipitant solution in a second stream.

11. The method of claim 1, wherein the oxalate compound includes tetraalkylammonium oxalate.

12. The method of claim 11, wherein the oxalate compound includes tetramethylammonium oxalate.

13. The method of claim 1, wherein the ceramic powder is substantially free of lead.

14. The method of claim 1, wherein the ceramic powder consists essentially of the precipitated powder after calcining.

15. A method for preparing a ceramic powder, the method comprising:

providing a plurality of precursor materials in solution comprising a barium nitrate, a calcium nitrate, a titanium chelate, a neodymium chelate, a zirconium chelate, a manganese chelate, and a yttrium chelate;

combining the plurality of precursor materials in solution with a precipitant solution including an oxalate compound and tetraalkylammonium hydroxide to cause co-precipitation of hydrated hydroxide-oxalate precipitates in a combined solution, wherein the hydrated hydroxide-oxalate precipitates are partly crystalline;

hydrothermally treating the hydrated hydroxide-oxalate precipitates to form a full-crystalline or near full-crystalline the powder precipitate;

separating the powder precipitate from the combined solution; and

calcining the separated powder precipitate to form the ceramic powder including a cubic perovskite composition-modified barium titanate having a relative permittivity of at least 18,000, wherein the cubic perovskite composition-modified barium titanate comprises calcium, neodymium, zirconium, manganese, and yttrium.

16. The method of claim 15, wherein:

the barium nitrate includes Ba(NO₃)₂;

the calcium nitrate includes Ca(NO₂)₂.4H₂O; and

each of the titanium, neodymium, zirconium, manganese, and yttrium chelates comprises a metal ion or a oxymetal ion and a chelate corresponding to a chelating agent that is an alpha-hydroxycarboxylic acid.

17. The method of claim 15, wherein the oxalate compound includes ammonium oxalate.

18. The method of claim 15, wherein the oxalate compound includes tetraalkylammonium oxalate.

19. The method of claim 18, wherein the oxalate compound includes tetramethylammonium oxalate.

20. The method of claim 15, wherein the ceramic powder is substantially free of lead.

21. The method of claim 15, wherein the ceramic powder consists essentially of the precipitated powder after calcining.