Method of preparing ceramic powders

• US 10,239,792 B2
• Filed: 09/02/2014
• Issued: 03/26/2019
• 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:
  US14/475,091
• Publication Number:
  US 20160023954A1
• Time in Patent Office: 1,666 Days
• 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:

injecting a first solution stream into a reactor the first solution stream comprising a first precursor material including a barium source, a second precursor including a titanium source, and a third precursor comprising a metal ion or oxometal ion and a chelating agent, the chelating agent being an alpha-hydroxycarboxylic acid;

concurrently with injecting the first solution stream into the reactor, injecting a second solution stream into the reactor, the second solution stream comprising 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 partially crystalline, wherein injecting the first solution stream and the second solution stream into the reactor is performed at a turbulence factor of at least 1.5×

10⁷ cm/s³, wherein a residence time within the reactor is at least 50 milliseconds;

hydrothermally treating the hydrated hydroxide-oxalate precipitates of the combined solution in an aqueous suspension by heating the aqueous suspension at a temperature of at least 150°

C. at a treatment pressure of at least 200 psi; and

after hydrothermally treating, decomposing and calcining to form the ceramic powder including composition-modified barium titanate particles.

2. The method of claim 1, wherein after decomposing and calcining, excluding particles having a size of less than 0.1 micrometers and excluding particles having a size greater than 10 micrometers, the composition-modified barium titanate particles have an average particle size in a range of 0.6 micrometers to 1.5 micrometers.

3. The method of claim 1, wherein heating the aqueous suspension solution is performed for a time period of 4 hours to 8 hours.

4. The method of claim 1, wherein hydrothermally treating the hydrated hydroxide-oxalate precipitates of the combined solution includes adding the aqueous suspension at a temperature of not greater than 100°

C. to a hydrothermal treatment vessel while heating the hydrothermal treatment vessel and while releasing steam from the hydrothermal treatment vessel.

5. The method of claim 1, wherein after decomposing and calcining, the ceramic powder is free of ball-milling debris.

6. The method of claim 1, wherein the composition-modified barium titanate particles include (Ba_1-α

-μ

-ν

A_μ

D_ν

Ca_α

)[Ti<sub>1-x-δ

-μ

′

-ν

′</sub>

Mn_δ

A′

_μ

D′

<sub>ν

′</sub>

Zr_x]_zO₃, where A=Ag, A′

=Dy, Er, Ho, Y, Yb, or Ga;

D=Nd, Pr, Sm, or Gd;

D′

=Nb or Mo, 0.10≤

x≤

0.25;

0≤

μ

≤

0.01, 0≤

μ

′

≤

0.01, 0≤

ν

≤

0.01, 0≤

ν

′

≤

0.01, 0<

δ

≤

0.01, 0.995≤

z≤

1, and 0≤

α

≤

0.005.

7. A method for preparing a ceramic powder of a general formula of ABO₃, the method comprising:

providing a first solution including a plurality of precursor materials, the first solution having a molar ratio of a total A precursor content to a total B precursor content of 1;

combining the first solution with a second solution, the second solution including an oxalate compound and tetraalkylammonium hydroxide, wherein combining the first solution and the second solution causes co-precipitation of hydrated hydroxide-oxalate precipitates in a combined solution, wherein the hydrated hydroxide-oxalate precipitates are partially crystalline;

performing a hydrothermal treatment on the hydrated hydroxide-oxalate precipitates of the combined solution; and

after performing the hydrothermal treatment, decomposing and calcining to form the ceramic powder, wherein within the ceramic powder, a molar ratio of a total A content to a total B content is 1, and the ceramic powder includes composition-modified barium titanate particles.

8. The method of claim 7, wherein:

the molar ratio of the total A precursor content to the total B precursor content is 1.000; and

within the ceramic powder, the molar ratio of a total A content to the total B content is 1.000.

9. The method of claim 8, wherein, after decomposing and calcining, the ceramic powder is free of ball-milling debris.

10. The method of claim 7, wherein the hydrothermal treatment is performed at a temperature of at least 150°

C. and at a pressure of at least 200 psi for a time period of 4 hours to 8 hours.

11. The method of claim 7, wherein decomposing and calcining is performed at a maximum temperature in a range of 1050°

C. to 1150°

C.

12. The method of claim 7, wherein after decomposing and calcining, excluding particles having a size of less than 0.1 micrometer and excluding particles having a size greater than 10 micrometers, and wherein the composition-modified barium titanate particles have an average particulate size in a range of 0.6to 1.5 micrometers.

13. The method of claim 7, wherein the composition-modified barium titanate particles include (Ba_1-α

-μ

-ν

A_μ

D_ν

Ca_α

)[Ti<sub>1-x-δ

-μ

′

-ν

′</sub>

Mn_δ

A′

_μ

D′

<sub>ν

′</sub>

Zr_x]_zO₃, where A=Ag, A′

=Dy, Er, Ho, Y, Yb, or Ga;

D=Nd, Pr, Sm, or Gd;

D′

=Nb or Mo, 0.10≤

x≤

0.25;

0≤

μ

≤

0.01, 0≤

μ

′

≤

0.01, 0≤

ν

≤

0.01, 0≤

ν

′

≤

0.01, 0<

δ

≤

0.01, 0.995≤

z≤

1, and 0≤

α

≤

0.005.

14. A method for preparing a ceramic powder of a general formula of ABO₃, the method comprising:

combining a first solution including a plurality of precursor materials with a second solution to cause co-precipitation of hydrated hydroxide-oxalate precipitates in a combined solution, wherein the hydrated hydroxide-oxalate precipitates are partially crystalline, the first solution including at least a barium containing material and a titanium containing material, the second solution including an oxalate compound and tetraalkylammonium hydroxide;

heating the hydrated hydroxide-oxalate precipitates of the combined solution at a temperature of at least 150°

C. at a treatment pressure of at least 200 psi; and

decomposing and calcining to form the ceramic powder including composition-modified barium titanate particles, wherein after decomposing and calcining, the ceramic powder is free of ball-milling debris.

15. The method of claim 14, further comprising hot pressing the ceramic powder after decomposing and calcining.

16. The method of claim 14, wherein excluding particles having a size of less than 0.1 micrometers and excluding particles having a size or greater than 10 micrometers, the composition-modified barium titanate particles have an average particulate size in a range of 0.6 to 1.5 micrometers.

17. The method of claim 16, wherein decomposing and calcining is performed at a maximum temperature of no greater than 1150°

C.

18. The method of claim 14, the composition-modified barium titanate particles include (Ba_1-α

-μ

-ν

A_μ

D_ν

Ca_α

)[Ti<sub>1-x-δ

-μ

′

-ν

′</sub>

Mn_δ

A′

_μ

D′

<sub>ν

′</sub>

Zr_x]_zO₃, where A=Ag, A′

=Dy, Er, Ho, Y, Yb, or Ga;

D=Nd, Pr, Sm, or Gd;

D′

=Nb or Mo, 0.10≤

x≤

0.25;

0≤

μ

≤

0.01, 0≤

μ

′

≤

0.01, 0≤

ν

≤

0.01, 0≤

ν

′

≤

0.01, 0<

δ

≤

0.01, 0.995≤

z≤

1, and 0≤

α

≤

0.005.

19. The method of claim 18, wherein ν

>

0, α

>

0, δ

>

0, and μ

>

0.