METHOD OF PREPARING CERAMIC POWDERS

• US 20160023954A1
• Filed: 09/02/2014
• Published: 01/28/2016
• 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.
• Granted Patent: US 10,239,792 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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, wherein each of the plurality of precursor materials in solution further comprises at least one constituent ionic species of a ceramic powder, 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;

combining the plurality of precursor materials in solution with a precipitant solution including an oxalate compound and tetraalkylammonium hydroxide to cause co-precipitation of metal oxide particles in a combined solution, wherein combining includes injecting the precursor material into a tubular reactor and 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;

flowing the mixed metal oxide particles in an aqueous suspension in a hydrothermal treatment vessel;

heating the aqueous suspension at a temperature of at least 150°

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

decomposing and calcining the mixed oxide particles to form the ceramic powder including composition-modified barium titanate particles having a relative permittivity of at least 50,000.

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

3. The method of claim 2, wherein the metal oxide particles have an average particle size in a range of 3 microns to 15 microns before heating the aqueous suspension.

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

5. The method of claim 1, adding an aqueous solution having a temperature of not greater than 100°

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

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

7. The method of claim 1, 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, and 0.995≦

z≦

1 and 0≦

α

≦

0.005.

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

providing a plurality of precursor materials in solution, wherein a molar ratio of a total A precursor content to a total B precursor content is 1.00;

combining the plurality of precursor materials in solution with a precipitant solution including an oxalate compound and tetraalkylammonium hydroxide to cause co-precipitation of metal oxide particles in a combined solution;

performing a hydrothermal treatment on the metal oxide particles in an aqueous; and

decomposing and calcining the mixed oxide particles to form the ceramic powder, wherein within the ceramic powder, a molar ratio of a total A content to a total B content is 1.00, and the ceramic powder including composition-modified barium titanate particles having a relative permittivity of at least 50,000.

9. The method of claim 8, 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.

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

11. The method of claim 8, 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.

12. The method of claim 8, wherein decomposing and calcining is performed at a maximum temperature of in a range of 1050°

C. to 1150°

C.

13. The method of claim 8, wherein after decomposing and calcining, excluding particles having a size of 0.1 micron or greater than 10 microns, the composition-modified barium titanate particles have an average particulate size in a range of 0.6 to 1.5 micrometers.

14. The method of claim 8, 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, and 0.995≦

z≦

1 and 0≦

α

≦

0.005.

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

providing a plurality of precursor materials in solution;

combining the plurality of precursor materials in solution with a precipitant solution including an oxalate compound and tetraalkylammonium hydroxide to cause co-precipitation of metal oxide particles in a combined solution;

heating the aqueous suspension at a temperature of at least 150°

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

decomposing and calcining the mixed oxide particles to form the ceramic powder including composition-modified barium titanate particles having a relative permittivity of at least 50,000, and after decomposing and calcining, the ceramic powder is free of ball-milling debris.

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

17. The method of claim 15, wherein excluding particles having a size of 0.1 micron or greater than 10 microns, the composition-modified barium titanate particles have an average particulate size in a range of 0.6 to 1.5 micrometers.

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

C.

19. The method of claim 15, 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, and 0.995≦

z≦

1 and 0≦

α

≦

0.005.

20. The method of claim 19, wherein ν

>

0, α

>

0, δ

>

0, and μ

>

0.