Method of preparing ceramic powders using ammonium oxalate

• US 7,993,611 B2
• Filed: 08/02/2006
• Issued: 08/09/2011
• Est. Priority Date: 08/02/2006
• Status: Active Grant

• Current Assignee: Eestor Inc. (FuelPositive Corp.)
• Original Assignee: Eestor Inc. (FuelPositive Corp.)
• Inventors: Nelson, Carl W., Weir, Richard D.
• Primary Examiner(s): Li; Jun
• Application Number:
  US11/497,744
• Publication Number:
  US 20080031796A1
• Time in Patent Office: 1,833 Days
• Field of Search: 423/352, 423/592.1, 423/598, 423/599, 423/594.16, 423/608, 423/356, 501/134, 501/135, 501/136, 501/137
• US Class Current: 423/1
• CPC Class Codes: C01B 13/363 Mixtures of oxides or hydroxides by precipitation
• CPC Class Codes: C01G 23/003 Titanates C01G23/001 takes precedence
• CPC Class Codes: C01G 23/006 Alkaline earth titanates
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C01P 2006/80 Compositional purity
• 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 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

Abstract

Wet-chemical methods involving the use of water-soluble hydrolytically stable metal-ion chelate precursors and an ammonium oxalate precipitant can be used in a coprecipitation procedure for the preparation of ceramic powders. Both the precursor solution and the ammonium oxalate precipitant solution are at neutral or near-neutral pH. A composition-modified barium titanate is one of the ceramic powders that can be produced. Certain metal-ion chelates can be prepared from 2-hydroxypropanoic acid and ammonium hydroxide.

Claims

1. A method of forming a ceramic powder, with a formula of (Ba_1-α

-μ

-vA_μ

D_vCa_α

)[Ti<sub>1-x-δ

-μ

′

-v′</sub>

Mn_δ

A′

<sub>μ

′</sub>

D′

_v′

Zr_x]_zO₃, where A=Ag or La, 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≦

v≦

0.01, 0≦

v′

≦

0.01, 0≦

δ

≦

0.01, 0.995≦

z≦

1, and 0≦

α

≦

0.005 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 the ceramic powder, a first precursor material of the plurality of precursor materials comprising barium nitrate, a second precursor material of the plurality of precursor materials comprising a titanium chelate, a third precursor material of the plurality of precursor materials being a metal chelate comprising a metal ion or oxometal ion and a chelating agent, the chelating agent being 2-hydroxypropanoic acid or an alpha-hydroxycarboxylic acid selected from the group consisting of 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;

combining the plurality of precursor materials in solution with an ammonium oxalate precipitant solution to cause co-precipitation of particles of the ceramic powder in a combined solution at a temperature from 85 to 90°

C., the particles including barium, titanium, and the metal ion or oxometal ion; and

separating the particles of the ceramic powder from the combined solution;

calcining the particles of the ceramic powder to form composition-modified barium titanate having a perovskite structure.

2. The method of claim 1 wherein the metal chelate is a water soluble hydrolytically stable chelate solution.

3. The method of claim 1 wherein the metal ion or oxometal ion of the metal chelate comprises at least one of Nd, Zr, Mn, La, Y, Pr, Sm, Gd, Dy, Er, Ho, Yb, Ga, Ag, Dy, Er, Ho, Nb, or Mo.

4. The method of claim 1 wherein the metal chelate comprises at least one of

zirconium(IV) bis(ammonium 2-hydroxypropanato)dihydroxide;

bis(ammonium 2-hydroxypropanato)manganese(II);

tris(ammonium 2-hydroxypropanato)yttrium(III);

tris(ammonium 2-hydroxypropanato) lanthanum(III);

or

tris(ammonium 2-hydroxypropanato)neodymium(III).

5. The method of claim 1 wherein the plurality of precursor materials in solution further comprises a second metal chelate in solution.

6. The method of claim 1 further comprising:

preparing the metal chelate using the chelating agent.

7. The method of claim 6 further comprising:

reacting a metal alkyl oxide with the chelating agent and an ammonium hydroxide solution.

8. The method of claim 6 further comprising:

reacting at least one of a metal-ion carbonate, a metal-ion nitrate, and an oxozirconium(IV)-ion nitrate with the chelating agent and an ammonium hydroxide solution.

9. The method of claim 1 wherein the ceramic powder is a composition-modified barium titanate powder.

10. The method of claim 1 wherein the plurality of precursor materials in solution further comprises Ca(NO₃)₂·

4H₂O.

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

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

12. The method of claim 11 further comprising:

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

introducing the ammonium oxalate precipitant solution in a second stream.

13. The method of claim 1 wherein the combining further comprises at least one of

mechanically mixing the plurality of precursor materials in solution and the ammonium oxalate precipitant solution;

or

ultrasonically mixing the plurality of precursor materials in solution and the ammonium oxalate precipitant solution.

14. The method of claim 1 wherein the separating the ceramic powder from the combined solution further comprises at least one of

filtering the ceramic powder from the combined solution;

centrifuging the combined solution;

sedimenting the combined solution;

spray drying the combined solution;

or

freeze drying the combined solution.

15. The method of claim 1 further comprising at least one of

washing the separated ceramic powder;

drying the separated ceramic powder;

calcining the separated ceramic powder;

or

sintering the separated ceramic powder.

16. The method of claim 1 wherein the plurality of precursor materials in solution further comprises Ca(NO₃)₂·

4H₂O.

17. The method of claim 1, wherein barium comprises 0.975 to 1.0 mole fraction of A sites of the perovskite structure.

18. A method for forming a ceramic powder, with a formula of (Ba_1-α

-μ

-vA_μ

D_vCa_α

)[Ti<sub>1-x-δ

-μ

′

-v′</sub>

Mn_δ

A′

<sub>μ

′</sub>

D′

_v′

Zr_x]_zO₃, where A=Ag or La, 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≦

v≦

0.01, 0≦

v′

≦

0.01, 0≦

δ

≦

0.01, 0.995≦

z≦

1, and 0≦

α

≦

0.005 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 the ceramic powder, a first precursor material of the plurality of precursor materials comprising barium nitrate;

a second precursor material of the plurality of precursor materials comprising a titanium chelate, a third precursor material of the plurality of precursor materials being a metal chelate comprising a metal ion or oxometal ion and a chelating agent, the chelating agent being 2-hydroxypropanoic acid or an alpha-hydroxycarboxylic acid selected from the group consisting of 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;

combining the plurality of precursor materials in solution with an ammonium oxalate precipitant solution to cause co-precipitation of particles of the ceramic powder in a combined solution at a temperature from 85 to 90°

C.;

separating the particles of the ceramic powder from the combined solution; and

calcining the particles of the ceramic powder to form composition-modified barium titanate comprising the barium, the titanium, and the metal ion or oxometal ion and having a perovskite structure.

19. The method of claim 18 wherein the metal ion or oxometal ion of the metal chelate comprises at least one of Nd, Zr, Mn, La, Y, Pr, Sm, Gd, Dy, Er, Ho, Yb, Ga, Ag, Dy, Er, Ho, Nb, or Mo.

20. The method of claim 18 wherein the metal chelate comprises at least one of

zirconium(IV) bis(ammonium 2-hydroxypropanato)dihydroxide;

bis(ammonium 2-hydroxypropanato)manganese(II);

tris(ammonium 2-hydroxypropanato)yttrium(III);

tris(ammonium 2-hydroxypropanato)lanthanum(III);

or

tris(ammonium 2-hydroxypropanato)neodymium(III).

21. The method of claim 18, wherein barium comprises 0.975 to 1.0 mole fraction of A sites of the perovskite structure.

22. A method for forming a ceramic powder, with a formula of (Ba_1-α

-μ

-vA_μ

D_vCa_α

)[Ti<sub>1-x-δ

-μ

′

-v′</sub>

Mn_δ

A′

<sub>μ

′</sub>

D′

_v′

Zr_x]_zO₃, where A=Ag or La, 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≦

v≦

0.01, 0≦

v′

≦

0.01, 0≦

δ

≦

0.01, 0.995≦

z≦

1, and 0≦

α

≦

0.005 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 the ceramic powder, a first precursor material of the plurality of precursor materials comprising barium nitrate;

a second precursor material of the plurality of precursor materials comprising a titanium chelate, a third precursor material of the plurality of precursor materials being a metal chelate comprising a metal ion or oxometal ion and a chelating agent, the chelating agent being 2-hydroxypropanoic acid or an alpha-hydroxycarboxylic acid selected from the group consisting of 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, the metal ion or oxometal ion of the metal chelate comprising an element selected from the group consisting of Nd, Zr, Mn, La, Y, Pr, Sm, Gd, Dy, Er, Ho, Yb, Ga, Ag, Dy, Er, Ho, Nb, and Mo;

combining the plurality of precursor materials in solution with an ammonium oxalate precipitant solution to cause co-precipitation of particles of the ceramic powder in a combined solution at a temperature from 85 to 90°

C., the particles comprising barium, titanium, and the metal ion or oxometal ion;

separating the particles of the ceramic powder from the combined solution; and

calcining the particles of the ceramic powder to form composition-modified barium titanate having a perovskite structure.

23. The method of claim 22, wherein barium comprises 0.975 to 1.0 mole fraction of A sites of the perovskite structure.

24. The method of claim 22, wherein the composition-modified barium titanate comprises Ca, Nd, Zr, Mn, and Y.