Method of preparing ceramic powders using chelate precursors

• US 20070148065A1
• Filed: 03/07/2006
• Published: 06/28/2007
• Est. Priority Date: 04/12/2001
• Status: Active Grant

• Current Assignee: Eestor Inc. (FuelPositive Corp.)
• Original Assignee: Eestor Inc. (FuelPositive Corp.)
• Inventors: Nelson, Carl, Weir, Richard
• Granted Patent: US 7,914,755 B2
• Time in Patent Office: Days
• US Class Current: 423/1
• CPC Class Codes: C01B 13/363 Mixtures of oxides or hydroxides by precipitation
• CPC Class Codes: C01G 1/02 Oxides
• 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 2235/442 Carbonates
• CPC Class Codes: C04B 2235/443 Nitrates or nitrites
• 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: H01G 4/1227 based on alkaline earth titanates
• CPC Class Codes: H01G 4/30 Stacked capacitors H01G4/33 takes precedence

Abstract

Wet-chemical methods involving the use of water-soluble hydrolytically stable metal-ion chelate precursors and the use of a nonmetal-ion-containing strong base can be used in a coprecipitation procedure for the preparation of ceramic powders. Examples of the precipitants used include tetraalkylammonium hydroxides. 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 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, and wherein at least one of the plurality of precursor materials in solution is a chelate solution;

combining the plurality of precursor materials in solution with a precipitant solution to cause coprecipitation of the ceramic powder in a combined solution; and

separating the ceramic powder from the combined solution.

2. The method of claim 1 wherein the chelate solution is one of a metal ion chelate solution and an oxometal ion chelate solution.

3. The method of claim 1 wherein the chelate solution a water soluble hydrolytically stable chelate solution.

4. The method of claim 1 wherein the chelate solution further comprises a chelate of at least of:

Ba, Ca, Nd, Ti, Zr, Mn, La, Y, Pr, Sm, Gd, Dy, Er, Ho, Yb, Ga, Ag, Dy, Er, Ho, Nb, and Mo.

5. The method of claim 1 wherein the chelate solution further comprises at least one of:

zirconium(IV) bis(ammonium 2-hydroxypropanato)dihydroxide [zirconium(IV) bis(ammonium lactato)dihydroxide] {[CH₃CH(O—

)COONH₄]₂Zr(OH)₂};

titanium(IV) bis(ammonium 2-hydroxypropanato)dihydroxide [titanium(IV) bis(ammonium lactato)dihydroxide] {[CH₃CH(O—

)COONH₄]₂Ti(OH)₂};

bis(ammonium 2-hydroxypropanato)manganese(II) {Mn[CH₃CH(O—

)COONH₄]₂};

tris(ammonium 2-hydroxypropanato)yttrium(III) {Y[CH₃CH(O—

) COONH₄]₃};

tris(ammonium 2-hydroxypropanato)lanthunm(III) {La[CH₃CH(O—

)COONH₄]₃}; and

tris(ammonium 2-hydroxypropanato)neodymium(III) {Nd[CH₃CH(O—

)COONH₄]₃}.

6. The method of claim 1 wherein the a plurality of precursor materials in solution further comprises a plurality of chelates in solution.

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

8. The method of claim 1 wherein the plurality of precursor materials in solution further comprises at least one of:

Ba(NO₃)₂; and

Ca(NO₃)₂. 4H₂O.

9. The method of claim 1 the precipitant solution is a nonmetal-ion-containing strong base.

10. The method of claim 1 the precipitant solution further comprises a tetraalkylammonium hydroxide solution.

11. The method of claim 10 wherein the precipitant solution is tetramethylammonium hydroxide [(CH₃)₄NOH] in aqueous solution.

12. 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 colunm.

13. The method of claim 12 further comprising:

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

introducing the precipitant solution in a second stream.

14. 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 precipitant solution; and

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

15. 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; and

freeze drying the combined solution.

16. 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; and

sintering the separated ceramic powder.

17. The method of claim 1 further comprising:

preparing the chelate solution using a chelating agent, the chelating agent is one of 2-hydroxypropanoic acid and an alpha-hydroxycarboxylic acid.

18. The method of claim 17 the chelating agent an alpha-hydroxycarboxylic acid and further comprises one of:

2-hydroxyethanoic acid [(OH)CH₂COOH];

2-hydroxybutanedioic acid [HOOCCH₂CH(OH)COOH];

2,3-dihydroxybutanedioic acid [HOOCCH(OH)CH(OH)COOH];

2-hydroxy-1,2,3-propanetricarboxylic acid [(OH)C(COOH)(CH₂COOH)₂];

2-hydroxybutanoic acid [CH₃CH₂CH(OH)COOH];

2-hydroxypentanoic acid [CH₃(CH₂)₂CH(OH)COOH]; and

2-hydroxyhexanoic acid [CH₃(CH₂)₃CH(OH)COOH].

19. The method of claim 17 further comprising:

reacting a metal alkyl oxide with the chelating agent and a weak base solution.

20. The method of claim 17 further comprising:

reacting a metal ion carbonate with the chelating agent and a weak base solution.

21. A substantially contaminant free ceramic powder produced by a process 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, and wherein at least one of the plurality of precursor materials in solution is a chelate solution;

combining the plurality of precursor materials in solution with a nonmetal-ion-containing strong base precipitant solution to cause coprecipitation of the ceramic powder in a combined solution; and

separating the ceramic powder from the combined solution.

22. The substantially contaminant free ceramic powder of claim 21 wherein the precipitant solution further comprises a tetraalkylammonium hydroxide solution.

23. The substantially contaminant free ceramic powder of claim 22 wherein the precipitant solution is tetramethylammonium hydroxide [(CH₃)₄NOH] in aqueous solution.

24. The substantially contaminant free ceramic powder of claim 21 wherein the combining further comprises:

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

25. The substantially contaminant free ceramic powder of claim 21 wherein the combining fuirther comprises at least one of:

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

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

26. The substantially contaminant free ceramic powder of claim 21 wherein the separating the ceramic powder from the combined solution further comprises at least one of:

filtering the ceramic powder from the combined solution;

centrifuiging the combined solution;

sedimenting the combined solution;

spray drying the combined solution; and

freeze drying the combined solution.

27. The substantially contaminant free ceramic powder of claim 21 wherein the process further comprises at least one of:

washing the separated ceramic powder;

drying the separated ceramic powder;

calcining the separated ceramic powder; and

sintering the separated ceramic powder.