Method of preparing ceramic powders
AssigneeEEStor, Inc.
InventorsRichard D. Weir, Carl W. Nelson
Life of this patent
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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.
Claims19
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.
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.
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.
Dependencies are inferred from the claim text.