Synthesis and processing of monosized oxide powders

• US 4,543,341 A
• Filed: 12/23/1983
• Issued: 09/24/1985
• Est. Priority Date: 12/23/1983
• Status: Expired due to Fees

• Current Assignee: Massachusetts Institute of Technology
• Original Assignee: Massachusetts Institute of Technology
• Inventors: Barringer, Eric A., Fegley, M. Bruce Jr., Bowen, H. Kent
• Primary Examiner(s): McCarthy, Helen M.
• Application Number:
  US06/565,000
• Time in Patent Office: 641 Days
• Field of Search: 423/608, 423/622, 423/593, 423/338, 501/1, 501/94, 501/103, 501/105, 501/152, 501/134, 501/135, 264/56, 264/65, 264/0.5
• US Class Current: 501/1
• CPC Class Codes: B82Y 30/00 Nanotechnology for materials or surface science, e.g. nanocomposites
• CPC Class Codes: C01B 13/32 by oxidation or hydrolysis of elements or compounds in the liquid or solid state or in non-aqueous solution, e.g. sol-gel process
• CPC Class Codes: C01G 23/053 Producing by wet processes, e.g. hydrolysing titanium salts
• CPC Class Codes: C01G 25/02 Oxides
• CPC Class Codes: C01G 9/02 Oxides; Hydroxides
• CPC Class Codes: C01P 2004/03 obtained by SEM
• CPC Class Codes: C01P 2004/32 Spheres
• CPC Class Codes: C01P 2004/52 highly monodisperse size distribution
• CPC Class Codes: C01P 2004/62 Submicrometer sized, i.e. from 0.1-1 micrometer
• CPC Class Codes: C01P 2004/64 Nanometer sized, i.e. from 1-100 nanometer
• CPC Class Codes: C01P 2006/80 Compositional purity
• CPC Class Codes: C04B 35/453 based on zinc, tin, or bismuth oxides or solid solutions thereof with other oxides, e.g. zincates, stannates or bismuthates
• CPC Class Codes: C04B 35/46 based on titanium oxides or titanates containing also zirconium or hafnium oxides, zirconates or hafnates C04B35/49
• CPC Class Codes: C04B 35/486 Fine ceramics
• CPC Class Codes: C04B 35/622 Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
• CPC Class Codes: C04B 35/626 Preparing or treating the powders individually or as batches pigments for ceramics C09C1/0009; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B

Abstract

Uniform-size, high-purity, spherical oxide powders are formed by hydrolysis of alkoxide precursors in dilute alcoholic solutions. Under controlled conditions (concentrations of 0.03 to 0.2 M alkoxide and 0.2 to 1.5 M water, for example) oxide particles on the order of about 0.05 to 0.7 micron can be produced. Methods of doping such powders and forming sinterable compacts are also disclosed.

Claims

1. A method of forming generally spherical, sinterable metallic oxide metallic oxide powders with a narrow size distribution comprising:

(a) under inert atmosphere hydrolyzing a dilute alcoholic solution of a metallic alkoxide wherein the solution ranges from about 0.2 to about 1.5 molar water and the concentration of the alkoxide ranges from about 0.03 to 0.2 molar alkoxide; and

(b) collecting the precipitate.

2. The method of claim 1 wherein the alkoxide is chosen from the group of titanium alkoxides, zirconium alkoxides, zinc double alkoxide and mixtues thereof.

3. The method of claim 1 wherein the alkoxide is a titanium alkoxide and the resulting oxide is titania.

4. The method of claim 1 wherein the alkoxide is a zirconium alkoxide and the resulting oxide is zirconia.

5. The method of claim 1 wherein the alkoxide is a zinc alkoxide and the resulting oxide is zinc oxide.

6. The method of claim 1 wherein the hydrolyzing step further comprises cohydrolyzing an alkoxide of a suitable dopant to yield a doped powder.

7. The method of claim 1 wherein the hydrolyzing step further comprises co-precipitating a dopant from a soluble inorganic salt to yield a doped powder.

8. A method of forming sinterable compacts which yield uniformly dense ceramic structures upon sintering, the method comprising:

(a) dispersing particles of at least one metallic oxide in a solution having a low electrolyte concentration, the particles having generally spherical shapes, a narrow size distribution and a mean diameter ranging from about 0.05 microns to about 0.7 microns;

(b) maintaining the pH of the solution sufficiently above or below the isoelectric point to avoid agglomeration of the particles in solution; and

(c) forming the particles by sedimentation into an orderly packing arrangement in a desired shape.

9. A method of forming sinterable compacts which yield porous ceramic structures upon sintering, the method comprising:

(a) dispersing particles of at least one metallic oxide in a solution, the particles having a spherical shape, a narrow size distribution, and a mean diameter ranging from about 0.05 microns to about 0.7 micron;

(b) manipulating at least one parameter chosen from the group of electrolyte concentration and pH to permit controlled agglomeration; and

(c) forming the particles by sedimentation into a desired shape.