Method for continuous preparation of indium-tin coprecipitates and indium-tin-oxide nanopowders with substantially homogeneous indium/tin composition, controllable shape and particle size
First Claim
1. A process for preparing an indium-tin-oxide nanopowder having a substantially consistent indium-to-tin ratio, a desired particle size range and desired particle shape comprising:
- a) preparing a seeding solution including at least one indium salt, at least one tin salt, at least one solubility modifier, and at least one base in a solvent so as to form a substantially clear solution of intermediate indium compounds and tin compounds having a general formula expressed as [M(OH)xCy], where M is an indium or tin ion, and C is the cationic part of the at least one indium salt or the least one tin salt, x is a number greater than 0 and y=[M valence−
x]/C valence;
b) adjusting the pH of the seeding solution and the concentration of the solubility modifier so as to solubilize the indium and tin intermediate compounds to near the onset of precipitation wherein the pH of the seeding solution is about 0 to about 3;
c) continuously introducing into a reaction vessel the seeding solution having the indium and tin intermediate compounds therein;
d) continuously introducing into the reaction vessel a base solution comprising one or more bases;
e) continuously mixing in the reaction vessel the seeding solution and the base solution such that the indium and tin intermediate compounds react with the base solution to form a mixture including crystalline and amorphous precipitated indium-tin nanoparticles, the rate of the introduction of the seeding solution and the base solution to the reaction vessel each being independently adjustable so as to maintain the pH of the mixture in the reaction vessel at a substantially constant pH of greater than about 3 and a substantially constant ratio of indium intermediate compounds to tin intermediate compounds in the mixture;
f) continuously collecting and removing from the reaction vessel a portion of the mixture having therein indium-tin precipitated nanoparticles;
g) washing and drying the removed indium-tin precipitated nanoparticles; and
h) heating the washed and dried indium-tin precipitated nanoparticles so as to obtain the indium-tin-oxide nanopowder.
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Accused Products
Abstract
Disclosed herein are indium-tin-oxide nanoparticles and a method for continuously producing precipitated indium-tin nanoparticles having a particle size range of substantially from about 10 nm to about 200 nm and a substantially consistent ratio of indium to tin in the resultant nanoparticles across the duration of the continuous process, based on the ratio of indium to tin in a seeding solution. The method comprises preparing intermediate indium and tin compounds of the general formula [M(OH)xCy], where M represents the indium or tin ionic component of indium or tin salts, C represents the cationic component of indium or tin salt(s), x is a number greater than 0 and y=[M*valance−x]/C* valance in the seeding solution. The intermediate compounds are continuously precipitated with a base solution in a reaction vessel initially having a solvent contained therein. The method also provides a means for controlling the shape of the resultant nanoparticles. The resultant indium-tin nanoparticles may be further processed into dispersions.
78 Citations
23 Claims
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1. A process for preparing an indium-tin-oxide nanopowder having a substantially consistent indium-to-tin ratio, a desired particle size range and desired particle shape comprising:
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a) preparing a seeding solution including at least one indium salt, at least one tin salt, at least one solubility modifier, and at least one base in a solvent so as to form a substantially clear solution of intermediate indium compounds and tin compounds having a general formula expressed as [M(OH)xCy], where M is an indium or tin ion, and C is the cationic part of the at least one indium salt or the least one tin salt, x is a number greater than 0 and y=[M valence−
x]/C valence;b) adjusting the pH of the seeding solution and the concentration of the solubility modifier so as to solubilize the indium and tin intermediate compounds to near the onset of precipitation wherein the pH of the seeding solution is about 0 to about 3; c) continuously introducing into a reaction vessel the seeding solution having the indium and tin intermediate compounds therein; d) continuously introducing into the reaction vessel a base solution comprising one or more bases; e) continuously mixing in the reaction vessel the seeding solution and the base solution such that the indium and tin intermediate compounds react with the base solution to form a mixture including crystalline and amorphous precipitated indium-tin nanoparticles, the rate of the introduction of the seeding solution and the base solution to the reaction vessel each being independently adjustable so as to maintain the pH of the mixture in the reaction vessel at a substantially constant pH of greater than about 3 and a substantially constant ratio of indium intermediate compounds to tin intermediate compounds in the mixture; f) continuously collecting and removing from the reaction vessel a portion of the mixture having therein indium-tin precipitated nanoparticles; g) washing and drying the removed indium-tin precipitated nanoparticles; and h) heating the washed and dried indium-tin precipitated nanoparticles so as to obtain the indium-tin-oxide nanopowder. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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Specification