Process for preparing nanostructured materials of controlled surface chemistry

Inactive Publication Date: 2003-12-18
NANOPHASE TECH CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

0018] A further object of the present invention is the production of stoichiometric-nanostructured materials with unique s

Problems solved by technology

But prior art does not teach the synthesis of stoichiometric-nanostructured materials with controlled surface chemistry.
The use of oxidizing plasma environments is conventionally discouraged because the m

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example

EXAMPLE 1

Cerium Oxide--"Active Volume"

[0026] Two experiments utilizing nanostructured cerium oxide, synthesized with and without an "active volume" in the plasma, are presented.

[0027] The plasma was generated using a free-burning electric arc. The plasma gas was argon and the arc power was 62 kW.

[0028] The precursor material was particulate cerium oxide powder having an average particle size greater than 2 microns and 99.95% pure. The precursor was fluidized with a feed gas to create a heterogeneous precursor feed that was injected into cathodic arc column.

[0029] In Experiment 1 no "active volume" was created in the plasma. In Experiment 2 an "active volume" was created in the plasma by fluidizing the precursor with an oxidizing gas--oxygen--to form a heterogeneous precursor feed. In all other respects the two experiments were conducted under identical conditions.

[0030] Experiment 1 uses an inert gas to fluidize the precursor and is representative of prior teachings. In contrast, Ex...

Example

EXAMPLE 2

Cerium Oxide--"Active Volume" with Quench and Dilution

[0033] Two experiments utilizing nanostructured cerium oxide, synthesized with and without an "active volume" in the plasma followed by quenching and dilution, are presented.

[0034] The plasma was generated using a free-burning electric arc. The plasma gas was argon and the arc power was 62 kW.

[0035] The precursor material was particulate cerium oxide powder having an average particle size greater than 2 microns and 99.95% pure. The precursor was fluidized with a feed gas to create a heterogeneous precursor feed that was injected into cathodic arc column.

[0036] In Experiment 3 no "active volume" was created in the plasma. In Experiment 4 an "active volume" was created in the plasma by fluidizing the precursor with an oxidizing gas--oxygen--to form a heterogeneous precursor feed. A quench and dilution stream comprised of an oxidizing gas--oxygen--was injected just beyond the "active volume" in both experiments. In all othe...

Example

EXAMPLE 3

Extension of Process to Materials other than Cerium Oxide

[0040] The methods taught in this patent may be extended to materials other than cerium oxide. For example, stable aqueous dispersions may be formed from the following materials listed with their zeta-potentials.

1 Material Zeta-Potential Alumina 46.5 mV Antimony Tin Oxide 49.9 mV Indium Tin Oxide 37.9 mV

[0041] The preceding specific embodiments are illustrative of the practice of the invention. It is to be understood, however, that other expedients known to those skilled in the art, or disclosed herein, may be employed without departing from the spirit of the invention or the scope of the appended claims.

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Abstract

A process to prepare stoichiometric-nanostructured materials comprising generating a plasma, forming an "active volume" through introduction of an oxidizing gas into the plasma, before the plasma is expanded into a field-free zone, either (1) in a region in close proximity to a zone of charge carrier generation, or (2) in a region of current conduction between field generating elements, including the surface of the field generation elements, and transferring energy from the plasma to a precursor material to form in the "active volume" at least one stoichiometric-nanostructured material and a vapor that may be condensed to form a stoichiometric-nanostructured material. The surface chemistry of the resulting nanostructured materials is substantially enhanced to yield dispersion stable materials with large zeta-potentials.

Description

THE FIELD OF THE INVENTION[0001] The present invention is concerned generally with making nanostructured materials using plasma technologies. More particularly, the invention is concerned with a method of making a variety of stoichiometric-nanostructured materials by forming a unique "active volume" in a plasma through the introduction of an oxidizing gas. The surface chemistry of the resulting nanostructured material is substantially enhanced to yield dispersion stable materials with large zeta-potentials.[0002] Methods of plasma formation are previously known in the art and may be selected from a group of comprising radio-frequency fields, microwave discharges, free-burning electric arcs, transferred electric arcs, high-intensity lasers, capacitively coupled electro-thermal igniters, DC glow discharges, and DC cold cathode discharges.[0003] Methods for transferring energy to a precursor material by exposing a precursor material to the energy of a plasma are previously known in the...

Claims

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Application Information

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IPC IPC(8): H05H1/24B01J19/08B01J19/12C01B13/14C01F7/02C01F17/00C01G19/00C01G30/00C23C4/12C23C8/36C23C14/00C23C14/32
CPCB01J19/088Y10S977/844B01J19/129B01J2219/0809B01J2219/0847B01J2219/0886B01J2219/0894B82Y30/00C01B13/145C01F7/02C01F17/0043C01P2004/64C01P2006/12C01P2006/22C01P2006/90C23C4/121C23C4/127C23C8/36C23C14/0021C23C14/32Y10S977/811Y10S977/90Y10S977/847B01J19/126C23C4/123C23C4/134
Inventor SARKAS, HARRY W.PIEPENBRINK, JONATHAN
Owner NANOPHASE TECH CORP
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