US4957725A
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Vanadium dioxide formed by the sol-gel process
Assignee: Johns Hopkins University
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Filing: 1988-07-05
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Granted: 1990-09-18
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Expires: 2008-07-05
Abstract
Abstract Vanadium dioxide thin films have been prepared from tetrravalent vanadium organic compounds via the sol gel process. The vanadium dioxide was deposited from an alcoholic solution. Films were annealed between 200°-700° C. under nitrogen to achieve complete dehydration and crystallization.
Inventors
- 👤 Richard S. Potember
- 👤 Kenneth R. Speck
- 👤 Henry S. Hu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:33
CPC Classifications
C; C01; C01G; C01G31/00; C01G31/02; C01P; C01P2002/00; C01P2002/80; C01P2002/84; C01P2006/00; C01P2006/60
Claims Analysis
Total Claims: 28
Claim 1
Independent Claim
77 words
A process for the deposition of a crystalline vanadium dioxide thin film comprising: providing a solution comprising a vanadium tetraalkoxide and solvent; allowing hydrolysis and condensation reactions to progressively form a homogenous sol from the solution, applying a coating of the sol to the substrate; allowing a gel to form from the sol on the substrate by evaporating the solvent; dehydrating the gel by heat treatment under an inert atmosphere to form the crystalline vanadium dioxide film.
Claim 2
Dependent Claim
77 words
A process for the deposition of a crystalline vanadium dioxide thin film comprising: providing a solution comprising a vanadium tetraalkoxide and solvent; allowing hydrolysis and condensation reactions to progressively form a homogenous sol from the solution, applying a coating of the sol to the substrate; allowing a gel to form from the sol on the substrate by evaporating the solvent; dehydrating the gel by heat treatment under an inert atmosphere to form the crystalline vanadium dioxide film.
Claim 3
Dependent Claim
18 words
A process according to claim 1, wherein the vanadium tetraalkoxide is one of vanadium tetraisopropoxide and vanadium tetrais(t-butoxide).
Claim 4
Dependent Claim
95 words
A process according to claim 1, wherein the vanadium tetraalkoxide is vanadium tetrakis(t-butoxide) prepared according to the following process: dissolving vanadium tetrachloride in a solvent to form a solution; adding the solution dropwise to a suspension of a potassium tert-butoxide of eon of potassium, magnesium, lithium and sodium, in the solvent while stirring at below 0.° C. to form a reaction mixture; warming the reaction mixture to room temperature; filtering under an inert atmosphere to form a liquid comprising the solvent and vanadium tetrakis(t-butoxide); evaporating the solvent; and recovering the vanadium tetrakis(t-butoxide) by vacuum distillation.
Claim 5
Dependent Claim
13 words
A process according to claim 1, wherein the solvent is a polar solvent.
Claim 6
Dependent Claim
11 words
A process according to claim 4, wherein the solvent is alcohol.
Claim 7
Dependent Claim
17 words
A process according to claim 4, wherein the solvent is a parent alcohol to the vanadium tetraalkoxide.
Claim 8
Dependent Claim
15 words
A process according to claim 4, wherein the solvent is one of isopropanol and t-butanol.
Claim 9
Dependent Claim
19 words
A process according to claim 1, wherein the heat treatment comprises heating at 200-700° C. under an inert atmosphere.
Claim 10
Dependent Claim
16 words
A process according to claim 1, wherein the entire process is performed under an inert atmosphere.
Claim 11
Dependent Claim
21 words
A process according to claim 1, wherein the sol coating is applied by one of dip coating, spin coating and spraying.
Claim 12
Dependent Claim
19 words
A process according to claim 1, wherein the solution also comprises one of tungsten, molybdenum, tantalum, iron and chromium.
Claim 13
Dependent Claim
28 words
A process according to claim 1, wherein the solution also comprises at least one of a metal oxychloride, a metal alkoxide, a metal nitrate and a metal oxalate.
Claim 14
Dependent Claim
26 words
A process according to claim 1, wherein the solution also comprises one of tungsten (IV) oxytetrachloride, molybdenum (IV) oxytetrachloride, iron (III) nitrate and chromium (III) nitrate.
Claim 15
Dependent Claim
92 words
A process for the deposition of crystalline vanadium dioxide comprising: providing a solution comprising a vanadium tetraalkoxide and a solvent; allowing hydrolysis and condensation reactions to progressively form a homogeneous sol from the solution; dipping a substrate into the sol; withdrawing the substrate from the sol at a constant rate to form a coating of the sol on the substrate; allowing a gel to form for the sol on the substrate by evaporating the solvent; dehydrating the gel by heat treatment in an inert atmosphere to form the crystalline vanadium dioxide film.
Claim 16
Dependent Claim
92 words
A process for the deposition of crystalline vanadium dioxide comprising: providing a solution comprising a vanadium tetraalkoxide and a solvent; allowing hydrolysis and condensation reactions to progressively form a homogeneous sol from the solution; dipping a substrate into the sol; withdrawing the substrate from the sol at a constant rate to form a coating of the sol on the substrate; allowing a gel to form for the sol on the substrate by evaporating the solvent; dehydrating the gel by heat treatment in an inert atmosphere to form the crystalline vanadium dioxide film.
Claim 17
Dependent Claim
18 words
A process according to claim 14, wherein the vanadium tetraalkoxide is one of vanadium tetraisopropoxide and vanadium tetrakis(t-butoxide).
Claim 18
Dependent Claim
92 words
A process according to claim 14, wherein the vanadium tetraalkoxide is vanadium tetrakis(t-butoxide) prepared according to the following process: dissolving vanadium tetrachloride in a solvent to form a solution; adding the solution dropwise to a suspension of a tertbutoxide of one of potassium, magnesium, lithium and sodium, in the while stirring at below 0° C. to form a reaction mixture; warming the reaction mixture to room temperature; filtering under nitrogen to form a green liquid comprising the solvent and vanadium tetrakis(t-butoxide); evaporating the solvent; and recovering the vanadium tetrakis(t-butoxide) by vacuum distillation.
Claim 19
Dependent Claim
13 words
A process according to claim 14, wherein the solvent is a polar solvent.
Claim 20
Dependent Claim
11 words
A process according to claim 17, wherein the solvent is alcohol.
Claim 21
Dependent Claim
17 words
A process according to claim 17, wherein the solvent is a parent alcohol to the vanadium tetraalkoxide.
Claim 22
Dependent Claim
15 words
A process according to claim 17, wherein the solvent is one of isopropanol and t-butanol.
Claim 23
Dependent Claim
19 words
A process according to claim 14, wherein the heat treatment comprises heating at 200-700° C. in an inert atmosphere.
Claim 24
Dependent Claim
22 words
A process according to claim 14, wherein all process steps occur under an inert atmosphere comprising one of nitrogen, argon and helium.
Claim 25
Dependent Claim
20 words
A process according to claim 14, wherein the solution also comprises one of tungsten, molybdenum, tantalum, iron and chromium ions.
Claim 26
Dependent Claim
28 words
A process according to claim 14, wherein the solution also comprises at least one of a metal oxychloride, a metal alkoxide, a metal nitrate and a metal oxalate.
Claim 27
Dependent Claim
26 words
A process according to claim 14, wherein the metal oxychloride is one of tungsten (IV) oxytetrachloride, molybdenum (IV) oxytetrachloride, iron III nitrate and chromium III nitrate.
Claim 28
Dependent Claim
14 words
A process according to claim 14, wherein the constant rate is approximately 1 mm/sec.
References Cited (Backward Citations)
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