Electrically conducting ruthenium dioxide aerogel composite

• US 20030062512A1
• Filed: 09/19/2001
• Published: 04/03/2003
• Est. Priority Date: 12/01/1999
• Status: Active Grant

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Long, Jeffery W., Berry, Alan D., Merzbacher, Celia I., Ryan, Joseph V., Rolison, Debra R.
• Granted Patent: US 6,649,091 B2
• Time in Patent Office: Days
• US Class Current: 252/521.3
• CPC Class Codes: H01B 1/14 Conductive material dispersed in non-conductive inorganic material

Abstract

An electrically conducting composite is made by providing an aerogel structure of nonconducting material, exposing the aerogel structure to a mixture of RuO₄ and a nonpolar solvent in an inert atmosphere, wherein the mixture is held initially at a first temperature that is below the temperature at which RuO₄ decomposes into RuO₂ in the nonpolar solvent and in the presence of the aerogel, and allowing the mixture to warm to a second temperature that is above the temperature at which RuO₄ decomposes to RuO₂ in the nonpolar solvent and in the presence of the aerogel, wherein the rate of warming is controlled so that as the mixture warms and the RuO₄ begins to decompose into RuO₂, the newly formed RuO₂ is deposited throughout the aerogel structure as a three-dimensionally networked conductive deposit.

Claims

1. An electrically conducting composite comprising an aerogel structure of nonconducting material and an electrically connected conductive network of RuO₂ throughout the structure.

2. The electrically conducting composite of claim 1 wherein the aerogel structure is a partially densified silica aerogel.

3. An electrically conducting composite made by a method comprising the steps of:

providing an aerogel structure,

exposing the aerogel structure to a mixture of RuO₄ and a nonpolar solvent in an inert atmosphere, wherein the mixture is held initially at a first temperature that is below the ambient temperature and below the temperature at which RuO₄ decomposes into RuO₂ in the nonpolar solvent and in the presence of the aerogel, and

allowing the mixture to warm to a second temperature that is above the temperature at which RuO₄ decomposes to RuO₂ in the nonpolar solvent and in the presence of the aerogel, wherein the rate of warming is controlled so that as the mixture warms and the RuO₄ begins to decompose into RuO₂, the newly formed RuO₂ is deposited throughout the aerogel structure as an electrically connected conductive deposit.

4. A method of creating an electrically conductive composite comprising an aerogel structure and an electrically connected conductive deposit of RuO₂ throughout the structure, the method comprising the steps of:

providing an aerogel structure,

exposing the aerogel structure to a mixture of RuO₄ and a nonpolar solvent in an inert atmosphere, wherein the mixture is held initially at a first temperature that is below the ambient temperature and below the temperature at which RuO₄ decomposes into RuO₂ in the nonpolar solvent and in the presence of the aerogel, and

allowing the mixture to warm to a second temperature that is above the temperature at which RuO₄ decomposes to RuO₂ in the nonpolar solvent and in the presence of the aerogel, wherein the rate of warming is controlled so that as the mixture warms and the RuO₄ begins to decompose into RuO₂, the newly formed RuO₂ is deposited throughout the aerogel structure as an electrically connected conductive deposit.

5. The method of claim 4 including the subsequent steps of:

removing the solvent from the electrically conductive composite formed therein and

heating the electrically conductive composite at a temperature sufficient to convert the deposited RuO₂ from an amorphous state to a crystalline state.

6. The method of claim 4 wherein the aerogel structure is a partially densified silica aerogel.

7. The method of claim 4 wherein the nonpolar solvent is pentane.

8. A method of creating an electrically conductive composite comprising an aerogel structure of nonconducting material and an electrically connected conductive deposit of RuO₂ throughout the structure, the method comprising the steps of:

providing a silica aerogel structure,

sintering the silica aerogel structure to create a partially densified silica aerogel structure,

exposing the partially densified silica aerogel structure to a mixture of RuO₄ and pentane in an inert atmosphere, wherein the mixture is held initially at a temperature of about 31 78°

C.,

allowing the mixture to warm to about room temperature, wherein the rate of warming is controlled so that as the mixture warns, RuO₄ begins to decompose into RuO₂ and the newly formed RuO₂ is deposited throughout the aerogel structure to form an electrically connected conductive deposit,

removing the solvent from the electrically conductive composite formed thereby, and

heating the electrically conductive composite at a temperature sufficient to convert the deposited RuO₂ from an amorphous state to a crystalline state.