The United States of America As Represented by the Administrator of the

United States of America As Represented by the Administrator of Nasa

National Institute of Aerospace Associates

The United States of America As Represented by the United States

Diane M Stoakley

Anne K St Clair

Terry L St Clair

Sang Hyouk Choi

Yeonjoon Park

Glen C King

James R Elliott

Jae-Woo Kim

Sang-Hyon Chu

J Richard Pratt

Harold D Burks

Maggie L Caplan

James C Fletcher

Larry T Taylor

Peter T Lillehei

Jag J Singh

Patrick E Cassidy

James David Rancourt

Bruce D Little

Robin E Southward

John W Fitch, Iii

David W Thompson

Scott D Gronewald

Gilda A Miner

Gregory A Gaddy

Brent D Koplitz

Steven M Simpson

Michael F Lynch

Samuel C Ruffner

A new fabrication method for nanovoids-imbedded bismuth telluride (Bi&#x2014;Te) material with low dimensional (quantum-dots, quantum-wires, or quantum-wells) structure was conceived during the development of advanced thermoelectric (TE) materials. Bismuth telluride is currently the best-known candidate material for solid-state TE cooling devices because it possesses the highest TE figure of merit at room temperature. The innovative process described here allows nanometer-scale voids to be incorporated in Bi&#x2014;Te material. The final nanovoid structure such as void size, size distribution, void location, etc. can be also controlled under various process conditions.

Fabrication of nanovoid-imbedded bismuth telluride with low dimensional system

A novel method to prepare an advanced thermoelectric material has hierarchical structures embedded with nanometer-sized voids which are key to enhancement of the thermoelectric performance. Solution-based thin film deposition technique enables preparation of stable film of thermoelectric material and void generator (voigen). A subsequent thermal process creates hierarchical nanovoid structure inside the thermoelectric material. Potential application areas of this advanced thermoelectric material with nanovoid structure are commercial applications (electronics cooling), medical and scientific applications (biological analysis device, medical imaging systems), telecommunications, and defense and military applications (night vision equipments).

Fabrication of advanced thermoelectric materials by hierarchical nanovoid generation

Self-metallizing polyimide films are created by doping polyamic acid solutions with metallic ions and solubilizing agents. Upon creating a film, the film is exposed to coherent light for a specific time and then cured. The resulting film has been found to have a metallic surface layer and a metallic subsurface layer (interlayer). The layer separating the metallic layer has a uniform dispersion of small metal particulates within the polymer. The layer below the interlayer has larger metal particulates uniformly distributed within the polymer. By varying the intensity or time of exposure to the coherent light, three-dimensional control of metal formation within the film is provided.

Laser-induced fabrication of metallic interlayers and patterns in polyimide films

A lattice matched silicon germanium (SiGe) semiconductive alloy is formed when a {111} crystal plane of a cubic diamond structure SiGe is grown on the {0001} C-plane of a single crystalline AlOsubstrate such that a &#x3c;110&#x3e; orientation of the cubic diamond structure SiGe is aligned with a &#x3c;1,0,&#x2212;1,0&#x3e; orientation of the {0001} C-plane. A lattice match between the substrate and the SiGe is achieved by using a SiGe composition that is 0.7223 atomic percent silicon and 0.2777 atomic percent germanium. A layer of SiGeis formed on the cubic diamond structure SiGe. The value of X (i) defines an atomic percent of germanium satisfying 0.2277&#x3c;X&#x3c;1.0, (ii) is approximately 0.2777 where the layer of SiGeinterfaces with the cubic diamond structure SiGe, and (iii) increases linearly with the thickness of the layer of SiGe.

Graded index silicon geranium on lattice matched silicon geranium semiconductor alloy

Poly(aryl ether ketones) bearing alkylated side chains

Self-metallizing, flexible polyimide films with highly reflective surfaces are prepared by an in situ self-metallization procedure involving thermally initiated reduction of polymer-soluble silver(I) complexes. Polyamic acid solutions are doped with silver(I) acetate and solubilizing agents. Thermally curing the silver(I)-doped resins leads to flexible, metallized films which have reflectivities as high as 100%, abrasion-resistant surfaces, thermal stability and, in some cases, electrical conductivity, rendering them useful for space applications.

Reflective silvered polyimide films via in situ thermal reduction silver

An electrically conductive, thermooxidatively stable poltimide, especially a film thereof, is prepared from an intimate admixture of a particular polyimide and gold (III) ions, in an amount sufficient to provide between 17 and 21 percent by weight of gold (III) ions, based on the weight of electrically conductive, thermooxidatively stable polyimide. The particular polyimide is prepared from a polyamic acid which has been synthesized from a dianhydride/diamine combination selected from the group consisting of 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 2,2-bis[4-(4 -aminophenoxy)phenyl]hexafluoropropane; 3,3',4,4'-benzophenonetetracarboxylic dianhydride and 4,4'-oxydianiline; 2,2'-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride and 4,4'-oxydianiline; and 3,3'4,4'-benzophenonetetracarboxylic dianhydride and 2,2-bis(3-aminophenyl)hexafluoropropane.

Electrically conductive polyimide film containing gold (III) ions,

Polyimides with enhanced electrical conductivity are produced by adding a silver ion-containing additive to the polyamic acid resin formed by the condensation of an aromatic dianhydride with an aromatic diamine. After thermal treatment the resulting polyimides had surface conductivities in the range of 1.7.times.10.sup.-3 4.5 .OMEGA..sup.-1 making them useful in low the electronics industry as flexible, electrically conductive polymeric films and coatings.

Electrically conductive polyimides containing silver

An assembly of an article and a polyimide composition is prepared. The assembly resists dimensional change, delamination, or debonding when exposed to changes in temperature. An article is provided. A polyamic acid solution which yields a polyimide having a low coefficient of thermal expansion (CTE) was prepared. Equimolar quantities of an aromatic diamine and an aromatic dianhydride were reacted in a solvent medium to form a polyamic acid solution. A metal ion-containing additive was added to the solution. Examples of this additive are: TbCl.sub.3, DyCl.sub.3, ErCl.sub.3, TmCl.sub.3, Al(C.sub.5 H.sub.7 O.sub.2).sub.3, and Er.sub.2 S.sub.3. The polyamic acid solution was imidized and is combined with the article to form the assembly.

Process for preparing an assembly of an article and a polymide which

A process for preparing polyamides having enhanced melt flow properties is described. The process consists of heating a mixture of a high molecular weight poly(amic acid) or polyimide with a low molecular weight amic acid or imide additive in the range of 0.05 to 15% by weight of additive. The polyimide powders so obtained show improved processability, as evidenced by lower melt viscosity by capillary rheometry. Likewise, films prepared from mixtures of polymers with additives show improved processability with earlier onset of stretching by TMA.

Polyimide processing additives

An assembly of an article and a polyimide is prepared. The assembly resists dimensional change, delamination, or debonding when exposed to changes in temperature. An article is provided. A soluble polyimide resin solution having a low coefficient of thermal expansion (CTE) was prepared by dissolving the polyimide in solvent and adding a metal ion-containing additive to the solution. Examples of this additive are: Ho(OOCCH.sub.3).sub.3, Er(NPPA).sub.3, TmCl.sub.3, and Er(C.sub.5 H.sub.7 O.sub.2).sub.3. The soluble polyimide resin is combined with the article to form the assembly.

Process for preparing an assembly of an article and a soluble polyimide

A process for preparing polyimides having enhanced melt flow properties is described. The process consists of heating a mixture of a high molecular weight poly(amic acid) or polyimide with a low molecular weight amic acid or imide additive in the range of 0.05 to 15% by weight of additive. The polyimide powders so obtained show improved processability, as evidenced by lower melt viscosity by capillary rheometry. Likewise, films prepared from mixtures of polymers with additives show improved processability with earlier onset of stretching by TMA.

Linear aromatic polyimides with low dielectric constants are produced by adding a diamic acid additive to the polyamic acid resin formed by the condensation of an aromatic dianhydride with an aromatic diamine. The resulting modified polyimide is a better electrical insulator than state-of-the-art commercially available polyimides.

Process for lowering the dielectric constant of polyimides using diamic

A set of film clamps and a mounting block for use in the determination of tensile modulus and damping properties of films in a manually operated or automated Rheovibron. These clamps and mounting block provide uniformity of sample gripping and alignment in the instrument. Operator dependence and data variability are greatly reduced.

Tensile film clamps and mounting block for the rheovibron and autovibron

A product and the process for preparing the same to improve the moisture resistance properties of epoxidized TGMDA and DGEBA resin systems by chemically incorporating chromium (III) ions therein without impairing the mechanical strength properties of the resins.

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Poquoson, VA, United States of America

Diane M Stoakley