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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS2000

Porous article with surface functionality and method for preparing same

Porous organic articles having no surface functionality may be treated by remote plasma discharge to thereby introduce functionality to the surface of the article. The functionality is introduced throughout the article's surface, including the exterior surface and the surfaces of the pores. Little or no degradation of the porous organic article occurs as a result of the functionalization. Amino, hydroxyl, carbonyl and carboxyl groups may be introduced to the article. In this way, an essentially inert hydrophobic porous article, made from, for example, polyethylene, can have its surface modified so that the surface becomes hydrophilic. The remote plasma discharge process causes essentially no change in the bulk properties of the organic article. The remote plasma discharge process is preferably conducted so that no photons, and particularly no ultraviolet radiation, is transmitted from the plasma glow to the porous article. The surface-functionalized article may be used, for example, as a solid support in organic synthesis or in the chromatographic purification of organic or biochemicals.

Koontz, Steven L.↗
NASA NTRS1998

Advanced thermoelectric materials with enhanced crystal lattice structure and methods of preparation

New skutterudite phases including Ru.sub.0.5 Pd.sub.0.5 Sb.sub.3, RuSb.sub.2 Te, and FeSb.sub.2 Te, have been prepared having desirable thermoelectric properties. In addition, a novel thermoelectric device has been prepared using skutterudite phase Fe.sub.0.5 Ni.sub.0.5 Sb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor compounds and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor materials having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using powder metallurgy techniques. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities and good Seebeck coefficients. These materials have low thermal conductivity and relatively low electrical resistivity, and are good candidates for low temperature thermoelectric applications.

Fleurial, Jean-Pierre↗
NASA NTRS2004

Porous article with surface functionality and method for preparing same

Porous organic articles having no surface functionality may be treated by remote plasma discharge to thereby introduce functionality to the surface of the article. The functionality is introduced throughout the article's surface, including the exterior surface and the surfaces of the pores. Little or no degradation of the porous organic article occurs as a result of the functionalization. Amino, hydroxyl, carbonyl and carboxyl groups may be introduced to the article. In this way, an essentially inert hydrophobic porous article, made from, for example, polyethylene, can have its surface modified so that the surface becomes hydrophilic. The remote plasma discharge process causes essentially no change in the bulk properties of the organic article. The remote plasma discharge process is preferably conducted so that no photons, and particularly no ultraviolet radiation, is transmitted from the plasma glow to the porous article. The surface-functionalized article may be used, for example, as a solid support in organic synthesis or in the chromatographic purification of organic or biochemicals.

Koontz, Steven L.↗
NASA NTRS1997

High performance thermoelectric materials and methods of preparation

Transition metals (T) of Group VIII (Co, Rh and Ir) have been prepared as semiconductor alloys with Sb having the general formula TSb.sub.3. The skutterudite-type crystal lattice structure of these semiconductor alloys and their enhanced thermoelectric properties results in semiconductor materials which may be used in the fabrication of thermoelectric elements to substantially improve the efficiency of the resulting thermoelectric device. Semiconductor alloys having the desired skutterudite-type crystal lattice structure may be prepared in accordance with the present invention by using vertical gradient freeze techniques, liquid-solid phase sintering techniques, low temperature powder sintering and/or hot-pressing. Measurements of electrical and thermal transport properties of selected semiconductor materials prepared in accordance with the present invention, demonstrated high Hall mobilities (up to 8000 cm.sup.2.V.sup.-1.s.sup.-1), good Seebeck coefficients (up to 400 .mu.VK.sup.-1 between 300.degree. C. and 700.degree. C.), and low thermal conductivities (as low as 15 mW/cmK). Optimizing the transport properties of semiconductor materials prepared from elemental mixtures Co, Rh, Ir and Sb resulted in a two fold increase in the thermoelectric figure of merit (ZT) at temperatures as high as 400.degree. C. for thermoelectric elements fabricated from such semiconductor materials.

Fleurial, Jean-Pierre↗
DOE OSTI2021

Rapid consolidation method for preparing bulk metastable iron-rich materials

Interstitially modified compounds of rare earth element-containing, iron-rich compounds may be synthesized with a ThMn 12 tetragonal crystal structure such that the compounds have useful permanent magnet properties. It is difficult to consolidate particles of the compounds into a bulk shape without altering the composition and magnetic properties of the metastable material. A combination of thermal analysis and crystal structure analysis of each compound may be used to establish heating and consolidation parameters for sintering of the particles into useful magnet shapes.

Zhou, Chen↗
DOE OSTI2021

Continuous method for preparing carbonate esters

In one embodiment, a continuous process for preparing organic carbonate solvent of Formula (I) as described herein comprises contacting a first reactant (an alcohol) with a reactive carbonyl source (carbonyldiimidazole (CDI) or an alkylchloroformate) in the presence of a catalyst in reaction stream flowing through a continuous flow reactor at temperature 20° C. to about 160° C. and at a flow rate providing a residence time in the range of about 0.1 minute to about 24 hours; collecting a reactor effluent exiting from the continuous flow reactor; recovering a crude product from the reactor effluent; and distilling the crude product to obtain the organic carbonate compound of Formula (I). In another embodiment, the first reactant is an epoxide and the carbonyl source is carbon dioxide.

Dzwiniel, Trevor L.↗
DOE OSTI2021

Multi-layer coatings and methods of preparing the same

A multi-layer coating includes: a first basecoat layer applied over at least a portion of a substrate; and a second basecoat layer applied over the first basecoat layer. The first basecoat layer and second basecoat layer are formed from compositions having a polyhydrazide and core-shell particles dispersed in aqueous mediums. The core-shell particles of the first basecoat composition includes (1) a polymeric core at least partially encapsulated by (2) a polymeric shell comprising urea linkages, and keto and/or aldo functional groups. The polymeric core of the core-shell particles of the first basecoat composition and the second basecoat composition are each independently covalently bonded to at least a portion of the polymeric shell of the core-shell particles.

Xu, Xiangling↗
DOE OSTI2023

Lead-lead oxide-carbon nanocomposite for energy storage cells and method of preparation

Lead/lead oxide/carbon (“Pb—O—C”) nanocomposite materials are useful as electrode active materials for electrodes in lithium and sodium batteries. A Pb—O—C nanocomposite as described herein comprises Pb and lead oxide nanoparticles homogeneously dispersed in a carbon nanoparticle matrix. In the nanocomposite, the other element or elements (e.g., transition metals, Al, Si, P, Sn, Sb, and Bi) can be alloyed with the Pb nanoparticles, incorporated as a mixed oxide with the lead oxide nanoparticles, or can be present as distinct elemental or oxide nanoparticles within the carbon nanoparticle matrix. In some embodiments, the additional element or elements are present as alloys and mixed oxides with the Pb materials and as distinct elemental and/or oxide nanoparticles. In a preferred embodiment the Pb nanoparticles surface is oxidized to lead oxide thus creating a shell on core nanostructure.

Johnson, Christopher S.↗
DOE OSTI2023

Stabilized lithium metal oxide electrode material and method of preparation

A stabilized lithium metal oxide cathode material comprises microparticles of lithium metal oxide in which individual particles thereof a core of lithium metal oxide and a coating of a different lithium metal oxide surrounding the core. There is an interface layer between the cores and the coatings in which there are gradients of metal ions in the direction of coating to core. The materials are made by a three stage process involving coprecipitating precursor metal hydroxide core particles at a controlled pH; coprecipitating a different metal hydroxide coating on the particles without controlling the pH; and then calcining the resulting coated precursor particles with lithium hydroxide to form the stabilized lithium metal oxide material.

Lipson, Albert L.↗
DOE OSTI2023

Continuous method for preparing carbonate esters

In one embodiment, a continuous process for preparing organic carbonate solvent of Formula (I) as described herein comprises contacting a first reactant (an alcohol) with a reactive carbonyl source (carbonyldiimidazole (CDI) or an alkylchloroformate) in the presence of a catalyst in reaction stream flowing through a continuous flow reactor at temperature 20° C. to about 160° C. and at a flow rate providing a residence time in the range of about 0.1 minute to about 24 hours; collecting a reactor effluent exiting from the continuous flow reactor; recovering a crude product from the reactor effluent; and distilling the crude product to obtain the organic carbonate compound of Formula (I). In another embodiment, the first reactant is an epoxide and the carbonyl source is carbon dioxide.

Dzwiniel, Trevor L.↗
DOE OSTI2024

Stabilized lithium metal oxide electrode material and method of preparation

A stabilized lithium metal oxide cathode material comprises microparticles of lithium metal oxide in which individual particles thereof a core of lithium metal oxide and a coating of a different lithium metal oxide surrounding the core. There is an interface layer between the cores and the coatings in which there are gradients of metal ions in the direction of coating to core. The materials are made by a three stage process involving coprecipitating precursor metal hydroxide core particles at a controlled pH; coprecipitating a different metal hydroxide coating on the particles without controlling the pH; and then calcining the resulting coated precursor particles with lithium hydroxide to form the stabilized lithium metal oxide material.

Lipson, Albert L.↗
DOE OSTI2022

Hybrid quantum-classical approach for coupled-cluster Green's function theory

The three key elements of a quantum simulation are state preparation, time evolution, and measurement. While the complexity scaling of time evolution and measurements are well known, many state preparation methods are strongly system-dependent and require prior knowledge of the system's eigenvalue spectrum. Here, we report on a quantum-classical implementation of the coupled-cluster Green's function (CCGF) method, which replaces explicit ground state preparation with the task of applying unitary operators to a simple product state. While our approach is broadly applicable to many models, we demonstrate it here for the Anderson impurity model (AIM). The method requires a number of T gates that grows as O ( N 5 ) per time step to calculate the impurity Green's function in the time domain, where N is the total number of energy levels in the AIM. Since the number of T gates is analogous to the computational time complexity of a classical simulation, we achieve an order of magnitude improvement over a classical CCGF calculation of the same order, which requires O ( N 6 ) computational resources per time step.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗