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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Electrostatic Properties of Polymers Subjected to Atmospheric Pressure Plasma Treatment; Correlation of Experimental Results with Atomistic Modeling

this study, PE, PTFE, PS and PMMA were exposed to a He+O2, APGD and pre and post treatment surface chemistries were analyzed by X-ray photoelectron spectroscopy and contact angle measurements. Semi-empirical and ab-initio calculations were performed to correlate the experimental results with sonic plausible molecular and electronic structure features of the oxidation process. For the PE and PS, significant surface oxidation showing C-O, C=O, and O-C=O bonding, and a decrease in the surface contact angles was observed. For the PTFE and PM MA, little change in the surface composition was observed. The molecular modeling calculations were performed on single and multiple oligomers and showed regardless of oxidation mechanism, e.g. -OH, =O or a combination thereof, experimentally observed levels of surface oxidation were unlikely to lead to a significant change in the electronic structure of PE and PS, and that the increased hydrophilic properties are the primary reason for the observed changes in its electrostatic behavior. Calculations for PTFE and PMMA argue strongly against significant oxidation of those materials, as confirmed by the XPS results.

Trigwell, S.↗
NASA NTRS2019

Diamondites: Evidence for a Distinct Tectono-Thermal Diamond-Forming Event Beneath the Kaapvaal Craton

The petrogenesis and relationship of diamondite to well-studied monocrystalline and fibrous diamonds are poorly understood yet would potentially reveal new aspects of how diamond-forming fluids are transported through the lithosphere and equilibrate with surrounding silicates. Of twenty-two silicate- and oxide-bearing diamondites investigated, most yielded garnet intergrowths (n = 15) with major element geochemistry (i.e. Ca-Cr) classifying these samples as low-Ca websteritic or eclogitic. The garnet REE patterns fit an equilibrium model suggesting the diamond-forming fluid shares an affinity with high-density fluids (HDF) observed in fibrous diamonds, specifically on the join between the saline–carbonate end- members. The δ13C values for the diamonds range from -5.27 to -22.48 ‰ (V-PDB) with δ18O values for websteritic garnets ranging from +7.6 to +5.9 ‰ (V-SMOW). The combined C-O stable isotope data support a model for a hydrothermally altered and organic carbon-bearing subducted crustal source(s) for the diamond- and garnet-forming media. The nitrogen aggregation states of the diamonds require that diamondite-formation event(s) pre-dates fibrous diamond-formation and post-dates most of the gem monocrystalline diamond-formation events at Orapa. The modelled fluid compositions responsible for the precipitation of diamondites match the fluid-poor and fluid-rich (fibrous) monocrystalline diamonds, where all grow from HDFs within the saline-silicic-carbonatitic ternary system. However, while the nature of the parental fluid(s) share a common lithophile element geochemical affinity, the origin(s) of the saline, silicic, and/or carbonatitic components of these HDFs do not always share a common origin. Therefore, it is wholly conceivable that the diamondites are evidence of a distinct and temporally unconstrained tectono-thermal diamond-forming event beneath the Kaapvaal craton.

S Mikhail↗
DOE OSTI2021

Assessing the Role of Interfacial and Metal Sites in Pt/TiO2-Catalyzed Acetic Acid Hydrodeoxygenation

The work summarized in this presentation builds off of these studies, utilizing atomic-scale modeling to discern the role of Pt-metal and Pt-TiO2-interfacial sites in promoting key C-C bond-breaking, C-O bond-breaking, and (de)hydrogenation steps in acetic acid HDO. By considering Pt(111) and Pt-TiO2-interface surface models, adsorption and reaction energetics calculated by density funcational theory provide fundamental insights into the role of both interfacial sites and oxygen vacancies in promoting desired deoxygenation pathways over undesired decarboxylation/decarbonylation pathways.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2022

Graphite Oxidation Behavior: NRC Graphite Behavior Model

Graphite microstructure and oxidation Graphite crystal structure and basal planes Reactive surface area sites Zig-zag and Arm-chair Pore microstructure effects Interconnectivity Reactivity and oxygen transport Oxygen-graphitereaction Not C-O reaction! Temperature effects Oxygen diffusion to graphite Diffusion into the microstructure High temperature vs low temperature diffusion Oxidation: It’s a gradient of factors

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Controlling Reaction Routes in Noble‐Metal‐Catalyzed Conversion of Aryl Ethers

Abstract Hydrogenolysis and hydrolysis of aryl ethers in the liquid phase are important reactions for accessing functionalized cyclic compounds from renewable feedstocks. On supported noble metals, hydrogenolysis is initiated by a hydrogen addition to the aromatic ring followed by C−O bond cleavage. In water, hydrolysis and hydrogenolysis proceed by partial hydrogenation of the aromatic ring prior to water or hydrogen insertion. The mechanisms are common for the studied metals, but the selectivity to hydrogenolysis increases in the order Pd 2 pressure, thus, the selectivity to hydrogenolysis is maximized by increasing temperature and decreasing H 2 pressure. Selectivity to C−O bond cleavage reaches >95 % in water and alkaline conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Elucidating the Active Site and the Role of Alkali Metals in Selective Hydrodeoxygenation of Phenols over Iron-Carbide-based Catalyst

In this study, iron-carbide-based catalysts have been explored in the selective hydrodeoxygenation (HDO) of phenol, aiming at elucidating the role of active site and alkali metal. Complementary characterization such as X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and scanning transmission electron microscopy coupled with electron energy loss spectroscopy, together with catalytic evaluations revealed a rapid structural reconstruction of iron carbide (Fe 3 C) catalysts, leading to a stable defective graphene-covered metallic Fe active phase (G@Fe) under reaction conditions. Further studies using different alkali metals (i.e., Na, K, and Cs) revealed that alkali metals showed negligible effect on the phase transformation of Fe 3 C. However, the reconstructed G@Fe doped with alkali metals inhibited the tautomerization, a facile reaction pathway to saturation of the aromatic ring, leading to enhanced selectivity to arene. The extent of inhibition of tautomerization or selectivity to arene was closely related to the degree of electron donation of alkali metal to Fe.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

High-resolution spectroscopy of gaseous 83m Kr conversion electrons with the KATRIN experiment

Abstract In this work, we present the first spectroscopic measurements of conversion electrons originating from the decay of metastable gaseous 83m Kr with the Karlsruhe Tritium Neutrino (KATRIN) experiment. The obtained results represent one of the major commissioning milestones for the subsequent direct neutrino mass measurement with KATRIN. The successful campaign demonstrates the functionalities of the KATRIN beamline. Precise measurement of the narrow K-32, L 3 -32, and N 2,3 -32 conversion electron lines allowed to verify the eV-scale energy resolution of the KATRIN main spectrometer necessary for competitive measurement of the absolute neutrino mass scale.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Materials Data on CO2 by Materials Project

CO2 is Cyanogen Chloride-derived structured and crystallizes in the tetragonal P4_12_12 space group. The structure is zero-dimensional and consists of four carbon dioxide molecules. C4+ is bonded in a linear geometry to two equivalent O2- atoms. Both C–O bond lengths are 1.17 Å. O2- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CO by Materials Project

CO is alpha carbon monoxide structured and crystallizes in the cubic P2_13 space group. The structure is zero-dimensional and consists of four formaldehyde molecules. C2+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.14 Å. O2- is bonded in a single-bond geometry to one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CO2 by Materials Project

CO2 is Cyanogen Chloride-derived structured and crystallizes in the orthorhombic Pbcn space group. The structure is zero-dimensional and consists of four carbon dioxide molecules. C4+ is bonded in a linear geometry to two equivalent O2- atoms. Both C–O bond lengths are 1.18 Å. O2- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CO by Materials Project

CO is alpha carbon monoxide-like structured and crystallizes in the trigonal R3c space group. The structure is zero-dimensional and consists of twenty-four formaldehyde molecules. C2+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.14 Å. O2- is bonded in a single-bond geometry to one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on C3O2 by Materials Project

C3O2 is Cyanogen Chloride-derived structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of eight hydroxypropinol molecules. there are three inequivalent C+1.33+ sites. In the first C+1.33+ site, C+1.33+ is bonded in a single-bond geometry to one C+1.33+ and one O2- atom. The C–C bond length is 1.28 Å. The C–O bond length is 1.18 Å. In the second C+1.33+ site, C+1.33+ is bonded in a single-bond geometry to one C+1.33+ and one O2- atom. The C–C bond length is 1.28 Å. The C–O bond length is 1.18 Å. In the third C+1.33+ site, C+1.33+ is bonded in a linear geometry to two C+1.33+ atoms. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a single-bond geometry to one C+1.33+ atom. In the second O2- site, O2- is bonded in a single-bond geometry to one C+1.33+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on C4O3 by Materials Project

OC4O2 crystallizes in the trigonal R3 space group. The structure is zero-dimensional and consists of thirty-six formic anhydride molecules and seventy-two methane molecules.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CO2 by Materials Project

CO2 is Cyanogen Chloride-derived structured and crystallizes in the tetragonal P4_2/mnm space group. The structure is zero-dimensional and consists of two carbon dioxide molecules. C4+ is bonded in a linear geometry to two equivalent O2- atoms. Both C–O bond lengths are 1.17 Å. O2- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CO by Materials Project

CO is alpha carbon monoxide-like structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four formaldehyde molecules. C2+ is bonded in a single-bond geometry to one O2- atom. The C–O bond length is 1.22 Å. O2- is bonded in a single-bond geometry to one C2+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CO2 by Materials Project

CO2 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of two CO2 ribbons oriented in the (0, 1, 0) direction. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.19–1.40 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent C4+ atoms. In the second O2- site, O2- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on CO2 by Materials Project

CO2 crystallizes in the tetragonal I4_1/a space group. The structure is one-dimensional and consists of four CO2 ribbons oriented in the (0, 0, 1) direction. C4+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of C–O bond distances ranging from 1.19–1.42 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 120 degrees geometry to two equivalent C4+ atoms. In the second O2- site, O2- is bonded in a single-bond geometry to one C4+ atom.

36 MATERIALS SCIENCE↗