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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Electrical Conductivity and Electrochemical Characteristics of Na{sub 3}V{sub 2}(PO{sub 4}){sub 3}-Based NASICON-Type Materials

NASICON-type materials with the compositions Na{sub 3}V{sub 2–x}Al{sub x}(PO{sub 4}){sub 3}, Na{sub 3}V{sub 2-} {sub x}Fe{sub x}(PO{sub 4}){sub 3}, Na{sub 3+} {sub x}V{sub 2–x}Ni{sub x}(PO{sub 4}){sub 3}, and Na{sub 3}V{sub 2-} {sub x}Cr{sub x}(PO{sub 4}){sub 3} (x = 0, 0.03, 0.05, and 0.1) have been prepared and characterized by X-ray diffraction analysis, electron microscopy, and impedance spectroscopy. The results demonstrate that the highest electrical conductivity among the samples studied is offered by the material doped with 5% Fe: Na{sub 3}V{sub 1.9}Fe{sub 0.1}(PO{sub 4}){sub 3}. The activation energy for low-temperature conduction in the doped materials decreases from 84 ± 2 to 54 ± 1 kJ/mol and that for high-temperature conduction is ~33 kJ/mol. The discharge capacity of Na{sub 3}V{sub 1.9}Fe{sub 0.1}(PO{sub 4}){sub 3}/C under typical working conditions of cathodes of sodium ion batteries has been shown to exceed that of Na{sub 3}V{sub 2}(PO{sub 4}){sub 3}/C. The capacity of the more porous material prepared by the Pechini process (Na{sub 3}V{sub 1.9}Fe{sub 0.1}(PO{sub 4}){sub 3}/C-{II}) approaches the theoretical one at a low charge–discharge rate and retains its high level as the charge rate is raised (its discharge capacity was 117.6, 108.8, and 82.6 mAh/g at a discharge rate of 0.1C, 2C, and 8C, respectively).

25 ENERGY STORAGE↗
DOE OSTI2018

Effect of Conditions of Electrochemical Etching on the Morphological, Structural, and Optical Properties of Porous Gallium Arsenide

The properties of porous GaAs samples produced by the electrochemical etching of single-crystal n-GaAs(100) wafers are studied by X-ray diffraction analysis, electron microscopy, and infrared and ultraviolet spectroscopy. It is possible to show that, by choosing the composition of the electrolyte and the conditions of etching, samples can be produced not only with different degrees of porosity and pore sizes (nanopores/micropores), but with another type of sample surface as well. The etching of n-GaAs(100) wafers under the conditions chosen in the study does not change the orientation of the porous layer with respect to the orientation of the single-crystal GaAs(100) substrate. At the same time, etching induces a decrease in the half-width of the diffraction peak compared to that for the initial wafer, a splitting of the phonon mode in the infrared spectra and a partial shift of the components in accordance with the parameters of anodic etching, and a change in the optical properties in the ultraviolet region.

36 MATERIALS SCIENCE↗
NASA NTRS1974

Differential phonograms

A new noise measuring method is outlined that is based on electronic analysis of the radiated noise. Non-relevant components are suppressed, while the differential phonogram displayed on the oscilloscope screen discloses the information carrying components. It allows low skilled operators to perform: (1) correct alignment of equipment; (2) detection of incipient failure; and (3) checking of prototypes.

Halpert, E.↗
NASA NTRS1978

Use of satellite images in the evaluation of farmlands

Remote sensing techniques in the evaluation of farmland in Mexico are discussed. Electronic analysis techniques and photointerpretation techniques are analyzed. Characteristics of the basic crops in Mexico as related to remote sensing are described.

Lozano H., A. E.↗
NASA NTRS1978

Study program to develop and evaluate die and container materials for the growth of silicon ribbons

Initial sessile drop experiments on SiC, Si3N4 and A1N were conducted. Very promising results were achieved on both SiC and Si3N4 where minimal penetration of these CNTD coatings by molten silicon was observed. More detailed characterization of the CNTD microstructures was accomplished as well as X-ray characterization of the third and fourth candidate materials system sets (i.e. A1N and altered Si3N4). Polished sections of post sessile drop specimens were also prepared and evaluated. The techniques of full scale crucible hot pressing were developed and die grinding development was initiated. The apparatus for measurement of oxygen partial pressure was reconstructed and calibrated. The sessile drop temperature measurement procedure was calibrated for absorption by the pyrex view-port and additional Auger electron analysis was performed at the interface of molten silicon with CNTD Si3N4 and A1N.

Source record↗
NASA NTRS1987

Advanced hydrogen electrode for hydrogen-bromide battery

Binary platinum alloys are being developed as hydrogen electrocatalysts for use in a hydrogen bromide battery system. These alloys were varied in terms of alloy component mole ratio and heat treatment temperature. Electrocatalyst evaluation, performed in the absence and presence of bromide ion, includes floating half cell polarization studies, electrochemical surface area measurements, X ray diffraction analysis, scanning electron microscopy analysis and corrosion measurements. Results obtained to date indicate a platinum rich alloy has the best tolerance to bromide ion poisoning.

Kosek, Jack A.↗
NASA NTRS1991

Approaches for optimizing the first electronic hyperpolarizability of conjugated organic molecules

Conjugated organic molecules with electron-donating and -accepting moieties can exhibit large electronic second-order nonlinearities, or first hyperpolarizabilities, beta. The present two-state, four-orbital independent-electron analysis of beta leads to the prediction that its absolute value will be maximized at a combination of donor and acceptor strengths for a given conjugated bridge. Molecular design strategies for beta optimization are proposed which give attention to the energetic manipulations of the bridge states. Experimental results have been obtained which support the validity of this approach.

Marder, S. R.↗
NASA NTRS1998

Fundamentals of Passive Oxidation In SiC and Si3N4

The very slow oxidation kinetics of silicon carbide and silicon nitride, which derive from their adherent and passivating oxide films, has been explored at length in a broad series of studies utilizing thermogravimetric analysis, electron and optical micrography, energy dispersive spectrometry, x-ray diffractometry, micro-analytical depth profiling, etc. Some interesting microstructural phenomena accompanying the process of oxidation in the two materials will be presented. In Si3N4 the oxide is stratified, with an SiO2 topscale (which is relatively impervious to O2)underlain by a coherent subscale of silicon oxynitride which is even less permeable to O2- Such "defence in depth" endows Si3N4 with what is perhaps the highest oxidation resistance of any material, and results in a unique set of oxidation processes. In SiC the oxidation reactions are much simpler, yet new issues still emerge; for instance, studies involving controlled devitrification of the amorphous silica scale confirmed that the oxidation rate of SiC drops by more than an order of magnitude when the oxide scale fully crystallizes.

Thomas-Ogbuji, Linus U.↗
NASA NTRS1993

Pigmenting agents in Martian soils: inferences from spectral, Mossbauer, and magnetic properties of nanophase and other iron oxides in Hawaiian palagonitic soil PN-9

We have examined a Hawaiian palagonitic tephra sample (PN-9) that has spectroscopic similarities to Martian bright regions using a number of analytical techniques, including Mossbauer and reflectance spectroscopy, X-ray diffraction, instrumental neutron activation analysis, electron probe microanalysis, transmission electron microscopy, and dithionite-citrate-bicarbonate extraction. Chemically, PN-9 has a Hawaiitic composition with alkali (and presumably silica) loss resulting from leaching by meteoric water during palagonitization; no Ce anomaly is present in the REE pattern. Mineralogically, our results show that nanophase ferric oxide (np-Ox) particles (either nanophase hematite (np-Hm) or a mixture of ferrihydrite and np-Hm) are responsible for the distinctive ferric doublet and visible-wavelength ferric absorption edge observed in Mossbauer and reflectivity spectra, respectively, for this and other spectrally similar palagonitic samples. The np-Ox particles appear to be imbedded in a hydrated aluminosilicate matrix material; no evidence was found for phyllosilicates. Other iron-bearing phases observed are titanomagnetite, which accounts for the magnetic nature of the sample; olivine; pyroxene; and glass. By analogy, np-Ox is likely the primary pigmenting agent of the bright soils and dust of Mars.

Minerals/analysis↗
NASA NTRS1996

NASA Tech Briefs, September 1996

Topics: Data Acquisition and Analysis; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences; Books and Reports.

Source record↗
NASA NTRS1997

NASA Tech Briefs, September 1997

Topics include: Data Acquisition and Analysis; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Software; Mechanics; Machinery/Automation; Manufacturing/Fabrication; Mathematics and Information Sciences.

Source record↗
NASA NTRS1993

NASA Tech Briefs, July 1993

Topics include: Data Acquisition and Analysis: Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences.

Source record↗
NASA NTRS2012

The Shock State of Itokawa Sample

One of the fundamental aspects of any astromaterial is its shock history, since this factor elucidates critical historical events, and also because shock metamorphism can alter primary mineralogical and petrographic features, and reset chronologies [1]. Failure to take shock history into proper account during characterization can result in seriously incorrect conclusions being drawn. Thus the Hayabusa Preliminary Examination Team (HASPET) made shock stage determination of the Itokawa samples a primary goal [2]. However, we faced several difficulties in this particular research. The shock state of ordinary chondrite materials is generally determined by simple optical petrographic observation of standard thin sections. The Itokawa samples available to the analysis team were mounted into plastic blocks, were polished on only one side, and were of non-standard and greatly varying thickness, all of which significantly complicated petrographic analysis but did not prevent it. We made an additional estimation of the sample shock state by a new technique for this analysis - electron back-scattered diffraction (EBSD) in addition to standard petrographic techniques. We are also investigating the crystallinity of Itokawa olivine by Synchrotron X-ray diffraction (SXRD).

Zolensky, Michael↗
DOE OSTI2016

Data mining graphene: Correlative analysis of structure and electronic degrees of freedom in graphenic monolayers with defects

The link between changes in the material crystal structure and its mechanical, electronic, magnetic, and optical functionalities known as the structure-property relationship is the cornerstone of the contemporary materials science research. The recent advances in scanning transmission electron and scanning probe microscopies (STEM and SPM) have opened an unprecedented path towards examining the materials structure property relationships on the single-impurity and atomic-configuration levels. Lacking, however, are the statistics-based approaches for cross-correlation of structure and property variables obtained in different information channels of the STEM and SPM experiments. Here we have designed an approach based on a combination of sliding window Fast Fourier Transform, Pearson correlation matrix, linear and kernel canonical correlation, to study a relationship between lattice distortions and electron scattering from the SPM data on graphene with defects. Our analysis revealed that the strength of coupling to strain is altered between different scattering channels which can explain coexistence of several quasiparticle interference patterns in the nanoscale regions of interest. In addition, the application of the kernel functions allowed us extracting a non-linear component of the relationship between the lattice strain and scattering intensity in graphene. Lastly, the outlined approach can be further utilized to analyzing correlations in various multi-modal imaging techniques where the information of interest is spatially distributed and has usually a complex multidimensional nature.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Liquid Extraction Surface Analysis (LESA) Electron-Induced Dissociation and Collision-Induced Dissociation Mass Spectrometry of Small Molecule Drug Compounds

Here, we present liquid extraction surface analysis (LESA) coupled with electron-induced dissociation (EID) mass spectrometry in a Fourier-transform ion cyclotron resonance mass spectrometer for the analysis of small organic pharmaceutical compounds directly from dosed tissue. First, the direct infusion electrospray ionisation EID and collision-induced dissociation (CID) behaviour of erlotinib, moxifloxacin, clozapine and olanzapine standards were compared. EID mass spectra were also compared with experimental or reference electron impact ionisation mass spectra. The results show that (with the exception of erlotinib) EID and CID result in complementary fragment ions. Subsequently, we performed LESA EID MS/MS and LESA CID MS/MS on singly charged ions of moxifloxacin and erlotinib extracted from a thin tissue section of rat kidney from a cassette-dosed animal. Both techniques provided structural information, with the majority of peaks observed for the drug standards also observed for the tissue-extracted species. Overall, these results demonstrate the feasibility of LESA EID MS/MS of drug compounds from dosed tissue and extend the number of molecular structures for which EID behaviour has been determined. .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗