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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Pulse radiolysis of epoxy-based matrix materials

Electron beam pulse radiolysis (600 KeV, 3 nsec) experiments have been carried out on epoxy-based matrix materials. Time and wavelength resolved emission and transient absorption techniques as well as ESR studies have been utilized to identify and monitor short lived reactive intermediates resulting from energetic electron impact. An energy deactivation model based on the results of this work has been developed. Recombination of primary charged species is found to be fast, resulting in the formation of longer lived excited electronic states and radicals which control the subsequent energy deactivation.

Coulter, D. R.↗
NASA NTRS1991

Simulation of high-speed (orbital) releases of electron attachment materials in the ionosphere

The dynamics of ionospheric plasma irregularities produced by the release of electron attachment materials at orbital velocities across the geomagnetic field is studied. A two-dimensional electrostatic fluid model which includes electron attachment and mutual neutralization chemistry, self-consistent electric fields, and three-species transport is developed. Numerical simulations are performed to study the behavior at early and at late times after the release. At early times, of the order of or less than the attachment material neutral collision time, the negative ion cloud produced by the release may structure owing to the shear in the E x B velocity within the cloud. At high altitudes the cloud may bifurcate and form vortices on the back. At lower altitudes where ion-neutral collisional effects dominate, this structuring is suppressed. At late times, after a plasma depletion has formed due to neutralization chemistry, the cloud structures by the E x B interchange instability. Depending on the release altitude, the depletion structures by the collisional or inertial limit of this instability.

Scales, W. A.↗
DOE OSTI2023

Collective Energy Transport of Excitons in Two-dimensional Materials

Electronic thermal transport and thermoelectric measurements are pursued in this project to obtain unique insights into the unusual collective energy transport behaviors in two-dimensional (2D) heterostructures. Electronic thermal transport and thermoelectric measurements are essential techniques for characterizing bulk superconductors by probing the heat-carrying quasi-particles. Thermoelectric and electronic thermal transport measurements are expanded in this work beyond bulk systems to probe interactions among electrons, holes, and phonons in 2D heterostructures. In one experiment, a microbridge platform is advanced to demonstrate field-effect resistive-thermometry measurements of the electronic thermal conductivity of graphene heterostructures. Together with first principles theoretical calculations and analytical models, the experimental results suggest that tunable electron coupling with flexural phonons provides a knob to control quantum matters in graphene heterostructures with broken reflection symmetry. In another experiment, the Seebeck coefficient (S) is measured to probe interlayer interactions in electron-hole bilayers that are predicted to give rise to the emergence of a variety of correlated states. As a measure of the entropy, the measured S reveals the signature of electric injection of interlayer excitons in transition metal dichalcogenide (TMD) structures.

36 MATERIALS SCIENCE↗
DOE OSTI2021

High-Resolution Imaging of Unstained Polymer Materials

Electron microscopy has played an important role in polymer characterization. Traditionally, electron diffraction is used to study crystalline polymers while transmission electron microscopy is used to study microphase separation in stained block copolymers and other multiphase systems. We describe developments that eliminate the barrier between these two approaches - it is now possible to image polymer crystals with atomic resolution. The focus of this Review is on high-resolution imaging (30 Å and smaller) of unstained polymers. Recent advances in hardware allow for capturing numerous (as many as 105) low-dose images from an unperturbed specimen; beam damage is a significant barrier to high-resolution electron microscopy of polymers. Machine-learning-based software is then used to sort and average the images to retrieve pristine structural information from a collection of noisy images. Acknowledging the heterogeneity in polymer samples prior to averaging is essential. Molecular conformations in a wide range of amphiphilic block copolymers, polymerized ionic liquids, and conjugated polymers can be gleaned from two-dimensional projections (2D), three-dimensional (3D) tomograms, and four-dimensional (4D) scanning transmission electron microscopy (STEM) data sets where 2D diffraction patterns are taken as a function of position. Some methods such as phase contrast STEM have been used to image closely related materials such as metal-organic frameworks but not polymers. With improvements in hardware and software, such methods may soon be applied to polymers. Our goal is to provide a comprehensive understanding of the strategies toward the high-resolution imaging of radiation sensitive polymer materials at different length scales.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Precision Agriculture using Networks of Degradable Analytical Sensors (PANDAS) (Final Technical Report)

Precision agriculture, where sensing of soil, environment and crop conditions are used to precisely synchronize inputs (such as water and fertilizer) to crop needs enhances input use efficiency. This can improve yields and farm profitability while mitigating environmental losses, improving soil carbon content and substantially decreasing energy use for food, feed and fuel crops. Unfortunately, farmers are not yet able to harness the full potential of these management technologies as there is a lack of available management information, and there is therefore a need for sensors that are able to economically measure spatio-temporal variability in soil and crop properties of extremely heterogeneous farm fields precisely at high resolution and at low cost. Real-time, in-situ monitoring of agricultural soil conditions is today carried out using devices that limit the total number of nodes that can be used economically to typically one per acre or less. Higher spatio-temporal resolution sensing would enable more precise agricultural input optimization, with significant benefits to the farmer and the environment. In order to address this issue, this project focused on developing additively manufactured, biodegradable, soil sensors with predicted costs of < $\$$1 per unit to monitor crop inputs (such as water and fertilizer) that predictably, harmlessly degrade away into the soil when no longer needed. These sensor nodes should be easy to place, accurately and continuously monitor soil and crop conditions for an entire season, be read remotely using existing farm equipment, require no ongoing maintenance, not impede farm operations and produce no persistent waste. This approach could enable a >100× increase in information density over current solutions for precision farming of row and other crops, and lead to significant reductions in input energy use and provide increased yield for biofuel crops. Over the course of this project the team at the University of Colorado Boulder, University of California Berkeley, and Colorado State University/Kansas State University investigated a wide range of printable biodegradable electronic materials and sensor designs for determining soil moisture and soil nitrate concentration. These efforts expanded the available materials set for printed soil degradable electronic materials, particularly for conductors, enabling high conductivity and stability. Printed soil moisture and nitrate sensors with suitable sensitivity and selectivity were developed and characterized. Low power and passive wireless electronic systems were integrated with the soil sensors, and testing was carried out with completed sensors to understand their functionality under agricultural conditions. Additionally, other sensor types enabled by the biodegradable materials set created during this project, such as soil microbial activity sensors, were also developed and demonstrated. Project outputs include 10 peer reviewed publications, 4 patent applications, 21 technical presentations, 3 PhD thesis, 10 media reports, 8 additional grants worth over $\$$6M, and the formation of 3 start-up companies.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRSDate not supplied

Measurement of Secondary Electron Yield from Dielectric Materials

Secondary Electron Yield (SEY) is a material property that plays a fundamental role in material and spacecraft charging. SEY values for dielectric materials (insulators) are crucial inputs to models used to assess mission risk posed by high differential voltages and electrostatic discharge (ESD) on spacecraft. There are only two (non-NASA) facilities that attempt such measurements. The lack of NASA capability results in high cost and long, unpredictable schedules to obtain measurements. Future Artemis crewed lunar surface missions will involve the first use of many insulating materials for which SEY properties are poorly understood or absent entirely. Unconstrained SEY values in models increase uncertainty in charging/ESD risk assessment. The capability for reliable SEY determination will lead to improved charging and ESD risk assessments. We are developing a new capability, using pulsed ultralow (<femtoampere) incident electron beam intensity to eliminate sample charging, coupled with sensitive non-contact surface potential measurements, to measure secondary electron yield (SEY) from insulating materials. Present methods for SEY measurement on insulators suffer from highly inconsistent results due to sample charging from the incident electron beam during the measurement. In this first phase we are leveraging existing EM41 instrumentation, facilities, and expertise to perform proof-of-concept tests.

secondary electron emission↗
DOE OSTI2025

Using radioactive material to evaluate decontamination of contaminated electronics

Electronic materials are used everywhere and can get easily contaminated by their use in the field/laboratory. The goal of this project was to use radioactive material to track the effectiveness of a cleaning procedure using an off-the-shelf cleaning gel. Radioactive potassium bromide (KBr) was used as a model contaminant in four contamination scenarios to gauge the effectiveness of a cleaning gel in the decontamination of contaminated raspberry pi’s. Finally, the investigated decontamination technique was found to be 75–97% effective in removing contamination from the tested electronic devices. 95% of the contaminated electronic devices retained their functionality post-decontamination.

38 - RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCL↗
DOE OSTI2023

Benzoimidazolium-derived dimeric and hydride n-dopants for organic electron-transport materials: impact of substitution on structures, electrochemistry, and reactivity

1,3-Dimethyl-2,3-dihydrobenzo[ d ]imidazoles, 1H , and 1,1',3,3'-tetramethyl-2,2',3,3'-tetrahydro-2,2'-bibenzo[ d ]imidazoles, 1 2 , are of interest as n-dopants for organic electron-transport materials. Salts of 2-(4-(dimethylamino)phenyl)-4,7-dimethoxy-, 2-cyclohexyl-4,7-dimethoxy-, and 2-(5-(dimethylamino)thiophen-2-yl)benzo[ d ]imidazolium ( 1g–i + , respectively) have been synthesized and reduced with NaBH 4 to 1gH , 1hH , and 1iH , and with Na:Hg to 1g 2 and 1h 2 . Their electrochemistry and reactivity were compared to those derived from 2-(4-(dimethylamino)phenyl)- ( 1b + ) and 2-cyclohexylbenzo[ d ]imidazolium ( 1e + ) salts. E ( 1 + / 1 • ) values for 2-aryl species are less reducing than for 2-alkyl analogues, i.e., the radicals are stabilized more by aryl groups than the cations, while 4,7-dimethoxy substitution leads to more reducing E ( 1 + / 1 • ) values, as well as cathodic shifts in E ( 1 2 •+ / 1 2 ) and E ( 1H •+ / 1H ) values. Both the use of 3,4-dimethoxy and 2-aryl substituents accelerates the reaction of the 1H species with PC 61 BM. Because 2-aryl groups stabilize radicals, 1b 2 and 1g 2 exhibit weaker bonds than 1e 2 and 1h 2 and thus react with 6,13-bis(triisopropylsilylethynyl)pentacene ( VII ) via a “cleavage-first” pathway, while 1e 2 and 1h 2 react only via “electron-transfer-first”. 1h 2 exhibits the most cathodic E ( 1 2 •+ / 1 2 ) value of the dimers considered here and, therefore, reacts more rapidly than any of the other dimers with VII via “electron-transfer-first”. Crystal structures show rather long central C–C bonds for 1b 2 (1.5899(11) and 1.6194(8) Å) and 1h 2 (1.6299(13) Å).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1982

Functional organic materials for electronics industries

Topics closely related with organic, high molecular weight material synthesis are discussed. These are related to applications such as display, recording, sensors, semiconductors, and I.C. correlation. New materials are also discussed. General principles of individual application are not included. Materials discussed include color, electrochromic, thermal recording, organic photoconductors for electrophotography, and photochromic materials.

Shibayama, K.↗
NASA NTRS1972

Surveyor television camera, selected materials and electronic components, Appendix C

The locations of various parts of the Surveyor camera are presented. Tables were prepared with emphasis on: (1) exterior parts and surfaces that are directly exposed to space, (2) parts that shield others from space radiation, (3) representative or unique materials, and (4) electronic devices that may contain unique or well-characterized materials.

Carroll, W. F.↗
DOE OSTI2021

Dynamic structural views in solar energy materials by femtosecond electron diffraction

Solar materials convert light into other forms of energy through excited state processes occurring on ultrafast time and atomic length scales. Understanding and controlling such nonequilibrium processes is essential for applications ranging from photovoltaics to photocatalysis. These processes are commonly studied by transient optical techniques, which resolve charge carrier dynamics. However, optical spectroscopy does not directly probe the atomic-scale motions that play a central role in the ultimate functionality of these materials. Filling this missing gap, ultrafast electron and x-ray scattering techniques enable monitoring of structural dynamics in materials with femtosecond time resolution. In this work, we focus on the use of ultrafast electron diffraction (UED) techniques to probe photoinduced energy conversion dynamics in solar energy materials. First, we discuss the use of UED as an ultrafast lattice thermometer allowing a direct probe of nonradiative relaxations such as hot carrier cooling and Auger recombination. Second, we present a time-resolved atomic pair distribution function analysis enabled by UED, which uncovers lattice deformations arising from excitation localization in materials. Finally, we provide an outlook looking toward new approaches for resolving in situ energy conversion dynamics and uncovering structure–property relationships in solar energy materials.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Rationalizing energy level alignment by characterizing Lewis acid/base and ionic interactions at printable semiconductor/ionic liquid interfaces

Charge transfer and energy conversion processes at semiconductor/electrolyte interfaces are controlled by local electric field distributions, which can be especially challenging to measure. Furthermore, we leverage the low vapor pressure and vacuum compatibility of ionic liquid electrolytes to undertake a layer-by-layer, ultra-high vacuum deposition of a prototypical ionic liquid EMIM + (1-ethyl-3-methylimidazolium) and TFSI – (bis(trifluoromethylsulfonyl)-imide) on the surfaces of different electronic materials. We consider a case-by-case study between a standard metal (Au) and four printed electronic materials, where interfaces are characterized by a combination of X-ray and ultraviolet photoemission spectroscopies (XPS/UPS). For template-stripped gold surfaces, we observe through XPS a preferential orientation of the TFSI anion at the gold surface, enabling large electric fields (~10 8 eV m –1 ) within the first two monolayers detected by a large surface vacuum level shift (0.7 eV) in UPS.

14 SOLAR ENERGY↗
DOE OSTI2023

A microscopic Kondo lattice model for the heavy fermion antiferromagnet CeIn 3

Electrons at the border of localization generate exotic states of matter across all classes of strongly correlated electron materials and many other quantum materials with emergent functionality. Heavy electron metals are a model example, in which magnetic interactions arise from the opposing limits of localized and itinerant electrons. This remarkable duality is intimately related to the emergence of a plethora of novel quantum matter states such as unconventional superconductivity, electronic-nematic states, hidden order and most recently topological states of matter such as topological Kondo insulators and Kondo semimetals and putative chiral superconductors. The outstanding challenge is that the archetypal Kondo lattice model that captures the underlying electronic dichotomy is notoriously difficult to solve for real materials. Here we show, using the prototypical strongly-correlated antiferromagnet CeIn 3 , that a multi-orbital periodic Anderson model embedded with input from ab initio bandstructure calculations can be reduced to a simple Kondo-Heisenberg model, which captures the magnetic interactions quantitatively. We validate this tractable Hamiltonian via high-resolution neutron spectroscopy that reproduces accurately the magnetic soft modes in CeIn 3 , which are believed to mediate unconventional superconductivity. Our study paves the way for a quantitative understanding of metallic quantum states such as unconventional superconductivity.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Characterizing Electron Flow through Catechol‐Graphene Composite Hydrogels

Abstract Electronic materials that allow the controlled flow of electrons in aqueous media are required for emerging applications that require biocompatibility, safety, and/or sustainability. Here, a composite hydrogel film composed of graphene and catechol is electrofabricated, and that this composite offers synergistic properties is reported. Graphene confers metal‐like conductivity and enables charge‐storage through an electrical double layer mechanism. Catechol confers redox‐activity and enables charge‐storage through a redox mechanism. Importantly, there are two functional populations of catechols: conducting‐catechols (presumably in intimate contact with graphene) allow direct electron‐transfer; and non‐conducting‐catechols (presumably physically separated from graphene) require diffusible mediators to enable electron‐transfer. Using a variety of spectroelectrochemical measurements, that the capacity of the composite for charge‐storage increases in proportion to the extent by which the catechol‐groups can undergo redox‐state switching is demonstrated. To illustrate the broad relevance of this work, how the redox‐state switching can be related to both the charge storage of energy materials and the memory of molecular electronic materials is discussed. The authors believe this work is significant because it demonstrates that: conducting and redox‐active components enable distinctly different mechanisms for charge‐storage and electron‐transfer; these components act synergistically; and mediators provide unique opportunities to extend the capabilities of electronic materials.

36 MATERIALS SCIENCE↗
NASA NTRS1984

Pyroelectric materials as electronic pulse detectors of ultraheavy nuclei

The design and testing of ultraheavy-nucleus pulse detectors based on pyroelectric materials are reported, extending the preliminary findings of Tuzzolino (1983) and Simpson and Tuzzolino (1983). Uranium-ion beams of about 240 MeV/u are detected by a 39.5-micron-thick Si detector, degraded to about 175 MeV/u by Al absorbers, and then strike 700-micron-thick polyvinylidene fluoride or 1000-micron-thick LiTaO3 pyroelectric samples. Both detector systems are connected to a coincidence circuit via charge-sensitive preamplifiers, shaping amplifiers with 30-microsec effective time constants, and electronic discriminators. Sample spectra are shown, and the pulse heights measured are found to agree with theoretical calculations to within a factor of about 2. The response of the pyroelectric materials is found to be unaffected by exposure to about 10 Mrad of 2-7-MeV/u heavy ion radiation. With further study and improvement of the detection sensitivity, devices of this type could be applied to large-area space measurements of low ultraheavy-ion fluxes.

Simpson, J. A.↗