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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
DOE OSTI2024

Scalable bottom-up synthesis of Co-Ni–doped graphene

Introducing heteroatoms into graphene is a powerful strategy to modulate its catalytic, electronic, and magnetic properties. At variance with the cases of nitrogen (N)– and boron (B)–doped graphene, a scalable method for incorporating transition metal atoms in the carbon (C) mesh is currently lacking, limiting the applicative interest of model system studies. This work presents a during-growth synthesis enabling the incorporation of cobalt (Co) alongside nickel (Ni) atoms in graphene on a Ni(111) substrate. Single atoms are covalently stabilized within graphene double vacancies, with a Co load ranging from 0.07 to 0.22% relative to C atoms, controllable by synthesis parameters. Structural characterization involves variable-temperature scanning tunneling microscopy and ab initio calculations. The Co- and Ni-codoped layer is transferred onto a transmission electron microscopy grid, confirming stability through scanning transmission electron microscopy and electron energy loss spectroscopy. This method holds promise for applications in spintronics, gas sensing, electrochemistry and catalysis, and potential extension to graphene incorporation of similar metals.

Science & Technology - Other Topics↗
DOE OSTI2024

Microwave-assisted ammonia decomposition over metal nitride catalysts at low temperatures

The negative environmental impact of fossil fuel-based energy systems has unveiled the need to develop a CO x -free sustainable hydrogen (H 2 ) economy. Employing a microwave-assisted route, a ternary metal nitride catalyst (i.e., Co 2 Mo 3 N), and a low-temperature-pressure NH 3 decomposition process, this study investigated the possibility of developing a distributed H 2 production process. Here, this study not only explored lower cost-based catalyst systems but also the use of a microwave reactor to increase the energy efficiency of the process. Results from catalytic NH 3 decomposition experiments, performed in microwave reactors on Co 2 Mo 3 N catalyst, demonstrated the peak energy efficiency (of ~0.006 kgH 2 /kWh) at 400 °C in ambient pressure (with an NH 3 conversion >90%) which was around ninety times (~90 x) more efficient than a conventional system. Activation energy calculation also displayed a 20% less energy requirement for the microwave-based process (~31 kJ mol -1 ) than the conventional system (~37 kJ mol -1 ), indicating the advantage of the microwave-based process. Further microwave-assisted catalytic measurements and characterization of the Co 2 Mo 3 N catalyst, using x-ray diffraction (XRD) technique and scanning electron microscopic (SEM) images, revealed the excellent stability of this material at its peak performance (at 400 °C) and illustrated the potential of using this catalyst for a sustainable, economic, and energy-efficient approach for producing CO x -free H 2 .

08 HYDROGEN↗
DOE OSTI2025

Nanoscale and Element-Specific Lattice Temperature Measurements Using Core-Loss Electron Energy-Loss Spectroscopy

Measuring nanoscale local temperatures, particularly in vertically integrated and multicomponent systems, remains challenging. Spectroscopic techniques like X-ray absorption and core-loss electron energy-loss spectroscopy (EELS) are sensitive to lattice temperature, but understanding thermal effects is nontrivial. This work explores the potential for nanoscale and element-specific core-loss thermometry by comparing the Si L2,3 edge’s temperature- dependent redshift against plasmon energy expansion thermometry (PEET) in a scanning TEM. Using density functional theory (DFT), time-dependent DFT, and the Bethe−Salpeter equation, we ab initio model both the Si L 2,3 and plasmon redshift. We find that the core-loss redshift occurs due to bandgap reduction from electron−phonon renormalization. Our results indicate that despite lower core-loss signal intensity compared to plasmon features, core-loss thermometry has key advantages and can be more accurate through standard spectral denoising. Specifically, we show that the Varshni equation easily interprets the core-loss redshift for semiconductors, which avoids plasmon spectral convolution for PEET in complex junctions and interfaces. We also find that core-loss thermometry is more accurate than PEET at modeling thermal lattice expansion in semiconductors, unless the specimen’s temperature-dependent dielectric properties are fully characterized. Furthermore, core-loss thermometry has the potential to measure nanoscale heating in multicomponent materials and stacked interfaces with elemental specificity at length scales smaller than the plasmon’s wave function.

Bethe–Salpeter equation↗
NASA NTRS2001

Australian Red Dune Sand: A Potential Martian Regolith Analog

To demonstrate the potential scientific and technical merits of in situ microscopy on Mars, we analyzed a possible Martian regolith analog - an acolian red dune sand from the central Australian desert (near Mt. Olga). This sand was chosen for its ubiquitous red coating and the desert environment in which is it found. Grains of this sand were analyzed using a variety of microanalytical techniques. A database of detailed studies of such terrestrial analogs would assist the study of geological and astrobiological specimens in future missions to Mars. Potential instrument concepts for in situ deployment on Mars include local electrode atom probe nanoanalysis (LEAP), vertical scanning white light interferometry (VSWLI), scanning electron microscopies, energy dispersive x-ray microanalysis (EDX), atomic force microscopy (AFM) and X-ray diffraction (XRD). While in situ deployment of these techniques is many years away, ground-based studies using these analytical techniques extend our understanding of the data obtained from instruments to be flown in the near future.

Kuhlman, K. R.↗
NASA NTRS2018

Corrosion Failure in Electronic Devices for Aerospace Application

Corrosion of complex electronic systems is a growing and expensive concern. New materials and technology are constantly being introduced to increase performance of devices. There are many factors that can induce a corrosive environment during the various stages of manufacturing, processing, transport, and storage of these devices. The scope of this paper was to identify potential causes for the corrosion failure of optocoupler batches being used in launch applications. Optical microscope with surface profile measurements, scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and X-ray photoelectron spectroscopy (XPS) were used to identify and analyze the source of these failure. These studies revealed that the loss of adhesion between the electrolytic plated gold and nickel layers is the critical area that traps impurity ions into the chip allowing for blisters to form along the pins of the optocoupler.

Corrosion↗
DOE OSTI2024

Binding of Phosphate Species to Ca 2+ and Mg 2+ in Aqueous Solution

Phosphate derivatives and their interaction with metal cations are involved in many important biological phenomena, so an accurate characterization of the phosphate-metal interaction is necessary to properly understand the role of phosphate-metal contacts in mediating biological function. Herein, we improved the standard 12-6 Lennard-Jones (LJ) potential via the usage of the 12-6-4 LJ model, which incorporates ion-induced dipole interactions. Via parameter scanning, we fine-tuned the 12-6-4 LJ polarizability values to obtain accurate absolute binding free energies for the phosphate anions H 2 PO 4 – , HPO 4 2– , PO 4 3– coordinating with Ca 2+ and Mg 2+ . First, we modified the phosphate 12-6-4 LJ parameters to reproduce the solvation free energies of the series of phosphate anions using the thermodynamic integration (TI) method. Then, using the potential mean force (PMF) method, the polarizability of the metal-phosphate interaction was obtained. We show that the free energy profiles of phosphate ions coordinated to Ca 2+ and Mg 2+ generally show similar trends at longer metal–phosphate distances, while the absolute binding energy values increased with deprotonation. The resulting parameters demonstrate the flexibility of the 12-6-4 LJ-type nonbonded model and its usefulness in accurately describing cation–anion interactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Tuning working potential of silicon-phosphorus anode via microstructure control for high-energy lithium-ion batteries

The primary research on anode materials of lithium-ion batteries have been focused on increasing the specific capacity, while the working potential that is also closely related to the practical energy density of batteries has been paid much less attention. In this paper, starting from micrometer-sized silicon and black phosphorus, we have reported a high-energy silicon-phosphorus/carbon anode (denoted as mSPC) via a high-energy ball milling process, which demonstrates an average discharge working potential of 0.3 volts versus lithium, together with a high reversible capacity of > 2000 mAh/g, high initial coulombic efficiency of 84%, excellent cycle stability, and superior rate capability up to 15 A/g. Furthermore, in situ focused-ion-beam scanning electron microscopy reveals that the volume change of the mSPC anode during repeated (de) lithiation is effectively alleviated. In contrast, starting from nanometer-sized silicon, the resulted anode (denoted as nSPC) not only presents a lower reversible capacity (~1200 mAh/g), but also exhibits a higher charge/discharge working potential, leading to reduced energy density. Our results indicate the importance of composition/structure control in tailoring the working potential and specific capacity of alloying-type anodes towards high-energy lithium-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2022

Probing the hydrolytic degradation of UF 4 in humid air

This manuscript describes the chemical transformations that occur during hydrolysis of uranium tetrafluoride (UF 4 ) due to its storage in humid air (85% and 50% relative humidity) at ambient temperatures. This hydrolysis was previously reported to proceed slowly or not at all (depending on the percent relative humidity); however, previous reports relied primarily on X-ray diffraction methods to probe uranium speciation. Here, we employ a battery of physiochemical probing techniques to explore potential hydrolysis, including Raman spectroscopy, powder X-ray diffraction, 19 F nuclear magnetic resonance spectroscopy, scanning electron microscopy, and focused ion beam microscopy with energy-dispersive X-ray spectroscopy. Of these, only Raman spectroscopy proved to be particularly useful at observing chemical changes to UF 4 . It was found that anhydrous UF 4 slightly oxidizes over the course of thirteen days to Schoepite-like uranium complexes and possibly UO 3 . In contrast, UF 4 exposed to 50% relative humidity slightly decomposes into UO 2 F 2 , Schoepite-like uranium complexes, and possibly a high order uranium oxide that eluded chemical assignment (U x O y ). Despite the rich chemical speciation observed in our Raman spectroscopy measurements, X-ray diffraction and 19 F NMR measurements on the same material showed no changes. Microscopy measurements suggest that the observed reactions between UF 4 and water occur primarily on the surface of UF 4 particulates via a method that is visually similar to surface corrosion of metals. Therefore, we postulate that NMR spectroscopy and X-ray diffraction, which are well-suited for bulk analysis, are less suited than Raman spectroscopy to observe the surface-based reactions that occur to UF 4 when exposed to humid air. Considering the importance of UF 4 in the production of nuclear fuel and weapons, the results presented herein are widely applicable to numerous nuclear science fields where uranium detection and speciation in humid environments is of value, including nuclear nonproliferation and nuclear forensics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Effect of rotation on negative triangularity plasmas in DIII-D

At the DIII-D tokamak, plasmas with negative triangularity (NT) have been found to have similar energy confinement times as H-mode plasmas with positive triangularity. These NT plasmas also have a stable edge that inhibits H-mode, lacks dangerous edge transients, and has naturally low impurity confinement. For these reasons, NT plasmas have the potential to be a transformative reactor scenario. To determine the importance of strong co-current neutral beam torque for NT performance at DIII-D, scans of neutral beam torque at constant neutral beam power have been performed. These scans have shown that the energy confinement time for a basic, inductive NT scenario (q 95 ≈ 2.8) decreases by 16% when torque is reduced to reactor levels. This reduction in confinement can be replicated with gyrofluid modeling that isolates the role of E x B shear in the change in transport. In a separate set of discharges with lower plasma current (q 95 ≈ 2.5), no significant correlation between confinement time and rotation was found. Throughout this investigation, excellent MHD stability was observed, even with very low toroidal rotation. Further, low impurity confinement was found at multiple rotation levels. Throughout the campaign, rotation near the edge was counter-current, consistent with the measurement of counter-current intrinsic edge rotation, and these observations agree with NT results from the TCV tokamak.

confinement↗
DOE OSTI2023

Inaugural Technologist in Communities Scanning Tour: Automated and Electrified On-Demand Mobility (Follow-On Summary Report: April 24-25, 2023) [Slides]

In 2023, the Technologist in Communities (TIC) program hosted its inaugural scanning tour across the American Southwest, with a goal of investigating the region's leading public mobility systems and their integration with on-demand public mobility services. The scanning tour concept was inspired by and named after a U.S. Department of Transportation Federal Highway Administration practice of hosting "scanning tours," both domestically and abroad, to explore innovative transportation practices throughout the 1990s and early 2000s. Guided by the idea that "seeing is believing," scanning tours created opportunities for government and industry representatives to collectively experience new technologies and best practices firsthand. In 2023, the National Renewable Energy Laboratory (NREL) followed suit by leading the inaugural TIC scanning tour. TIC, part of the Technology Integration program within the U.S. Department of Energy's (DOE's) Vehicle Technologies Office, supports positive energy and mobility outcomes in communities across rural to urban contexts. TIC enables technical experts to work directly with leaders and stakeholders in communities and assist them in implementing promising new technologies. This first TIC scanning tour invited NREL, DOE, and industry experts to survey innovative public mobility practices and their integration into public transit systems across the Southwest. The tour's goals included examining the state of innovation in public mobility in cities, communities, and airports; facilitating collaboration between entities; and sparking potential new partnerships. The following report summarizes key findings from the scanning tour.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

Forward and backward stimulated Raman scattering in multi-speckled beams: Density dependence and effects on cross-beam energy transfer

Particle-in-cell simulations of cross-beam energy transfer (CBET) between multi-speckled beams reveal a potentially prominent energy loss from forward stimulated Raman scattering (FSRS) in the amplified seed beam [Yin et al., Phys. Plasmas 26, 082708 (2019)]. In this work, an intensity scan is used to examine this energy loss in the CBET-amplified seed beam at intensities of a few times 1014 W/cm2. Electron tracers demonstrate both the trapping in the electron plasma waves that is sustained over multiple speckles and the subsequent acceleration to velocities well beyond the phase velocity. Motivated by expanding our understanding of this energy loss mechanism, we isolate the FSRS density dependence by using a 2×1014 W/cm2 pulse to scan densities between 0.06 ncr and 0.12 ncr; a spectral analysis characterizes the energy losses from scattering with the changing densities. At saturation, both greater beam attenuation is measured at the laser frequency and larger scattering FSRS angles are observed as density increases, along with a rapid transition to primarily backscatter SRS between 0.10 ncr and 0.12 ncr, earlier than predicted by linear theory. Density gradients are shown to effectively mitigate oblique FSRS and beam energy losses in the two lower density cases, whereas 0° forward scattering is primarily suppressed in the higher density cases. Finally returning to the two-beam CBET system of interest, the interplay and mitigation of the secondary instabilities at larger domain and beam spatial scales are discussed, here also examining backward stimulated Brillouin scattering.

Stark, D. J. (ORCID:0000000203642733)↗
NASA NTRSDate not supplied

In-Situ Alloying of GRCop-42 via Additive Manufacturing: Precipitate Analysis

GRCop-42, a Cu-4at% Cr-2at% Nb alloy, was designed as a high temperature, high strength, high heat flux material for rocket engine combustion chamber liners by NASA Glenn Research Center. In situ alloying of GRCop-42 (ISGRCop-42) using powder bed fusion (PBF) additive manufacturing (AM) takes elemental powders of Cu, Cr, and Nb to be introduced into the PBF environment and develop the GRCop alloy while simultaneously building an AM component. Elemental powders were milled together prior to printing in an effort to facilitate the alloying process. Success of the in situ alloying process may provide lower cost, faster lead times, alloying optimization, and more design freedom in the development of regeneratively-cooled rocket propulsion systems. Evaluation of the ISGRCop-42 was conducted using a phase extraction procedure to isolate the Cr2Nb precipitates from the pure Cu matrix. The isolated precipitates were then examined using x-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy dispersion spectroscopy (EDS). It was found that ISGRCop-42 successfully and repeatedly formed Cr2Nb at a yield as high as 89% of potential Cr2Nb. Further, it was identified that the preparation of the powder was the most influential factor in alloying success, and the second most influential factor was the laser power.

In Situ alloying↗
DOE OSTI2025

Highly Active Hydrogen Evolution Reaction (HER) Catalysts Formed by Energetic Pt n Cluster Deposition: Deposition Dynamics and the HER Mechanism

Mass-selected Pt n + (n ≤ 7) were deposited at variable energies on highly oriented pyrolytic graphite (HOPG), creating highly active hydrogen evolution reaction (HER) electrocatalysts. HER mass activities were ~2 to >10 times higher than those for the surface atoms in bulk Pt and for Pt n deposited on several other supports. Thus, high activity reflects the Pt-C structures formed by energetic Pt n -HOPG impacts, in addition to high Pt surface availability. The Pt n /HOPG electrodes were probed by X-ray photoelectron spectroscopy, low energy ion scattering, and electron microscopy. Born-Oppenheimer molecular dynamics (BOMD) was used to simulate Pt n - HOPG impacts, revealing the types of structures formed at different energies, then DFT was used to probe their most important HER pathways. For low deposition energies, the Pt n deposit onto the HOPG surface with sub-unit sticking probability, aggregating at defects. With increasing deposition energy, the sticking probability initially decreases, then rises to unity as subplantation and defect creation allow formation of strongly bonded platinum-carbon structures. Barriers for HER on these structures were found to be low and weakly dependent on Pt n size, consistent with experiment. The activities were highest for small covalently-bonded Pt-C structures created at high deposition energies. The larger aggregated structures formed at low energies were less active, but still substantially better than the bulk Pt surface monolayer. The catalysts were stable in repeated potential cycling at reducing potentials, but electrodes containing subplanted Pt became more active when scanned to oxidizing potentials, due to emergence of subplanted Pt onto the surface.

08 HYDROGEN↗
DOE OSTI2024

Field Emission Properties of Cu-Filled Vertically Aligned Carbon Nanotubes Grown Directly on Thin Cu Foils

Copper-filled vertically aligned carbon nanotubes (Cu@VACNTs) were grown directly on Cu foil substrates of 0.1 mm thicknesses at different temperatures via plasma-enhanced chemical vapor deposition (PECVD). By circumventing the need for additional catalyst layers or intensive substrate treatments, our in-situ technique offers a simplified and potentially scalable route for fabricating Cu@VACNTs with enhanced electrical and thermal properties on thin Cu foils. Comprehensive analysis using field emission scanning microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) mappings, and X-ray diffraction (XRD) revealed uniform Cu filling within the VACNTs across a range of synthesis temperatures (650 °C, 700 °C, and 760 °C). Field emission (FE) measurements of the sample synthesized at 700 °C (S700) showed low turn-on and threshold fields of 2.33 V/μm and 3.29 V/μm, respectively. The findings demonstrate the viability of thin Cu substrates in creating dense and highly conductive Cu-filled VACNT arrays for advanced electronic and nanoelectronics applications.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Grain boundary energy control in zinc aluminate nanoceramics

This study investigates the grain boundary energy dependence on segregated dopants in nanocrystalline zinc aluminate ceramics. Atomistic simulations of Σ3 and Σ9 grain boundaries showed that trivalent ions of varying ionic radii [Sc 3+ (74.5 pm), In 3+ (80.0 pm), Y 3+ (90.0 pm), and Nd 3+ (98.3 pm)] have a tendency to segregate to both interfaces, with Y 3+ presenting the highest segregation potentials. The connection between segregation and the reduction of interfacial energies was explored by measuring the grain boundary energy on nanoceramics fabricated via high‐pressure spark plasma sintering (HP‐SPS) using differential scanning calorimetry (DSC). The results revealed that Y 3+ doping at 0.5 mol% reduces the grain boundary energy in zinc aluminate nanoceramics from 1.1–1.3 J/m 2 to 0.6–0.8 J/m 2 ; the range correlates with the observed size dependence of the excess energy, with higher values observed for the smaller grain sizes (∼17 nm). The noted decrease in interfacial energies for doped samples suggests it is indeed possible to alter the stability of zinc aluminate grain boundaries via dopant segregation.

36 MATERIALS SCIENCE↗
DOE OSTI2023

A Planetary Defense System For Responsive Space Missions

As King et al succinctly write, “Collision between the Earth and small objects in the solar system are known to occur regularly, and can result in extinction-level events at their most energetic or more commonly widespread loss of life or economic destruction even for relatively low-energy impacts.” Currently, the JPL Sentry System and the NASA NEO Surveyor mission track, identify, and monitor potential asteroid threats. The JPL Sentry System4 is an automated collision monitoring system which scans the current asteroid catalog for potential impact trajectories with Earth. A 2017 study led by P. Tricarico titled “The near-Earth asteroid population from two decades of observations” analyzes the combined observations of nine leading asteroid surveys. The NASA NEO Surveyor mission seeks to identify 90% of near-Earth objects (NEO) with diameters greater than 140 meters (460 feet) within 10 years. The NEO Surveyor combines data from two infrared imaging detectors to measure NEO size, composition, shape, rotational state, and orbits. Recently, the NASA Double Asteroid Redirection Test (DART) mission successfully altered the orbit of asteroid moon Dimorphos in 2022. This demonstrated that orbit alteration is possible. Thus, collisions between the Earth and asteroids are both likely and demonstrate potential for great harm. There is ongoing work to identify, catalog, and track potential threats. However, when a threat is identified there is not yet a system in place to target the threatening asteroid and defend the planet from potentially existential threats. Building on the DART Mission, we explore a planetary defense system to mitigate asteroid threats.

42 ENGINEERING↗
DOE OSTI2022

Computed Tomography Scanning and Geophysical Measurements of the Smackover Formation from the Roberson 18-19 Core

The computed tomography (CT) facilities and the Multi-Sensor Core Logger (MSCL) at the U.S. Department of Energy’s (DOE) National Energy Technology Laboratory (NETL) site in Morgantown, West Virginia, were used to characterize the Upper Jurassic (Oxfordian) Smackover limestone in the Roberson 18-19 1-15H core retrieved from the Atlanta Field, Columbia County, Arkansas. The 365.68-ft long Roberson core came from a vertical well at depths 8,802 ft to 9,169.60 ft, drilled by Southwestern Energy targeting the Smackover Formation as a potential unconventional oil reservoir. The primary impetus of this work was to non-destructively characterize core from the Smackover Formation that was acquired through a core exchange with Southwestern Energy. The Smackover Formation is an unconventional limestone play in southern Arkansas. This report and the associated scans provide detailed datasets not typically made publicly available from unconventional limestone for analysis. The resultant datasets are presented in this report and can be accessed from NETL’s Energy Data eXchange (EDX) online system using the following link: https://edx.netl.doe.gov/dataset/roberson-smackover.

58 GEOSCIENCES↗