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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 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Ceramic susceptor for induction bonding of metals, ceramics, and plastics

A thin (.005) flexible ceramic susceptor (carbon) was discovered. It was developed to join ceramics, plastics, metals, and combinations of these materials using a unique induction heating process. Bonding times for laboratory specimens comparing state of the art technology to induction bonding were cut by a factor of 10 to 100 times. This novel type of carbon susceptor allows for applying heat directly and only to the bondline without heating the entire structure, supports, and fixtures of a bonding assembly. The ceramic (carbon film) susceptor produces molten adhesive or matrix material at the bond interface. This molten material flows through the perforated susceptor producing a fusion between the two parts to be joined, which in many instances has proven to be stronger than the parent material. Bonding can be accomplished in 2 minutes on areas submitted to the inductive heating. Because a carbon susceptor is used in bonding carbon fiber reinforced plastics and ceramics, there is no radar signature or return making it an ideal process for joining advanced aerospace composite structures.

Fox, Robert L.↗
NASA NTRS2001

Teeing Off With an Entirely New Material

Liquidmetal(R) alloy is part of an entirely new class of vitrified metals, and is also known as metallic glass, or Vitreloy(R). A vitrified metal is a frozen liquid that fails to crystallize during solidification, unlike common metals such as titanium, steel, and aluminum. The technology takes the non-crystalline structure of glass and combines it with the properties of metal, a combination not found in nature, allowing for a product that offers the strength of a metal with the elasticity of a polymer. This unique technology is more than twice as strong as titanium and has a higher elastic limit. Liquidmetal(R) Golf presents this space-age development in a complete line golf clubs. Clubs made with this technology have a lower vibration response along with a softer, more solid feel. Because less energy is absorbed by the club's head upon impact, more energy is transferred directly to the ball. Vitreloy has potential commercial uses in sporting equipment: tennis rackets, bicycle frames, and baseball bats. The material may find applications in the medical industry for the manufacturing of surgical instruments and prosthetics. The Liquidmetal alloy is projected to replace many high performance materials, such as titanium, in the industries of aerospace, defense, military, automotives, medical instrumentation, and sporting goods

Source record↗
NASA NTRS2004

Lunar and Planetary Science XXXV: Organics and Alteration in Carbonaceous Chondrites: Goop and Crud

The session "Organics and Alteration in Carbonaceous Chondrites: Goop and Crud" included the following reports:Organics on Fe-Silicate Grains: Potential Mimicry of Meteoritic Processes?; Molecular and Compound-Specific Isotopic Study of Monocarboxylic Acids in Murchison and Antarctic Meteorites; Nanoglobules, Macromolecular Materials, and Carbon Sulfides in Carbonaceous Chondrites; Evidence for Terrestrial Organic Contamination of the Tagish Lake Meteorite; Nitrogen Isotopic Imaging of Tagish Lake Carbon Globules; Microscale Distribution of Hydrogen Isotopes in Two Carbonaceous Chondrites; The Nature and Origin of Aromatic Organic Matter in the Tagish Lake Meteorite; Terrestrial Alteration of CM Chondritic Carbonate; Serpentine Nanotubes in CM Chondrites; Experimental Study of Serpentinization Reactions; Chondrule Glass Alteration in Type IIA Chondrules in the CR2 Chondrites EET 87770 and EET 92105: Insights into Elemental Exchange Between Chondrules and Matrices; Aqueous Alteration of Carbonaceous Chondrites: New Insights from Comparative Studies of Two Unbrecciated CM2 Chondrites, Y 791198 and ALH 81002 ;and A Unique Style of Alteration of Iron-Nickel Metal in WIS91600, an Unusual C2 Carbonaceous Chondrite.

Source record↗
NASA NTRS2018

The Effects of Background Pressure on SPT-140 Thruster Performance at Multiple Power Levels

NASA's planned Psyche mission is scheduled to launch in 2022 and begin a 3.5-year cruise to the metallic asteroid Psyche, where it would examine this unique body. The baseline spacecraft design is a hybrid of JPL's deep-space heritage subsystems with commercial partner SSL's power, structure, and SPT-140 electric propulsion subsystems. Since the deep-space implementation of the SPT-140 differs from the commercial implementation, primarily in the need for deep power throttling, characterization of the system at lower powers is necessary. One specific area of interest is the sensitivity of thruster performance to background pressure in ground-based test facilities, which can have an impact on the prediction of in-space performance. Measurements of this pressure dependence were performed on a qualification-model SPT-140 thruster over the 0.9-4.5 kW range of interest for the Psyche mission. Thrust sensitivity to pressure, in an absolute sense, was largest at 4.5 kW and decreased with power until there was little-to-no measurable effect at 0.9 kW. In a relative sense, thrust sensitivity was similar at all powers above 0.9 kW with about 2-4% higher thrust measured at 10 μTorr than at the lowest operating pressure. Thruster stability margin, examined as a function of magnet current, did not have a strong dependence on facility pressure. Finally, an investigation of low-power operation at the lowest facility pressure showed that a combination of added cathode keeper current and additional cathode propellant flow significantly mitigated the larger negative cathode-to-ground voltages that were observed. These test results, combined with thruster life test results, inform the selection of proper low-power operating conditions for Psyche.

Snyder, John S.↗
NASA NTRS2018

The Effects of Background Pressure on SPT-140 Hall Thruster Performance

NASA’s planned Psyche mission is scheduled to launch in 2022 and begin a 3.5-year cruise to the metallic asteroid Psyche, where it would examine this unique body. The baseline spacecraft design is a hybrid of JPL’s deep-space heritage subsystems with commercial partner SSL’s power, structure, and SPT-140 electric propulsion subsystems. Since the deepspace implementation of the SPT-140 differs from the commercial implementation, primarily in the need for deep power throttling, characterization of the system at lower powers is necessary. One specific area of interest is the sensitivity of thruster performance to background pressure in ground-based test facilities, which can have an impact on the prediction of in-space performance. Measurements of this pressure dependence were performed on a qualification-model SPT-140 thruster over the 0.9-4.5 kW range of interest for the Psyche mission. Thrust sensitivity to pressure, in an absolute sense, was largest at 4.5 kW and decreased with power until there was little-to-no measurable effect at 0.9 kW. In a relative sense, thrust sensitivity was similar at all powers above 0.9 kW with about 2-4% higher thrust measured at 10 µ µTorr than at the lowest operating pressure. Thruster magnetic field sensitivity, examined as a function of magnet current, did not have a strong dependence on facility pressure. Finally, an investigation of low-power operation at the lowest facility pressure showed that a combination of added cathode keeper current and additional cathode propellant flow significantly mitigated the larger negative cathode-to-ground voltages that were observed. These test results, combined with thruster life test results, inform the selection of proper low-power operating conditions for Psyche.

Mackey, Jonathan A.↗
NASA NTRS2020

Electric Propulsion for the Psyche Mission: Development Activities and Status

NASA’s Psyche mission will launch in 2022 and begin a 3.6-year cruise to the metallic asteroid Psyche, where it will examine this unique body. The baseline spacecraft design is a hybrid of JPL’s deep-space heritage subsystems with commercial partner Maxar’s electric propulsion, power, and structure subsystems. All primary propulsion will be done with SPT-140 thrusters, which will be the first use of Hall thrusters for a NASA mission. The electric propulsion subsystem and its implementation for the Psyche mission are described here. Major testing activities have included the successful completion of subsystem integrated testing with the design modifications required for Psyche, and a series of low-power thrust repeatability tests that were performed in support of navigation analyses. Thruster performance models have been further validated with new SPT-140 flight data, and new analyses of thruster swirl torque have been performed that result in much higher values than previously estimated. Analysis of recent Maxar flight data has also provided a new understanding of in-flight propellant usage uncertainties. Subsystem integration and test activities are now underway and the status and plans are discussed.

Johnson, Ian↗
DOE OSTI2022

Designing Glass and Crystalline Phases of Metal–Bis(acetamide) Networks to Promote High Optical Contrast

Owing to their high tunability and predictable structures, metal–organic materials offer a powerful platform to study glass formation and crystallization processes and to design glasses with unique properties. In this work, we report a novel series of glass-forming metal–ethylenebis(acetamide) networks that undergo reversible glass and crystallization transitions below 200 °C. The glass-transition temperatures, crystallization kinetics, and glass stability of these materials are readily tunable, either by synthetic modification or by liquid-phase blending, to form binary glasses. Pair distribution function (PDF) analysis reveals extended structural correlations in both single and binary metal–bis(acetamide) glasses and highlights the important role of metal–metal correlations during structural evolution across glass–crystal transitions. Notably, the glass and crystalline phases of a Co–ethylenebis(acetamide) binary network feature a large reflectivity contrast ratio of 4.8 that results from changes in the local coordination environment around Co centers. These results provide new insights into glass–crystal transitions in metal–organic materials and have exciting implications for optical switching, rewritable data storage, and functional glass ceramics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Watching Excited State Dynamics with Optical and X-ray Probes: The Excited State Dynamics of Aquocobalamin and Hydroxocobalamin

Femtosecond time-resolved X-ray absorption (XANES) at the Co K-edge, X-ray emission (XES) in the Co Kβ and valence-to-core regions, and broadband UV–vis transient absorption are combined to probe the femtosecond to picosecond sequential atomic and electronic dynamics following photoexcitation of two vitamin B12 compounds, hydroxocobalamin and aquocobalamin. Polarized XANES difference spectra allow identification of sequential structural evolution involving first the equatorial and then the axial ligands, with the latter showing rapid coherent bond elongation to the outer turning point of the excited state potential followed by recoil to a relaxed excited state structure. Time-resolved XES, especially in the valence-to-core region, along with polarized optical transient absorption suggests that the recoil results in the formation of a metal-centered excited state with a lifetime of 2–5 ps. In conclusion, this combination of methods provides a uniquely powerful tool to probe the electronic and structural dynamics of photoactive transition-metal complexes and will be applicable to a wide variety of systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

C 1 Chemistry on Metal Carbide Nanoparticles: Boosting the Conversion of CO 2 and CH 4

The studies described in this Perspective show that transition metal carbide (TMC) nanoparticles can be very useful for the activation of three molecules located at the heart of C 1 chemistry: H 2 , CH 4 , and CO 2 . They also can play a major role in the trapping and conversion of two major greenhouse gases. A combination of experiment and theory has shed light on the physical and chemical properties of these systems, which can be very different from those of bulk carbides. Molecular clusters of these compounds, which can be inserted inside the cages of zeolites or carbon nanotubes, have unsaturated metal and carbon atoms that frequently work in a cooperative way when dealing with hard-to-activate molecules, such as CH 4 and CO 2 . These molecular clusters can evolve into nanoparticles of small to medium size (<15 nm) that have unique carbon/metal ratios and structures not seen in the bulk metal carbides. Even when their structures are cuts from bulk lattices, the TMC nanoparticles have corner or edge atoms that are active for the cleavage and conversion of C–H and C–O bonds. In this paper, we cover experimental and theoretical studies with well-defined metal carbide nanoparticles prepared by different methods, free and supported on diverse substrates. The Perspective ends with a discussion of current challenges and potential applications.

03 NATURAL GAS↗
DOE OSTI2025

Pressure‐Induced Metallization and Isostructural Transitions in 3R‐MoS2

At ambient conditions 3R-polytypes of transition metal dichalcogenides (TMDs) demonstrate fascinating properties because of their unique layer stacking. Understanding the structure-property relationship is essential for the realization of their use in spintronic, valleytronic, and optoelectronic applications. Herein, after the high pressure-temperature synthesis of 3R-MoS2 in a large volume cubic press, a concomitant experimental and theoretical high-pressure study of 3R-MoS2 is reported, leading to the discovery of pressure-induced reversible isostructural phase transitions without symmetry breaking. Concurrent with the isostructural transitions, a semiconductor-to-metal transition is observed, owing to strong interlayer interaction and charge redistribution across the van der Waals gap under pressure. The pressure-induced enhancement of interlayer interactions together with the robust intrinsic layer stacking in 3R-MoS2 prevent the layers from sliding under pressure and hinder a corresponding volume collapse. This study on continuous pressure-tuning of crystal and electronic structure in 3R-MoS2 will play a vital role in developing the next-generation devices involving coupling of structural, optical, and electrical properties of 3R-polytypes of TMDs and other layered materials.

Ahmad, Azkar Saeed↗
DOE OSTI2022

MgO(111) Nanocatalyst for Biomass Conversion: A Study of Carbon Coating Effects on Catalyst Faceting and Performance

Solid base metal oxide catalysts such as MgO offer utility in a wide variety of syntheses from pharmaceuticals to fuels. The (111) facet of MgO shows enhanced, unique properties relative to the other facets. Carbon coatings have emerged as a promising modification to impart metal oxide catalyst stability. Here, we report the synthesis, characterization, and catalytic properties of commercial MgO, MgO(111), and carbon coated derivatives thereof for 2-pentanone condensation. The dimer and trimer products of this reaction can be used as precursors for biofuels upon oxygen removal and thus have relevance in environmental sustainability. Additionally, MgO(111) maintained impressive selectivity towards the dimer product after carbon coating, whereas the other catalysts experienced a decrease in conversion and selectivity as a consequence of the carbon coating. Our findings highlight the catalytic efficacy of MgO(111), provide insight into carbon coating for catalyst stability, and pave the way for continued mechanistic investigations.

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

High-pressure synthesis and neutron scattering study of tantalum hydride TaH 1.23(5) and a tantalum polymorph with A15-type structure

A unique type of tantalum hydride was synthesized by exposing tantalum dihydride to the high hydrogen pressure of 9 GPa and a temperature of using toroid-type high-pressure chambers. The samples of this hydride were cooled down to 100 K, recovered to ambient pressure, and studied in a metastable state by hot extraction, powder x-ray and neutron diffraction, and inelastic neutron scattering. X-ray diffraction demonstrated that this hydride had an A15-type crystal structure of metal lattice (space group , Ta atoms at the 2a and 6c Wyckoff positions) and a lattice parameter of a = 5.150(5) Å at T = 85 K. The hydrogen content determined by hot extraction was H/Ta - 1.23(5). Hydrogen desorption during heating the sample in vacuum proceeded in two steps—first, Δ⁢H⁡/Ta=0.2 was desorbed at around -70 °⁢C, and then the rest of the hydrogen was desorbed between 100 ⁢°C and 390 ⁢°⁢C. The A⁢15-type metal lattice was preserved upon hydrogen removal, leaving a unique polymorph of tantalum. Neutron diffraction of A⁢15-TaH 1.23⁢(5) demonstrated that hydrogen atoms occupy the 24⁢k and 16⁢i Wyckoff sites in the crystal structure, and annealing at 250 K resulted in a decrease of the 24⁢k and an increase of the 16⁢i site occupancies. Inelastic neutron scattering revealed four vibrational modes in the fundamental band of A⁢15-TaH 1.23⁢(5) at 72, 135, 145, and 166 meV, the first three and the last one of which were tentatively assigned to the vibrations of H atoms at the 24⁢k and 16⁢i sites, respectively. No superconductivity was found in A⁢15-TaH 1.1 and hydrogen-free A15-Ta at temperatures down to 1.5 K.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Decoding the Oxygen Activity with Iron through Ligand-to-Metal Charge Transfer in Li-Rich Layered Cathodes

The quest for high-energy-density and cost-effective cathode materials has revitalized lithium-rich iron-based oxides, where Fe 3+ ions with their stable half-filled d 5 electronic configuration demonstrate unique potentials in regulating oxygen redox activity through ligand-to-metal charge transfer. Using operando 57 Fe Mössbauer spectroscopy, synchrotron X-ray techniques, and density functional theory calculations, we unravel the enhanced Fe–O redox activity through the LMCT process and the concomitant evolution of local structure distortion in the Li-rich layered system Li 1.2 MO 2 (M = Ni, Mn, Fe). The metastable Fe 4+ intermediates facilitate early activation of oxygen redox through LMCT along with increased delithiation at a lowered potential (below 4.5 V). Here, this process inherently suppresses Jahn–Teller distortion of Fe 4+ and exhibits Fe–O redox dominance over conventional Fe 3+ /Fe 4+ redox in Li-rich oxides. The Fe–O coupling redox exhibits improved initial Coulombic efficiency and 95% capacity retention over 200 cycles at 4.4 V. However, the LMCT process is accompanied by aggravated cation migration and voltage fade at low cutoff potentials, which requires further mitigation for the utilization of Fe–O redox. Overall, these findings demonstrate the regulating mechanism of iron for oxygen redox through LMCT and provide fundamental insights into the design principles for high-performance, cost-effective iron-based cathode materials.

36 MATERIALS SCIENCE↗
DOE OSTI2020

A Review on Metallic Alloys Fabrication Using Elemental Powder Blends by Laser Powder Directed Energy Deposition Process

The laser powder directed energy deposition process is a metal additive manufacturing technique, which can fabricate metal parts with high geometric and material flexibility. The unique feature of in-situ powder feeding makes it possible to customize the elemental composition using elemental powder mixture during the fabrication process. Thus, it can be potentially applied to synthesize industrial alloys with low cost, modify alloys with different powder mixtures, and design novel alloys with location-dependent properties using elemental powder blends as feedstocks. This paper provides an overview of using a laser powder directed energy deposition method to fabricate various types of alloys by feeding elemental powder blends. At first, the advantage of laser powder directed energy deposition in manufacturing metal alloys is described in detail. Then, the state-of-the-art research and development in alloys fabricated by laser powder directed energy deposition through a mix of elemental powders in multiple categories is reviewed. Finally, critical technical challenges, mainly in composition control are discussed for future development.

36 MATERIALS SCIENCE↗
DOE OSTI2021

A metal ion orients SARS-CoV-2 mRNA to ensure accurate 2'- O methylation of its first nucleotide

The SARS-CoV-2 nsp16/nsp10 enzyme complex modifies the 2'-OH of the first transcribed nucleotide of the viral mRNA by covalently attaching a methyl group to it. The 2'-O methylation of the first nucleotide converts the status of mRNA cap from Cap-0 to Cap-1, and thus, helps the virus evade immune surveillance in host cells. Here, we report two structures of nsp16/nsp10 representing pre- and post-release states of the RNA product (Cap-1). We observe overall widening of the enzyme upon product formation, and an inward twisting motion in the substrate binding region upon product release. These conformational changes reset the enzyme for the next round of catalysis. The structures also identify a unique binding mode and the importance of a divalent metal ion for 2'-O methylation. We also describe underlying structural basis for the perturbed enzymatic activity of a clinical variant of SARS-CoV-2, and a previous SARS-CoV outbreak strain.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Regulating Exciton–Phonon Coupling to Achieve a Near‐Unity Photoluminescence Quantum Yield in One‐Dimensional Hybrid Metal Halides

Abstract Low‐dimensional hybrid metal halides are emerging as a highly promising class of single‐component white‐emitting materials for their unique broadband emission from self‐trapped excitons (STEs). Despite substantial progress in the development of these metal halides, many challenges remain to be addressed to obtain a better fundamental understanding of the structure–property relationship and realize the full potentials of this class of materials. Here, via pressure regulation, a near 100% photoluminescence quantum yield (PLQY) of broadband emission is achieved in a corrugated 1D hybrid metal halide C 5 N 2 H 16 Pb 2 Br 6 , which possesses a highly distorted structure with an initial PLQY of 10%. Compression reduces the overlap between STE states and ground state, leading to a suppressed phonon‐assisted non‐radiative decay. The PL evolution is systematically demonstrated to be controlled by the pressure‐regulated exciton–phonon coupling which can be quantified using Huang–Rhys factor S . Detailed studies of the S ‐PLQY relation for a series of 1D hybrid metal halides (C 5 N 2 H 16 Pb 2 Br 6 , C 4 N 2 H 14 PbBr 4 , C 6 N 2 H 16 PbBr 4 , and (C 6 N 2 H 16 ) 3 Pb 2 Br 10 ) reveal a quantitative structure–property relationship that regulating S factor toward 28 leads to the maximum emission.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Ionization-Induced Subcycle Metallization of Nanoparticles in Few-Cycle Pulses

Strong-field laser-matter interactions in nanoscale targets offer unique avenues for the generation and detailed characterization of matter under extreme conditions. Field-driven, sub-cycle ionization-induced metallization of nanoscale solids in intense laser fields has been predicted (Peltz et al. Time-Resolved X-ray Imaging of Anisotropic Nano-plasma Expansion. Phys. Rev. Lett. 2014, 113, 133401), but its observation was hampered by a lack of a smoking gun. Here, we report the ultrafast metallization of isolated dielectric and semiconducting nanoparticles under intense few-cycle laser pulses. The highest-energy electron emission is found to be a decisive proof that shows a characteristic cutoff modification to a metallic limit for intensities high enough to ignite carrier avalanching in the volume of the particles. Furthermore, semiclassical Mean-field Mie Monte-Carlo transport simulations reveal the underlying dynamics and explain the observed evolution by near-field driven electron backscattering from the metallizing target.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗