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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Direct formation of gold nanoparticles using ultrasound

The invention provides a green chemistry, aqueous method to synthesize gold nanoparticles directly from bulk gold sources. The method involves the ultrasonication of bulk gold in water in the presence of an alkythiol species and a quaternary ammonium surfactant. An organic bilayer forms on the surface of the gold which renders it susceptible to material ejection from the violent collapse of cavitation bubbles. This ejected material is stabilized in solution by the formation of an organic bilayer and can be easily separated. It can then be subjected to an aqueous digestive ripening step to give a gold nanoparticle ensemble with a well-defined plasmon resonance. This method is applicable to a number of different sources of bulk gold. The method can be applied to an environmentally important problem; the recovery of gold from electronic waste streams. For example, gold nanoparticles can be extracted directly from the surface of SIM cards, with no prior manipulation of the cards necessary.

Huber, Dale L.↗
DOE OSTI2025

Synthesis of Gold Hydride at High Pressure and High Temperature

Gold is an unreactive metal and its chemical interactions with hydrogen have only recently been explored. Here, in this study, we report the formation of gold hydride above 40 GPa and 2200 K in X-ray free electron laser heated diamond anvil cells using various hydrocarbons as hydrogen sources. Above 40 GPa, a hexagonal phase emerges close to the gold melting point, corresponding to a hydride with stoichiometry Au 2 H x , with x increasing from 0 to near 1 with pressure from 40 to 80 GPa. This is a high-temperature phase which reverts to face centered cubic gold on cooling to 295 K. Accompanying DFT-MD simulations are in excellent agreement with experiment and reveal the structure to consist of an hexagonal close packed gold lattice with atomic hydrogen disordered in the interstices. The hydrogen is superionic and exhibits high diffusivity through the crystalline gold lattice. Our results present the first solid-state binary compound of gold and hydrogen.

Ab initio calculations↗
DOE OSTI2022

Syntheses of gold supported on metal oxides and their application in organic transformations

Herein, we report a general and straightforward synthesis method for gold supported on mesoporous and microporous metal oxides. Supported materials, in general, show higher crystallinity compare to unsupported systems as verified through powder X-ray diffraction (XRD). Also, through XRD, most of the metal is observed to be in its oxide form, whereas the gold support was found to be in its metallic state, which has been further confirmed from TEM. In terms of surface area, the catalyst was not found to follow any trend. Morphology wise, there are no changes observed after doping except in few cases. Combined results from XRD, X-ray fluorescence spectroscopy, Auger, and X-ray photoelectron spectroscopy suggest that gold is mainly in the bulk and very little (0.04% in case of gold doped calcium oxide) or non (in case of gold doped mixed manganese-cerium oxide) on the surface. The presence of Au (0) 4f peaks in XPS further confirms the metallic state of the gold. Oxides of indium, magnesium and calcium have been studied for the organic transformation reactions. An enhancement in activity and product selectivity was observed in the case of the gold supported catalysts. Indium serves as a great catalyst for C–C coupling and electrophilic aromatic substitution reactions and gives >99% conversion. Interestingly, 88% selectivity for C–C coupling and >99% selectivity for aromatic substitution have been achieved at 100 °C and room temperature respectively. Magnesium and calcium give Knoevenagel condensation products. At room temperature with very low catalyst loading, >99% conversion and selectivity were observed for the Knoevenagel reaction with as high as 35.30 TOF. Finally, a mechanism for the C–C coupling reaction has been proposed based on these results.

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

Influence of Microstructure on the Absorption of Tritium into Gold-Plated 316 Stainless Steel

The interaction of tritium with metal surfaces is the initial step in the overall absorption of tritium by the substrate metal. As a result, limiting the adsorption of tritium to the surface may effectively reduce the quantity of tritium absorbed by a metal when it is in contact with tritium gas. To limit tritium adsorption, many tritium users electroplate gold onto the substrate metal. The gold layer is expected to reduce tritium adsorption, and subsequently absorption, by reducing water adsorption. The present work shows a comparison between tritium inventories in nonplated 316 stainless steel to the inventories in 316 stainless-steel samples electroplated with gold by various commercial vendors and laboratories. Of the various gold-plated samples, only one type of plating shows ~25% reduction in tritium inventory, relative to non-plated steel samples. The degree of tritium absorption appears to be significantly influenced by the porosity, texture, and completeness of the gold layer. Incomplete and/or porous layers lead to increased absorption, while gold layers with smaller surface features lead to similar tritium inventories as non-plated samples. Furthermore, reduced tritium absorption was observed only for complete gold layers with small surface features.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Analysis of the Selective Flotation of Elemental Gold from Pyrite Using Diisobutyl Monothiophosphate

The gold contained in copper ores is an important resource for the gold industry. In some cases, elemental gold is present and can be recovered by selective flotation. It has been reported that the gold grade and recovery can be increased, without sacrificing the copper recovery, by replacing AERO 3477 (diisobutyl dithiophosphate (DTP)) with AERO 7249 (mixture of diisobutyl monothiophosphate (MTP) and diisobutyl dithiophosphate (DTP)) as the main collector. The fundamental understanding of the improvement in selectivity with the addition of MTP in the flotation of elemental gold from pyrite is limited and is the subject of this paper. In this regard, the hydrophobicity and selectivity of DTP and MTP in the flotation of pyrite and gold are compared and discussed. Density functional theory (DFT) was used to examine the electron density, reactivity, highest occupied molecular orbital (HOMO), and lowest unoccupied molecular orbital (LUMO) of the MTP and DTP collectors. The interaction energies for the adsorption of MTP and DTP from fresh pyrite, oxidized pyrite and gold surfaces were calculated and discussed with respect to the experimental results reported in the literature. Molecular dynamics simulation (MDS) was used to examine the adsorption state of MTP and DTP on the pyrite (100) and Au (111) surfaces.

58 GEOSCIENCES↗
NASA NTRS1993

On the origin of (4)He and (40)Ar in natural gold

In a first report on our investigations of noble gases in native gold we demonstrated that placer gold contains an excess of radiogenic (4)He and (40)Ar relative to the concentrations expected from in situ decay of U, Th, and K, respectively, during the geologic age of about 30 Ma of the samples. We also showed that the U/Th-(4)He age of 36 Ma of vein-type gold from the Southern Alps agrees with its K-Ar formation age derived from associated muscovite and biotite. We now studied the question of the origin of the (4)He and (40)Ar excesses of placer gold. We conclude that gold contains two components of noble gases, a low-temperature component from fluid inclusions or phases which release noble gases at less than 800 C and a high-temperature component released when gold melts (1064 C). In some samples extremely high U and K concentrations or an unreasonably high formation age would be required to explain the observed (4)He abundances. Thus, trapped (4)He and (40)Ar must be present in gold.

Eugster, O.↗
NASA NTRS1997

Annealing Effects on the Surface Plasmon of MgO Implanted with Gold

Gold ion implantation was carried out with the energy of 1.1 MeV into (100) oriented MgO single crystal. Implanted doses are 1, 3, 6, 10 x 10(exp 16) ions/sq cm. The gold irradiation results in the formation of gold ion implanted layer with a thickness of 0.2 microns and defect formation. In order to form gold colloids from the as-implanted samples, we annealed the gold implanted MgO samples in three kinds of atmospheres: (1)Ar only, (2)H2 and Ar, and (3)O2 and Ar. The annealing over 1200 C enhanced the gold colloid formation which shows surface plasmon resonance band of gold. The surface plasmon bands of samples annealed in three kinds of atmospheres were found to be at 535 nm (Ar only), 524 nm(H2+Ar), and 560 nm (02+Ar), The band positions of surface plasmon can be reversibly changed by an additional annealing.

Ueda, A.↗
NASA NTRS2007

Brazing of Stainless Steel to Yttria-Stabilized Zirconia Using Gold-Based Brazes for Solid Oxide Fuel Cell Applications

Two gold-base active metal brazes (gold-ABA and gold-ABA-V) were evaluated for oxidation resistance to 850 C, and used to join yttria-stabilized zirconia (YSZ) to a corrosion-resistant ferritic stainless steel for possible use in solid oxide fuel cells. Thermogravimetric analysis and optical microscopy and scanning electron microscopy coupled with energy-dispersive spectroscopy were used to evaluate the braze oxidation behavior, and microstructure and composition of the YSZ/braze/steel joints. Both gold-ABA and gold-ABA-V exhibited nearly linear oxidation kinetics at 850 C, with gold-ABA-V showing faster oxidation than gold-ABA. Both brazes produced metallurgically sound YSZ/steel joints due to chemical interactions of Ti and V with the YSZ and steel substrates.

Singh, M.↗
DOE OSTI2022

Freestanding high-aspect-ratio gold masks for low-energy, phase-based x-ray microscopy

High-resolution, x-ray phase contrast microscopy, a key technique with promising potential in biomedical imaging and diagnostics, is based on narrow-slit high-aspect-ratio gold gratings. Here we present the development, fabrication details, and experimental testing of the freestanding 10 μm thick gold membrane masks with an array of 0.9–1.5 μm void slit apertures for a novel low-energy x-ray microscope. The overall mask size is 4 mm × 4 mm, with a grating pitch of 7.5 μm, 6.0–6.6 μm wide gold bars are supported by 3 μm wide crosslinks at 400 μm intervals. The fabrication process is based on gold electroplating into a silicon mold coated with various thin films to form a voltage barrier, plating base, and sacrificial layer, followed by the mold removal to obtain the freestanding gold membrane with void slit apertures. We discuss key aspects for the materials and processes, including gold structures homogeneity, residual stresses, and prevention of collapsing of the grid elements. We further demonstrate the possibility to obtain high-resolution, high contrast 2D images of biological samples using an incoherent, rotating anode x-ray tube.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2021

Elucidating the Role of Halides and Iron during Radiolysis-Driven Oxidative Etching of Gold Nanocrystals Using Liquid Cell Transmission Electron Microscopy and Pulse Radiolysis

Graphene liquid cell transmission electron microscopy (TEM) has enabled the observation of a variety of nanoscale transformations. Yet understanding the chemistry of the liquid cell solution and its impact on the observed transformations remains an important step toward translating insights from liquid cell TEM to benchtop chemistry. Gold nanocrystal etching can be used as a model system to probe the reactivity of the solution. FeCl 3 has been widely used to promote gold oxidation in bulk and liquid cell TEM studies, but the roles of the halide and iron species have not been fully elucidated. In this work, we observed the etching trajectories of gold nanocrystals in different iron halide solutions. We observed an increase in gold nanocrystal etch rate going from Cl - - to Br - - to I - -containing solutions. Furthermore, this is consistent with a mechanism in which the dominant role of halides is as complexation agents for oxidized gold species. Additionally, the mechanism through which FeCl 3 induces etching in liquid cell TEM remains unclear. Ground-state bleaching of the Fe(III) absorption band observed through pulse radiolysis indicates that iron may react with Cl 2 · - radicals to form an oxidized transient species under irradiation. Complete active space self-consistent field (CASSCF) calculations indicate that the FeCl 3 complex is oxidized to an Fe species with an OH radical ligand. Together our data indicate that an oxidized Fe species may be the active oxidant, while halides modulate the etch rate by tuning the reduction potential of gold nanocrystals.

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

Finding a needle in a haystack: quantitative HERFD-XRF imaging and HERFD-XANES characterization of trace platinum in gold solidi from the Late Roman and Byzantine Empires

High-Energy Resolution Fluorescence Detection X-Ray Fluorescence (HERFD-XRF) imaging and HERFD X-ray Absorption Near Edge Structure (XANES) spectroscopy are used to quantify and characterize trace platinum (Pt) in gold solidi from the Late Roman and Byzantine Empires. Historically, the elemental analysis of coins has been pivotal in distinguishing authentic artifacts from forgeries, elucidating minting practices, and understanding economic shifts. Notably, a new gold source with high platinum content appeared in the fourth century CE, transforming the Roman economy. Traditional methods struggled to detect platinum due to the overwhelming gold matrix. Here, this study demonstrates the effectiveness of HERFD techniques in resolving this challenge. Three gold solidi, minted between 654 and 659 CE, were analyzed alongside reference gold materials with known Pt concentrations. The HERFD-XRF imaging revealed spatial distributions of platinum, highlighting non-uniformities within the coins. Additionally, HERFD-XANES spectroscopy identified the oxidation states and chemical speciation of platinum. Results demonstrate that platinum in the solidi primarily exists as metallic Pt, with some surface oxidation. The findings align with previous measurements but reveal higher Pt concentrations and significant inhomogeneities. This research confirms the reliability of HERFD methods for quantifying trace elements and provides new insights into the raw material sources and minting techniques of ancient gold coins. The non-destructive nature of this approach allows for extensive analyses, offering valuable data for historical, economic, and archaeological studies. This innovative application of HERFD-XRF imaging and XANES in cultural heritage research underscores the potential for detailed material characterization and conservation, enhancing our understanding of ancient economies and trade patterns.

Van Loon, Lisa L.↗
DOE OSTI2025

Gold L-shell emission spectroscopy as a temperature diagnostic in laser-driven experiments

Measurements of plasma conditions within gold hohlraums are challenging but provide important information about hohlraum energy transport. To date, there are no reliable passive diagnostic approaches that produce information about the hohlraum plasma conditions. Gold L-shell emission spectroscopy is a promising method to measure the electron temperature in multi-keV gold hohlraum plasmas. In this study, we compare time-resolved measurements of gold L-shell spectra against a more conventional electron temperature-sensitive diagnostic, K-shell emission from zinc, a mid-Z dopant. The Au L-shell and Zn K-shell spectra are taken simultaneously. The analysis of both sets of data exhibits good agreement with a singular rad-hydro model, suggesting a similar evolution in the mean electron temperature of the hohlraum plasma. These findings support the use of L-shell spectroscopy of gold as a method to study gold plasma conditions.

Emission spectroscopy↗
NASA NTRS2018

Gaps in Thermal Design Guidelines in the Goddard Space Flight Center GOLD Rules

The GSFC (Goddard Space Flight Center) GOLD Rules (Goddard Open Learning Design; GSFC-STD-1000) provide a reasonably comprehensive list of guidelines for the design and testing of spacecraft and instruments based on the long heritage of successful GSFC missions. In general, all GSFC missions are required to comply with the GOLD Rules across a number of subsystems or to seek waivers to particular GOLD rules where compliance is not practical, either due to the risk posture of a mission or the cost and/or schedule associated with compliance. In thermal subsystems, GOLD Rules are applied to design margins throughout the project life cycle and include temperature margins, heater power margins, and two-phase transport margins. However, no explicit guidance is provided for two thermal design aspects: heater control authority (for stability requirements) and cryogenic design margins (which are often not reasonable to express in terms of temperatures). This can lead to ambiguity and inconsistency among projects when demonstrating GOLD Rules compliance. Two current GSFC projects, TIRS-2 (Thermal InfraRed Sensor 2) and WFIRST (Wide Field InfraRed Survey Telescope), are both missions with cryogenic aspects and active thermal control for stability. This paper seeks to outline the characterization of cryogenic margins during the design process for TIRS-2 and WFIRST as well as the project derived guidelines for heater control authority margin. This effort serves as potential first steps for updating the GOLD Rules to address these two areas in guiding thermal designs at GSFC.

Modeling↗
NASA NTRS2023

Thermospheric Temperature and ΣO/N 2 Variations as Observed by GOLD and Compared to MSIS and WACCM-X Simulations During 2019–2020 at Deep Solar Minimum

The ultraviolet-imaging spectrograph that comprises Global-scale Observations of the Limb and Disk (GOLD) mission in geostationary orbit at 47.5°W longitude has taken full disk images at high cadence throughout the deep solar minimum period of 2019–2020. Synoptic (i.e., concurrent and spatially unified and resolved) observations of thermospheric temperature and composition at ∼150 km altitude are made for the first time, allowing GOLD to disambiguate temporal and spatial variations. Here we analyze the daytime effective temperature and column integrated O and N2 density ratio (ΣO/N 2 ) data simultaneously observed by GOLD over 120°W–20°E longitude and 60°S–60°N latitude from 13 October 2019 to 12 October 2020. Daily zonal mean values are calculated for each latitude and compared with NRLMSIS 2.0 and simulations from the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X). On average, the GOLD observations show higher temperatures than Mass Spectrometer Incoherent Scatter radar (MSIS) and WACCM-X by ∼20–60 K (5%–10%) and 80–120 K (12%–18%), respectively. The ΣO/N 2 ratios observed by GOLD are larger than the MSIS results by ∼0.4 (40%) but smaller than the WACCM-X simulations by ∼0.3 (30%). The observed and modeled results are correlated at most latitudes (r = 0.4–0.8), and GOLD, MSIS, and WACCM-X all display a similar seasonal variation and change with latitude. WACCM-X simulates a larger annual variation in ΣO/N 2 , suggesting that the thermospheric circulation is overestimated and atmospheric waves and turbulence transport are not properly represented in the model.

Guiping Liu↗
NASA NTRS2023

Thermospheric Temperature and ΣO/N2 Variations as Observed by GOLD and Compared to MSIS and WACCM-X Simulations During 2019–2020 at Deep Solar Minimum

The ultraviolet-imaging spectrograph that comprises Global-scale Observations of the Limb and Disk (GOLD) mission in geostationary orbit at 47.5°W longitude has taken full disk images at high cadence throughout the deep solar minimum period of 2019–2020. Synoptic (i.e., concurrent and spatially unified and resolved) observations of thermospheric temperature and composition at ∼150 km altitude are made for the first time, allowing GOLD to disambiguate temporal and spatial variations. Here we analyze the daytime effective temperature and column integrated O and N 2 density ratio (ΣO/N 2 ) data simultaneously observed by GOLD over 120°W–20°E longitude and 60°S–60°N latitude from 13 October 2019 to 12 October 2020. Daily zonal mean values are calculated for each latitude and compared with NRLMSIS 2.0 and simulations from the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X). On average, the GOLD observations show higher temperatures than Mass Spectrometer Incoherent Scatter radar (MSIS) and WACCM-X by ∼20–60 K (5%–10%) and 80–120 K (12%–18%), respectively. The ΣO/N2 ratios observed by GOLD are larger than the MSIS results by ∼0.4 (40%) but smaller than the WACCM-X simulations by ∼0.3 (30%). The observed and modeled results are correlated at most latitudes (r = 0.4–0.8), and GOLD, MSIS, and WACCM-X all display a similar seasonal variation and change with latitude. WACCM-X simulates a larger annual variation in ΣO/N 2 , suggesting that the thermospheric circulation is overestimated and atmospheric waves and turbulence transport are not properly represented in the model.

Guiping Liu↗
DOE OSTI2022

Extraction of gold, mercury, and lead with TEVA resin from HCl and HNO 3

The extraction behavior of 212 Pb, 197m Hg, and 194 Au on TEVA resin in HCl and HNO 3 solutions was studied with batch uptake, kinetics, and column studies. The uptake of mercury and gold was extremely high from HCl solutions, with maximum k’ >80,000 for both elements. The uptake of mercury was lower in HNO3 than HCl with a maximum k’ of ~ 8,000 in 0.02 M HNO 3 and decreasing uptake at higher concentrations of HNO3, which agrees well with previous work. The batch uptake of gold in HNO 3 was not measured, as it had been reported previously. The uptake of lead on TEVA resin in HCl was low with a maximum k’ of only ~ 90 in 1 M HCl. The uptake of lead in HNO 3 was negligible. The uptake kinetics of gold and mercury were characterized in HCl and HNO 3 solutions and high uptake was seen after ~ 60 s for both elements. Column separations of 212 Pb, 197m Hg, and 194 Au on TEVA resin from HCl and HNO 3 solutions are reported with high yields of mercury and lead, but with high losses of gold, which is retained on the resin. A rapid, high yield separation of 197m Hg from irradiated gold foils is presented with yields of ~ 100% for both elements and a total separation time of < 2 h.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

New concept of radiolytic synthesis of gold nanoparticles in continuous flow

Radiolytic synthesis has been used to produce a plethora of unsupported and supported metallic nanoparticles in batch. As proof of a new concept, we evaluated the formation of gold nanoparticles by radiolytic synthesis in continuous flow using a millifluidic reactor. A mixture of gold ions solution, branched polyethyleneimine, and ethylene glycol yielded gold nanoparticles with a mean size of 3.4 ± 1.0 nm after irradiation with an X-ray irradiator (127 Gy/min) at an absorbed dose of 5.1 kGy. The morphology and size distribution of gold nanoparticles was influenced by AgNO 3 , where its absence resulted in a mean size of 20.9 ± 15.8 nm. The radiolytic synthesis of gold nanoparticles in continuous flow was achieved in short reaction times (<60 min), at room temperature, and with low concentrations of both stabilizing and reducing agents. Furthermore, these results demonstrate the potential of radiolytic synthesis in continuous flow for high-throughput formation of metallic nanoparticles with controlled specifications in size and distribution.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Selective Lanthanide Sensing with Gold Nanoparticles and Hydroxypyridinone Chelators

The octadentate hydroxypyridinone chelator 3,4,3-LI(1,2-HOPO) is a promising therapeutic agent because of its high affinity for f-block elements and noncytotoxicity at medical dosages. The interaction between 3,4,3-LI(1,2-HOPO) and other biomedically relevant metals such as gold, however, has not been explored. Gold nanoparticles functionalized with chelators have demonstrated great potential in theranostics, yet thus far, no protocol that combines 3,4,3-LI(1,2-HOPO) and colloidal gold has been developed. Here, we characterize the solution thermodynamic properties of the complexes formed between 3,4,3-LI(1,2-HOPO) and Au 3+ ions and demonstrate how under specific pH conditions the chelator promotes the growth of gold nanoparticles, acting as both reducing and stabilizing agent. 3,4,3-LI(1,2-HOPO) ligands on the nanoparticle surface remain active and selective toward f-block elements, as evidenced by gold nanoparticle selective aggregation. Finally, a new colorimetric assay capable of reaching the detection levels necessary for the quantification of lanthanides in waste from industrial processes is developed based on the inhibition of particle growth by lanthanides.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗