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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Heterometallic Ce IV / V V Oxo Clusters with Adjustable Catalytic Reactivities

Heterometallic Ce IV /M oxo clusters are underexplored yet and can benefit from synergistic properties from combining cerium and other metal cations to produce efficient redox catalysts. Herein, we designed and synthesized a series of new Ce 12 V 6 oxo clusters with different capping ligands: Ce 12 V 6 -SO 4 , Ce 12 V 6 -OTs (OTs: toluenesulfonic acid), and Ce 12 V 6 -NBSA (NBSA: nitrobenzenesulfonic acid). Single crystal X-ray diffraction (SCXRD) for all three structures reveals a Ce 12 V 6 cubane core formulated [Ce 12 (VO) 6 O 24 ] 18+ with cerium on the edges of the cube, vanadyl capping the faces, and sulfate on the corners. While infrared spectroscopy (IR), ultraviolet–visible spectroscopy (UV–vis), electrospray ionization mass spectrometry (ESI-MS), and proton nuclear magnetic resonance ( 1 H NMR) proved the successful coordination of the organic ligands to the Ce 12 V 6 core, liquid phase 51 V NMR and small-angle X-ray scattering (SAXS) confirmed the integrity of the clusters in the organic solutions. Furthermore, functionalization of the Ce 12 V 6 core with organic ligands both provides increased solubility in term of homogeneous application and introduces porosity to the assemblies of Ce 12 V 6 -OTs and Ce 12 V 6 -NBSA in term of heterogeneous application, thus allowing more catalytic sites to be accessible and improving reactivity as compared to the nonporous and less soluble Ce 12 V 6 -SO 4 . Meanwhile, the coordinated ligands also influenced the electronic environment of the catalytic sites, in turn affecting the reactivity of the cluster, which we probed by the selective oxidation of 2-chloroethyl ethyl sulfide (CEES). Furthermore, this work provides a strategy to make full use of the catalytic sites within a class of inorganic sulfate capped clusters via organic ligand introduction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Phase transition mechanism and bandgap engineering of Sb2S3 at gigapascal pressures

Abstract Earth-abundant antimony trisulfide (Sb 2 S 3 ), or simply antimonite, is a promising material for capturing natural energies like solar power and heat flux. The layered structure, held up by weak van-der Waals forces, induces anisotropic behaviors in carrier transportation and thermal expansion. Here, we used stress as mechanical stimuli to destabilize the layered structure and observed the structural phase transition to a three-dimensional (3D) structure. We combined in situ x-ray diffraction (XRD), Raman spectroscopy, ultraviolet-visible spectroscopy, and first-principles calculations to study the evolution of structure and bandgap width up to 20.1 GPa. The optical band gap energy of Sb 2 S 3 followed a two-step hierarchical sequence at approximately 4 and 11 GPa. We also revealed that the first step of change is mainly caused by the redistribution of band states near the conduction band maximum. The second transition is controlled by an isostructural phase transition, with collapsed layers and the formation of a higher coordinated bulky structure. The band gap reduced from 1.73 eV at ambient to 0.68 eV at 15 GPa, making it a promising thermoelectric material under high pressure.

Cui, Zhongxun (ORCID:0000000275044177)↗
DOE OSTI2024

LDRD poster - Identifying the speciation of salt-based actinides in the presence of contaminants

Molten salt reactors (MSRs) are among the most promising Generation IV nuclear reactors. The salts used in these reactors exhibit a high affinity for moisture and oxygen, and heating does not eliminate the oxides that are formed. Additionally, due to the high operating temperatures, reactor parts experience pronounced corrosion, and the resulting corrosion products integrate into the fuel salt system. It is hypothesized that the speciation of f-elements in molten salts would change in the presence of oxides and corrosion products. These changes in local structure can alter the rheological properties, which are critical to the operational and safety parameters of the reactors. Therefore, an in-depth understanding of how corrosion products influence lanthanide/actinide speciation is crucial. To test this hypothesis, lanthanides (as surrogates for actinides) and actinide chlorides were mixed with oxides (such as nickel oxide and lithium oxide) and/or corrosion products (e.g., nickel chloride) and reacted in molten salts. The resulting phases were analyzed using techniques such as powder X-ray diffraction, Raman spectroscopy, UV-Visible spectroscopy, and nuclear magnetic resonance spectroscopy. In the presence of oxides, due to the high oxophilicity of f-elements, these elements capture oxygen from the oxides, forming lanthanide/actinide oxide or oxychloride phases. Specifically, with cerium chloride, the introduction of lithium oxide to the formation of various final products depending on the oxide concentration. At lower oxide concentrations, cerium oxychloride (CeOCl) in the +3 oxidation state was observed, while an increase in the oxide concentration led to the formation of cerium dioxide (CeO2), where cerium is in the +4 oxidation state. In contrast, with nickel oxide, CeOCl formation was consistently observed, regardless of the oxide concentration. This project successfully determined that the speciation of f-elements change in the presence of oxides and different oxides in molten salts result in different final products. When the influence of nickel chloride was examined, changes in f-element speciation were not observed. However, it reacted with lithium chloride to generate a lithium-nickel-chloride (Li6NiCl8) phase, which was also observed when nickel oxide was reacted. Computational models were developed to simulate the phases anticipated under experimental conditions.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗
DOE OSTI2022

Revealing aggregation of non-fullerene acceptors in intermixed phase by ultraviolet-visible absorption spectroscopy

Non-fullerene acceptor (NFA) aggregation is crucial in determining bulk-heterojunction (BHJ) organic photovoltaic (OPV) performance. However, it is still a big challenge to characterize the nanostructure of NFAs in the disordered donor-acceptor intermixed phase. Here, we demonstrate a method to characterize NFA aggregation and composition in the intermixed phase by measuring NFA concentration-dependent ultraviolet-visible (UV-vis) absorption spectroscopy of BHJ films. In various polymer:NFA films, an absorption shift as a function of increasing molecular concentration (ASIMC) phenomenon is observed, and different NFA aggregation behaviors can be distinguished. The ASIMC method was then applied to study the influence of processing conditions on the NFA concentration in the intermixed phase of devices to establish a correlation with device efficiency. The current work provides a feasible tool to study the nanostructure of NFAs in the complex polymer matrix and to understand the variations in the NFA concentration in the intermixed phase under non-equilibrium conditions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Reversible Crosslinked Polymer Binder for Recyclable Lithium Sulfur Batteries with High Performance

Owing to the negative impact of the extensive utilization of batteries on the environment, sustainability of the cells needs to be included in the systemic research of batteries. In this work, a dissolvable ionic crosslinked polymer (DICP) is exploited as a binder for lithium–sulfur batteries by crosslinking the polyacrylic acid and polyethyleneimine through carboxy-amino ionic interaction. This interaction is pH-controlled, and therefore, the crosslinked binder network can be readily dissociated under basic conditions, providing a facile strategy enabling valuable components recycled through a convenient washing method. The sulfur cathode prepared using the recycled carbon–sulfur composite can deliver comparable capacity as that of fresh electrode. In addition, evidence from cell performance and characterizations, such as in situ X-ray absorption spectroscopy, in situ UV–visible spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculation, confirms that DICP is a more effective binder than its commercial counterpart on suppressing polysulfide dissolution in the electrolyte. Exploiting reversible crosslinked polymer binder for recyclable Li–S batteries with ameliorated electrochemical performance, this study illuminates sustainable development for large-scale energy storage systems.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Adsorption of molecular iodine and alkyl iodides from spent-nuclear-fuel-reprocessing off-gas using reduced silver mordenite

Radioactive iodine is a hazardous byproduct of spent-nuclear-fuel reprocessing that must be removed from the off-gas stream before it can be discharged. Reduced silver mordenite (Ag 0 Z) is currently the baseline material for iodine capture in the U.S. Although the performance characteristics and capture mechanisms of I 2 and CH 3 I have been established, similar investigations into long-chain organic iodides have yet to be performed. In this study, thin beds of Ag 0 Z were loaded with I 2 , CH 3 I, C 4 H 9 I, and C 12 H 25 I (5 ppm to 50 ppm) carried in a dry air stream at 150°C. The maximum iodine capacity was 105 ± 5 mg I/g Ag 0 Z for all species. Saturated Ag 0 Z samples were characterized using scanning electron microscopy, X-ray fluorescence, X-ray photoelectron spectroscopy, diffuse reflectance UV–visible spectroscopy, pair distribution function analysis, and thermogravimetric analysis. Further, near-complete Ag utilization and similar physical/chemical properties were observed for all samples. Through a comparison with previous studies and an investigation of aged Ag 0 Z, we propose that iodine species react with Ag + at exchange sites, forming α-AgI within the mordenite channels, and with surface Ag 0 nanoparticles, yielding β-/γ-AgI. The available Ag sites in the interior (Ag + ) and exterior (Ag 0 ) of mordenite determine the adsorption capacity since α-AgI formation is limited by the total pore volume. Potential iodine uptake routes were summarized for aging and non-aging environments. A scalable predictive model was implemented for deep-bed iodine removal, and predictions were in good agreement with experimental data. Sensitivity analysis suggests that iodine uptake kinetics is governed by pore diffusion.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2024

The SparkPix-S ASIC for the sparsified readout of 1 MHz frame-rate X-ray cameras at LCLS-II: pixel design and simulation results

Exploiting the “sparse” nature of the information in XPCS (X-ray Photon Correlation Spectroscopy) and XSVS (Speckle Visibility Spectroscopy) experiments, we present the SparkPix-S, a 3-sides buttable Application Specific Integrated Circuit (ASIC) based on a sparsified readout strategy for large-format hybrid detectors. The SparkPix-S architecture, based on the successful ePix family, will be composed as follows: a front-end 2-D matrix of 384×352 square pixels with 50 µm pitch is arranged to match the dimensions of a PIN Si-sensor matrix; charge readout, signal shaping and amplitude discrimination is performed at pixel-level, by means of a low-power (<18 µW) analog processor, which, in case of an event, negotiates access to an analog bus placed every other column; on the chip periphery (balcony), the information on each bus is digitized by an array of successive approximation analog-to-digital converters (SAR-ADCs) running at 10 Msps; on the digital back-end the global logic will generate the output data stream using low-voltage differential signalling (LVDS). A first prototype of the SparkPix-S, with a reduced matrix size of 96×96 pixels, is currently under production on a 130 nm CMOS technology. Simulated performance results show an equivalent noise charge <60 el. r.m.s. at 1 MHz repetition rate, with a maximum input energy of 60 keV and capability to discriminate charge signals with equivalent energy as low as 900 eV.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2022

Structural and electronic properties of rare-earth chromites: A computational and experimental study

Here, in this work, the structural, optical, and electronic properties of rare-earth perovskites of the general formula R⁢ CrO 3 , where R⁢ represents the rare-earth Gd, Tb, Dy, Ho, Er, and Tm, have been studied in detail. These compounds were synthesized through a facile citrate route. X-ray diffraction, Raman spectroscopy, and UV-Visible spectroscopy were utilized to reveal the structural evolutions in R⁢ ⁢CrO 3 . The lattice parameters, Cr 3+ –O 2 –Cr 3+ bond angle, and CrO 6 octahedral distortions were found to strongly depend on the ionic radii of R⁢ . First-principles calculations based on density-functional theory within the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) and strongly constrained and appropriately normed (SCAN) meta-GGA were also employed to calculate the structural and electronic properties of R⁢ ⁢CrO 3 . The ground-state energy, lattice constants, electronic structures, and density of states of R⁢ ⁢CrO 3 were calculated. These provide some insights into the electronic characteristics of the R⁢ ⁢CrO 3 compounds. The calculated values of lattice parameters and band gaps with Hubbard U correction (SCAN+ U ) agree well with values measured experimentally and show more accuracy in predicting the ground-state crystal structure and band structure compared to PBE+ U approximation. The band gap of R⁢ ⁢CrO 3 is found to be independent of the ionic radii of R⁢ from both experiments and calculations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1982

IUE spectroscopy, visible-band polarimetry, and radiometry of V641 Mon

This hot, double line, ellipsoidal variable member of NGC 2264 has been shown previously to be either a semi-detached or contact close binary. Low-resolution IUE spectra are best fitted to a Kurucz model atmosphere for very small (approximately 0.08 mag) E(B-V). The familiar interstellar absorption dip near lambda 2200 is apparently absent. A suitable model atmosphere can be fitted to the IUE fluxes, but flux excesses (compared to the model) appear for all the published U through L magnitudes. The spectrum of the B through L excess appears to follow a .0001 lambda dependence. It is shown that this cannot be interpreted as arising from another star fortuitously observed in the visible band or IR. Ground based polarization measures indicate V641 Mon to be a polarization variable. Previous and new V light curves show the amplitude of light variability itself to be variable by about a factor of 2. It is suggested that all these observed characteristics are best explained by postulating "third light" and identifying part of it with Rayleigh scattered starlight very near to the stars. From this same region there arise circumstellar absorptions which give rise to nontheoretical strengths for Si II and Si III lines.

Koch, R. H.↗
NASA NTRS1985

IUE spectroscopy, visible-band photometry, and polarimetry of HD 47732 (V641 Monocerotis)

Several high- and low-dispersion IUE spectra are described for the hot, massive close binary HD 47732. The stellar silicon lines do not show theoretically expected strength, the weakness being attributed to incipicent emission. A weak stellar wind is measurable with an expansion velocity of about 500 km/s. There is difficulty in fitting a model atmosphere to all of the IUE continuum and visible band and IR measures. These difficulties are resolved by appealing to a 22,500 K model atmosphere and a distinctive interstellar extinction law. Numerous V band measures show the polarization to be variable, but not strongly in a phased-locked way. This suggests sporadic outbursts of gas feeding the shell. Several seasonal V band light curves are discussed, and the seasonal variations among them are attributed to variable developments of a systemic shell which scatters the photospheric light and dilutes to a variable degree the light variation due to ellipticity of figure of the component stars.

Koch, R. H.↗
NASA NTRS2000

Visible Wavelength Spectroscopy of Ferric Minerals: A Key Tool for Identification of Ancient Martian Aqueous Environments

The mineralogic signatures of past aqueous alteration of a basaltic Martian crust may include iron oxides and oxyhydroxides, zeolites, carbonates, phyllosilicates, and silica. The identities, relative abundances, and crystallinities of the phases formed in a particular environment depend on physicochemical conditions. At one extreme, hot spring environments may be characterized by smectite-chlorite to talc-kaolinite silicate assemblages, plus crystalline ferric oxides dominated by hematite. However, most environments, including cold springs, pedogenic layers, and ponded surface water, are expected to deposit iron oxides and oxyhydroxides, carbonates, and smectite-dominated phyllosilicates. A substantial fraction of the ferric iron is expected to occur in nanophase form, with the exact mineralogy strongly influenced by Eh-pH conditions. Detection of these phases has been an objective of a large body of terrestrial telescopic, Mars orbital, and landed spectral investigations and in situ compositional measurements. However, clear identifications of many of these phases is lacking. Neither carbonate nor silica has been unequivocally detected by any method. Although phyllosilicates may occur near the limit of detection by remote sensing, in general they appear to occur in only poorly crystalline form. In contrast, compelling evidence for ferric iron minerals has been gathered by recent telescopic investigations, the Imager for Mars Pathfinder (IMP), and the Thermal Emission Spectrometer (TES) on the Mars Global Surveyor (MGS). These data yield two crucial findings: (1) In the global, high spatial resolution TES data set, highly crystalline ferric iron (as coarse-grained 'gray' hematite) has been recognized but with only very limited spatial occurrence and (2) Low-resolution telescopic reflectance spectroscopy, very limited orbital reflectance spectroscopy, and landed multispectral imaging provide strong indications that at least two broad classes of ferric iron minerals are commonplace in non-dust covered regions.

Murchie, Scott L.↗
NASA NTRS2003

Planet detection and spectroscopy in visible light with a single aperture telescope and a nulling coronagraph

This talk describes a new concept for visible direct detection of Earth like extra solar planets using a nulling coronagraph instrument behind a 4m telescope in space. In the baseline design, a 4 beam nulling interferometer is synthesized from the telescope pupil, producing a very deep theta^4null which is then filtered by a coherent array of single mode fibers to suppress the residual scattered light. With perfect optics, the stellar leakage is less than 1e-11 of the starlight at the location of the planet. With diffraction limited telescope optics (lambda/20), suppression of the starlight to ~1e-10 is possible. The concept is described along with the key advantages over more traditional approaches such as apodized aperture telescopes and Lyot type coronagraphs.

coronagraph↗
NASA NTRS2012

Visible Light Spectroscopy of GEO Debris

Our goal is to understand the physical characteristics of debris at geosynchronous orbit (GEO). Our approach is to compare the observed reflectance as a function of wavelength with laboratory measurements of typical spacecraft surfaces to understand what the materials are likely to be. Because debris could be irregular in shape and tumbling at an unknown rate, rapid simultaneous measurements over a range of wavelengths are required. Acquiring spectra of optically faint objects with short exposure times to minimize these effects requires a large telescope. We describe optical spectroscopy obtained during 12-14 March 2012 with the IMACS imaging spectrograph on the 6.5-m 'Walter Baade' Magellan telescope at Las Campanas Observatory in Chile. When used in f/2 imaging mode for acquisition, this instrument has a field of view of 30 arc-minutes in diameter. After acquisition and centering of a GEO object, a 2.5 arc-second wide slit and a grism are moved into the beam for spectroscopy. We used a 200 l/mm grism blazed at 660 nm for wavelength coverage in the 500-900 nm region. Typical exposure times for spectra were 15-30 seconds. Spectra were obtained for five objects in the GEO regime listed as debris in the US Space Command public catalog, and one high area to mass ratio GEO object. In addition spectra were obtained of three cataloged IDCSP (Initial Defense Communications Satellite Program) satellites with known initial properties just below the GEO regime. All spectra were calibrated using white dwarf flux standards and solar analog stars. We will describe our experiences using Magellan, a telescope never used previously for orbital debris spectroscopy, and our initial results.

Seitzer, Patrick↗
DOE OSTI2020

Infrared absorption spectroscopy of dynamically compressed water

Streaked visible spectroscopy is well established in dynamic compression research. Infrared measurements remain problematic, however, due to the diminishing sensitivity of streak camera photocathodes beyond 800 nm. Time-stretch techniques offer an alternative method for probing infrared features during single-event experiments. This paper discusses the development of a time-stretch spectroscopy diagnostic using dispersed supercontinuum laser pulses. The technique is applied to near-infrared measurements of liquid water during multiple shock compression.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Initial Characterization of Active Transitioning Centaur, P/2019 LD{sub 2} (ATLAS), Using Hubble, Spitzer, ZTF, Keck, Apache Point Observatory, and GROWTH Visible and Infrared Imaging and Spectroscopy

We present visible and mid-infrared imagery and photometry of temporary Jovian co-orbital comet P/2019 LD{sub 2} taken with Hubble Space Telescope/Wide Field Camera 3 (HST/WFC3), Spitzer Space Telescope/Infrared Array Camera (Spitzer/IRAC), and the GROWTH telescope network, visible spectroscopy from Keck/Low-Resolution Imaging Spectrometer (LRIS), and archival Zwicky Transient Facility observations taken between 2019 April and 2020 August. Our observations indicate that the nucleus of LD{sub 2} has a radius between 0.2 and 1.8 km assuming a 0.08 albedo and a coma dominated by ∼100 μm-scale dust ejected at ∼1 m s{sup −1} speeds with a ∼1′ jet pointing in the southwest direction. LD{sub 2} experienced a total dust mass loss of ∼10{sup 8} kg at a loss rate of ∼6 kg s{sup −1} with Afρ/cross section varying between ∼85 cm/125 km{sup 2} and ∼200 cm/310 km{sup 2} from 2019 April 9 to 2019 November 8. If the increase in Afρ/cross section remained constant, it implies LD{sub 2}'s activity began ∼2018 November when within 4.8 au of the Sun, implying the onset of H{sub 2}O sublimation. We measure CO/CO{sub 2} gas production of ≲10{sup 27} mol s{sup −1}/≲10{sup 26} mol s{sup −1} from our 4.5 μm Spitzer observations; g–r = 0.59 ± 0.03, r–i = 0.18 ± 0.05, and i–z = 0.01 ± 0.07 from GROWTH observations; and H{sub 2}O gas production of ≲80 kg s{sup −1} scaling from our estimated C {sub 2} production of Q{sub C{sub 2}}≲7.5×10{sup 24} mol s{sup −1} from Keck/LRIS spectroscopy. We determine that the long-term orbit of LD{sub 2} is similar to Jupiter-family comets having close encounters with Jupiter within ∼0.5 Hill radius in the last ∼3 y and within 0.8 Hill radius in ∼9 y. Additionally, 78.8% of our orbital clones are ejected from the solar system within 1 × 10{sup 6} yr, having a dynamical half-life of 3.4 × 10{sup 5} yr.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Chloride-Based Volatility for Waste Reduction and/or Reuse of Metallic-, Oxide- and Salt-Based Reactor Fuels

The objective of the chloride based volatility project (CBV) was to demonstrate the ability to separate uranium from used fuel to enable process improvements resulting in 10x reduction of waste volume, while maintaining safeguards standards and global backend costs at $\$$1/MW-hr. Current industrial practices perform separations of used fuel using solvent media in the form of aqueous and molten salt processes, resulting in contaminated process waste. The CBV approach utilized solid state chemistry with no solvent media and was successful in chlorinating uranium and fission product oxides that sublimed into the gas phase and were collected in targeted condensation zones based on temperature gradients of chlorinated products. Recovery of better than 95% of initial uranium in the form of UCl4 was demonstrated when simulated used nuclear fuel was used. Laser induced breakdown spectroscopy, LIBS, and ultraviolet-visible spectroscopy, UV-Vis, were combined into a high temperature flow cell design and utilized as process monitoring techniques to observed chlorinated products leave the reaction vessel in real time.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗