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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Rapid determination of actinides in seawater samples

A new rapid method for the determination of actinides in seawater samples has been developed at the Savannah River National Laboratory. The actinides can be measured by alpha spectrometry or inductively-coupled plasma mass spectrometry. The new method employs novel pre-concentration steps to collect the actinide isotopes quickly from 80 L or more of seawater. Actinides are co-precipitated using an iron hydroxide co-precipitation step enhanced with Ti +3 reductant, followed by lanthanum fluoride co-precipitation. Stacked TEVA Resin and TRU Resin cartridges are used to rapidly separate Pu, U, and Np isotopes from seawater samples. TEVA Resin and DGA Resin were used to separate and measure Pu, Am and Cm isotopes in seawater volumes up to 80 L. This robust method is ideal for emergency seawater samples following a radiological incident. It can also be used, however, for the routine analysis of seawater samples for oceanographic studies to enhance efficiency and productivity. In contrast, many current methods to determine actinides in seawater can take 1–2 weeks and provide chemical yields of ~30–60 %. This new sample preparation method can be performed in 4–8 h with tracer yields of ~85–95 %. By employing a rapid, robust sample preparation method with high chemical yields, less seawater is needed to achieve lower or comparable detection limits for actinide isotopes with less time and effort.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2014

Comparison of structural and electrical properties of Co{sup 2+}doped Mn-Zn soft nano ferrites prepared via coprecipitation and hydrothermal methods

Graphical abstract: - Highlights: • Coprecipitation and hydrothermal synthesis of Co{sup 2+} doped Mn-Zn ferrites. • Dielectric measurements at 3 MHz and 1 GHz frequencies. • Enhanced DC electrical resistivity for samples prepared from hydrothermal technique. • Impedance studies for the prepared samples showing major contribution due to grains. - Abstract: A series of Co doped Mn-Zn ferrites compounds with the formula Mn{sub 0.5}Zn{sub 0.5−x}Co{sub x}Fe{sub 2}O{sub 4} (x = 0, 0.15, 0.25, 0.35 and 0.50) were successfully synthesized by polyethylene glycol-assisted coprecipitation and hydrothermal methods. The structural characterization of the samples was done using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FTIR). All the samples found to have cubic spinel structure. The average crystallite size of all nanoparticles were estimated using Scherrer's formula and found to lie between 10 and 25 ± 3 nm with small size distribution of particles prepared by hydrothermal method. The FTIR spectrum showed two absorption bands of tetrahedral and octahedral metal-oxygen sites. DC electrical resistivity varied from 4.12 × 10{sup 7} to 8.32 × 10{sup 10} ohm cm with cobalt doping. The dielectric measurements were performed from 20 Hz to 3 MHz and from 1 MHz to 1 GHz frequency ranges. The value of dielectric constant (ε′) varies from 15.54 to 106.25 (1 MHz) and 6.73–16.48 (1 GHz) for all the samples at room temperature. Impedance spectroscopy was carried out from 20 Hz to 3 MHz, at room temperature to study the grains and grain boundaries effect.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Quantifying Phospholipids in Organic Samples Using a Hydrophilic Interaction Liquid Chromatography–Inductively Coupled Plasma High-Resolution Mass Spectrometry (HILIC-ICP-HRMS) Method

Here, in this study, a novel method using hydrophilic interaction liquid chromatography (HILIC) coupled with inductively coupled plasma high-resolution mass spectrometry (ICP-HRMS) was introduced for the quantification of phospholipids in oil samples. The method employed a bridged ethyl hybrid (BEH) stationary phase HILIC column with a tetrahydrofuran (THF)/water mobile phase, enhancing the solubility and detection of phospholipids. During the study, a gradient/matrix effect on ICP-HRMS sensitivity was observed and successfully compensated for experimentally, ensuring reliable quantification results. This approach has proven effective for a wide range of different oil samples including vegetable oils, animal fats, and phospholipid supplements. Notably, this method allowed the direct quantification of phospholipids in oil samples, bypassing the need for prior sample preparation methods, such as solid phase extraction (SPE), thereby streamlining the analytical process. The precision, accuracy, and reduced need for extensive sample preparation offered by this method mark a significant advancement in lipids analysis. Its robustness and broad applicability have substantial implications for industries such as food and renewable energy production, where both efficient and accurate lipid identification and quantification are crucial.

09 BIOMASS FUELS↗
DOE OSTI2018

Direct Visualization of Nano and Microscale Polymer Morphologies in As-Prepared and Dialyzed Polyampholyte Hydrogels by Electron Microscopy Techniques

The structure of polymer networks in hydrogels determines the properties. In this study, we investigated the structure of a charge-balanced polyampholyte, poly(4-vinylbenzenesulfonate-co-[3-(methacryloylamino) propyl] trimethylammonium chloride). From as-prepared samples, nanoscale globules were visualized in polyampholyte hydrogels for the first time. The impact of dialyses processes on polymer structures were also studied. In deionized water, salt ions are leached out, thus polymer chains undergo zipping process to form cellular structure with micrometer-thick polymer walls that allow mechanical toughness to the hydrogel. Samples dialyzed in 6 M potassium hydroxide solution did not show such cellular structure, as in the case of as-prepared samples.

Li, Xinda↗
DOE OSTI2017

Measurement Error in Atomic-Scale Scanning Transmission Electron Microscopy—Energy-Dispersive X-Ray Spectroscopy (STEM-EDS) Mapping of a Model Oxide Interface

Abstract With the development of affordable aberration correctors, analytical scanning transmission electron microscopy (STEM) studies of complex interfaces can now be conducted at high spatial resolution at laboratories worldwide. Energy-dispersive X-ray spectroscopy (EDS) in particular has grown in popularity, as it enables elemental mapping over a wide range of ionization energies. However, the interpretation of atomically resolved data is greatly complicated by beam–sample interactions that are often overlooked by novice users. Here we describe the practical factors—namely, sample thickness and the choice of ionization edge—that affect the quantification of a model perovskite oxide interface. Our measurements of the same sample, in regions of different thickness, indicate that interface profiles can vary by as much as 2–5 unit cells, depending on the spectral feature. This finding is supported by multislice simulations, which reveal that on-axis maps of even perfectly abrupt interfaces exhibit significant delocalization. Quantification of thicker samples is further complicated by channeling to heavier sites across the interface, as well as an increased signal background. We show that extreme care must be taken to prepare samples to minimize channeling effects and argue that it may not be possible to extract atomically resolved information from many chemical maps.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

On the measurement of austenite in supermartensitic stainless steel by X-ray diffraction

Sections of a 13Cr supermartensitic stainless steel were investigated to determine the optimum sample preparation for measurement of the austenite content by X-ray diffraction. The surface of several samples was mechanically ground or polished using media of grit sizes in the range 1–120 μm. The strained surface layer was afterwards removed stepwise by electropolishing, and the austenite content measured at each step. It was found that any level of mechanical grinding or polishing results in a reduction of the measured austenite fraction relative to the true bulk value, and that coarser grinding media impart greater damage and greater reduction in the measured austenite content. The results thus highlight the importance of the electropolishing step in preparation of such samples, but suggest that the American Society for Testing and Materials standard E975-03 substantially overestimates the amount of material which needs to be removed to recover the true “bulk” content. - Highlights: • Quantitative Rietveld analysis of austenite/martensite ratio in supermartensitic stainless steels • Critical evaluation of sample preparation for residual austenite measurements by X-ray diffraction • Highlighting of the importance of electropolishing as a final preparation step.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Role of sonic energy on growth morphology and optical properties of ZnO:S nanostructures

ZnO nanopowders doped with sulphur were prepared by sonochemical method. The input power of ultrasound was varied as 40%, 50% and 60% of the maximum power (375 W) in both continuous and pulsed mode. XRD results show the average size of the nanoparticles is the least for those prepared with 50% input power as well as the micro-strain. FESEM studies showed the formation of nanorods clubbed together to form flower like structure for these samples. In rest of the cases, no definite morphology was obtained. High resolution transmission electron microscopy (HRTEM) reveals the formation of nanorods oriented along c-axis for those samples prepared with 50% input power. No cavitation at 40% and excessive dissolution at 60% may lead to this type of morphology. Absorption studies showed high absorbance for sulphur doped samples but this was highest for the samples prepared with 60% input power.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Pt nanoparticles modified by rare earth oxides: Electronic effect and influence to catalytic hydrogenation of 3-phenoxybenzaldehyde

Graphical abstract: - Highlights: • The rare earths modified Pt/Al{sub 2}O{sub 3} were prepared by colloidal deposition method. • Modification of Pt by the rare earth enhanced catalytic hydrogenation activity. • The activity improvement is due to electron interaction between Pt and rare earth. • The hydrogenation mechanism of rare earth modified Pt catalyst was proposed. - Abstract: The rare earth elements (La, Ce, Nd, Sm, Pr, and Gd) modified Pt/Al{sub 2}O{sub 3} catalysts were prepared by the colloidal deposition and chemical reduction methods, respectively. Pt nanoparticles with average size 3 ± 0.5 nm were uniformly dispersed on the surface of Al{sub 2}O{sub 3} for the samples prepared by the colloidal deposition method, which exhibited higher activities in the hydrogenation of 3-phenoxybenzadehyde than the corresponding samples prepared by chemical reduction method. Moreover, except Gd, the catalysts modified by rare earth elements showed better catalytic performance than unmodified Pt/Al{sub 2}O{sub 3}. For Pt–Ce/Al{sub 2}O{sub 3} catalyst, when the weight percent of Pt and Ce was 0.5 and 0.25, respectively, the hydrogenation conversion of 3-phenoxybenzaldehyde was 97.3% after 6 h reaction. This activity improvement is due to the electronic interaction between Pt and rare earth elements, which was investigated by X-ray photoelectron spectroscopy.

36 MATERIALS SCIENCE↗
DOE OSTI2018

On the improvement of measurement accuracy of retained austenite in steel with X-ray diffraction

Highlights: • Improved procedure to determine austenite in steels with crystallographic texture • Extension to X-ray area detectors • Electropolishing is essential to get correct results. - Abstract: An improved measurement scheme for the determination of the retained austenite fraction with X-ray diffraction is extended to area detectors. The scheme reduces the error due to crystallographic texture in phase analysis of steel by averaging the results of diffraction patterns at different sample positions. The method is based on the standard ASTM E975, but it can be easily extended to other crystal structures, multi-phase materials or X-ray wavelengths. Phase transformation, induced by mechanical sample preparation, may lead to a significant reduction of the retained austenite fraction. Electropolishing before the measurement is beneficial to remove the layer affected by sample preparation.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Synthesis and electrochemical properties of layered structure Li[Ni{sub 0.5}Co{sub 0.25}Mn{sub 0.25}]O{sub 2} cathode material

Lithium ion (Li-ion) batteries are currently the energy source of choice for cell phones, laptops, and other mobile electronic devices due to their balance of high energy density with high power density compared to other electrochemical energy carriers. In the present study, mixed hydroxide method is used to prepare Li[Ni{sub 0.5}Co{sub 0.25}Mn{sub 0.25}]O{sub 2} from the precursors and analyze qualitatively and studied the electrochemical properties. The XRD spectrum exhibited predominant (003) orientation at 2θ =18.39{sup o} corresponding to hexagonal layered structure of R3m symmetry with evaluated lattice parameters are a= 2.84 Å, c= 14.43 Å. Raman measurements were performed to understand the microstructure and vibrational modes of the prepared sample. From the electrochemical (EC) studies an initial discharge capacity of about 140 mAhg{sup −1} with good cyclic stability was observed for the prepared sample in the potential range 0.0 −1.0V in aqueous medium.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2017

Current Status of the Irradiated Materials Characterization Laboratory at INL with Limited PIE Microstructural Characterization

The Irradiated Materials Characterization Laboratory at Idaho National Laboratory is a post-irradiation examination (PIE) facility focused on high end microscopy enclosed in shielded enclosures. Planned PIE activities include: sample preparation, microscopy (FIB, EPMA, and TEM), and thermal property measurements. An overview of the facility, its operational status, and its future growth will be presented. A detailed discussion of the shielding/confinement surrounding the PIE equipment will be provided. The shielded sample preparation area, SSPA, will be discussed, focusing on instruments being incorporated to achieve high quality sample finishes for microscopy and thermal property measurements. With various instruments of IMCL operational, PIE results of irradiated fuels using the EPMA, FIB, and TEM will be provided. A detailed explanation of the capabilities of the PIE equipment will be presented and how these instruments are being incorporated in preforming high quality microstructural characterization on highly irradiated materials.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2015

Mock-Up activities for the extraction of samples from a salt-stone disposal unit - 15502

Mock-up testing with respect to the core-drilling of simulant salt-stone grout was conducted to support the future retrieval of field-emplaced salt-stone samples from salt-stone Disposal Unit (SDU) Cell 2A. The primary objectives of extracting samples from SDU Cell 2A are to enable measurement of field-emplaced samples with respect to properties that influence long-term performance, such as saturated hydraulic conductivity, and to compare the measured properties for field-emplaced and comparable samples prepared in the laboratory. Initial mock-up activities (Phases 1 and 2) were conducted in Fiscal Years (FY) 2013 and 2014 in order to demonstrate the viability of standard core-drilling techniques that are typically employed for sampling concrete structures. The primary requirement for the core-drilling technique was that it should minimize the potential of physical or chemical sample changes that would artificially degrade key grout properties. Mock-up activities were aimed at optimizing the techniques for core-drilling, and subsequent sample extraction, using a set-up that mimicked, to the extent practical, both the physical characteristics, and operational complexities, of core-drilling salt-stone grout from the roof of the SDU. Samples extracted from the grout monolith were subsequently characterized with respect to saturated hydraulic conductivity and compressive strength, and compared to data for cast samples prepared using the same simulant salt-stone material. The comparison of these properties for the two sample types was expected to highlight potential flaws (e.g., micro-cracking) introduced by the core-drilling process. While the data for saturated hydraulic conductivity were virtually identical (approximately 2 E-09 cm/sec), the compressive strength of the core-drilled samples (approximately 3.5 MPa (500 psi)) was on average half that measured for the cast samples. It was suspected that increased water saturation and surface scoring of the core-drilled samples might account for the disparate compressive Strength data. During Phases 1 and 2 it was determined that cores could be successfully drilled and extracted to a depth of approximately 0.9 meters (3 feet) below the grout surface. Phase 3 (FY 2105) has been initiated and is primarily directed at demonstrating the ability to core-drill through approximately 1.8 meters (6 feet) of overlying grout to retrieve the desired sample from the SDU. The original drill depth of 0.6 - 0.9 meters (2-3 feet) was based on an SDU fill height of 5.6 meters (18.5 feet) and sample location of approximately 4.9 meters (16 feet); recently the allowable fill height in the SDUs has been increased to 6.5 meters (21.25 feet); hence the increased depth of overlying grout above the samples to be retrieved. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Transformation of Ferrihydrite to Goethite and the Fate of Plutonium

Understanding the interactions between plutonium and iron (oxy)hydroxide minerals is necessary to gain a predictive understanding of plutonium environmental mobility and to evaluate long-term performance of nuclear waste repositories. We investigated the fate of plutonium during the formation of ferrihydrite and its subsequent transformation into goethite. Ferrihydrite was synthesized with varying quantities of Pu(IV) following either a sorption or coprecipitation process; the ferrihydrite was then aged hydrothermally to yield goethite. Additionally, the synthesized materials were characterized via extended X-ray absorption fine structure spectroscopy, transmission electron microscopy, and acid leaching to elucidate the nature of plutonium association with ferrihydrite and goethite. In samples prepared following the sorption method, plutonium was identified in two different forms: a PuO 2 precipitate and a surface-sorbed plutonium complex. For the samples prepared via coprecipitation, no PuO 2 formation occurs in the ferrihydrite precursor and in the goethite experiments where plutonium concentration is ≤1000 ppm (mg kg –1 ). In these coprecipitation products, plutonium is strongly bound to the minerals either via formation of an inner sphere complex, or via an incorporation process. In the coprecipitation experiments, PuO 2 formation only occurs at the highest plutonium concentration (3000 ppm), suggesting that during ferrihydrite transformation into goethite, part of the plutonium can be remobilized to form PuO 2 nanoparticles. Collectively, our results demonstrate that the nature of plutonium associated with the precursor ferrihydrite (adsorbed vs coprecipitated) will have a direct impact on the association of plutonium with its alteration product (goethite). Furthermore, the data illustrate that some properties of plutonium association with the precursor ferrihydrite are retained through the transformation into goethite. These findings show that plutonium strongly associates with iron (oxy)hydroxides formed through coprecipitation processes and in these materials, plutonium can be strongly retained by the iron minerals.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Development of Fast Decay-Energy Spectroscopy With Magnetic Microcalorimeters

Decay energy spectroscopy (DES) is an increasingly important radiometric technique arising from the unique thermal detection physics and the precision of low-temperature microcalorimetry. DES can enable high-precision analysis of very small amounts of radioactive material with simple and rapid sample preparation, making it a key new tool for nuclear safeguards, nuclear forensics, the improvement of nuclear data, measurements of absolute activity, and other applications. For problems in nuclear safeguards and nuclear forensics it is highly desirable to increase the count rates achievable in DES, while maintaining simple and rapid sample preparation. Here, in this report, we describe progress in a new project to achieve high count rates in DES by taking advantage of the physics of magnetic microcalorimetry. We describe the results of initial modeling and experiment to validate the idea, a sample fabrication technique suitable for nuclear materials laboratories, the preparation and initial tests of paramagnetic Au-Er alloy in thin foil form, and the development of a sensing coil geometry that will perform well with the increased-thickness sensor used in the new technique.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2013

Silver doped nanobioactive glass particles for bone implant applications

Silica based silver doped nanobioactive glass compositions (58SiO{sub 2}-33CaO-9P{sub 2}O{sub 5} and 58SiO{sub 2}-23CaO-9P{sub 2}O{sub 5}-10Ag{sub 2}O(mol%)) were synthesized by a simple sol-gel route. The prepared samples were comprehensively characterised by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy and scanning electron microscopic studies. The results reveal that the prepared samples have amorphous phase with spherical morphology and having a particle size less than 100 nm. The specific surface areas were 90 and 61 m{sup 2}g{sup -1} respectively. The in vitro bioactivity of glass samples were confirmed by the formation of hydroxyapatite layer on glass surfaces. The Ag{sub 2}O-doped nanobioactive glasse samples shows reveal significant antibacterial activity compare with base glasses.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Selenium Metabolism in Cancer Cells: The Combined Application of XAS and XFM Techniques to the Problem of Selenium Speciation in Biological Systems

Determining the speciation of selenium in vivo is crucial to understanding the biological activity of this essential element, which is a popular dietary supplement due to its anti-cancer properties. Hyphenated techniques that combine separation and detection methods are traditionally and effectively used in selenium speciation analysis, but require extensive sample preparation that may affect speciation. Synchrotron-based X-ray absorption and fluorescence techniques offer an alternative approach to selenium speciation analysis that requires minimal sample preparation. We present a brief summary of some key HPLC-ICP-MS and ESI-MS/MS studies of the speciation of selenium in cells and rat tissues. We review the results of a top-down approach to selenium speciation in human lung cancer cells that aims to link the speciation and distribution of selenium to its biological activity using a combination of X-ray absorption spectroscopy (XAS) and X-ray fluorescence microscopy (XFM). The results of this approach highlight the distinct fates of selenomethionine, methylselenocysteine and selenite in terms of their speciation and distribution within cells: organic selenium metabolites were widely distributed throughout the cells, whereas inorganic selenium metabolites were compartmentalized and associated with copper. New data from the XFM mapping of electrophoretically-separated cell lysates show the distribution of selenium in the proteins of selenomethionine-treated cells. Future applications of this top-down approach are discussed.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Study of Maxwell–Wagner (M–W) relaxation behavior and hysteresis observed in bismuth titanate layered structure obtained by solution combustion synthesis using dextrose as fuel

Graphical abstract: X-ray diffraction studies show that phase formation and crystallinity was reached only after calcinations at 800 °C. Dielectric constant versus temperature curve shows ferroelectric to paraelectric transition temperature (T{sub c}) to be 650 °C. Complex impedance curves show deviation from Debye behavior. The material shows a thin PE Loop with low remnant polarization due to high conductivity in the as prepared sample. - Highlights: • Bi{sub 4}Ti{sub 3}O{sub 12} is synthesized using solution combustion technique with dextrose as fuel. • Dextrose has high reducing capacity (+24) and generates more no. of moles of gases. • Impedance studies show that the sample follows Maxwell–Wagner relaxation behavior. • Shows lower remnant polarization due to higher c-axis ratio. - Abstract: Structural, dielectric and ferroelectric properties of bismuth titanate (Bi{sub 4}Ti{sub 3}O{sub 12}) obtained by solution combustion technique using dextrose as fuel is studied extensively in this paper. Dextrose is used as fuel as it has high reducing valancy and generates more number of moles of gases during the reaction. X-ray diffraction studies show that phase formation and crystallinity was reached only after calcinations at 800 °C. Dielectric constant versus temperature curve shows ferroelectric to paraelectric transition temperature (T{sub c}) to be 650 °C. The dielectric loss is very less (tan δ < 1) at lower temperatures but increases around T{sub c} due to structural changes in the sample. Complex impedance curves show deviation from Debye behavior. The material shows a thin PE Loop with low remnant polarization due to high conductivity in the as prepared sample.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Synthesis of ZnO decorated graphene nanocomposite for enhanced photocatalytic properties

Zinc oxide/Graphene (GZ) composites with different concentrations of ZnO were successfully synthesized through simple chemical precipitation method. The X-ray diffraction pattern and the micro-Raman spectroscopic technique revealed the formation of GZ composite, and the energy dispersive X-ray spectrometry analysis showed the purity of the prepared samples. The ZnO nanoparticles decorated graphene sheets were clearly visible in the field emission scanning electron micrograph. Raman mapping was employed to analyze the homogeneity of the prepared samples. The diffuse-reflectance spectra clearly indicated that the formation of GZ composites promoted the absorption in the visible region also. The photocatalytic activity of ZnO and GZ composites was studied by the photodegradation of Methylene blue dye. The results revealed that the GZ composites exhibited a higher photocatalytic activity than pristine ZnO. Hence, we proposed a simple wet chemical method to synthesize GZ composite and its application on photocatalysis was demonstrated.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗