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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Organizing thermodynamic data obtained from multicomponent polymer electrolytes: Salt-containing polymer blends and block copolymers

The objective of this review is to organize literature data on the thermodynamic properties of salt-containing polystyrene/poly(ethylene oxide) (PS/PEO) blends and polystyrene-b-poly(ethylene oxide) (SEO) diblock copolymers. These systems are of interest due to their potential to serve as electrolytes in all-solid rechargeable lithium batteries. Mean-field theories, developed for pure polymer blends and block copolymers, are used to describe phenomenon seen in salt-containing systems. An effective Flory–Huggins interaction parameter, χ eff , that increases linearly with salt concentration is used to describe the effect of salt addition for both blends and block copolymers. Segregation strength, χ eff N, where N is the chain length of the homopolymers or block copolymers, is used to map phase behavior of salty systems as a function of composition. Domain spacing of salt-containing block copolymers is normalized to account for the effect of copolymer composition using an expression obtained in the weak segregation limit. The phase behavior of salty blends, salty block copolymers, and domain spacings of the latter systems, are presented as a function of chain length, composition and salt concentration on universal plots. Finally, while the proposed framework has limitations, the universal plots should serve as a starting point for organizing data from other salt-containing polymer mixtures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Superior Performance of a Lithium-Sulfur Battery Enabled by a Dimethyl Trisulfide Containing Electrolyte

The lithium-sulfur (Li-S) battery offers a high theoretical energy density of ≈2600 Wh/kg -1 and low cost, positioning it as a promising candidate for next-generation battery technology. However, problems including disastrous Li polysulfides dissolution and irreversible Li 2 S deposition have severely retarded the development of Li-S batteries. To solve these issues, we recently reported a functional dimethyl disulfide (DMDS)-containing electrolyte that promoted an alternate electrochemical reaction pathway for sulfur cathodes by a formation of dimethyl polysulfides and Li organosulfides as intermediates and reduction products, leading to significantly boosted Li-S cell capacity with improved cycling reversibility and stability. Here in this work, dimethyl trisulfide (DMTS), a primary discharge-charge intermediate in the DMDS-containing electrolyte, which is also a commercially available reagent, was further investigated as a co-solvent in functional electrolytes for Li-S batteries. Due to the higher theoretical capacity of DMTS and its better reactivity with Li 2 S than DMDS, a 25 vol% DMTS-containing electrolyte enables Li-S batteries with even higher cell capacity and improved cycling performance than using previous optimal 50 vol% DMDS-containing electrolyte.

25 ENERGY STORAGE↗
DOE OSTI2018

Interface Analyses Between a Case-Hardened Ingot Casting Steel and Carbon-Containing and Carbon-Free Refractories

Corrosion tests of carbon-free and carbon-containing refractories were performed. The carbon-free crucibles corroded, whereas the carbon-containing crucibles were negligibly attacked. On them, inclusions were attached. This study investigates melt oxygen contents, interface properties, and steel compositions with their non-metallic inclusions in order to explore the inclusion formation and deposition mechanisms. The carbon-free crucibles were based on alumina, mullite, and zirconia- and titania-doped alumina (AZT). The carbon-containing (-C) ones were alumina-C and AZT-C. Furthermore, nanoscaled carbon and alumina additives (-n) were applied in an AZT-C-n material. In the crucibles, the case-hardened steel 17CrNiMo7-6 was remelted at 1580 °C. It was observed that the melt and steel oxygen contents were higher for the tests in the carbon-free crucibles. Into these crucibles, the deoxidizing alloying elements Mn and Si diffused. Reducing contents of deoxidizing elements resulted in higher steel oxygen levels and less inclusions, mainly of the inclusion group SiO 2 -core-MnS-shell (2.5 to 8 μm). These developed from smaller SiO 2 nuclei. The inclusion amount in the steel was highest after remelting in AZT-C-n for 30 minutes but decreased strongly with increasing remelting time (60 minutes) due to inclusions’ deposition on the refractory surface. The Ti from the AZT and the nanoadditives supported inclusion growth and deposition. Other inclusion groups were alumina and calcium aluminate inclusions. Their contents were high after remelting in carbon- or AZT-containing crucibles but generally decreased during remelting. On the AZT-C-n crucible, a dense layer formed from vitreous compositions including Al, Ca, Mg, Si, and Ti. To summarize, for reducing forming inclusion amounts, mullite is recommended as refractory material. For capturing formed inclusions, AZT-C-n showed a high potential.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Formation Mechanisms and Leachability of Hexavalent Chromium in Cr{sub 2}O{sub 3}-Containing Refractory Castables of Electric Arc Furnace Cover

Cr (III)-containing refractories are widely used as electric-arc furnace cover because of their excellent corrosion resistance properties. However, the formation of hexavalent chromium [Cr(VI)] remains a matter of concern during the service and subsequent disposal of the spent refractories. Moreover, the Cr(VI) formation mechanism and total amount of Cr(VI) generated are not clearly understood. In this study, samples from different parts of a spent electric arc furnace cover were collected from a local integrated steel plant. The phase composition, microstructure, formation and leachability of Cr(VI) were investigated using X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, and TRGS 613 leaching test (Technische Regeln für Gefahrstoffe-TRGS 613-October 2002)/multiple leaching tests. A Cr(VI)-containing phase namely CaCrO{sub 4} existed in the sample at a medium temperature range, while another Cr(VI)-containing phase namely hauyne (Ca{sub 4}Al{sub 6}CrO{sub 16}) and a Cr(III)-containing phase (Al{sub 2}O{sub 3}–Cr{sub 2}O{sub 3} solid solution) formed in the high temperature region. Concentrations of Cr(VI) in the leachates (as in the TRGS 613 procedure) exceeded the European permissible limit. During the leaching tests in an acid condition, Cr(VI) was reduced by Fe{sup 2+}, which was primarily derived from the dissolution of FeO in the samples, while more Cr(VI) leached out with distilled water. Formation of an Al{sub 2}O{sub 3}–Cr{sub 2}O{sub 3} solid solution can inhibit Cr(VI) generation.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Pitting Corrosion of Supermartensitic Stainless Steel in Chloride Solutions Containing Thiosulfate or H{sub 2}S

Deepwater oil and gas extraction environment have high salinity, low oxygen content, and the presence of carbon dioxide and hydrogen sulfide (H{sub 2}S). Handling of H{sub 2}S-containing gaseous mixtures should be carried out in laboratories with special installations, owing to the high toxicity of this gas. An alternative is the use of non-toxic substances that can generate H{sub 2}S in the medium, such as sodium thiosulfate. The objective of this work is to study the viability of substituting H{sub 2}S by thiosulfate for the evaluation of the susceptibility to pitting corrosion in sour environments of the supermartensitic stainless steel (SMSS). The electrochemical behavior of SMSS in NACE TM0177-2016 solution C solution containing different concentrations of H{sub 2}S or thiosulfate ions at 10{sup −3} mol/L was performed by using cyclic potentiodynamic polarization (CPP). The condition of shorter OCP time (300 s) prevents the formation of a passive layer and allows the generation of H{sub 2}S due to the reaction of the solution with the metal surface. The CPP curves of SMSS in the media containing 3% H{sub 2}S/Ar (2.96 kPa) and 10{sup −3} M of thiosulfate ions (OCP 300 s) were similar, the pitting potential was about − 322.5 ± 8.7 and − 338.8 ± 11.4 mV{sub Ag/AgCl}, respectively, and the pit morphology showed several small pits on the steel surface in both conditions, suggesting the viability of the use of thiosulfate-containing brines to simulate H{sub 2}S solutions.

36 MATERIALS SCIENCE↗
DOE OSTI2019

The Anodic Role of Ni-Containing LPSO Phases During the Microgalvanic Corrosion of Mg{sub 98}Gd{sub 1.5}Ni{sub 0.5} Alloy

In the present study, the corrosion characteristics of cast Mg{sub 98}Gd{sub 1.5}Ni{sub 0.5} alloy with Ni-containing long-period stacking ordered (LPSO) structures were investigated. The results reveal that the Ni-containing LPSO phases were more active than the Mg matrix and preferentially eroded during the immersion process. This behavior indicates that the Ni-containing LPSO phases could have acted as microanodes, in contrast to the cathodic role of the Ni-free LPSO phases in other Mg alloys. Furthermore, the potential difference of approximately 600 mV between the phases accelerated the dissolution rate of the LPSO phase. Corrosion of the Mg matrix also occurred due to the inhomogeneous microstructure of the matrix. The synergetic corrosion between the Ni-containing LPSO phases and the enrichment of Cl{sup −} in the thick corrosion product films dominated the propagation of corrosion, which substantially deteriorated the corrosion resistance and accelerated the corrosion process of the Mg{sub 98}Gd{sub 1.5}Ni{sub 0.5} alloy.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Cell-free synthesis system suitable for disulfide-containing proteins

Highlights: ► Cell-free synthesis system suitable for disulfide-containing proteins is proposed. ► Disulfide bond formation was facilitated by the use of glutathione buffer. ► DsbC catalyzed the efficient shuffling of incorrectly formed disulfide bonds. ► Milligram quantities of functional {sup 15}N-labeled BPTI and lysozyme C were obtained. ► Synthesized proteins were both catalytically functional and properly folded. -- Abstract: Many important therapeutic targets are secreted proteins with multiple disulfide bonds, such as antibodies, cytokines, hormones, and proteases. The preparation of these proteins for structural and functional analyses using cell-based expression systems still suffers from several issues, such as inefficiency, low yield, and difficulty in stable-isotope labeling. The cell-free (or in vitro) protein synthesis system has become a useful protein production method. The openness of the cell-free system allows direct control of the reaction environment to promote protein folding, making it well suited for the synthesis of disulfide-containing proteins. In this study, we developed the Escherichia coli (E. coli) cell lysate-based cell-free synthesis system for disulfide-containing proteins, which can produce sufficient amounts of functional proteins for NMR analyses. Disulfide bond formation was facilitated by the use of glutathione buffer. In addition, disulfide isomerase, DsbC, catalyzed the efficient shuffling of incorrectly formed disulfide bonds during the protein synthesis reaction. We successfully synthesized milligram quantities of functional {sup 15}N-labeled higher eukaryotic proteins, bovine pancreatic trypsin inhibitor (BPTI) and human lysozyme C (LYZ). The NMR spectra and functional analyses indicated that the synthesized proteins are both catalytically functional and properly folded. Thus, the cell-free system is useful for the synthesis of disulfide-containing proteins for structural and functional analyses.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Fe-containing phases in hydrated cements

In this study synchrotron X-ray absorption spectroscopy (XAS) has been applied, an element specific technique which allows Fe-containing phases to be identified in the complex mineral mixture of hydrated cements. Several Fe species contributed to the overall Fe K-edge spectra recorded on the cement samples. In the early stage of cement hydration ferrite was the dominant Fe-containing mineral. Ferrihydrite was detected during the first hours of the hydration process. After 1 day the formation of Al- and Fe-siliceous hydrogarnet was observed, while the amount of ferrihydrite decreased. The latter finding agrees with thermodynamic modeling, which predicts the formation of Fe-siliceous hydrogarnet in Portland cement systems. The presence of Al- and Fe-containing siliceous hydrogarnet was further substantiated in the residue of hydrated cement by performing a selective dissolution procedure. - Highlights: • Fe bound to ferrihydrite at early age hydration • Fe found to be stable in siliceous hydrogarnet at longer term age hydration • Fe-containing AFt and AFm phases are less stable than siliceous hydrogarnet. • The study demonstrates EXAFS used to identify amorphous or poorly crystalline phases.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Hygro-thermo-mechanical modeling of partially saturated air-entrained concrete containing dissolved salt and exposed to freeze-thaw cycles

Highlights: • A model for cyclic freezing of air-entrained concrete containing salt is proposed. • The freeze-thaw hysteresis, also including the effect of dissolved salt, is modeled. • The diffusive and convective flux of salt is coupled to the freeze-thaw processes. • The freeze-thaw response of air-entrained concrete containing salt is reproduced. • Liquid absorption from reservoirs increases with an increased concentration of salt. In cold regions, understanding the freeze-thaw behavior of air-entrained concrete is important for designing durable structures and assessing the remaining service life of existing structures. This study presents a hygro-thermo-mechanical multiphase model that describes the cyclic freeze-thaw behavior of partially saturated air-entrained concrete containing dissolved salt. An equilibrium and a non-equilibrium approach are adopted to model the ice formation, including the freeze-thaw hysteresis, inside the porous network. The model also considers the diffusive and convective transport of the dissolved salt coupled to the freeze-thaw processes. Two examples are presented to verify and highlight the capabilities of the model. The first example shows that the model is capable of reproducing the experimentally observed mechanical response of specimens containing NaC1-solutions of different concentrations. In the second example, a larger absorption of liquid from an external reservoir is obtained with an increasing salt concentration in the reservoir, which is consistent with experimental observations.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Influencing mechanism of Al-containing Zn coating on interfacial microstructure and mechanical properties of friction stir spot welded Mg–steel joint

Highlights: • Al-containing Zn coating improved Mg–steel interfacial wettability during friction stir spot welding (FSSW). • Pre-existing Al{sub 5}Fe{sub 2} phase in coating on steel surface promoted Mg–steel metallurgical bonding. • A high tensile-shear load of 4.3 kN was obtained in FSSW AZ31–steel joint. - Abstract: 2.4 mm thick AZ31 Mg alloy sheet and 1.5 mm Q234 steel sheet with a hot-dipped Al-containing Zn coating were friction stir spot welded (FSSW) using a pinless tool. It was shown that the Al-containing Zn coating played a crucial role in joining the Mg alloy and steel during FSSW. The Zn coating observably improved the Mg–steel interfacial wettability during FSSW, and the Al{sub 5}Fe{sub 2} phase in the Zn coating on the steel substrate surface promoted the metallurgical bonding of Mg alloy and steel. It was confirmed that the Al{sub 5}Fe{sub 2} phase on the steel surface resulted from the reaction between the steel substrate and the Al in the Zn coating during hot-dipping, and was not related to the Al-containing Mg alloy substrate. The tensile-shear load of the FSSW Mg–steel joint reached 4.3 kN. The fracture of the joint occurred along the interface on the steel substrate side. The interface between the Al{sub 5}Fe{sub 2} layer and Mg alloy substrate was the weakest region of the Mg–steel joint.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2017

On the kinetics of transgranular particle embrittlement during simulated carburizing in steel containing grain-refining additions of aluminum and niobium plus aluminum

Here, the kinetics of toughness degradation resulting from transgranular particle embrittlement are evaluated as a function of composition and processing history for simulated carburizing operations in air-melt steel containing grain-refining additions of aluminum and aluminum plus niobium. The kinetics of particle embrittlement are inherently linked to the ripening of AlN precipitates after extended austenitization in steel containing carbon contents representative of both the case and core of a carburized component. Embrittlement in steel containing AlN occurs with an activation energy similar to the value for aluminum diffusion in austenite, although an AlN volume fraction effect on the embrittlement kinetics is manifested as decreases in activation energy with decreases in the [Al]/[N] ratio of steel. In contrast, the presence of niobium substantially retards the kinetics of particle embrittlement in steel containing 120–200 ppm N. Observations of AlN precipitates coated with Nb(C,N) indicate that the decreases in embrittlement kinetics are related to a reduction in the potential for AlN ripening during austenitization.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Development of a testing method for asbestos fibers in treated materials of asbestos containing wastes by transmission electron microscopy

Highlights: • A high sensitive and selective testing method for asbestos in treated materials of asbestos containing wastes was developed. • Asbestos can be determined at a limits are a few million fibers per gram and a few μg g{sup −1}. • High temperature melting treatment samples were determined by this method. Asbestos fiber concentration were below the quantitation limit in all samples, and total fiber concentrations were determined as 47–170 × 10{sup 6} g{sup −1}. - Abstract: Appropriate treatment of asbestos-containing wastes is a significant problem. In Japan, the inertization of asbestos-containing wastes based on new treatment processes approved by the Minister of the Environment is promoted. A highly sensitive method for testing asbestos fibers in inertized materials is required so that these processes can be approved. We developed a method in which fibers from milled treated materials are extracted in water by shaking, and are counted and identified by transmission electron microscopy. Evaluation of this method by using asbestos standards and simulated slag samples confirmed that the quantitation limits are a few million fibers per gram and a few μg/g in a sample of 50 mg per filter. We used this method to assay asbestos fibers in slag samples produced by high-temperature melting of asbestos-containing wastes. Fiber concentrations were below the quantitation limit in all samples, and total fiber concentrations were determined as 47–170 × 10{sup −6} f/g. Because the evaluation of treated materials by TEM is difficult owing to the limited amount of sample observable, this testing method should be used in conjunction with bulk analytical methods for sure evaluation of treated materials.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2023

Iodine Removal from Carbonate-Containing Alkaline Liquids Using Strong Base Resins, Hybrid Resins, and Silver Precipitation

The ability of several material types to remove aqueous iodine from a mildly alkaline, carbonate-rich nuclear waste stream was evaluated: strong base anion exchange resins (SBAR), hybrid resins, Ag-containing materials and Bi-containing hybrid resins. A combination of batch testing and flow through column testing were used in the evaluation. In batch testing, hybrid resins CHM-20, SIR-110-CE and RTBI were shown to have high efficiency for the removal of both iodide and iodate simultaneously, while Ag-containing materials and SBAR demonstrated high capacity for iodide removal. One example of each material type (CHM-20, A532E and Ionex 400) were further evaluated for their sorption isotherms and column performance. The Langmuir isotherm, or a Langmuir-Freundlich hybrid isotherm, best described the sorption of iodide to the CHM-20 hybrid resin and Purolite A532E. The Freundlich isotherm best described the uptake of iodate to CHM-20 and A532E and for both iodide and iodate to the Ag-containing Ionex-400. In column testing the Purolite A532E had exceptional performance for overall iodide removal. With the capacity demonstrated the A532E resin would exceed Class C waste classification before breakthrough initiated, and column change outs in processing would be dictated by eventual waste classification, not breakthrough. The Ionex 400, a Ag-zeolite, was observed to degrade over time in the column in the mild alkaline conditions whereas the hybrid CHM-20 was limited in the single pass through design and would be best suited for applications where iodide and iodate are present and recirculation of the column effluent is feasible. Here this work highlights the feasibility of commercially available materials to separate radioiodine from liquid environments.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Core Level Shifts of Hydrogenated Pyridinic and Pyrrolic Nitrogen in the Nitrogen-Containing Graphene-Based Electrocatalysts: In-Plane vs Edge Defects

A combination of N 1s X-ray photoelectron spectroscopy (XPS) and first principles calculations of nitrogen-containing model electrocatalysts was used to elucidate the nature of the nitrogen defects that contribute to the binding energy (BE) range of the N 1s XPS spectra of these materials above ~400 eV. Experimental core level shifts were obtained for a set of model materials, namely N-doped carbon nanospheres, Fe–N–carbon nanospheres, polypyrrole, polypyridine, and pyridinium chloride, and were compared to the shifts calculated using density functional theory. The results confirm that the broad peak positioned at ~400.7 eV in the N 1s XPS spectra of N-containing catalysts, which is typically assigned to pyrrolic nitrogen, contains contributions from other hydrogenated nitrogen species such as hydrogenated pyridinic functionalities. Namely, N 1s BEs of hydrogenated pyridinic-N and pyrrolic-N were calculated as 400.6 and 400.7 eV, respectively, using the Perdew–Burke–Ernzerhof exchange-correlation functional. A special emphasis was placed on the study of the differences in the XPS imprint of N-containing defects that are situated in the plane and on the edges of the graphene sheet. Density functional theory calculations for BEs of the N 1s of in-plane and edge defects show that hydrogenated N defects are more sensitive to the change in the chemical environment in the carbon matrix than the non-hydrogenated N defects. In conclusion, calculations also show that edge-hydrogenated pyridinic-N and pyrrolic-N defects only contribute to the N 1s XPS peak located at ~400.7 eV if the graphene edges are oxygenated or terminated with bare carbon atoms.

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

Highly fluorescent purine-containing conjugated copolymers with tailored optoelectronic properties

Conjugated copolymers containing electron donor and acceptor units in their main chain have emerged as promising materials for organic electronic devices due to their tunable optoelectronic properties. In this work, we describe the use of direct arylation polymerization to create a series of fully π-conjugated copolymers containing the highly tailorable purine scaffold as a key design element. To create efficient coupling sites, dihalopurines are flanked by alkylthiophenes to create a monomer that is readily copolymerized with a variety of conjugated comonomers, ranging from electron-donating 3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine to electron-accepting 4,7-bis(5-bromo-3-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole. The comonomer choice and electronic nature of the purine scaffold allow the photophysical properties of the purine-containing copolymers to be widely varied, with optical bandgaps ranging from 1.96–2.46 eV, and photoluminescent quantum yields as high as Φ = 0.61. Frontier orbital energy levels determined for the various copolymers using density functional theory tight binding calculations track with experimental results, and the geometric structures of the alkylthiophene-flanked purine monomer and its copolymer are found to be nearly planar. The utility of direct arylation polymerization and intrinsic tailorability of the purine scaffold highlight the potential of these fully conjugated polymers to establish structure–property relationships based on connectivity pattern and comonomer type, which may broadly inform efforts to advance purine-containing conjugated copolymers for various applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Luminescence of phosphorus containing oxide materials: Crystalline SiO{sub 2}‐P and 3P{sub 2}O{sub 5}⋅7SiO{sub 2}; CaO⋅P{sub 2}O{sub 5}; SrO⋅P{sub 2}O{sub 5} glasses

Luminescence of phosphate glasses such as CaO⋅P{sub 2}O{sub 5} and SrO⋅P{sub 2}O{sub 5} is compared with that of phosphorus doped crystalline α-quartz and phosphosilicate glass with content 3P{sub 2}O{sub 5}⋅7SiO{sub 2}. Water and OH groups are found by IR spectra in these materials. The spectrum of luminescence contains many bands in the range 1.5 - 5.5 eV. The luminescence bands in UV range at 4.5-5 eV are similar in those materials. Decay duration in exponential approximation manifests a time constant about 37 ns. Also a component in μs range was detected. PL band of μs component is shifted to low energy with respect to that of ∼37 ns component. This shift is about 0.6 eV. It is explained as singlet-triplet splitting of excited state. Below 14 K increase of luminescence kinetics duration in μs range was observed and it was ascribed to zero magnetic field splitting of triplet excited state of the center. Yellow-red luminescence was induced by irradiation in phosphorus doped crystalline α-quartz, phosphosilicate glasses. The yellowl uminescence contains two bands at 600 and 740 nm. Their decay is similar under 193 nm laser and may be fitted with the first order fractal kinetics or stretched exponent. Thermally stimulated luminescence contains only band at 600 nm. The 248 nm laser excites luminescence at 740 nm according to intra center process with decay time constant about 4 ms at 9 K. Both type of luminescence UV and yellow were ascribed to different defects containing phosphorus. P-doped α-quartz sample heated to 550 co become opalescent. Ir spectra related to water and OH groups are changed. Photoluminescence intensity of all three bands, UV (250 nm), yellow (600 nm) and red (740 nm) strongly diminished and disappeared after heating to 660 C°. Radiation induced red luminescence of non-bridging oxygen luminescence center (NBO) appeared in crystal after heat treatment. We had observed a crystalline version of this center (l. Skuja et al, Nuclear Instruments and Methods in Physics Research B 286,159-168 (2012)). Effect of heat treatment explained as sedimentation of phosphorus in some state. Keeping of treated sample at 450-500 C° leads to partial revival of ability to create yellow luminescence center under irradiation.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Airborne Release Fractions from Surrogate Nuclear Waste Fires Containing Lanthanide Nitrates and Depleted Uranium Nitrate in 30% Tributyl Phosphate in Kerosene

Airborne contaminants from fires containing nuclear waste represent significant health hazards and shape the design and operation of nuclear facilities. Much of the data used to formulate DOE-HDBK-3010-94, “Airborne Release Fractions/Rates and Respirable Fractions for Nonreactor Nuclear Facilities,” from the U.S. Department of Energy, were taken over 40 years ago. The objectives of this study were to reproduce experiments from Pacific Northwest Laboratories conducted in June 1973 employing current aerosol measurement methods and instrumentation, develop an enhanced understanding of particulate formation and transport from fires containing nuclear waste, and provide modeling and experimental capabilities for updating current standards and practices in nuclear facilities. A special chamber was designed to conduct small fires containing 25 mL of flammable waste containing lutetium nitrate, ytterbium nitrate, or depleted uranium nitrate. Carbon soot aerosols showed aggregates of primary particles ranging from 20 to 60 nm in diameter. In scanning electron microscopy, ~200-nm spheroidal particles were also observed dispersed among the fractal aggregates. The 200-nm spherical particles were composed of metal phosphates. Airborne release fractions (ARFs) were characterized by leaching filter deposits and quantifying metal concentrations with mass spectrometry. The average mass-based ARF for 238 U experiments was 1.0 × 10 -3 with a standard deviation of 7.5 × 10 -4 . For the original experiments, DOE-HDBK-3010-94 states, “Uranium ARFs range from 2 × 10 -4 to 3 × 10 -3 , an uncertainty of approximately an order of magnitude.” Therefore, current measurements were consistent with DOE-HDBK-3010-94 values. ARF values for lutetium and ytterbium were approximately one to two orders of magnitude lower than 238 U. Furthermore, metal nitrate solubility may have varied with elemental composition and temperature, thereby affecting ARF values for uranium surrogates (Yb and Lu). In addition to ARF data, solution boiling temperatures and evaporation rates can also be deduced from experimental data.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Atomic layer deposition of boron-containing films using B{sub 2}F{sub 4}

Ultrathin and conformal boron-containing atomic layer deposition (ALD) films could be used as a shallow dopant source for advanced transistor structures in microelectronics manufacturing. With this application in mind, diboron tetrafluoride (B{sub 2}F{sub 4}) was explored as an ALD precursor for the deposition of boron containing films. Density functional theory simulations for nucleation on silicon (100) surfaces indicated better reactivity of B{sub 2}F{sub 4} in comparison to BF{sub 3}. Quartz crystal microbalance experiments exhibited growth using either B{sub 2}F{sub 4}-H{sub 2}O for B{sub 2}O{sub 3} ALD, or B{sub 2}F{sub 4}-disilane (Si{sub 2}H{sub 6}) for B ALD, but in both cases, the initial growth per cycle was quite low (≤0.2 Å/cycle) and decreased to near zero growth after 8–30 ALD cycles. However, alternating between B{sub 2}F{sub 4}-H{sub 2}O and trimethyl aluminum (TMA)-H{sub 2}O ALD cycles resulted in sustained growth at ∼0.65 Å/cycle, suggesting that the dense –OH surface termination produced by the TMA-H{sub 2}O combination enhances the uptake of B{sub 2}F{sub 4} precursor. The resultant boron containing films were analyzed for composition by x-ray photoelectron spectroscopy, and capacitance measurements indicated an insulating characteristic. Finally, diffused boron profiles less than 100 Å were obtained after rapid thermal anneal of the boron containing ALD film.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗