Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “fluorination”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Role of quadrupole deformation and continuum effects in the “island of inversion” nuclei 28,29,31 F

The peculiar properties of nuclei in the so-called “island of inversion” around Z = 10 and N = 20 are the focus of current nuclear physics research. Recent studies showed that 28 F has a negative-parity ground state and thus lies within the southern shore of the island of inversion, and 29 F presents a halo structure in its ground state, but it is unclear which effects, such as deformation, shell evolution due to tensor forces, or couplings to the continuum, lead to this situation. Here, we investigate the role of quadrupole deformation and continuum effects on the single-particle structure of 28,29,31 F from a relativistic mean-field approach and show how both phenomena can lead to a negative-parity ground state in 28 F and halo structures in 29,31 F. We solve the Dirac equation in the complex-momentum (Berggren) representation for a potential with quadrupole deformation at the first order obtained from relativistic mean-field calculations using the NL3 interaction and calculate the continuum level densities using the Green’s function method. We extract single-particle energies and widths from the continuum level densities to construct the Nilsson diagrams of 28,29,31 F in the continuum and analyze the evolution of both the widths and occupation probabilities of relevant Nilsson orbitals in 28 F and find that some amount of prolate deformation must be present. In addition, we calculate the density distributions for bound Nilsson orbitals near the Fermi surface in 29,31 F and reveal that, for a quadrupole deformation 0.3 ≤ β 2 ≤ 0.45 (prolate), characteristic halo tails appear at large distances. Using the relativistic mean-field approach in the complex-momentum representation with the Green’s function method, we demonstrate that in neutron-rich fluorine isotopes, while in the spherical case the pf shells are already inverted and close to the neutron emission threshold, a small amount of quadrupole deformation can dramatically reduce the gap between positive- and negative-parity states and increase the role of continuum states, ultimately leading to the negative parity in the ground state of 28 F and the halo structures in 29,31 F.

20 ≤ A ≤ 38↗
DOE OSTI2020

Coherent elastic neutrino-nucleus scattering with directional detectors

We study the sensitivity of detectors with directional sensitivity to coherent elastic neutrino-nucleus scattering (CE$\textit{ν}$NS), and how these detectors complement measurements of the nuclear recoil energy. In this work we consider stopped pion and reactor neutrino sources, and use gaseous helium and fluorine as examples of detector material. We generate Standard Model predictions, and compare to scenarios that include new, light vector or scalar mediators. We show that directional detectors can provide valuable additional information in discerning new physics, and we identify prominent spectral features in both the angular and the recoil energy spectrum for light mediators, even for nuclear recoil energy thresholds as high as ~50 keV. Combined with energy and timing information, directional information can play an important role in extracting new physics from CE$\textit{ν}$NS experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Distributed Fiber Sensors With High Spatial Resolution in Extreme Radiation Environments in Nuclear Reactor Cores

This paper is a comprehensive experimental report on the neutron radiation effects of distributed optical fiber sensors with enhanced Rayleigh scattering profiles in an in-pile environment. Femtosecond laser direct writing was used to inscribe Type-II modifications in standard telecom fibers and radiation-hardened fibers with fluorine-doped cores. Rayleigh backscattering signals were enhanced for continuous 1.5 m. In-pile lead-out sensors tests were carried out at the MIT Research Reactor for two months, which was operated at a nominal power of 5.7 MW with fast neutron (>0.1 MeV) flux of 1.29 × 1014 n/cm2/s and an in-core temperature of up to 560°C. Using the Optical Frequency Domain Reflectometry technique, the backscattering profiles of fiber sensors were interrogated with a 3-cm spatial resolution to monitor the temperature profile of the reactor. Results show that laser inscribed Type-II modifications in the form of nanogratings are highly stable against extreme temperature and ionizing radiation. Both standard telecom fibers and radiation-hardened fibers with laser-enhanced Rayleigh profiles can continuously perform distributed temperature measurements over the entire duration of the in-pile testing. Temperature coefficients of sensors and spectral shift quality were studied as functions of total radiation fluence. To the best of our knowledge, we present for the first time, the temperature profile of an operating nuclear reactor core with 3-cm spatial resolution, enabled by distributed fiber sensors with laser-enhanced Rayleigh scattering profiles. The high spatial resolution measurements can provide valuable data for the design and validation of digital twin and virtual reality of nuclear energy systems.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2020

Self-Cleaning Hybrid Hydrophobic–Hydrophilic Surfaces: Durability and Effect of Artificial Soilant Particle Type

Dew accelerates the soiling rates and increases the dust adhesion. To use dew for self-cleaning, a fluorinated ethylene propylene coating was applied to suppress the reactions between dust and glass as well as to facilitate the dew to condense as mobile droplets. An array of rectangular hydrophilic channels in the coating increases the condensation rates and droplet slide-off diameters. Furthermore, the durability of the coating was evaluated by artificial UV weathering. Four different types of soilants were used in the artificial soiling tests to assess the effect of soilant type and surface properties on the soiling rates and self-cleaning efficacy under the simulated dew conditions. Soil deposition and self-cleaning mechanisms are being reported.

42 ENGINEERING↗
DOE OSTI2023

SnO2 Buffer Layers for High Efficiency CdSeTe/CdTe Devices

SnO2 buffer layers of different thickness were deposited onto TEC 15 Fluorine doped tin oxide coated glass substrates using rf magnetron sputtering. The buffer layers were then incorporated into Cu-doped CdSeTe/CdTe devices using a range of CdCl 2 activation treatments and CuCl2 annealing temperatures to determine the effects of buffer layer thickness on device performance. Results show that all devices fabricated with thinner buffer layers resulted in much better J - V characteristics than their thicker counterparts. This was mainly due to a reduced open-circuit voltage (Voc) when using thicker buffer layers. The best device produced a conversion efficiency of 16.59%, fill factor of 71.62%, Jsc of 28.44 mA/cm 2 and Voc of 814.23 mV.

buffer layers↗
DOE OSTI2023

Structural insights into hydrolytic defluorination of difluoroacetate by microbial fluoroacetate dehalogenases

Fluorine forms the strongest single bond to carbon with the highest bond dissociation energy among natural products. However, fluoroacetate dehalogenases (FADs) have been shown to hydrolyze this bond in fluoroacetate under mild reaction conditions. Furthermore, two recent studies demonstrated that the FAD RPA1163 fromRhodopseudomonas palustriscan also accept bulkier substrates. In this study, we explored the substrate promiscuity of microbial FADs and their ability to defluorinate polyfluorinated organic acids. Enzymatic screening of eight purified dehalogenases with reported fluoroacetate defluorination activity revealed significant hydrolytic activity against difluoroacetate in three proteins. Product analysis using liquid chromatography‐mass spectrometry identified glyoxylic acid as the final product of enzymatic DFA defluorination. The crystal structures of DAR3835 fromDechloromonas aromaticaand NOS0089 fromNostocsp. were determined in the apo‐state along with the DAR3835 H274N glycolyl intermediate. Structure‐based site‐directed mutagenesis of DAR3835 demonstrated a key role for the catalytic triad and other active site residues in the defluorination of both fluoroacetate and difluoroacetate. Computational analysis of the dimer structures of DAR3835, NOS0089, and RPA1163 indicated the presence of one substrate access tunnel in each protomer. Moreover, protein‐ligand docking simulations suggested similar catalytic mechanisms for the defluorination of both fluoroacetate and difluoroacetate, with difluoroacetate being defluorinated via two consecutive defluorination reactions producing glyoxylate as the final product. Thus, our findings provide molecular insights into substrate promiscuity and catalytic mechanism of FADs, which are promising biocatalysts for applications in synthetic chemistry and bioremediation of fluorochemicals.

Biochemistry & Molecular Biology↗
DOE OSTI2020

Si-based materials for lithium-ion batteries III: Surface-modified Si/C/polyvinylidine difluoride powder

X-ray photoelectron spectroscopy was used to analyze Si/C/polyvinylidine difluoride powder obtained from Paraclete Energy Inc. The spectra were obtained using incident monochromatic Al K α radiation at 1486.6 eV (0.834 01 nm). An initial survey spectrum together with F 1s, O 1s, C 1s, and Si 2p are presented. A final survey spectrum was collected to ascertain the amount of beam-induced damage, which appears to be minimal. Finally, the spectra indicate the principal core level photoelectron and Auger electron signals with only minor nitrogen signal and show the expected silicon-carbon and silicon-fluorine species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure.

25 ENERGY STORAGE↗
DOE OSTI2020

Si-based materials for lithium-ion batteries X: 70% surface-modified Si/C/polyvinylidine difluoride-carbon black/lithiated polyacrylic acid electrode

X-ray photoelectron spectroscopy was used to analyze a 70% Si/C/polyvinylidine difluoride/carbon black/lithiated polyacrylic acid electrode fabricated at the Cell Analysis, Modeling, and Prototyping Facility (CAMP), Argonne National Laboratory. The spectra were obtained using incident monochromatic Al Kα radiation at 1486.6 eV (0.834 01 nm). A survey spectrum together with O 1s, C 1s, and Si 2p are presented. The spectra indicate the principal core level photoelectron and Auger electron signals with only minor copper and lithium signals and show the expected silicon-carbon and silicon-fluorine species related to the surface modification process in addition to oxidized carbon and silicon due to atmospheric exposure.

Haasch, Richard T. (ORCID:0000000194792595)↗
DOE OSTI2025

Controlled phosphate doping into nanoscopic SiO 2 proton conducting membranes

This article describes a method to introduce phosphate (PO 4 ) into SiO 2 atomic layer deposition (ALD) films in a self-limiting fashion. The method involves the use of a less common phosphate precursor, trimethyl phosphite [P(OMe) 3 ], to introduce PO 4 as a low-level dopant, <1 at. %, into a SiO 2 ALD process using bis(ethylmethylamino)silane and a modified O 3 conversion. P(OMe) 3 does not deposit a film with typical oxygen sources but incorporates as PO 4 in an ABC-type ALD scheme at deposition temperatures ranging from 100 to 300 °C. Addition of up to ∼1 at. % of PO 4 does not significantly impact the film density or concentrations of carbon and nitrogen impurities, which are both <0.4 at. %. Despite the relatively low dopant concentrations, PO 4 incorporation is shown to have a large impact on transport properties of the film. When explored as proton (H + )-conducting membranes, undoped SiO 2 ALD films showed H + conductivities (3 × 10 −6 –8 × 10 −5 S cm −1 ) and low H 2 permeabilities (<10 −9 cm 2 s −1 ) when measured at room temperature. The addition of PO 4 is shown to increase H + conductivity to 2 × 10 −4 S cm −1 , while maintaining low H 2 permeability of <10 −9 cm 2 s −1 . The ratio of H + conductivity to H 2 permeability, a key performance metric for H + -conducting membranes used in water electrolyzers, exceeds that of commercial Nafion-117 membranes. Here, the moderate H + conductivity and very low H 2 permeability of PO 4 -doped SiO 2 films make them promising candidates as fluorine-free replacements for Nafion in applications such as water electrolysis, hydrogen fuel cells, and redox flow batteries.

Atomic layer deposition↗
DOE OSTI2020

Rational synthesis of atomically precise graphene nanoribbons directly on metal oxide surfaces

Atomically precise graphene nanoribbons (GNRs) attract great interest because of their highly tunable electronic, optical, and transport properties. However, on-surface synthesis of GNRs is typically based on metal surface–assisted chemical reactions, where metallic substrates strongly screen their designer electronic properties and limit further applications. In this work, we present an on-surface synthesis approach to forming atomically precise GNRs directly on semiconducting metal oxide surfaces. The thermally triggered multistep transformations preprogrammed in our precursors’ design rely on highly selective and sequential activations of carbon-bromine (C-Br) and carbon-fluorine (C-F) bonds and cyclodehydrogenation. The formation of planar armchair GNRs terminated by well-defined zigzag ends is confirmed by scanning tunneling microscopy and spectroscopy, which also reveal weak interaction between GNRs and the rutile titanium dioxide substrate.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Relaxor ferroelectric polymer exhibits ultrahigh electromechanical coupling at low electric field

Electromechanical (EM) coupling—the conversion of energy between electric and mechanical forms—in ferroelectrics has been used for a broad range of applications. Ferroelectric polymers have weak EM coupling that severely limits their usefulness for applications. Here, we introduced a small amount of fluorinated alkyne (FA) monomers (<2 mol %) in relaxor ferroelectric poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) (PVDF-TrFE-CFE) terpolymer that markedly enhances the polarization change with strong EM coupling while suppressing other polarization changes that do not contribute to it. Under a low–dc bias field of 40 megavolts per meter, the relaxor tetrapolymer has an EM coupling factor (k 33 ) of 88% and a piezoelectric coefficient (d 33 ) >1000 picometers per volt. These values make this solution-processed polymer competitive with ceramic oxide piezoelectrics, with the potential for use in distinct applications.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Engineering ligand reactivity enables high-temperature operation of stable perovskite solar cells

Perovskite solar cells (PSCs) consisting of interfacial two- and three-dimensional heterostructures that incorporate ammonium ligand intercalation have enabled rapid progress toward the goal of uniting performance with stability. However, as the field continues to seek ever-higher durability, additional tools that avoid progressive ligand intercalation are needed to minimize degradation at high temperatures. We used ammonium ligands that are nonreactive with the bulk of perovskites and investigated a library that varies ligand molecular structure systematically. Here, we found that fluorinated aniliniums offer interfacial passivation and simultaneously minimize reactivity with perovskites. Using this approach, we report a certified quasi–steady-state power-conversion efficiency of 24.09% for inverted-structure PSCs. In an encapsulated device operating at 85°C and 50% relative humidity, we document a 1560-hour T85 at maximum power point under 1-sun illumination.

14 SOLAR ENERGY↗
DOE OSTI2022

Ion Chromatography and Combustion Ion Chromatography Analysis of Fuel Cell Effluent Water During Open Circuit Voltage

Open circuit voltage tests were conducted on sixteen 3M Ionomer and eight Nafion™ NR211 membranes. Lifetime distributions were determined, and ion chromatography (IC) techniques were used to measure fluoride, sulfate, trifluoro acetate, and oxalate ions. Combustion Ion Chromatography (CIC) was used to determine the total organic fluoride (TOF) associated with water soluble membrane degradation fragments. The ratio of these products relative to the fluoride release rates were used to infer the likely degradation mechanism for each membrane. Peroxide attack at the sulfonic acid side chain was determined to be the least relevant reaction pathway while the long-proposed polymer chain end unzipping appears to be the dominant mechanism. Abstraction of the tertiary fluorine in the NR211 backbone and side chain is evident by organic fluoride release rates higher than can be explained by unzipping alone.

25 ENERGY STORAGE↗
DOE OSTI2022

Performance Improvement of Lithium Metal Batteries Enabled By LiBF 3 CN as a New Electrolyte Additive

A newly synthesized electrolyte additive, lithium trifluoro(cyano) borate (LiBF 3 CN), has been investigated for electrochemical performance improvement of lithium metal batteries. The LiBF 3 CN has a structure where one fluorine atom of BF 4 – is substituted with a cyano group (–CN) prepared by the reaction of boron trifluoride etherate with lithium cyanide. The electrochemical performance in symmetric Li/Li cells and NCM523/Li cells is significantly improved upon the incorporation of LiBF 3 CN as an electrolyte additive into a carbonate-based electrolyte. Extensive characterization of the deposited lithium metal reveals that a thin (≈20 nm) and robust SEI composed of LiN x O y , Li 3 N and Li 2 O is formed by the reductive decomposition of the LiBF 3 CN additive, which plays an important role in decreasing the resistance and stabilizing lithium deposition/stripping. The insight into the substitution effect of a functional group obtained from this work provides guidance for the design of new electrolyte additives.

25 ENERGY STORAGE↗
DOE OSTI2026

Solvent–Diluent Engineering of Normal-Concentration Organosulfur Electrolytes for High-Voltage Lithium-Ion Batteries

Enabling high‑voltage batteries depends critically on rational electrolyte design. Conventional carbonate electrolytes with LiPF 6 suffer from insufficient oxidative stability, motivating the use of lithium bis(fluorosulfonyl)imide (LiFSI) for its superior high‑temperature and high‑voltage performance. However, LiFSI is relatively costly, and its electrolytes often require high concentrations to suppress aluminum current collector corrosion in cathode architectures and to adequately passivate electrode interfaces. Here, a low‑concentration LiFSI electrolyte is realized by combining a high‑voltage organosulfur solvent, ethyl methyl sulfone (EMS), with a non‑solvating fluorinated diluent, fluorobenzene (FB). Extended cycling of LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) full cells to 4.5 V reveals substantial long‑term performance advantages over conventional carbonate electrolytes. Comparison with a popular cyclic sulfone, tetramethylene sulfone (TMS), shows that ring‑containing structures such as TMS strongly influence passivation behavior, ultimately limiting performance and narrowing the viable operating window. Overall, EMS is identified as a uniquely stable solvent for LiFSI‑based electrolytes operating at moderately high voltages.

Dato, Michael A. [Argonne National Laboratory (ANL↗
DOE OSTI2025

Statistical Design of Experiments Enables Rapid Exploration of Perfluorobutane Sulfonate Degradation

The phase-out of long-chain PFAS has led to the proliferation of highly recalcitrant short-chain analogs, and mineralization technologies for these short-chain PFAS are needed to mitigate their deleterious effects on environmental and human health. In this study, we utilize a statistical design of experiments, specifically, response surface methodology, to rapidly evaluate the electrochemical degradation of the short-chain PFAS, perfluorobutane sulfonate (PFBS). We evaluate the impacts of the three primary electrochemical parameters (concentration of PFBS, concentration of supporting electrolyte, and applied current) over multiple orders of magnitude on the three primary reaction outcomes of electrochemical PFBS degradation (incomplete PFBS decomposition, complete PFBS mineralization as fluorine, and anodic energy consumption). Our results correspond with literature and clearly identify the well-known tradeoff between energy consumption and complete mineralization. Intriguingly, partial PFBS decomposition and energy consumption demonstrate nonlinear dependencies in the current/supporting electrolyte concentration space and the current/PFBS concentration space, respectively. These findings highlight the utility of the response surface methodology model to efficiently interrogate a large parameter space, identifying both common results and less-obvious interactions between electrochemical parameters and their influences on reaction outcomes.

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

ENDF/B-VIII.1

The ENDF/B-VIII.1 release is the newest evaluated nuclear data library produced, distributed, and recommended by CSEWG for use in nuclear science and technology applications. Among the many key advances, relative to the previous version ENDF/B-VIII.0, are: re-evaluation of 239Pu file by a joint international effort; updated 16,18O, 19F, 28-30Si, 50-54Cr, 55Mn, 54,56,57Fe, 63,65Cu, 139La, 233,235,238U, and 240,241Pu neutron nuclear data by the IAEA-coordinated INDEN collaboration; significant changes for 3He, 6Li, 9Be, 51V, 88Sr, 103Rh, 140,142Ce, Dy, 181Ta, Pt, 206-208Pb, and 234,236U neutron data; new nuclear data for the photo-nuclear, being 196 adopted from the IAEA2019 Photonuclear Data Library and one new file from JENDL-5; and new evaluations for the charged-particle and atomic sublibraries. Numerous thermal neutron scattering kernels were re-evaluated or provided for the very first time. Additionally, new covariance testing was implemented. ENDF/B-VIII.1 reduced bias in the simulations of many integral experiments with particular progress noted for fluorine, copper and stainless steel containing benchmarks. Data issues which had hindered the deployment of ENDF/B-VIII.0 for commercial nuclear power applications in high burn-up situations, were addressed. ENDF/B-VIII.1 data are distributed in both ENDF-6 and GNDS formats.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗