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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Fluoroalkyl containing salts combined with fluorinated solvents for electrolytes

Provided are electrochemical cells and electrolytes used to build such cells. An electrolyte may include a fluoroalkyl-substituted LiPF.sub.6 salt or a fluoroalkyl-substituted LiBF.sub.4 salt. In some embodiments, at least one fluorinated alkyl of the salt has a chain length of from 1 to 8 or, more specifically, between about 2 and 8. These fluorinated alkyl groups, in particular, relatively large fluorinated alkyl groups improve solubility of these salts in fluorinated solvents that are less flammable than, for example, conventional carbonate solvents. At the same time, the size of fluoroalkyl-substituted salts should be limited to ensure adequate concentration of the salt in an electrolyte and low viscosity of the electrolyte. In some embodiments, the concentration of a fluoroalkyl-substituted salt is at least about 0.5M. Examples of fluorinated solvents include various fluorinated esters, fluorinated ethers, and fluorinated carbonates, such a 1-methoxyheptafluoropropane, methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, 1,1,1,2,2,3,4,5,5,5-decafluoro-3-methoxy-4-(trifluoromethyl)-pentane, 3-ethoxy-1,1,1,2,3,4,4,5,5,6,6,6-dodecafluoro-2-trifluoromethyl-hexane, and 1,1,1,2,3,3-hexafluoro-4-(1,1,2,3,3,3-hexafluoropropoxy)-pentane.

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

A Fluorination Method for Improving Cation-Disordered Rocksalt Cathode Performance

In Li-rich cation-disordered rocksalt oxide cathodes (DRX), partial fluorine substitution in the oxygen anion sublattice can increase the capacity contribution from transition-metal (TM) redox while reducing that from the less reversible oxygen redox. To date, limited fluorination substitution has been achieved by introducing LiF precursor during the solid-state synthesis. To take full advantage of the fluorination effect, however, a higher F content is desired. In the present study, the successful use of a fluorinated polymeric precursor is reported to increase the F solubility in DRX and the incorporation of F content up to 10–12.5 at% into the rocksalt lattice of a model Li-Mn-Nb-O (LMNO) system, largely exceeding the 7.5 at% limit achieved with LiF synthesis. Higher F content in the fluorinated-DRX (F-DRX) significantly improves electrochemical performance, with a reversible discharge capacity of ≈255 mAh g –1 achieved at 10 at% of F substitution. After 30 cycles, up to a 40% increase in capacity retention is achieved through the fluorination. Overall, the study demonstrates the feasibility of using a new and effective fluorination process to synthesize advanced DRX cathode materials.

25 ENERGY STORAGE↗
DOE OSTI2012

Low temperature fluorination of Sr{sub 3}Fe{sub 2}O{sub 7-x} with polyvinylidine fluoride: An X-ray powder diffraction and Moessbauer spectroscopy study

Fluorination of the Ruddlesden Popper phase, Sr{sub 3}Fe{sub 2}O{sub 7-x} by heat treatment with polyvinylidine fluoride (PVDF) gives a range of novel oxide fluoride compounds. Fluorination with 1 mol equivalent PVDF leads to a filling of the normal Ruddlesden Popper structure anion sites and a material of composition Sr{sub 3}Fe{sub 2}O{sub 5+x}F{sub 2-x} (x Almost-Equal-To 0.28(4)) which contains both Fe{sup 4+} and Fe{sup 3+}. Increasing the amount of PVDF to 2 mol equivalent leads to an increase in anion content due to filling of half the interstitial sites within the structure, with iron being completely reduced to Fe{sup 3+} leading to a composition Sr{sub 3}Fe{sub 2}O{sub 4}F{sub 4}. An increase in the amount of PVDF to Almost-Equal-To 3 mol equivalent leads to a further increase in unit cell volume, attributed to complete filling of the interstitial sites and a composition Sr{sub 3}Fe{sub 2}O{sub 3}F{sub 6}. {sup 57}Fe Moessbauer spectra in the temperature range 10-300 K demonstrated the complexity of the magnetic interactions in each of the three phases which reflect different local compositions of oxygen and fluorine around the iron ions thus influencing the superexchange pathways. - Graphical abstract: Low temperature (375 Degree-Sign C) fluorination of Sr{sub 3}Fe{sub 2}O{sub 7-x} with poly(vinylidene fluoride) leads to the production of three new Ruddlesden Popper oxide fluorides with progressive filling of the anion sites within the structure. Highlights: Black-Right-Pointing-Pointer The fluorination of Sr{sub 3}Fe{sub 2}O{sub 7-x} using PVDF. Black-Right-Pointing-Pointer The control of the fluorine content with amount of PVDF used. Black-Right-Pointing-Pointer The synthesis of three new Fe based oxide fluorides. Black-Right-Pointing-Pointer The identification of the structures of these oxide fluorides.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Introduction of oxygen vacancies and fluorine into TiO{sub 2} nanoparticles by co-milling with PTFE

Solid-state processes of introducing oxygen vacancies and transference of fluorine to n-TiO{sub 2} nanoparticles by co-milling with poly(tetrafluoroethylene) (PTFE) powder were examined by diffuse reflectance spectroscopy (DRS) of UV, visual, near- and mid-IR regions, thermal analyses (TG-DTA), energy-dispersive X-ray spectroscopy (EDXS), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The broad absorption peak at around 8800 cm{sup -1} (1140 nm) was attributed to the change in the electronic states, viz. electrons trapped at the oxygen vacancies (Vo) and d-d transitions of titanium ions. Incorporation of fluorine into n-TiO{sub 2} was concentrated at the near surface region and amounted to ca. 40 at% of the total fluorine in PTFE, after co-milling for 3 h, as confirmed by the F1s XPS spectrum. The overall atomic ratio, F/Ti, determined by EDXS was 0.294. By combining these analytical results, a mechanism of the present solid state processes at the boundary between PTFE and n-TiO{sub 2} was proposed. The entire process is triggered by the partial oxidative decomposition of PTFE. This is accompanied by the abstraction of oxygen atoms from the n-TiO{sub 2} lattices. Loss of the oxygen atoms results in the formation of the diverse states of locally distorted coordination units of titania, i.e. TiO{sub 6-n}Vo{sub n}, located at the near surface region. This leads subsequent partial ligand exchange between F and O, to incorporate fluorine preferentially to the near surface region of n-TiO{sub 2} particles, where local non-crystalline states predominate. - Graphical abstract: Scheme of the reaction processes: (a) pristine mixture, (b) oxygen abstraction from TiO{sub 2} and (c) fluorine migration from PTFE to TiO{sub 2}. Highlights: Transfer of fluorine from PTFE to n-TiO{sub 2} in a dry solid state process was confirmed. Black-Right-Pointing-Pointer 40% of F in PTFE was incorporated to the near surface region of n-TiO{sub 2} nanoparticles. Black-Right-Pointing-Pointer The transfer process is triggered by the oxidative decomposition of PTFE. Black-Right-Pointing-Pointer Fluorine incorporation is mediated by the formation of oxygen vacancies. Black-Right-Pointing-Pointer The sequential mechanisms are verified by XPS, EDXS, HRTEM, TG and DRS.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

Study of surface fluorination of photocatalytic TiO{sub 2} by thermal shock method

Surface fluorinated TiO{sub 2} powders were prepared by thermal shock method and an overall comparative study was achieved on the basis of XRD, SEM, UV-vis and XPS analyses. The main objective was to elucidate the influences of surface fluorination on the crystallite structures, morphologies, optical properties and surface chemistry with the temperature. According to the results, the surface fluorination under thermal shock method below 600 Degree-Sign C did not change the crystallite structure and the particles size, but successfully created chemisorbed fluoride ions, oxygen vacancies and increased the hydroxyl groups on the surface of TiO{sub 2}. The presence of oxygen vacancies was assigned to the red shift of TiO{sub 2} optical absorption edge, which was the origin of visible-light-induced photocatalytic activity of these samples. For the thermal shock temperatures over 600 Degree-Sign C, the K{sub 2}Ti{sub 6}O{sub 13}-like phase was formed, resulting from the decrease of surface hydroxyl groups and the blue shift in absorption edge which reduced the photocatalytic activity. - Graphical abstract: The influence of fluorination on the surface of TiO{sub 2} by thermal shock method at several temperatures has been investigated by following the evolution of the F1s spectra obtained by X-ray photoelectron spectroscopy. The blank peaks are assigned to the chemisorbed fluoride ions on the samples surface and the filled peaks to fluorine atoms in oxygenated environment of solid solution TiO{sub 2-x}F{sub x}, which is originated from the substitution of F ions for O ions in the TiO{sub 2} lattice. Highlights: Black-Right-Pointing-Pointer Surface fluorination of TiO{sub 2} P25 by thermal shock method. Black-Right-Pointing-Pointer Structure, morphology, surface and photocatalytic properties of fluorinated TiO{sub 2}. Black-Right-Pointing-Pointer Low thermal shock temperatures increase the photocatalytic activity. Black-Right-Pointing-Pointer Fluoride ions chemisorbed on the surface without structure and morphology change. Black-Right-Pointing-Pointer Formation of K{sub 2}Ti{sub 6}O{sub 13} phase at high thermal shock temperatures.

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

Terminally fluorinated glycol ether electrolyte for lithium metal batteries

Despite being an excellent candidate for lithium metal batteries due to its stability towards lithium metal, ethereal solvent suffers from relatively low anodic stability, rendering it incompatible with high voltage cathode. Although the anodic stability of ethereal solvent can be enhanced by fluorination, the lithium solvating ability of fluorinated ethers is largely reduced. As a result, common hydrofluoroethers, such as 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropylether (TTE) and bis(2,2,2-trifluoroethyl) ether (BTFE) are not able to dissolve any lithium salt, albeit enhanced oxidation potential. Therefore, new fluorinated glycol ethers were synthesized in this research. The diglyme analog, which was terminally fluorinated, demonstrated high anodic stability and excellent capability to facilitate lithium plating/stripping. Unlike its non-fluorinated counterpart, the fluorinated diglyme analog displayed outstanding compatibility with lithium hexafluorophosphate, which is an essential salt in lithium-ion batteries. Here it was shown that the electrolyte based on fluorinated diglyme analog with fluoroethylene carbonate as co-solvent enabled highly stable cycling of Li-metal batteries pairing with layered oxide cathode.

25 ENERGY STORAGE↗
DOE OSTI2016

Systematic Fluorination of P3HT: Synthesis of P(3HT- co -3H4FT)s by Direct Arylation Polymerization, Characterization, and Device Performance in OPVs

We present a strategy for tuning physical properties of P3HT-based copolymers by incorporating a fluorinated thiophene repeat unit. The synthesis and characterization of a series of fluorinated polythiophene P(3HT-co-3H4FT) materials are described, where the percentage of fluorinated repeat units in the polymer backbone is systematically varied from 0 to 100%. These P(3HT-co-3H4FT)s (P0, P25, P50, P75, and P100) were synthesized via direct arylation polymerization (DArP) methods. By varying the feed ratio of the two monomers, the percent of fluorinated repeat units (3H4FT) could be precisely controlled. As fluorination is increased, there is a strong effect on the electronic properties of the polymers, evidenced by a 0.4 eV drop in the E HOMO level for P100 when compared to P0. GIWAXS and TEM were used to determine the crystallinity and morphology. TEM analysis of thin film polymer/PCBM bulk-heterojunction blends indicates that increased fluorination does not result in stronger phase separation. As a result, organic photovoltaic devices were fabricated to evaluate changes in device performance as a result of fluorination.

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

Controlled Formation of Mixed Nanoscale Domains of High Capacity Fe 2 O 3 –FeF 3 Conversion Compounds by Direct Fluorination

In this paper, we report a direct fluorination method under fluorine gas atmosphere using a fluidized bed reactor for converting nanophase iron oxide (n-Fe 2 O 3 ) to an electrochemically stable and higher energy density iron oxyfluoride/fluoride phase. Interestingly, no noticeable bulk iron oxyfluoride phase (FeOF) phase was observed even at fluorination temperature close to 300 °C. Instead, at fluorination temperatures below 250 °C, scanning transmission electron microscopy coupled with electron energy loss spectroscopy (STEM-EELS) and X-ray photoelectron spectroscopy (XPS) analysis showed surface fluorination with nominal composition, Fe 2 O 3-x F 2x (x < 1). At fluorination temperatures of 275 °C, STEM-EELS results showed porous interconnected nanodomains of FeF 3 and Fe 2 O 3 coexisting within the same particle, and overall the particles become less dense after fluorination. We performed potentiometric intermittent titration and electrochemical impedance spectroscopy studies to understand the lithium diffusion (or apparent diffusion) in both the oxyfluoride and mixed phase FeF 3 + Fe 2 O 3 composition, and correlate the results to their electrochemical performance. Finally and further, we analyze from a thermodynamical perspective, the observed formation of the majority fluoride phase (77% FeF 3 ) and the absence of the expected oxyfluoride phase based on the relative formation energies of oxide, fluoride, and oxyfluorides.

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

Short-Range Order and Unusual Modes of Nickel Redox in a Fluorine-Substituted Disordered Rocksalt Oxide Lithium-Ion Cathode

Fluorine substitution for oxygen in cation-disordered lithium-excess transition metal oxides (Li 1+x TM 1-x O 2 ) used as lithium-ion cathodes was recently demonstrated to improve the reversibility of the processes taking place on charge and discharge by reducing the amount of oxygen loss on charge and preventing major structural rearrangements at high voltage. Yet, little is understood about how fluorine incorporates the oxide structure and impacts its electrochemical properties. We use a combination of experimental (solid-state nuclear magnetic resonance (NMR) spectroscopy) and theoretical techniques (density functional theory (DFT) calculations and Monte Carlo simulations) to investigate the evolution of the local structure around fluorine and lithium and the oxidation state of redox-active nickel during charge and discharge of the Li 1.15 Ni 0.45 Ti 0.3 Mo 0.1 O 1.85 F 0.15 (LNF15) cathode. We show that fluorine doping introduces short-range order in as-synthesized LNF15 by incorporating in lithium-rich sites with five or six lithium nearest neighbors. We observe the emergence of new signals in the ex situ 19 F NMR spectra taken at high states of charge, which we tentatively assign to undercoordinated, diamagnetic fluorine environments seen in our computed models. Our theoretical results also suggest that octahedral nickel ions directly bonded to fluorine follow a different oxidation mechanism than those surrounded by six oxygens, forming Ni 3+ intermediates instead of oxidizing from Ni 2+ directly to Ni 4+ . While the oxidation of Ni 2+ toward Ni 4+ is incomplete in oxides, due to overlap between the oxygen and the nickel valence states, this result suggests that fluorination may be an efficient strategy to utilize the Ni 2+ /Ni 4+ redox reservoir to a greater extent.

25 ENERGY STORAGE↗
DOE OSTI2016

A study of the degree of fluorination in regioregular poly(3-hexylthiophene)

Here, we systematically varied the degree of fluorination along the backbone of a series of highly regioregular 3-hexylthiophene-based polymers, P3HT-50F, P3HT-33F and P3HT-25F, in which 50%, 33% and 25% of the thiophene units within the polymer chain contain fluorine atoms in the available 4-position. These materials were homopolymerized using the Kumada catalyst transfer polycondensation method from a set of mono-fluorinated bi-, ter- and quarterthiophenes, to ensure high polymer regioregularity and evenly-spaced fluorine atoms along the conjugated thiophene backbone. The monomers were obtained from a synthetic route consisting of iterative Migita-Stille couplings of fluorinated and non-fluorinated 3- hexylthiophenes. The effect of the fluorine atoms on both polymer structure and properties is presented, with supporting quantum mechanical calculations that rationalize the intrinsic conformation preferences of the three P3HT derivatives. P3HT-50F (M¯ n = 34 kg/mol, 98.5% rr), P3HT-33F (M¯ n = 46 kg/mol, 98% rr) and P3HT-25F (M¯ n = 53 kg/mol, 95% rr) displayed HOMO levels of -5.34, -5.26 and -5.24 eV, bandgaps of 1.98, 1.98 and 1.97 eV, and average field-effect transistor hole mobilities of 4.5 × 10 -3 , 2.7 × 10 -2 , and 1.2 × 10 -2 cm 2 V -1 s -1 , respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2023

A fluorinated cation introduces new interphasial chemistries to enable high-voltage lithium metal batteries

Abstract Fluorides have been identified as a key ingredient in interphases supporting aggressive battery chemistries. While the precursor for these fluorides must be pre-stored in electrolyte components and only delivered at extreme potentials, the chemical source of fluorine so far has been confined to either negatively-charge anions or fluorinated molecules, whose presence in the inner-Helmholtz layer of electrodes, and consequently their contribution to the interphasial chemistry, is restricted. To pre-store fluorine source on positive-charged species, here we show a cation that carries fluorine in its structure is synthesized and its contribution to interphasial chemistry is explored for the very first time. An electrolyte carrying fluorine in both cation and anion brings unprecedented interphasial chemistries that translate into superior battery performance of a lithium-metal battery, including high Coulombic efficiency of up to 99.98%, and Li 0 -dendrite prevention for 900 hours. The significance of this fluorinated cation undoubtedly extends to other advanced battery systems beyond lithium, all of which universally require kinetic protection of highly fluorinated interphases.

25 ENERGY STORAGE↗
DOE OSTI2025

Enzymatic carbon–fluorine bond cleavage by human gut microbes

Fluorinated compounds are used for agrochemical, pharmaceutical, and numerous industrial applications, resulting in global contamination. In many molecules, fluorine is incorporated to enhance the half-life and improve bioavailability. Fluorinated compounds enter the human body through food, water, and xenobiotics including pharmaceuticals, exposing gut microbes to these substances. The human gut microbiota is known for its xenobiotic biotransformation capabilities, but it was not previously known whether gut microbial enzymes could break carbon-fluorine bonds, potentially altering the toxicity of these compounds. Here, through the development of a rapid, miniaturized fluoride detection assay for whole-cell screening, we identified active gut microbial defluorinases. We biochemically characterized enzymes from diverse human gut microbial classes including Clostridia, Bacilli, and Coriobacteriia, with the capacity to hydrolyze (di)fluorinated organic acids and a fluorinated amino acid. Whole-protein alanine scanning, molecular dynamics simulations, and chimeric protein design enabled the identification of a disordered C-terminal protein segment involved in defluorination activity. Domain swapping exclusively of the C-terminus conferred defluorination activity to a nondefluorinating dehalogenase. To advance our understanding of the structural and sequence differences between defluorinating and nondefluorinating dehalogenases, we trained machine learning models which identified protein termini as important features. Models trained on 41-amino acid segments from protein C termini alone predicted defluorination activity with 83% accuracy (compared to 95% accuracy based on full-length protein features). This work is relevant for therapeutic interventions and environmental and human health by uncovering specificity-determining signatures of fluorine biochemistry from the gut microbiome.

Probst, Silke I↗
DOE OSTI2024

Asymmetric photoenzymatic incorporation of fluorinated motifs into olefins

Enzymes capable of assimilating fluorinated feedstocks are scarce. This situation poses a challenge for the biosynthesis of fluorinated compounds used in pharmaceuticals, agrochemicals, and materials. We developed a photoenzymatic hydrofluoroalkylation that integrates fluorinated motifs into olefins. The photoinduced promiscuity of flavin-dependent ene-reductases enables the generation of carbon-centered radicals from iodinated fluoroalkanes, which are directed by the photoenzyme to engage enantioselectively with olefins. This approach facilitates stereocontrol through interaction between a singular fluorinated unit and the enzyme, securing high enantioselectivity at β, γ, or δ positions of fluorinated groups through enzymatic hydrogen atom transfer—a process that is notably challenging with conventional chemocatalysis. Furthermore, this work advances enzymatic strategies for integrating fluorinated chemical feedstocks and opens avenues for asymmetric synthesis of fluorinated compounds.

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

Tuning Fluorination of Linear Carbonate for Lithium-Ion Batteries

Liquid electrolyte engineering plays a critical role in modern lithium-ion batteries. However, the existing electrolytes fall short when used with some trending battery chemistries such as high-voltage and high-energy-density electrodes. Fluorination of electrolyte solvents has been identified as an effective approach for improved cyclability, but few works systematically studied the effects of fluorination extent of carbonate solvents on battery performance. Here we design and synthesize a family of fluorinated ethyl methyl carbonates. Different numbers of F atoms are finely tuned to yield monofluoroethyl methyl carbonate (F1EMC), difluoroethyl methyl carbonate (F2EMC) and trifluoroethyl methyl carbonate (F3EMC). The cycling behavior of several types of lithium-ion pouch cells, including graphite (Gr)/single-crystalline LiNi 0.8 Mn 0.1 Co 0.1 O 2 (SC-NMC811), Gr-SiO x /LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC622), high-voltage Gr/LiNi 0.5 Mn 1.5 O 4 (LNMO), Gr/layered Li-rich Mn-based oxide (LLMO) and fast-charging Gr/NMC622, were systematically investigated to understand the impact of fluorination degree. Compared to the commercially available F3EMC, we found that the partially-fluorinated F1EMC and F2EMC in some cases showed improved cycling stability, which we attribute to their locally-polar –CH 2 F and –CHF 2 groups and thus fast ion conduction than –CF 3 . This work suggests that highly or fully fluorinated solvents are not necessarily desirable; instead, fluorination degree needs to be rationally and finely tuned for optimized lithium-ion cell performance.

25 ENERGY STORAGE↗
DOE OSTI2019

Non-Aqueous Electrochemical Fluorination of Used Nuclear Fuel as an Advanced Separation Process

Development of efficient and environmentally benign methods to reprocess used nuclear fuel (UNF) will enable technologies for a nuclear renaissance. Electrochemical and fluorination methods for reprocessing UNF have been proposed, but combinations of electrochemical and fluorination methods have not been investigated. Electrochemical fluorination may reduce waste volumes compared to the main large-scale aqueous methods for processing used nuclear fuel. A non-aqueous electrochemical fluorination reprocessing method has been developed and demonstrated that enables gas phase uranium recovery while allowing for potential control of the reaction using a single process. Thermodynamic modeling showed a galvanic reaction between UNF and a fluorinating agent, such as NF 3 , in a molten fluoride electrolyte was possible and could selectively fluorinate U to UF 6 . To verify the model results, a reactor system for electrochemical fluorination was constructed along with vessels for product collection and analysis. Initial trials of the electrochemical reaction were performed and characterized by several electrochemical methods. The electrochemical oxidation of U using NF 3 as an oxidizing agent was demonstrated and UF 6 as a reaction product was detected.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2024

Photoenzymatic asymmetric incorporation of fluorinated motifs into olefins

Enzymes capable of assimilating fluorinated feedstocks are scarce, which poses a challenge for the biosynthesis of fluorinated compounds used in pharmaceuticals, agrochemicals, and materials. We develop a photoenzymatic hydrofluoroalkylation that adeptly integrates fluorinated motifs into olefins. The photoinduced promiscuity of flavin-dependent ene-reductases enables generation of carbon-centered radicals from iodinated fluoroalkanes, which are directed by the photoenzyme to engage enantioselectively with olefins. This approach facilitates stereocontrol through interaction between a singular fluorinated unit and the enzyme, securing high enantioselectivity at β-, γ-, or δ-positions of fluorinated groups via enzymatic hydrogen atom transfer, a process notably challenging with conventional chemocatalysis. This work advances enzymatic strategies for integrating fluorinated chemical feedstocks and opens new avenues for asymmetric synthesis of fluorinated compounds.

Li, Maolin↗
NASA NTRS1959

Design and Operating Criteria for Fluorine Disposal by Reaction with Charcoal

Experiments with the charcoal-fluorine reaction for the disposal of fluorine have shown generally that this method is effective over a wide range of conditions. Pure fluorine or fluorine diluted with nitrogen to concentrations as low as 0.3 percent fluorine may be disposed of efficiently within the rate limitation. Maximum feed rates have been established and are inversely proportional to the charcoal-bed particle diameter. Moisture content in the charcoal had no appreciable effect on the disposal efficiency after the reaction zone was established and the moisture was driven off by the heat of reaction. There was no evidence of bed poisoning resulting from continued use. Design parameters may be based on the stoichiometric requirements plus sufficient excess charcoal to maintain desired efficiency toward the end of a disposal operation. The length of time a given reactor may be used continuously is limited by the rate of fluorine input and the resistance of the system to heat and fluorine attack. Refractory-lined reactors have been in routine field use at the Lewis Research Center for over a year and have given satisfactory service over a wide range of conditions.

Schmidt, Harold W.↗
DOE OSTI2013

Fluorine compounds for doping conductive oxide thin films

Methods of forming a conductive fluorine-doped metal oxide layer on a substrate by chemical vapor deposition are described. The methods may include heating the substrate in a processing chamber, and introducing a metal-containing precursor and a fluorine-containing precursor to the processing chamber. The methods may also include adding an oxygen-containing precursor to the processing chamber. The precursors are reacted to deposit the fluorine-doped metal oxide layer on the substrate. Methods may also include forming the conductive fluorine-doped metal oxide layer by plasma-assisted chemical vapor deposition. These methods may include providing the substrate in a processing chamber, and introducing a metal-containing precursor, and a fluorine-containing precursor to the processing chamber. A plasma may be formed that includes species from the metal-containing precursor and the fluorine-containing precursor. The species may react to deposit the fluorine-doped metal oxide layer on the substrate.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗