Partial Substitution Of Fluorine Research Articles

Compositions of Composite Polymer-Oxide Coatings on Aluminum from Pyrolytic Gas Chromatography Mass-Spectrometry Data

Data on the composition of the external polymer part of the composite polytetrafluoroethylene (PTFE) oxide coatings obtained on an aluminum substrate by plasma electrolytic oxidation (PEO) within a single stage are presented. The coatings were formed in an aqueous silicate electrolyte with addition of PTFE dispersed powder in a siloxane–acrylate emulsion. It has been established that the external polymer-like layer of the PTFE/PEO coatings does not represent a physical mixture of the siloxane–acrylate copolymer and PTFE particles, but is composed of fragments of them. A partial substitution of fluorine by hydrogen in fluorocarbons contained in the coatings has been revealed. The obtained data are crucial for expanding knowledge on the formation, structure, composition, and properties of the composite polymer-containing oxide coatings formed within a single stage by means of plasma electrolytic oxidation on the valve metal surface.

Novel Core–Shell FeOF/Ni(OH)2 Hierarchical Nanostructure for All‐Solid‐State Flexible Supercapacitors with Enhanced Performance

Well‐controlled core–shell hierarchical nanostructures based on oxyfluoride and hydroxide are for the first time rationally designed and synthesized via a simple solvothermal and chemical precipitation route, in which FeOF nanorod acts as core and porous Ni(OH)2 nanosheets as shell. When evaluated as electrodes for supercapacitors, a high specific capacitance of 1452 F g−1 can be obtained at a current density of 1 A g−1. Even as the current density increases to 10 A g−1, the core–shell hybrid still reserves a noticeable capacitance of 1060 F g−1, showing an excellent rate capacity. Furthermore, all‐solid‐state flexible asymmetric supercapacitor based on the FeOF/Ni(OH)2 hybrid as a positive electrode and activated carbon as a negative electrode shows high power density, high energy density, and long cycling lifespan. The excellent electrochemical performance of the FeOF/Ni(OH)2 core–shell hybrid is ascribed to the unique microstructure and synergistic effects. FeOF nanorod from FeF3 by partial substitution of fluorine with oxygen behaves as a low intrinsic resistance, thus facilitating charge transfer processes. While the hierarchical Ni(OH)2 nanosheets with large surface area provide enough active sites for redox chemical reactions, leading to greatly enhanced electrochemical activity. The well‐controllable oxyfluoride/hydroxide hybrid is inspiring, opening up a new way to design new electrodes for next‐generation all‐solid‐state supercapacitors.

PEDOT Encapsulated FeOF Nanorod Cathodes for High Energy Lithium-Ion Batteries.

Conversion-reaction cathodes can potentially double the energy density of current Li-ion batteries. However, the poor cycling stability, low energy efficiency, and low power density of conversion-reaction cathodes limit their applications for Li-ion batteries. Herein, we report a revolutionary advance in a conversion-reaction cathode by developing a core-shell FeOF@PEDOT nanorods, in which partial substitution of fluorine with oxygen in FeF3 substantially enhance the reaction kinetics and reduce the potential hysteresis, while conformal nanolayer PEDOT coating provides a roubst fast electronic connection and prevents the side reactions. The FeOF@PEDOT nanorods deliver a capacity of 560 mA h g(-1) at 10 mA g(-1) with an energy density of >1100 W h kg(-1), which is more than two times higher than the theoretical energy density of LiCoO2. The FeOF@PEDOT nanorods can maintain a capacity of ~430 mA h g(-1) at 50 mA g(-1) (840 W h kg(-1)) for over 150 cycles with capacity decay rate of only 0.04% per cycle, which is 2 orders of magnitude lower than the capacity decay rate ever reported among all conversion-reaction cathodes. Detailed characterizations were conducted to identify the structure and mechanism responsible for these significant improvements that could translate into a Li-ion cell with a 2× increase in energy density.

Synthesis of AlPO4-34 and its large single crystal by partially substituting framework fluorine with oxygen species

AlPO4-34 is a fluorine containing aluminophosphate with two fluorine atoms located in the bridge of two octahedrally coordinated Al atoms of a 4-ring. It has a unit cell composition (C4H10NO+)2 (AlPO4)6F2 − with the stoichiometric value of Al:P:F being 3:3:1 (F/Al = 0.33) and to be named as AlPO4-34F. The presence of fluorine in the reacting gels favors the formation of AlPO4-34 structure, but hinders the growth of its large crystals. In present work, a seesaw effect between organic template and hydrofluoric acid on the crystallization of AlPO4-34 has been found and used to synthesize AlPO4-34 with F/Al in the framework lower than 0.33. Large single crystal of AlPO4-34 has been prepared from a gel having the molar ratio of HF/Al2O3 = 0.125. Single crystals refinement has shown that the unit cell formula of the AlPO4-34 is (C4H10NO+)2(AlPO4)6F 1.18 − (OH) 0.82 − (H2O)0.5. The molar ratio of Al:P:F:Ob is 3:3:0.59:0.41 with 40% fluoride ions being substituted by oxygen species (Ob: oxygen atoms in the bridges of Al–O–Al). Ion chromatography analysis has confirmed the partial substitution of fluorine by oxygen. It was named as AlPO4-34P. Thermal analyses have shown that oxygen species in the bridge position of two octahedrally coordinated Al atoms are more instable than fluoride ions. Under heating, the AlPO4-34P will transform to chabazite structure at a temperature lower than AlPO4-34F.

Morphologically Controlled Synthesis of Hydroxyapatite with Partial Substitution of Fluorine

Morphologies of hydroxyapatite with partial substitution of fluorine (FHAp) have been finely modulated from prickly spheres, whisk brooms, flowers, dandelions, and nanofibers to ultralong nanoribbons through altering the reaction conditions and adding glutamic acid. X-ray diffraction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, and so forth were performed for characterizing the resultant powders and analyzing the growth process. Condition experiments were compared comprehensively and revealed that FHAp crystals with various morphologies were formed, generally, through a fractal growth process of double splitting.

Short-range magnetic order in LaMn(O1−x Fx)3 from 139La and 19F NMR data

The temperature behavior of the 139La and 19F NMR spectra was studied for polycrystalline LaMn(O1−xFx)3 with a partial substitution of fluorine for oxygen. The temperature dependences of the 139La and 19F NMR line shapes were found to be substantially different. An appreciable broadening of the 19F NMR spectrum and a fixed position of line maximum with lowering temperature is indicative of the presence of a short-range magnetic order in the paramagnetic temperature region (T>T N ).

The Effect of Fluorine on the Phase Formation and Properties of Tl-based Superconductors

Fluorine was found to affect the phase formation and superconducting properties of Tl-based superconductors. By varying x in (Tl0.5Pb0.5)Sr1.6Ba0.4Ca2Cu3OyFx synthesized superconductors, an increase was found in the transition temperature and critical current density. These improvements in the superconducting properties are discussed in terms of partial substitution of fluorine into the oxygen sites which in turn affects the hole doping in this material. Structure, microstructure and elemental analysis by XRD, SEM and EDX techniques are reported; the latter of which shows the fluorine distribution.

Halocarbon hydrolysis rates ‐ a search for ionic strength and heterogeneous effects

Abstract Ten chlorinated or fluorinated alkanes and alkenes were hydrolyzed in deionized aqueous solution, in “sea water”;, or in the presence of 11 different crushed solid minerals including sulfides, oxides, hydroxides, and aquifer materials. No changes in the observed hydrolysis rates were found upon changing from a pure water environment to one of high ionic strength or of significant potential heterogeneous catalytic activity for these typical halogenated hydrocarbons. Successive partial substitution of fluorine for chlorine in the ethanes was shown to retard hydrolysis by one to five orders of magnitude.