Effect Of Fluorine Content Research Articles

Effect of fluorine on the electrochemical performance of spherical LiNi0.8Co0.1Mn0.1O2 cathode materials via a low temperature method

Abstract Spherical LiNi0.8Co0.1Mn0.1O2 materials have been synthesized by hydroxide co-precipitation method. Layered oxyfluoride LiNi0.8Co0.1Mn0.1O2 − zFz (0 ≤ z ≤ 0.06) cathodes have been synthesized by firing NH4F with LiNi0.8Co0.1Mn0.1O2 oxides at the relatively low temperature of 450 °C. The effect of fluorine content on the structure, morphology and electrochemical performance of the LiNi0.8Co0.1Mn0.1O2 − zFz has been extensively studied. The results indicated that the initial discharge capacity slightly decreased with the increase in the content of fluorine substitution. However, cycling performance and rate capability were improved by the fluorine substitution. Capacity retentions after 100 cycles at room temperature were 79.7% for z = 0, 94.3% for z = 0.02, 91.5% for z = 0.04, and 86.9% for z = 0.06. In addition, after being stored at 90 °C for 5 h in a fully charged state, fluorine substituted LiNi0.8Co0.1Mn0.1O2 exhibited better cycling performance than pristine LiNi0.8Co0.1Mn0.1O2. Overall, fluorine substitution was an effective way to improve electrochemical performance.

Effect of fluorine content on the crystallization and flexural strength of fluoro-mica glass ceramics

Abstract Two glasses with different contents of fluorine were fabricated. A single phase, KMg 3.25 Si 3.625 O 10 F 2 , precipitated in both of the glass samples after heat treatment. Both the crystallization activation energy ( En ) and the frequency factor ( ν ) increased with increasing fluorine content. This means that the fluorine content has a dual effect on the crystallization of fluorosilicic mica glass; the effect on the frequency factor is predominant. The flexural strength of the as-cerammed glass ceramic containing more fluorine is larger than that containing less fluorine when heated to the same temperature.

SiO2–Al2O3–CaO glass-ceramics: Effects of CaF2 on crystallization, microstructure and properties

The effects of fluorine content on the nucleation and crystallization behavior of SiO2–Al2O3–CaO glass ceramics system have been investigated. The crystalline phases were determined by X-ray diffraction (XRD). The crystallization kinetics was determined by differential thermal analysis (DTA). The microstructures were examined by using scanning electron microscope (SEM). Fourier transformed infrared spectra (FTIR) analysis was used to study the glass structure. The results showed that by increasing the fluorine content, both the crystallization peak temperature (Tp) and activation energy (E) decreased. Wollastonite, anorthite and gehlenite are the main crystalline phases that exist in the glass ceramics system. The study shows that fluorine promoted initial crystallization of glass and can be used as an effective nucleating agent in the SiO2–Al2O3–CaO system.

The Effect of Fluorine on the Viscosity and Crystallization of Lithium Aluminosilicate Glasses

Lithium aluminosilicate glasses have high viscosities, resulting in high melting temperatures and processing temperatures. In this study, F was added to the LAS glasses to reduce the melting temperature and viscosity for float process. The effects of fluorine content on the viscosity and crystallization of the parent glasses were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA) and rotation viscometer. It was found that the addition of F was useful in reducing the melting temperature and viscosity. The main crystalline phase of resulting glass-ceramics was β-spodumene. The activation energy (E) of LAS glasses was decreased from 460.3 KJ/mol to 417.7 KJ/mol with the addition of 2.63 wt% F, which accelerated the crystallization and enhanced the crystallinity of specimens.

Effect of Fluorine Content on the Electrochemical Properties of PVDF-Derived Carbons for Lithium Ion Battery

The carbon materials prepared by PVDF carbonization at different temperatures have similar BET surface area and pores volume. The content of fluorine in the carbons decreased with the carbonization temperature from 1.46% (atm %) at 600°C to 0.18 %( atm %) at 1000°C. The first cycle specific capacity and the initial coulombic efficiency decreases with the decrease of fluorine content in the samples. The first cycle discharge capacity decreased from 982 mAh/ g at 600°C to 752 mAh/ g at 1000°C and the initial coulombic efficiency decreased from 31.8% at 600°C to 24% at 1000°C. It is believed that fluorine contained in the carbon materials has a positive effect to improve the electrochemical properties as anode materials for Li-ion batteries.

Synthesis and characterization of UV-curable waterborne polyurethane acrylate possessing perfluorooctanoate side-chains

The dispersion of UV-curable waterborne polyurethane acrylate possessing perfluorooctanoate side-chains (FPUA) terminated with pentaerythritol triacrylate (PETA) was synthesized by incorporating fluorine groups into the side chains of the polyurethane macromolecular from condensation polymerization by using perfluorooctanoate glycerate (OF-diols) as chain extender, while the polyurethane macromolecular was synthesized from isophoronediisocyanate (IPDI), dimethylol propionic acid (DMPA), and poly (propylene glycol) (PPG) etc. The chain extender was prepared from 2,2-dimethyl-1,3-dioxolane-4-methyl perfluorooctanoate (OF-diols-pg) by acid hydrolysis with trifluoroacetic acid. The structure of FPUA was characterized by FTIR, NMR, elemental analysis, UV–vis and Mass spectra, and the properties of the synthesized FPUA emulsion were also discussed. The effect of fluorine content on the UV-curing dynamics was studied and the UV-curing speed decreased with increment in fluorine content. Contact angle measurements shown that the hydrophobic property of the surface greatly increased by incorporation of fluorine into the polyurethane chain. In addition, scanning electron spectroscopy (SEM) analysis was applied to characterize the morphology of the fracture surface of the UV-cured FPUA which became phase-mixed after annealing.

The effect of fluorine content on the mechanical properties of poly (ɛ-caprolactone)/nano-fluoridated hydroxyapatite scaffold for bone-tissue engineering

In this study, the effect of fluorine content on the mechanical properties of the novel poly (ɛ-caprolactone)/nano-fluoridated hydroxyapatite nanocomposite scaffolds was investigated. Poly (ɛ-caprolactone)/nano-fluoridated hydroxyapatite (PCL–FHA) scaffolds were produced by solvent casting/particulate leaching method. The fluoridated hydroxyapatite nanopowders had a chemical composition of Ca 10(PO 4) 6OH 2− x F x (where x values were selected equal to 0.5, 1, 1.5 and 2.0). Various weight percentages (10, 20, 30 and 40) of the FHA were added to the PCL. Sodium chloride (NaCl) particles having diameter of 300–500 μm were used as porogen. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) were used to identify the phase structure and functional groups of obtained scaffolds. Mechanical properties of the prepared scaffolds were also determined. Results showed that the compressive strength of scaffolds increases with decreasing the weight percent of fluorine in FHA.

Structural, optical, electrical properties and FTIR studies of fluorine doped SnO2 films deposited by spray pyrolysis

Thin films of SnO2:F were prepared by ultrasonic spray pyrolysis method. The effect of fluorine concentration on the structural, optical, and electrical properties of SnO2:F films was investigated. The X-ray diffraction results showed the preferred growth along (110). FTIR was employed to study the defects in SnO2 lattice. The evidence of oxygen vacancy and substitution of fluorine for oxygen in FTIR were investigated. It was found that at low doping levels, fluorine ions preferred to replace the oxygen in the lattice. While beyond a certain doping level, fluorine ions started to occupy interstitial site, which had a negative effect on carrier concentration that, in turn, affected the infrared reflectivity of SnO2:F films. The increased disorder of SnO2 at high doping levels was also shown by FTIR. The discussion of carrier scattering suggested that ionized impurity and/or neutral impurity scattering were the dominant scattering mechanisms in SnO2:F films.

A Novel ABC Triblock Copolymer with Very Low Surface Energy: Poly(dimethylsiloxane)‐block‐Poly(methyl methacrylate)‐block‐Poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate)

AbstractPoly(dimethylsiloxane)‐block‐poly(methyl methacrylate)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) was successfully synthesized via ATRP. The chemical composition and structure of the copolymer was characterized by NMR and FT‐IR spectroscopy and molecular weight measurement. Gel permeation chromatography was used to study the molecular weight distribution of the triblock copolymer. The surface properties of the resulting copolymer were investigated. The effects of fluorine content and bulk structure on surface energy were investigated by static water contact angle measurements. Surface composition was studied by XPS.magnified image

Effect of fluorine content on sintering and crystallisation behaviour of CaO–Al2O3–SiO2 glass ceramic system

The effect of fluorine content on the sinterability and crystallisation of glass belonging to CaO–Al2O3–SiO2 system was investigated. It was shown that increasing fluorine content promotes sinterability and crystallisation simultaneously. The Avrami exponent and activation energy for crystallisation of the most promising specimen were determined according to the Marotta method. The calculated Avrami exponent confirms a surface crystallisation mechanism. Results in the present paper suggest that with increasing fluorine content, the sinterability, crystallisation and mechanical properties of the system are improved whereas the chemical resistance is degraded.

Synthesis and characterization of poly(dimethylsiloxane)-block-poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate) diblock copolymers with low surface energy prepared by atom transfer radical polymerization

Well-defined poly(dimethylsiloxane)-block-poly(2,2,3,3,4,4,4-heptafluorobutyl methacrylate) (PDMS-b-PHFBMA) diblock copolymers are synthesized via atom transfer radical polymerization (ATRP). The chemical composition and structure of the copolymers are characterized by nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy, and molecular weight measurement. Gel permeation chromatography (GPC) is also used to study the molecular weight distributions of the PDMS- b-PHFBMA diblock copolymers. The microstructure of the resulting copolymers is investigated by transmission electron microscopy (TEM). The results of TEM show that the diblock copolymers are microphase-separated if the bulk contains enough PHFBMA segments. The effect of fluorine content on the surface energy and the bulk structure is investigated by static water contact angle. Surface energy of PDMS-b-PHFBMA films is indirectly obtained from contact angle.

EFFECT OF FLUORINE CONTENT ON THE MORPHOLOGICAL, STRUCTURAL, OPTICAL AND ELECTRICAL PROPERTIES OF NANOSTRUCTURED SnO2 FILMS

This paper reports morphological and structural details, optical and electrical properties of fluorine doped SnO 2 thin films prepared via spray pyrolysis route using SnCl 2·2 H 2 O as precursor and methanol as a solvent. The effect of fluorine concentration on the properties of the films is presented and discussed. X-ray diffraction pattern reveals the presence of SnO 2 films in the rutile structure with a preferential growth along the (200) direction. FTIR spectrum confirms the films to be made of SnO 2. EDS was used to estimate the fluorine concentration. SEM reveals the surface of FTO to be made of nanocrystalline particles. The grain size calculated using Debye–Scherrer formula is in the range of 8–34 nm. Film thickness measured using optical transmission method is in the range of 425–538 nm. The sheet resistance was found to decrease with increase in fluorine concentration, to a minimum of 6.35 Ω/□ for 7.5 mol% of NH 4 F , and it showed an increase beyond this concentration. The 2.5 mol% of F doped films gave 95.20% transmission at 704 nm. The calculated reflectivity in the IR region is 93.57% for 7.5 mol% of F doping, and figure of merit for the same film is 0.025(Ω/□)-1 at 550 nm. The total work was optimized by fixing the temperature at 550°C for the usage of Electrochromic Device preparations on FTO coated glass substrates.

Improvement of Electrochemical Performances of Li [ Ni0.8Co0.1Mn0.1 ] O2 Cathode Materials by Fluorine Substitution

Layered (, 0.02, 0.04, and 0.06) materials having spherical morphology have been synthesized by a hydroxide coprecipitation method. The effect of fluorine content on the structure, morphology, electrochemical properties, and thermal stability of the has been extensively studied. Electrochemical impedance spectroscopy and electron microscopy showed that fluorine substitution played the important role of reducing the interfacial resistance between cathode and electrolyte, resulting from stabilization of the host structure. The fluorine substitution for oxygen substantially improved the overall electrochemical properties of , such as the capacity retention, rate capability, and thermal stability.

Effect of fluorine content on mechanical properties of sintered fluoridated hydroxyapatite

The effect of fluorine content, preparing method, and sintering temperature on both the bulk density and biaxial flexural strength of sintered fluoridated hydroxyapatite (FHA) was studied. Both uniaxially pressed un-milled (UPU) and cold isostatically pressed milled (IPM) FHA discs were sintered at temperatures between 1200∼1400 °C at an interval of 100 °C. It was found that the fluorine content had significant impact on the sintering behavior, densification, and mechanical properties of FHA discs. At a low fluorine content, the specimens decomposed between 1200–1400 °C, which resulted in a relatively low sintered density and biaxial flexural strength of the specimens. In comparison, the specimens with high fluorine content did not decompose even at the sintering temperature of 1400 °C. The sintered density and biaxial flexural strength of these specimens increased with the sintering temperature. The maximum sintered density and biaxial flexural strength of the UPU specimens were only 85% of the theoretical density and 45 MPa, respectively. In contrast, much higher sintered density (∼95% of the theoretical density) and mechanical strength (∼100 MPa) were attained for the specimens subjected to the cold isostatic pressing and ball milling. A close correlation between the sintered density and biaxial flexural strength of the specimens was revealed, where the biaxial flexural strength increased exponentially with the sintered density.

The Effect of Cell Behavior on Apatites with Different Fluorine Contents

Fluoridated hydroxyapatite (FHA) discs with various fluorine contents have been used to study the effect of fluorine content on early-stage cell behavior. FHA powders with fluorine content in the range 0-0.577 (mol F /mol apatite) were pressed into discs and sintered at 1200°C for 1 hour. SAOs-2 rat osteosarcoma cells were cultured on each FHA disc and tissue culture polystyrene (control) with the same seeding density for 4 hours. The cell count was conducted using Alamarblue, and the morphology of cell attachment was observed using environmental scanning electron microscopy. It was apparent that the fluorine content in FHA had significant impact on the early cell behavior.

高度泥質変成岩の部分溶融過程における黒雲母のフッ素含有量の効果—実験岩石学的解析と日高・スリランカ・南極への応用—

高度泥質変成岩の部分溶融過程における黒雲母のフッ素含有量の効果—実験岩石学的解析と日高・スリランカ・南極への応用—

Effect of Fluorine Content on the Crystallization and Flexural Strength of Fluorosilicic Mica Glass-Ceramic

Effect of Fluorine Content on the Crystallization and Flexural Strength of Fluorosilicic Mica Glass-Ceramic

Effect of fluorine content on the crystallization of fluorsilicic mica glass

The effect of fluorine content on the crystallization of fluorsilicic mica glass was investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscope (SEM). A single phase, KMg3.25Si3.625O10F2, precipitates in all the glasses. Both the crystallization activation energy (E n ) and the frequency factor (ν) increase with the increase of the fluorine content. This means that the fluorine content has dual effects on the crystallization of fluorsilicic mica glass, while the effect on the frequency factor is predominant.

Effects of fluorine addition on driving force for CVD diamond growth

The driving force for the diamond growth from the vapor phase with fluorine addition was studied according to a non-equilibrium thermodynamic coupling model. There exists a temperature range that the driving force for diamond growth is positive but that for activated graphite is negative. Inside the temperature range, the growth of diamond under low pressures is possible. The effects of fluorine content on driving force for the diamond growth were also discussed. The theoretical results can offer quantitative predictions for optimizing experimental conditions.

Effect of fluorine on the combustion of “clean” surface boron particles

A detailed chemically reacting flow model was developed to study the full-fledged combustion of an initially oxide-free boron particle in a quiescent environment of combustion products. In the model, a surface chemistry mechanism previously developed for fluorine-free environments was extended to include fluorine. The effect of fluorine concentration as well as ambient gas temperature and particle size on burning rates was studied under diffusive- and chemical kinetically controlled conditions. In order to determine the dominant surface reactions, a sensitivity analysis was performed. Model results indicate that: (1) the addition of fluorine shifts the main products from B 2 O 3 (g) and HOBO(g) to OBF(g) and BF 3 (g); (2) for ratios of fluorine to oxygen atoms (F/O) less than 1, the kinetically controlled burning rate decreases slightly, while the diffusive-controlled burning rate decreases significantly with increasing F/O ratio; (3) for F/O ratios greater than 1, the kinetically controlled burning rate increases with F/O ratio, while the diffusive-controlled burning rate is insensitive to F/O ratio; and (4) the surface reactions of B 2 O 3 (g), O 2 (g) and F(g) are found to be the rate-controlling surface reactions with the relative importance of these processes dependent on F/O ratio.