Papers by Keyword: Fluorine

Abstract: Tin oxide (SnO₂) thin film is a form of modification of semiconductor material in nanosize. The thin film study aims to analyze the effect of triple doping (Aluminum, Indium, and Fluorine) on the optical properties of SnO₂: (Al + In + F) thin films. Aluminum, Indium, and Fluorine as doping SnO₂ with a mass percentage of 0, 5, 10, 15, 20, and 25% of the total thin-film material. The addition of Al, In, and F doping causes the thin film to change optical properties, namely the transmittance and absorbance values ​​changing. The transmittance value is 67.50, 73.00, 82.30, 87.30, 94.6, and 99.80 which is at a wavelength of 350 nm for the lowest to the highest doping percentage, respectively. The absorbance value increased with increasing doping percentage at 300 nm wavelength of 0.52, 0.76, 0.97, 1.05, 1.23, and 1.29 for 0, 5, 10, 15, 20, and 25% doping percentages, respectively. The absorbance value is then used to find the gap energy of the SnO₂: (Al + In + F) thin film of the lowest doping percentage to the highest level i.e. 3.60, 3.55, 3.51, 3.47, 3.42, and 3.41 eV. Thin-film activation energy also decreased with values of 2.27, 2.04, 1.85, 1.78, 1.72, and 1.51 eV, respectively for an increasing percentage of doping. The thin-film SnO₂: (Al + In + F) which experiences a gap energy reduction and activation energy makes the thin film more conductive because electron mobility from the valence band to the conduction band requires less energy and faster electron movement as a result of the addition of doping.

Abstract: The manufacture of a thin layer of SnO₂: (Al + F + In) was carried out by using the sol-gel spin coating method on a glass substrate with various temperatures (25, 50, 100, 150, and 200 °C).The purpose of this study is to determine the optical properties of thin layers which include transmittance, absorbance, band gap energy and activation energy. The optical properties of the coating were characterized using a UV-Vis spectrophotometer with a wavelength of 200-1100 nm. The results showed that the absorbance value increased with increasing temperature at a wavelength of 300 nm. The absorbance values ​​obtained for temperature variations were in the percentages of 95: 5% and 75: 25%, respectively 3.46-4.50 and 3.96-5.76. The transmittance value obtained increased, namely 73.00-86.30% and 74.20-99.30%. In addition, the energy band gap decreased from 3.60-3.41 eV and 3.57-3.31 eV for direct allowed, while 3.69-3.58 eV and 3.65-3.54 eV for indirect allowed. Activation energy decreased from 2.00-1.18 eV and 1.60-1.12 eV. In general, the absorbance and transmittance values ​​increase with increasing ripening temperature and the addition of doping aluminum, fluorine, and indium, while the bandgap energy and activation energy values ​​obtained decrease with increasing ripening temperature and increasing the doping percentage of aluminum, fluorine, and indium. The decrease in the value of the bandgap energy and the activation energy can make it easier for electrons to move from the valence band to the conduction band so that the material is slightly conductive and acts as a semiconductor.

Abstract: This work presents studies on the material composition and physico-mechanical characteristics of an alumina-containing estimate formed during the production of aluminum on electrolyzers with self-baking anodes during technological operations. The material is a mixture of fine powder 2.5 mm in size (62.78% on average mass) with the presence of pieces of material ranging in size from 0.5 to 6 cm (average 20.26% by weight). The samples contain pieces of hardened aluminum with sizes from 5 to 20 mm (16.96%). The largest content in the sample has the fineness classes-0.315 + 0.16 mm in the volume of 29.85% and the largest class +2.5 mm-37.22%. B It was established that aluminum is concentrated in the fractions-0.315 + 0.16 mm (45.7%) and 0.16 + 0 mm (48.8%), silicon in the fraction-0.63 + 0.315 mm (1.91%), iron at-1.25 + 0.63 mm (0.601%) and-0.63 + 0.315 mm (0.62%). The material consists of cryolite (Na₃AlF₆), chiolite (Al₃F₁₄Na₅), quartz, feldspar, carbonaceous matter and the technogenic phase of the composition (NaF) 1.5CaF₂ AlF₃. The material is characterized as non-abrasive (working index Ai - 0.0184) and very soft in relation to impact crushing (working index CWi - 3.64), the working index of ball grinding Bond (BWi - 6.47) characterizes a very low resistance to ball grinding. The implementation of the crushing operation of an alumina-containing estimate will allow the use of dry cascade-gravity and centrifugal classification to separate impurities in the form of SiO_2, and Fe₂O₃ for the use of alumina-containing material in primary aluminum technology. On the basis of laboratory tests, it is established that alumina-containing raw materials can be separated and photometric and gravitational separation methods can be used. A mathematical model of the motion of particles of primary and prepared alumina-containing raw materials in a cascade-gravity classifier was developed. The criteria and factors characterizing the alumina-containing material, as well as influencing and determining the maximum material enrichment, are established.

Abstract: Effects of CF₄ etching on 4H-SiC MOS capacitor were investigated. Fluorine atoms were introduced to surface of 4H-SiC using CF₄ dry etching process as a surface treatment, and 4H-SiC MOS capacitors with dry-oxide were fabricated with this treatment. As the results, breakdown electric field of the MOS capacitors was increased and variation of the characteristics became lower than that of MOS capacitor without this treatment.

Abstract: Etiology of halitosis is often concerned with gram-negative anaerobic bacteria, which produce the malodorous compounds such as volatile sulfur compounds (VSC), hydrogen sulfide and methyl mercaptan. The absorbents for the malodorous compounds are expected to prevent the teeth from decaying and peiodontics disease. The VSC adsorption capabilities of layered double hydroxides, of which composition is A_1-xB_x(OH)₂C_x/n·mH₂O, where A and B are Mg and Fe ions, and C are carbonate (CO₃^2- : MgFe LDH CO₃) and fluorine (F ^- : MgFe LDH F) ions in aqueous medium was studied by GC/FPD. The concentration of H₂S rapidly decreased for first 1 hours of soaking in H₂S water and fell to 0% in 4-5 h when MgFe LDH CO₃ was applied. MgFe LDH F was used, then the H₂S concentration was quickly decreased the same as MgFe LDH CO₃, and 8 mg/l of fluorine was released at a time. The iron ion was not detected in the H₂S water after soaking for 18 hours. The MgFe LDHF are expected to be likely adsorbent for the fast removal of VSC from the mouth and fluorine releasing agent.

Abstract: Production of high energy permanent magnets (HEPM) on the basis of rare-earth metals is one of leading knowledge intensive branches of world industry. Raw materials for production of magnets are magnetic alloys. In order to increase magnetic features scientists implement the additives of certain metals and their compounds, such as dysprosium and terbium additives in substantial amounts – up to 7-8 %.Within the framework of a ladle fluoride technology of HEPM manufacturing on the basis of a system Nd-Fe-B, developed by authors, scientists implement the additives of dysprosium and terbium fluoride, by virtue where of there was conducted a research on fluoration kinetics of corresponding oxides by elemental fluorine. The present article quotes results of such research and defines main kinetic parameters of examined processes – diffusion coefficient, kinetic constant and activation energy. Aiming to cost reduction of fluoride manufacture ammonium fluoride was used as a fluorinating agent by the example of fluoration of neodymium oxide.

Abstract: The paper describes the advantages and characteristics of the fluoride technology applicable for the recovery of oxides of rare earth elements with the help of a fluorinating agent of elemental fluorine. A metallurgical mixture (2.5 m²/g) of rare earth elements oxides of the cerium subgroup, containing % wt.: CeO₂ - 50-55; La₂ O₃ - 23-25; Pr₆O₁₁ - 6-9, and Nd₂O₃ - 13-16 were studied. It has been shown, that using fluoride technology allows recovering mixture of rare earth elements with outlet no less than 98.9 %.

Abstract: The article provides a mathematical description of the thermal processes in the experimental electrolyzer. We have performed computer simulation and verified the adequacy of the model obtained. All thermal processes occurring in the installation during its operation have been identified. The data are currently being used in the synthesis of automatic control systems (ACS).

Abstract: Hydroxyapatite [Ca₅(PO₄)₃(OH)] is a form of calcium phosphate inorganic compound of great importance in the health area because of its presence in bone as in teeth where it provides structural rigidity to the matrix. Hydroxyapatite is often used in the biomaterial area as a primary material for implants that help regenerate tissues. The addition of doping agents may improve the degree of crystallization providing new characteristics to the material without losing its biocompatibility. The present study shows characterization results for a hydroxyapatite biomaterial doped with silver and/or fluorine prepared through combustion method. The mineralogy was determined using X-Ray diffraction identifying the following phases: Ca₅(PO₄)₃OH, Ca₂P₂O₇, Ag₃PO₄, Ca₅(PO₄)₃F and CaF₂; the oxidation state of elements was determined by X-ray photoelectron spectroscopy; the morphological structure was studied by scanning electron microscopy and atomic force microscopy. Biocompatibility tests through intramuscular and subcutaneous implantation were performed in rodents to evaluate inflammatory response at 7, 14 and 30 days.

Abstract: It was shown that Ba (BrF₄)₂ acts like a highly-active brominating agent in case of interaction with p-nitrotoluene, the pure 3-bromo-nitrotoluene is formed. It was shown, that typical electrophilic bromination of aromatic compound with electron-donating and electron-accepting substituents occurs without any catalysts and hard conditions.