574 results on '"Tetrafluoride"'
Search Results
2. Searching for Monomeric Nickel Tetrafluoride: Unravelling Infrared Matrix Isolation Spectra of Higher Nickel Fluorides.
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Li, Lin, Sakr, Ahmed K., Schlöder, Tobias, Klein, Siri, Beckers, Helmut, Kitsaras, Marios‐Petros, Snelling, Howard V., Young, Nigel A., Andrae, Dirk, and Riedel, Sebastian
- Subjects
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MATRIX isolation , *NICKEL , *FLUORIDES , *MOLECULAR structure , *LASER ablation , *TRANSITION metals - Abstract
Binary transition metal fluorides are textbook examples combining complex electronic features with most fundamental molecular structures. High‐valent nickel fluorides are among the strongest known fluorinating and oxidizing agents, but there is a lack of experimental structural and spectroscopic investigations on molecular NiF3 or NiF4. Apart from their demanding synthesis, also their quantum‐chemical description is difficult due to their open shell nature and low‐lying excited electronic states. Distorted tetrahedral NiF4 (D2d) and trigonal planar NiF3 (D3h) molecules were produced by thermal evaporation and laser ablation of nickel atoms in a fluorine/noble gas mixture and spectroscopically identified by a joint matrix‐isolation and quantum‐chemical study. Their vibrational band positions provide detailed insights into their molecular structures. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
3. Is Titanium Tetrafluoride (TiF4) Effective to Prevent Carious and Erosive Lesions? A Review of the Literature.
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Wiegand, Annette, Magalhães, Ana Carolina, and Attin, Thomas
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CLINICAL trials ,TITANIUM ,DENTAL care ,DENTAL enamel ,DENTAL fluoride treatment - Abstract
The present review summarises the effects of titanium tetrafluoride (TiF4) on the development and progression of carious and erosive lesions. The mode of action of TiF4 is due to the formation of an acid-stable surface layer, which provides mechanical protection to the surface, and to an increased fluoride uptake, which might chemically reduce demineralisation of dental hard tissues. Most in vitro studies showed that TiF4 is effective in reducing the formation of carious and erosive enamel and dentine lesions. Thereby, TiF4 was equally or more effective than sodium fluoride (NaF), amine fluoride (AmF) or stannous fluoride (SnF2). While clinical data confirm the caries-preventive effect, clinical trials analysing the anti-erosive effect of TiF4 are lacking. Few data available from in situ studies revealed conflicting results by showing either no effect or a beneficial effect of TiF4 on enamel erosion. Even though research focused on TiF4, there is also evidence to show that other metal fluorides, such as zirconium and hafnium tetrafluorides, affect enamel and dentine demineralisation. Conclusion: The potential of TiF4 to prevent acid demineralisation requires further research to confirm the promising in vitro results obtained by in situ studies and clinical trials. [ABSTRACT FROM AUTHOR]
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- 2010
4. Superhalogen Boron Tetrafluoride Surface Modification Reduces the Formation of Organic Cation Vacancies on the Surface of Halide Perovskite Films
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He Zhang, Xinxin Lai, Anqi Yang, Chunjun Liang, and Dan Li
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Surface (mathematics) ,Materials science ,Inorganic chemistry ,Halide ,chemistry.chemical_element ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,General Energy ,chemistry ,Tetrafluoride ,Surface modification ,Physical and Theoretical Chemistry ,Boron ,Perovskite (structure) - Published
- 2021
5. Superhalogens Among 3d-Metal Compounds: MF4, MF6, MF12, and MF18 (M = Sc–Zn)
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Bala R. Ramachandran, Gennady L. Gutsev, Katharine Moore Tibbetts, and Lavrenty G. Gutsev
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010304 chemical physics ,Electron ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Ion ,Metal ,chemistry.chemical_compound ,Crystallography ,Hexafluoride ,chemistry ,Functional methods ,visual_art ,Electron affinity ,0103 physical sciences ,Bound state ,Tetrafluoride ,visual_art.visual_art_medium ,Physical and Theoretical Chemistry - Abstract
The ground states of the neutral and anionic tetrafluoride and hexafluoride series of 3d-metal atoms from Sc to Zn were assigned by using a double-check approach in which the pure and hybrid density functional methods were interchangeably used. It was confirmed that all these neutral fluorides are superhalogens except for TiF4. The electron affinities of the hexafluorides were shown to be consistently higher than those of the tetrafluorides in accordance with the superhalogen conception of the extra electron delocalization over a larger number of the electronegative ligands. In the search for mononuclear fluorides possessing higher electron affinities, we considered the M(F2)6- and M(F3)6- series where M = Sc-Zn. We found that the optimized geometrical structures in both series may be described as MF6-- k(F2), k = 3 and 6, of which the geometry of the MF6- core mimics that of the corresponding hexafluoride anion and the F2 dimers are kept in a bound state by polarizing forces. In these cases, the electron affinity is decreased by tenths of eV with respect to the electron affinity of the core hexafluorides due to a confinement of the extra electron by the F2 environment.
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- 2021
6. Total Total Ionization Cross Sections due to Electron Impact of Carbon Tetrafluoride from Ionization Threshold to 10 MeV
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Dr. Kiran Pal, Dr. Amrita, Dr. Yogesh Kumar, Dr. Manoj Kumar, Dr. Pramod Kumar, Dr. Kiran Pal, Dr. Amrita, Dr. Yogesh Kumar, Dr. Manoj Kumar, and Dr. Pramod Kumar
- Abstract
Modified Khare-BEB model has been used to calculate the electron impact ionization cross section for carbon tetrafluoride (CF4) from ionization threshold to 10 MeV. The collisional parameters CRP and also has been calculated. The calculations are compared with available experimental data . A good agreement is found among the present results, other previous calculations, and experimental data.
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- 2022
7. Synthesis of Cerium Tetrafluoride and Cerium Trifluoride Nanoscale Polycrystals from Ammonium Hydrogen Difluoride
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Xinyi Yang, Sun Yongju, Li Taosheng, and Huaping Mei
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Materials science ,Scanning electron microscope ,General Chemical Engineering ,chemistry.chemical_element ,General Chemistry ,Article ,chemistry.chemical_compound ,Cerium ,Chemistry ,chemistry ,Transmission electron microscopy ,Tetrafluoride ,Nanorod ,Selected area diffraction ,High-resolution transmission electron microscopy ,QD1-999 ,Powder diffraction ,Nuclear chemistry - Abstract
This paper reported a dry synthesis and characterization of cerium tetrafluoride (CeF4) and cerium trifluoride (CeF3) nanoscale polycrystals (NPs). The CeF4 NPs were spherical or flaky and approximately 10 ± 2 nm in diameter. The CeF3 NPs were rod-shaped nanorods with a length of about 150 ± 5 nm and a diameter of about 20 ± 2 nm. The first step was to synthesize the intermediate product-(NH4)4CeF8 by mixing CeO2 and NH4HF2 at a molar ratio of 1:6 at 390 K. The structural characterization was analyzed by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). Then, (NH4)4CeF8 was heated in an argon gas flow to synthesize the CeF3 and CeF4 NPs. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The properties of CeF3 and CeF4 NPs were further evaluated by transmission electron microscopy (TEM), selected area electron diffraction pattern (SAED), and high-resolution transmission electron microscopy (HRTEM). The findings provided an alternative strategy for the synthesis of nanometer fluorides, which could be a reference for high-performance research on other nanometer fluorides.
- Published
- 2021
8. Investigation of material removal characteristics of Si (100) wafer during linear field atmospheric-pressure plasma etching
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Weijia Guo, A. Senthil Kumar, and Peng Xu
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Technology ,Materials science ,Scanning electron microscope ,Atmospheric-pressure plasma ,02 engineering and technology ,01 natural sciences ,Industrial and Manufacturing Engineering ,Oxygen effect ,chemistry.chemical_compound ,Etching (microfabrication) ,Wafer ,Gas composition ,Composite material ,Removal characteristics ,Instrumentation ,Plasma etching ,Mechanical Engineering ,010401 analytical chemistry ,fungi ,AP plasma etching ,021001 nanoscience & nanotechnology ,Engineering (General). Civil engineering (General) ,0104 chemical sciences ,Grinding ,chemistry ,Tetrafluoride ,TA1-2040 ,0210 nano-technology ,Surface morphology - Abstract
Atmospheric-pressure (AP) plasma etching provides an alternative method for mechanical grinding to realize wafer thinning of Si wafer. It can avoid the damages and micro-cracks that would be introduced by mechanical stress during the grinding process. In this study, the material removal characteristics of Si (100) wafer processed by linear field AP plasma generated using carbon tetrafluoride (CF4) as the reactive source were analyzed. This linear field plasma etching tool has a typical removal profile and the depth removal rate that can reach up to 1.082 μm/min. The effect of O2 concentration on the removal rate was discussed and the surface morphology during the process was characterized using scanning electron microscopy. It is shown that the subsurface damage layer was gradually removed during the etching process and the surface was observed to be smoothened with the increase of the etching depth. This present work contributes a basic understanding of the linear field AP plasma etching performance with different gas composition and the typical characteristics would be further applied to damage-free precision removal of Si.
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- 2020
9. Efficient synthesis of lithium rare-earth tetrafluoride nanocrystals via a continuous flow method
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Junyu Yan, Kai Wang, Guangsheng Luo, and Jinsong Sui
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Materials science ,Continuous reactor ,chemistry.chemical_element ,02 engineering and technology ,Flow chemistry ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Photon upconversion ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,Nanocrystal ,Yield (chemistry) ,Tetrafluoride ,Silicon carbide ,General Materials Science ,Lithium ,Electrical and Electronic Engineering ,0210 nano-technology - Abstract
As an important upconversion illuminant material, LiREF4 nanocrystals were efficiently synthesized in a continuous reactor with the assistant of a new precursor solution. The employed trioctylamine solvent in the solution had a strong interaction with HF, and helped to avoid the generation of unnecessary solid components as LiF and NH4REF4 during the reaction. A silicon carbide reactor was developed to carry out the synthesis reaction, where LiYF4:Yb,Er/Ho/Tm quickly nucleated in 5 min at 300 °C. The reaction time to successfully prepare 15 nm sized nanocrystals was less than 30 min, and the space-time yield of the flow synthesis method was 14.8 times that of a control group batch reaction. The prepared nanocrystals had a strong illuminant ability, which could find its use in the area of security mark printing.
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- 2020
10. Synthesis and Characterization of Manganese Tetrafluoride β‐MnF 4
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Florian Kraus, Malte Sachs, Sergei I. Ivlev, Michael Serafin, Bernd G. Müller, Matthias Conrad, Jascha Bandemehr, and Clemens Pietzonka
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Inorganic Chemistry ,chemistry.chemical_compound ,chemistry ,Tetrafluoride ,Fluorine ,chemistry.chemical_element ,Manganese ,Characterization (materials science) ,Nuclear chemistry - Published
- 2020
11. Enhancing the stability and water resistance of CsPbBr3 perovskite nanocrystals by using tetrafluoride and zinc oxide as protective capsules
- Author
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Swelm Wageh, Bo Qiao, Zheng Xu, Pengjie Song, Ahmed A. Al-Ghamdi, Jingyue Cao, Gaoqian Zhang, Suling Zhao, Dandan Song, and Zhaohui Shen
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Materials science ,Water resistance ,020502 materials ,Mechanical Engineering ,Sodium ,Halide ,chemistry.chemical_element ,02 engineering and technology ,Zinc ,chemistry.chemical_compound ,0205 materials engineering ,chemistry ,Nanocrystal ,Chemical engineering ,Mechanics of Materials ,Tetrafluoride ,General Materials Science ,Luminescence ,Perovskite (structure) - Abstract
Lead halide perovskite materials are popular in optoelectronic applications due to their excellent properties, while their instability is still a bottleneck for their potential application. In this work, sodium yttrium fluoride (NaYF4) and zinc oxide (ZnO) were used as capsules to protect CsPbBr3 nanocrystals, greatly enhancing the resistance of CsPbBr3 nanocrystals to water and polar solvents. Water-resistant and stable luminescent CsPbBr3@NaYF4 and CsPbBr3@ZnO nanocrystals were obtained by using a simple solution-phase method. These water-stable enhanced perovskite nanocrystals are suitable for long-term stable optoelectronic applications in the atmosphere.
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- 2020
12. Conductance interference effects in an electron-beam-resist-free chemical vapor deposition graphene device sandwiched between two h-BN sheets
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Nobuyuki Aoki, Bi-Yi Wu, Gil-Ho Kim, Masahiro Matsunaga, Chieh-Wen Liu, Chi-Te Liang, Takashi Taniguchi, Chiashain Chuang, Masaaki Mineharu, and Kenji Watanabe
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Fabrication ,Materials science ,Graphene ,business.industry ,Annealing (metallurgy) ,Heterojunction ,02 engineering and technology ,General Chemistry ,Chemical vapor deposition ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,Boron nitride ,law ,Tetrafluoride ,Optoelectronics ,General Materials Science ,0210 nano-technology ,business ,Lithography - Abstract
We report fabrication and measurements of hexagonal boron nitride (h-BN)/chemical vapor deposition (CVD) graphene/h-BN heterostructure devices without using expensive, time-consuming electron-beam lithography and toxic carbon tetrafluoride or sulfur tetrafluoride etching. We use efficient transfer of h-BN/CVD graphene by polypropylene carbonate onto a pre-prepared metal contacts/h-BN/SiO2 substrate. In this case, CVD-graphene is suspended from the h-BN substrate which allows efficient gas annealing process for improving the device mobility. Interestingly, we find that the top h-BN capping layer could enhance the carrier interference effect in CVD graphene, a great advantage for low-cost graphene-based interference-type electronic devices.
- Published
- 2019
13. Titanium tetrafluoride and dental caries: a systematic review Tetrafluoreto de titânio e cárie dentária: uma revisão sistemática
- Author
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Rubiane Diógenes Alves, Tatyana Maria Silva de Souza, and Kenio Costa de Lima
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Cárie dentária ,Titânio ,Tetrafluoreto ,Cariostáticos ,Dental caries ,Titanium ,Tetrafluoride ,Cariostatic agents ,Dentistry ,RK1-715 - Abstract
The aim of this systematic review was to evaluate the effectiveness of titanium tetrafluoride as a preventive or cariostatic agent against caries. The databases used to find the articles analyzed were MEDLINE LILACS, and BBO. In MEDLINE and LILACS the search strategy utilized was "titanium" [Words] and "tetrafluoride" [Words] and Spanish or English or Portuguese [Language], whereas In BBO "titânio" [Words] and "tetrafluoreto" [Words] and Espanhol or Inglês or Português [Language]. Out of a total of 42 studies found, which assessed possible preventive/cariostatic effects of titanium tetrafluoride against caries in vivo, only 2 were selected. In both studies, titanium tetrafluoride was shown to be effective against caries. However, given that the quality and consequently the validity of these two clinical studies are questionable, their results do not allow to conclude that titanium tetrafluoride is effective against caries clinically.Esta revisão sistemática foi desenvolvida com o objetivo de avaliar a eficácia do tetrafluoreto de titânio como agente preventivo contra a cárie e/ou cariostático. Foram revisados, através da BIREME, artigos publicados nas revistas indexadas nas bases de dados MEDLINE, LILACS e BBO, utilizando as estratégias de busca titanium [Palavras] and tetrafluoride [Palavras] and Spanish or English or Portuguese [Idioma] na MEDLINE e no LILACS, já na BBO foram utilizados titânio [Palavras] and tetrafluoreto [Palavras] and Espanhol or Inglês or Português [Idioma]. De um total de 42 trabalhos diferentes encontrados, que avaliaram os efeitos preventivo/cariostático do tetrafluoreto de titânio contra a cárie in vivo, apenas 2 foram selecionados. Em ambos os estudos, o tetrafluoreto de titânio se mostrou efetivo contra a cárie. No entanto, considerando que a qualidade e, conseqüentemente, as validades desses poucos trabalhos clínicos existentes estão abertas para alguns questionamentos, conclui-se que os resultados apresentados não nos permitem dizer se o tetrafluoreto de titânio apresenta benefícios nos cuidados relacionados à cárie.
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- 2005
- Full Text
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14. Feasibility study of the production of bulk stable Ge isotopes by the hydrogen plasma chemical reduction of fluorides
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R.A. Kornev, A.M. Potapov, Nickolay Abrosimov, P.G. Sennikov, A.D. Bulanov, and V.A. Gavva
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010302 applied physics ,Zone melting ,Materials science ,Hydrogen ,Isotopes of germanium ,Mechanical Engineering ,Inorganic chemistry ,chemistry.chemical_element ,Germanium ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Condensed Matter Physics ,Germanium tetrafluoride ,01 natural sciences ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Yield (chemistry) ,0103 physical sciences ,Tetrafluoride ,General Materials Science ,0210 nano-technology ,Fluoride - Abstract
A «fluoride» method for preparation of germanium isotopes was developed and tested, including two main stages: 1) germanium deposition in the process of plasma chemical hydrogen reduction of germanium tetrafluoride with the subsequent compaction of the deposited polycrystalline germanium; 2) zone refining and single grystal growth of germanium if required. Degree of conversion of germanium tetrafluoride of 90–95% was achieved with a productivity of up to 10 g/h. The total yield of about 38% was attained for 72Ge n-type single crystal with a purity of >7 N. The method suggested has been compared with methods described in literature. Its advantage is the high yield production of germanium isotopes directly from enriched tetrafluoride without optional reagents. Plasma-chemical reduction of germanium tetrafluoride does not require sophisticated equipment. Thus, the “fluoride” method could be promising for production of germanium isotopes on industrial scale.
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- 2019
15. Thermodynamic properties of CH4, CCl4 and CF4 on the melting line. Theory and computer simulation
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L. N. Yakub and E. S. Bodiul
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010302 applied physics ,Materials science ,Physics and Astronomy (miscellaneous) ,Monte Carlo method ,General Physics and Astronomy ,Thermodynamics ,Melting line ,01 natural sciences ,Methane ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,Tetrafluoride ,Tetrafluoromethane ,Sublimation (phase transition) ,Physics::Chemical Physics ,010306 general physics ,Monoclinic crystal system - Abstract
Thermodynamic properties of the condensed phases of methane CH4, carbon tetrafluoride CF4 and carbon tetrachloride CCl4 on the melting line and in the high-pressure region were studied using the equations of state developed earlier for methane in the framework of the thermodynamic perturbation theory. We also present the results of Monte Carlo computer simulations of fcc phases of methane, carbon tetrachloride, and of the monoclinic tetrafluoromethane phase using a potential model that takes into account both the central and octupole–octupole interaction. The contribution of the octupole–octupole interaction to the thermodynamic properties of crystals are evaluated. The simulation results are compared with the available experimental data on the sublimation and melting lines, as well as to results of previous calculations based on the equations of state.
- Published
- 2019
16. Decomposition Modeling of Carbon Tetrafluoride With Nitrogen Thermal Plasma
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Yung-Tien Lin, Shiaw-Huei Chen, and Shiu-Wu Chau
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Thermal equilibrium ,Nuclear and High Energy Physics ,Materials science ,Chemical process of decomposition ,chemistry.chemical_element ,Thermodynamics ,Condensed Matter Physics ,Decomposition ,Chemical reaction ,chemistry.chemical_compound ,chemistry ,Tetrafluoride ,Transport phenomena ,Carbon ,Water vapor - Abstract
For modeling the carbon tetrafluoride disposal required in the semiconductor fabrication process, this paper proposes a numerical approach to predict the decomposition characteristics of carbon tetrafluoride in a reaction chamber via a nontransferred, direct-current torch, where the magnetohydrodynamic equations, such as the continuity, momentum, energy, and current continuity equations together with turbulence transport equations, are solved with a parallelized finite-volume approach. The thermal plasma is assumed in local thermal equilibrium, and a kinetics model is adopted to consider the transport phenomena as well as the chemical reactions of various species arising in the decomposition process. The proposed model is validated for a rod-type torch operating at 100 SLPM, 80 A, and 18 kW, whereas carbon tetrafluoride of various concentrations well premixed with the nitrogen of 300 SLPM is injected into the hollow torch with the possible presence of water vapor. The major products stemming from the decomposition mechanism of carbon fluoride with water are H2O, OH, H, O, H2, O2, HO2, H2O2, O3, H+, O+, F, HF, CF, CO, CH, F2, CHF, CF2, COF, CO2, CH2F, CF3, COF2, CH2F2, CF4, CHF3, and electron, where 28 species and 75 chemical reactions are considered in the proposed model. The measured destruction and removal efficiency of carbon tetrafluoride slightly decreases with the increase of the incoming concentration of CF4. The numerical model delivers a quantitative and qualitative agreement with the experimental measurement. The discrepancy can be explained by the secondary decomposition of the process gas after exiting the reaction chamber and before leaving the detoxifying system.
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- 2019
17. Searching for Monomeric Nickel Tetrafluoride: Unravelling Infrared Matrix Isolation Spectra of Higher Nickel Fluorides
- Author
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Lin Li, Marios-Petros Kitsaras, Dirk Andrae, Nigel A. Young, Tobias Schlöder, Helmut Beckers, Siri Klein, Ahmed K. Sakr, Sebastian Riedel, and H.V. Snelling
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Technology ,Materials science ,Infrared spectroscopy ,chemistry.chemical_element ,tetrafluoride ,010402 general chemistry ,01 natural sciences ,Catalysis ,Transition metal ,Molecule ,Open shell ,Trigonal planar molecular geometry ,010405 organic chemistry ,Communication ,nickel fluorides ,Matrix isolation ,matrix isolation ,General Chemistry ,General Medicine ,Communications ,0104 chemical sciences ,Nickel ,chemistry ,IR spectroscopy ,trifluoride ,Fluorine ,Physical chemistry ,500 Naturwissenschaften und Mathematik::540 Chemie::540 Chemie und zugeordnete Wissenschaften ,ddc:600 ,Fluorides | Hot Paper - Abstract
Binary transition metal fluorides are textbook examples combining complex electronic features with most fundamental molecular structures. High‐valent nickel fluorides are among the strongest known fluorinating and oxidizing agents, but there is a lack of experimental structural and spectroscopic investigations on molecular NiF3 or NiF4. Apart from their demanding synthesis, also their quantum‐chemical description is difficult due to their open shell nature and low‐lying excited electronic states. Distorted tetrahedral NiF4 (D 2d) and trigonal planar NiF3 (D 3h) molecules were produced by thermal evaporation and laser ablation of nickel atoms in a fluorine/noble gas mixture and spectroscopically identified by a joint matrix‐isolation and quantum‐chemical study. Their vibrational band positions provide detailed insights into their molecular structures., Molecular NiF3 and NiF4 are the missing tri‐ and tetrafluorides of the otherwise known binary first‐row transition‐metal fluorides that are predicted to be stable. These elusive high‐valent molecular nickel fluorides were identified in rare‐gas matrices aided by high‐level quantum chemical electronic structure calculations. They are among the most powerful known fluorination and oxidation agents.
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- 2021
- Full Text
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18. A New Scheme for Residual CF4 Detection in Gas-Insulated Switchgear Using Plasma-induced CF4 Decomposition into CO2
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Michihiko Nakano, Junya Suehiro, Masafumi Inaba, Daichi Maenosono, Nisarut Phansiri, and Hidefumi Sato
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Materials science ,0211 other engineering and technologies ,Analytical chemistry ,Infrared spectroscopy ,02 engineering and technology ,Dielectric barrier discharge ,Nonthermal plasma ,021001 nanoscience & nanotechnology ,Decomposition ,Gas analyzer ,Dilution ,chemistry.chemical_compound ,chemistry ,Tetrafluoride ,021108 energy ,0210 nano-technology ,Spectroscopy - Abstract
This paper presents a new scheme for the detection of residual carbon tetrafluoride (CF 4 ) gas in gas-insulated switchgear (GIS) for its diagnosis. For the diagnosis of GIS, the decomposition gas species including CF 4 generated by partial discharges or breakdown are analyzed. Accumulation of the gas species indicates the history of the failure of GIS. However, most of the gas species are removed by an absorbent placed in a GIS vessel. The only CF 4 stays in GIS vessel for the long term. In this study, it is aimed to develop an easy and rapid CF 4 detection method. Because direct detection of CF 4 is difficult, an indirect detection method of CF 4 is proposed, in which CF 4 is processed by non-thermal plasma (NTP). In this paper, the conversion of CF 4 using dielectric barrier discharge (DBD) was examined. The infrared absorption band among SF 6 , CF 4 , and CO 2 was observed by Fourier transform infrared (FT-IR) spectroscopy. The amount of CO 2 generated in the case of CF 4 (10,000 ppm) and O 2 (10,000 ppm) diluted in Ar or SF 6 was analyzed. In the case of Ar dilution, CO 2 gradually increased with increasing time of DBD application by using a compact CO 2 NDIR sensor. In the case of SF 6 dilution, CO 2 , CO, O 2 , and SO 2 were detected by using a portable gas analyzer. The latter case showed a higher CO 2 generation rate of 400 ppm/hr, whereas the other showed 50 ppm/hr. In addition, a zeolite-filled column was installed for removing SO 2 from the processed gas.
- Published
- 2020
19. Simple Fabrication of Transparent, Colorless, and Self-Disinfecting Polyethylene Terephthalate Film via Cold Plasma Treatment
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Sung-Gyu Park, Junfei Ma, Ji-Hyeon Kim, Seunghun Lee, Chang Su Kim, and ChaeWon Mun
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Fabrication ,Materials science ,General Chemical Engineering ,chemistry.chemical_element ,Article ,lcsh:Chemistry ,chemistry.chemical_compound ,chemistry ,Chemical engineering ,lcsh:QD1-999 ,polyethylene terephthalate ,self-disinfecting ,Tetrafluoride ,CF4 plasma treatment ,Transmittance ,Polyethylene terephthalate ,General Materials Science ,Dry etching ,dry etching ,Antibacterial activity ,Carbon ,Nanopillar ,nanopillar structure - Abstract
Cross-infection following cross-contamination is a serious social issue worldwide. Pathogens are normally spread by contact with germ-contaminated surfaces. Accordingly, antibacterial surface technologies are urgently needed and have consequently been actively developed in recent years. Among these technologies, biomimetic nanopatterned surfaces that physically kill adhering bacteria have attracted attraction as an effective technological solution to replace toxic chemical disinfectants (biocides). Herein, we introduce a transparent, colorless, and self-disinfecting polyethylene terephthalate (PET) film that mimics the surface structure of the Progomphus obscurus (sanddragon) wing physically killing the attached bacteria. The PET film was partially etched via a 4-min carbon tetrafluoride (CF4) plasma treatment. Compared to a flat bare PET film, the plasma-treated film surface exhibited a uniform array structure composed of nanopillars with a 30 nm diameter, 237 nm height, and 75 nm pitch. The plasma-treated PET film showed improvements in optical properties (transmittance and B*) and antibacterial effectiveness over the bare film, the transparency and colorlessness slightly increased, and the antibacterial activity increased from 53.8 to 100% for Staphylococcus aureus, and from 0 to 100% for Escherichia coli. These results demonstrated the feasibility of the CF4 plasma-treated PET film as a potential antibacterial overcoating with good optical properties.
- Published
- 2020
- Full Text
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20. Evaluation of carbon tetrafluoride as a xenon surrogate for underground gas transport
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Steven R Biegalski, Brianna S. Barth, Brandon De Luna, Matthew Paul, Derek A. Haas, and Margaret Flicker Byers
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Nuclear explosion ,010504 meteorology & atmospheric sciences ,Health, Toxicology and Mutagenesis ,Public Health, Environmental and Occupational Health ,Analytical chemistry ,chemistry.chemical_element ,010403 inorganic & nuclear chemistry ,Mass spectrometry ,01 natural sciences ,Pollution ,0104 chemical sciences ,Analytical Chemistry ,Sulfur hexafluoride ,chemistry.chemical_compound ,Xenon ,Nuclear Energy and Engineering ,chemistry ,TRACER ,Tetrafluoride ,Environmental science ,Radiology, Nuclear Medicine and imaging ,Diffusion (business) ,Carbon ,Spectroscopy ,0105 earth and related environmental sciences - Abstract
Detection of radioxenon is a critical component of underground nuclear explosion monitoring. Sulfur hexafluoride (SF6) has historically served as a Xe tracer. This work explores the use of carbon tetrafluoride (CF4) as an alternative for field tests given its general suitability as a tracer and reduced greenhouse gas potential compared to SF6. Gas Chromatography–Mass Spectrometry measurements characterized the diffusive behavior of CF4 in a 2-bulb apparatus to determine how well int approximates Xe. The measured diffusion coefficient of SF6 was 78% of that of Xe, agreeing with literature values, while CF4 diffused at 97% the rate of Xe.
- Published
- 2018
21. Colloidal synthesis of NaYF4 nano- and microparticles by sacrificial template method
- Author
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Gabriela Guida, Leonardo Ribeiro da Cruz, and Paulo C. de Sousa Filho
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chemistry.chemical_compound ,Materials science ,chemistry ,Chemical engineering ,Tetrafluoride ,Nano ,Hexagonal phase ,chemistry.chemical_element ,Nanoparticle ,Yttrium ,Luminescence ,Photon upconversion ,Template method pattern - Abstract
Lanthanide-doped sodium yttrium tetrafluoride nanoparticles show intense upconversion emissions which raise great attention in a variety of luminescence applications. This host lattice shows specially attractive properties in its hexagonal phase, which normally requires high temperature reactions and complex procedures to be synthesized. In this work, we synthesized nano- and micro-sized NaYF4 particles with controllable cubic or hexagonal structure via sacrificial colloidal template method under mild conditions of 50 oC/1 atm in a 3 h-long reaction.
- Published
- 2019
22. Sustainable degradation of carbon tetrafluoride to non-corrosive useful products by incorporating reduced electron mediator within electro-scrubbing
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Y. H. Cho, Il-Shik Moon, G. Muthuraman, Ewan J. McAdam, and A. G. Ramu
- Subjects
Mass transfer coefficient ,Materials science ,General Chemical Engineering ,Inorganic chemistry ,02 engineering and technology ,Electrolyte ,010402 general chemistry ,021001 nanoscience & nanotechnology ,Electrochemistry ,01 natural sciences ,CF4 degradation ,Cathode ,0104 chemical sciences ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,Hetero-bimetal ,MER ,Tetrafluoride ,Fourier transform infrared spectroscopy ,0210 nano-technology ,Spectroscopy ,Electron paramagnetic resonance ,Ethanol formation - Abstract
The degradation of CF4 gas using existing technologies produces other types of greenhouse gas (CO2) and corrosive side products. The main aim of this study is to degrade CF4 gas at room temperature into useful products without producing corrosive side products by mediated electrochemical reduction (MER) process using an electrogenerated Cu1+[Ni2+(CN)4]1− mediator. Initial studies on the electrolytic reduction of the hetero-bimetallic complex in catholyte solution at anodized Ti cathode was monitored by oxidation/reduction potential (ORP) variation whether the Cu2+ or Ni2+ was reduced in the Cu2+[Ni2+(CN)4] and confirmed by electron spin resonance (ESR) spectroscopy the Cu1+[Ni2+(CN)4]1− formation. The concentration variation of Cu1+[Ni2+(CN)4]1− during CF4 injection demonstrated the degradation of CF4 followed the MER by electrogenerated Cu1+[Ni2+(CN)4]1−. Maximum removal efficiency of CF4 using electroscrubbing process was 96% at room temperature. Through the variation in gas phase parameters, the gas phase mass transfer coefficient was calculated that can facilitate scale up the developed process. Fourier transform infrared spectroscopy analysis in both the gas and solution phases showed that CH3CH2OH was the main product that formed during the removal of CF4 by electrogenerated Cu1+[Ni2+(CN)4]1− at electroscrubber along with a small amount of CF3CH3 intermediate. Importantly, this mechanism also avoided formation of the corrosive product HF.
- Published
- 2018
23. Anomalous Broadening of CF4 Molecule Lines. Observation of Carbon Tetrafluoride Hydrates?
- Author
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A. A. Lugovskoi, L. N. Sinitsa, and Viktor I. Serdyukov
- Subjects
Materials science ,Physics and Astronomy (miscellaneous) ,Absorption spectroscopy ,Precipitation (chemistry) ,Inorganic chemistry ,chemistry.chemical_element ,Snow ,01 natural sciences ,010305 fluids & plasmas ,Atmosphere ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,Tetrafluoride ,Molecule ,010306 general physics ,Carbon ,Water vapor - Abstract
Spectroscopic studies of pure carbon tetrafluoride and carbon tetrafluoride in the presence of water vapor have been carried out. Studies have revealed changes in the absorption spectrum of the 1280 cm‒1 band of CF4, indicating the formation of new molecules, CF4–H2O hydrates. The bond between CF4 and H2O is not chemical in nature. The formation of these molecules can accelerate the removal of carbon tetrafluoride from the atmosphere with precipitation in the form of rain or snow.
- Published
- 2019
24. Radiation damage and annealing in plutonium tetrafluoride
- Author
-
Bruce K. McNamara, Calvin H. Delegard, Lucas E. Sweet, Amanda J. Casella, Sergey I. Sinkov, Kaylyn McCoy, and Tatjana Jevremovic
- Subjects
Nuclear and High Energy Physics ,Thermogravimetric analysis ,Hanford Site ,Radiochemistry ,Metallurgy ,Oxide ,chemistry.chemical_element ,010403 inorganic & nuclear chemistry ,01 natural sciences ,0104 chemical sciences ,Plutonium ,chemistry.chemical_compound ,Nuclear Energy and Engineering ,chemistry ,Plutonium tetrafluoride ,Differential thermal analysis ,Tetrafluoride ,Radiation damage ,General Materials Science - Abstract
A sample of plutonium tetrafluoride that was separated prior to 1966 at the Hanford Site in Washington State was analyzed at the Pacific Northwest National Laboratory (PNNL) in 2015 and 2016. The plutonium tetrafluoride, as received, was an unusual color and considering the age of the plutonium, there were questions about the condition of the material. These questions had to be answered in order to determine the suitability of the material for future use or long-term storage. Therefore, thermogravimetric/differential thermal analysis and X-ray diffraction evaluations were conducted to determine the plutonium's crystal structure, oxide content, and moisture content; these analyses reported that the plutonium was predominately amorphous and tetrafluoride, with an oxide content near ten percent. Freshly fluorinated plutonium tetrafluoride is known to be monoclinic. During the initial thermogravimetric/differential thermal analyses, it was discovered that an exothermic event occurred within the material near 414 °C. X-ray diffraction analyses were conducted on the annealed tetrafluoride. The X-ray diffraction analyses indicated that some degree of recrystallization occurred in conjunction with the 414 °C event. The following commentary describes the series of thermogravimetric/differential thermal and X-ray diffraction analyses that were conducted as part of this investigation at PNNL.
- Published
- 2017
25. Desizing of PVA sized pet/cotton fabrics with atmospheric pressure plasma
- Author
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Mohamed Bourham, Peter J. Hauser, Carrie E. Cornelius, and Marian McCord
- Subjects
010407 polymers ,Materials science ,Chromatography ,Polymers and Plastics ,chemistry.chemical_element ,Atmospheric-pressure plasma ,02 engineering and technology ,Plasma ,021001 nanoscience & nanotechnology ,01 natural sciences ,Polyvinyl alcohol ,Oxygen ,0104 chemical sciences ,chemistry.chemical_compound ,chemistry ,Ultimate tensile strength ,Tetrafluoride ,Composite material ,0210 nano-technology ,Carbon ,Desizing - Abstract
Atmospheric pressure plasma treatment was evaluated as a desizing aid for the removal of polyvinyl alcohol from polyester/cotton fabric. The effect of plasma gas mixture and plasma duration was examined using helium gas with fractions of oxygen and carbon tetrafluoride, and for plasma exposures ranging from 0.5–10 min. The percent desizing was measured for samples exposed only to plasma, and for samples subsequently washed in hot or cold water for 2–30 min. Plasma treatment increased desizing of samples washed in cold water, but complete desizing was unattainable. Hot water removed almost all size, regardless of plasma treatment. However, for cold water washes at short durations, greater desizing was achieved for samples treated with helium/carbon tetrafluoride plasma than for a control. Tensile testing demonstrated no loss in tensile or elongation properties due to plasma treatment, and dye absorption was not adversely affected.
- Published
- 2017
26. Current gain of a pulsed DC discharge in low-pressure gases
- Author
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Polina Ogloblina, Vladimir Yegorenkov, Valeriy Lisovskiy, A. N. Dakhov, and Stanislav Dudin
- Subjects
010302 applied physics ,Pulsed DC ,Analytical chemistry ,chemistry.chemical_element ,Condensed Matter Physics ,01 natural sciences ,Oxygen ,Nitrogen ,010305 fluids & plasmas ,Surfaces, Coatings and Films ,Sulfur hexafluoride ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,Tetrafluoride ,Current (fluid) ,Instrumentation ,Carbon ,Voltage - Abstract
Current and voltage waveforms of a pulsed discharge have been measured in a wide frequency range (20–300 kHz) for the two pressure values of 0.1 and 1 Torr using four different technology-relevant gases: nitrogen, oxygen, carbon tetrafluoride and sulfur hexafluoride. It is shown that the current can be substantially increased in the pulsed dc discharge, especially with electronegative gases, as compared with the discharge current relating to the same but constant voltage. The maximum 9-fold current gain is obtained with sulfur hexafluoride. Carbon tetrafluoride furnishes up to 4-fold amplification, while nitrogen and oxygen show the typical current gain of 1–2. Physical mechanism of this phenomenon is discussed.
- Published
- 2017
27. Calculations and analyses of molecular features and properties of nitrogen / carbon tetrafluoride mixture
- Author
-
Liye Xiao, Liwei Jing, Zhihao Zhou, Jianhui Chen, Guomin Zhang, Yuping Teng, Yanxing Zhao, Qingquan Qiu, Naihao Song, and Hongjie Zhang
- Subjects
Electron density ,Atoms in molecules ,Intermolecular force ,chemistry.chemical_element ,Charge (physics) ,Condensed Matter Physics ,Biochemistry ,Quantum chemistry ,chemistry.chemical_compound ,chemistry ,Chemical physics ,Tetrafluoride ,Density of states ,Physical and Theoretical Chemistry ,Carbon - Abstract
Nitrogen / carbon tetrafluoride (N2/CF4) may have a feasibility for use as the coolant or insulator of power apparatus but few studies have been carried out to figure out the characteristics of it. In order to have a better understanding of such mixture, some molecular features and properties concerning N2, CF4 and their compound are calculated through computational quantum chemistry methods and discussed in this paper with the emphasis focusing on molecular surfaces and intermolecular interactions. Concretely, the phase equilibrium curves are predicted according to several parameters obtained through the analysis of molecular surfaces. Furthermore, surface electrostatic potentials (ESPs) are studied and the mutual interpenetration distance was obtained. In addition, in order to have a further understanding of intermolecular interactions between N2 and CF4, the density of states (DOS) and charge decomposition analysis (CDA) are discussed as well as an analysis of electron density difference (EDD) and quantum theory of atoms in molecules (QTAIM). Finally, a prediction of electric strength is performed and it could be found from the prediction that N2/CF4 has an electric strength superior to N2 but inferior to CF4.
- Published
- 2021
28. Crystal growth of ultra-large MgF2 and LiCaAlF6 single crystals by a double-crucible Czochralski technique
- Author
-
Marilou Cadatal-Raduban, Tsuguo Fukuda, Toshihiko Shimizu, Nobuhiko Sarukura, and Kazuya Takahashi
- Subjects
Magnesium fluoride ,Materials science ,Analytical chemistry ,chemistry.chemical_element ,Crucible ,Crystal growth ,Condensed Matter Physics ,Inorganic Chemistry ,Crystal ,chemistry.chemical_compound ,Neutron capture ,chemistry ,Tetrafluoride ,Materials Chemistry ,Lithium ,Boron - Abstract
We report the successful growth of ultra-large sized magnesium fluoride (MgF2) and lithium calcium aluminum fluoride (LiCaAlF6) single crystals using the Czochralski growth method with a double-layer crucible. The 8-inch diameter MgF2 crystal was grown in argon atmosphere at a growth rate of 2 mm/h up to a length of 10 cm while the 4-inch diameter LiCaAlF6 crystal was grown in carbon tetrafluoride atmosphere at a growth rate of 1 mm/h up to a length of 30 cm. The 8-inch diameter satisfies the required size for the moderator that slows down neutrons in Boron Neutron Capture Therapy (BNCT), a noninvasive radiation therapy that selectively targets only the cancer cells. The successful growth of these ultra-large single crystals will not only advance BNCT but will also open new possibilities for optical materials such as lenses and windows in the vacuum ultraviolet region.
- Published
- 2021
29. A thermogravimetric study of the fluorination of zirconium and hafnium oxides with fluorine gas
- Author
-
Monnahela, Oduetse S., Vilakazi, Bernard M., Wagener, Jacobus B., Roodt, Andreas, Carstens, Pieter A.B., and Retief, Willem L.
- Subjects
- *
THERMOGRAVIMETRY , *FLUORINATION , *HAFNIUM oxide , *ZIRCONIUM oxide , *FLUORINE , *RING formation (Chemistry) , *X-ray diffraction - Abstract
Abstract: The fluorination of ZrO2 and HfO2 and the understanding of the fundamental chemistry of formation of ZrF4 and HfF4 in a fluorine atmosphere were investigated using a thermobalance. The fluorination of these species was performed to understand the chemical behavior of the tetrafluoride species of these metals. Thermogravimetrical analysis indicated that the formation of ZrF4/HfF4 is via the oxyfluorides. X-ray powder diffraction was used to confirm the results. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
30. Protective Effect of Different Tetrafluorides on Erosion of Pellicle-Free and Pellicle-Covered Enamel and Dentine.
- Author
-
Wiegand, A., Meier, W., Sutter, E., Magalhães, A. C., Becker, K., Roos, M., and Attin, T.
- Subjects
- *
FLUORIDES , *TITANIUM , *ZIRCONIUM , *DENTAL enamel , *HAFNIUM , *DENTIN , *SALIVA - Abstract
The aim was to analyze the protective effects of titanium, zirconium and hafnium tetrafluorides on erosion of pellicle-free and pellicle-covered enamel and dentine in vitro. Eight groups of 20 specimens each of bovine enamel and bovine dentine were prepared. Half the specimens in each group were immersed in human saliva for 2 h for pellicle formation. Specimens were then left untreated (controls) or were treated for 120 s with TiF4, ZrF4 or HfF4 solutions (0.4 or 1%) or 1.25% AmF/NaF gel. All specimens were eroded by exposure to hydrochloric acid, pH 2.6, for 25 min. Cumulative calcium release into the acid was monitored in consecutive 30-second intervals for 5 min, then at 2-min intervals up to a total erosion time of 25 min using the Arsenazo III procedure. Data were analyzed by ANOVA. 1% TiF4 solution offered the best protective effect, especially in dentine (reduction of calcium loss about 50% at 25 min). 1% ZrF4, 1% HfF4 and 0.4% TiF4 also reduced calcium loss, but to a lesser extent. Long-term effects were limited to dentine, while reduction of enamel erosion (about 25%) was restricted to 1-min erosion. The fluoride gel had a protective effect only in dentine. The efficacy of the tetrafluorides was influenced by the presence of the pellicle layer, in that the protection against dentine erosion by TiF4 and ZrF4 was greater on pellicle-covered specimens. Tetrafluoride solutions, especially 1% TiF4, could decrease dental erosion, but were more effective on dentine than on enamel. Copyright © 2008 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
31. Solid-Phase Conversion of Depleted Uranium Tetrafluoride into Oxides Using Mechanoactivated Quartz with the Addition of Sodium Fluoride
- Author
-
S. V. Chizhevskaya, A. V. Zhukov, Eldar P. Magomedbekov, and G. D. Polenov
- Subjects
inorganic chemicals ,020209 energy ,Inorganic chemistry ,Radiochemistry ,technology, industry, and agriculture ,Mixing (process engineering) ,chemistry.chemical_element ,02 engineering and technology ,Uranium ,021001 nanoscience & nanotechnology ,complex mixtures ,chemistry.chemical_compound ,Nuclear Energy and Engineering ,chemistry ,Phase conversion ,Tetrafluoride ,Depleted uranium ,Sodium fluoride ,0202 electrical engineering, electronic engineering, information engineering ,0210 nano-technology ,Quartz - Abstract
The role of sodium fluoride, added to quartz before the latter is mechanically activated, in the solid-phase conversion of depleted uranium tetrafluoride into uranium oxides without mixing of the components of the mixture is determined.
- Published
- 2017
32. Solid-Phase Interaction of Uranium Tetrafluoride with Aluminum Silicates
- Author
-
A. V. Zhukov, A. B. Arzmanova, G. D. Polenov, and S. V. Chizhevskaya
- Subjects
inorganic chemicals ,Materials science ,020209 energy ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,Uranium tetrafluoride ,complex mixtures ,chemistry.chemical_compound ,Nuclear Energy and Engineering ,chemistry ,Aluminium ,Phase (matter) ,Reagent ,Bentonite ,Tetrafluoride ,Depleted uranium ,0202 electrical engineering, electronic engineering, information engineering ,Kaolinite - Abstract
The influence of the phase and chemical compositions of two aluminum silicate minerals – bentonite and kaolinite – on the solid-phase conversion of depleted uranium tetrafluoride into U 3 O 8 was investigated. It is shown that after their preliminary preparation by heat treatment or mechanical activation aluminum silicates can be used as reagents alternative to silica.
- Published
- 2017
33. Innovative reductive remediation of carbon tetrafluoride at room temperature by using electrogenerated Co 1+
- Author
-
G. Muthuraman and Il-Shik Moon
- Subjects
Environmental Engineering ,Health, Toxicology and Mutagenesis ,Inorganic chemistry ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,law.invention ,chemistry.chemical_compound ,Magazine ,law ,Zeta potential ,Environmental Chemistry ,Organic chemistry ,Waste Management and Disposal ,Ethanol ,021001 nanoscience & nanotechnology ,Pollution ,0104 chemical sciences ,chemistry ,Tetrafluoride ,Degradation (geology) ,Cyclic voltammetry ,Absorption (chemistry) ,0210 nano-technology ,Carbon - Abstract
Among the non-CO2 greenhouse gases, carbon tetrafluoride (CF4) is the most recalcitrant and should be eliminated from the atmosphere. In the present study, a non-combustion electroscrubbing method was used in an attempt to degrade CF4 with an electrogenerated Co1+ mediator in a highly alkaline medium. The initial absorption experiments revealed 165 mg L−1 CF4 gas dissolved in 10 M NaOH. Different mediator precursors, [Co(II)(CN)5]3−, [Ni(II)(CN)4]2−, [Cu(II)(OH)4]2−, and [Co(II)(OH)4]2−, were used and the electroscrubbing results showed that the electrogenerated Co1+ or [Co(II)(OH)4]2− precursor effectively degraded up to 99.25% of the CF4 gas. The variations in [Co(II)(OH)4]2− reduction efficiency and cyclic voltammetry revealed CF4 degradation followed by electrogenerated Co1+ mediated reduction. The increased zeta potential (+6 mV) of the electrogenerated Co1+ showed that the degradation reaction occurs preferably at the solution interface. Electroscrubbing for CF4 removal and the resulting products were controlled by the carrier gas. Air and H2 carrier gases lead to the formation of CHF3 and COF2. N2 as the carrier gas caused 99.25% degradation with ethanol as a product. An 80% CF4 degradation efficiency with CHF3 as the product was observed when a mixture of N2 and air was used as the carrier gas.
- Published
- 2017
34. mCharacteristics of Carbon Tetrafluoride Plasma Resistance of Various Glasses
- Author
-
Jae Ho Choi, Yoon Soo Han, Hyung Bin Park, Sung-Min Lee, Hyeong-Jun Kim, and Sung Churl Choi
- Subjects
010302 applied physics ,Materials science ,Borosilicate glass ,Oxide ,Mineralogy ,chemistry.chemical_element ,Calcium aluminosilicate ,02 engineering and technology ,Yttrium ,Porous glass ,021001 nanoscience & nanotechnology ,Microstructure ,01 natural sciences ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Aluminosilicate ,0103 physical sciences ,Tetrafluoride ,Ceramics and Composites ,0210 nano-technology - Abstract
Etch rate, surface roughness and microstructure as plasma resistance were evaluated for six kinds of oxide glass with different compositions. Borosilicate glass (BS) was found to be etched at the highest etch rate and zinc aluminum phosphate glass (ZAP) showed a relatively lower etch rate than borosilicate. On the other hand, the etching rate of calcium aluminosilicate glass (CAS) was measured to be similar to that of sintered alumina while yttrium aluminosilicate glass (YAS) showed the lowest etch rate. Such different etch rates by mixture plasma as a function of glass compositions was dependent on whether or not fluoride compounds were formed on glass and sublimated in high vacuum. Especially, in view that CaF₂ and YF₃ with high sublimation points were formed on the surface of CAS and YAS glasses, both CAS and YAS glasses were considered to be a good candidate for protective coating materials on the damaged polycrystalline ceramics parts in semi-conductor and display processes.
- Published
- 2016
35. A new modality for the detection of chemical vapors using middle infrared femtosecond pulse propagation effects
- Author
-
Craig Zuhlke, Dennis R. Alexander, and William Conner Thomas
- Subjects
Materials science ,Femtosecond pulse ,business.industry ,Pulse (signal processing) ,Amplifier ,Dimethyl methylphosphonate ,Laser ,law.invention ,chemistry.chemical_compound ,Optics ,chemistry ,law ,Tetrafluoride ,Middle infrared ,Principal component analysis ,business - Abstract
We have shown recently that unique optical signatures can be observed with the measurement of ultrashort middle infrared laser pulses that have been transmitted through molecular vapors. Here, we report on an increased signal-to-noise ratio of the pulse measurements by using a cross-correlation technique with a lockin amplifier. Carbon tetrafluoride and dimethyl methylphosphonate (DMMP) cross-correlation signatures are highly discriminated using principal component analysis. A squared exponential Gaussian process regression model is used to quantitatively predict the concentration of DMMP.
- Published
- 2019
36. Preparation of UF4 by Carbochlorination of U3O8 and Solid-State Halogen Exchange Reaction
- Author
-
Cristina Noemi Guibaldo, Georgina de Micco, and Ana E. Bohé
- Subjects
inorganic chemicals ,Materials science ,Scanning electron microscope ,URANIUM ,Analytical chemistry ,Infrared spectroscopy ,INGENIERÍAS Y TECNOLOGÍAS ,02 engineering and technology ,SYNTHESIS ,010403 inorganic & nuclear chemistry ,01 natural sciences ,Fluorescence spectroscopy ,chemistry.chemical_compound ,CARBOCHLORINATION ,Fourier transform infrared spectroscopy ,X-ray spectroscopy ,Radiation ,Ingeniería de Procesos Químicos ,020502 materials ,TETRAFLUORIDE ,0104 chemical sciences ,Ingeniería Química ,0205 materials engineering ,Nuclear Energy and Engineering ,chemistry ,Tetrafluoride ,Halogen ,X-ray crystallography - Abstract
Uranium tetrafluoride was synthesized using a novel method, which consists of a combination of carbochlorination reaction between a mixture of U3O8 and sucrose carbon with chlorine, and a solid-state halogen exchange reaction between the products of the carbochlorination reaction and sodium fluoride. The thermodynamic feasibility to produce the halogen exchange reaction between UCl4 and NaF was analyzed. Reactions are favorable in standard conditions, even at low temperature. We have prepared a mixture of UCl4 and UCl2O2 by U3O8 treatment in Cl2 atmosphere with presence of sucrose carbon at 900 °C. UCl4 and UCl2O2 were obtained as a condensed product, which was collected in a quartz capsule containing NaF. The capsules were sealed after several repeated stages of argon purges and mechanic vacuum. Subsequently, they were treated at 300-350 °C for 2 h. We obtained that when NaF is the limiting reagent, the solid product of the thermal treatment of the capsules consists in a mixture of UF4 and NaCl. Solid products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), fluorescence spectroscopy, and energy dispersive X-ray spectroscopy. Gaseous products were identified by Fourier-transform infrared spectroscopy. Fil: Guibaldo, Cristina Noemi. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia Complejo Tecnológico Pilcaniyeu; Argentina Fil: de Micco, Georgina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia Complejo Tecnológico Pilcaniyeu; Argentina Fil: Bohe, Ana Ester. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia Complejo Tecnológico Pilcaniyeu; Argentina
- Published
- 2019
37. Satellites of the resonance transitions of alkali atoms in mixtures with CF4
- Author
-
Tigran A. Vartanyan, P. Yu. Serdobintsev, V. A. Alekseev, A. S. Pazgalev, P. A. Petrov, and A. A. Pastor
- Subjects
Radiation ,Materials science ,010504 meteorology & atmospheric sciences ,Analytical chemistry ,Alkali metal ,01 natural sciences ,Resonance (particle physics) ,Atomic and Molecular Physics, and Optics ,chemistry.chemical_compound ,chemistry ,Tetrafluoride ,Molecule ,Absorption (chemistry) ,Luminescence ,Ground state ,Spectroscopy ,Excitation ,0105 earth and related environmental sciences - Abstract
The absorption and luminescence excitation spectra of gas phase mixtures of alkali metals atoms A (A = K, Rb, Cs) with carbon tetrafluoride molecules CF4 are studied in the region of transitions from the ground state A(2S1/2) to the lowest resonance states A(2P1/2, 3/2). It is shown that these transitions have intense satellites corresponding to the simultaneous vibrational excitation of the carbon tetrafluoride molecule, A(2S1/2) + CF4(v3=0) + hv → A(2P1/2, 3/2) + CF4(v3=1), where v3 is the IR active mode of CF4 with a vibrational quantum energy of 1281 cm–1. The satellites are relatively narrow bands (FWHM ~ 30 cm–1) slightly (
- Published
- 2021
38. Centrifugal Separation of Carbon Isotopes Using Carbon Tetrafluoride as Processing Gas
- Author
-
G Pei, C Jian, Q Sun, and M Zhou
- Subjects
History ,chemistry.chemical_compound ,Materials science ,chemistry ,Isotopes of carbon ,Tetrafluoride ,Inorganic chemistry ,chemistry.chemical_element ,Carbon ,Computer Science Applications ,Education ,Centrifugal separation - Abstract
At present, the application of carbon isotope is becoming more and more extensive, especially in the field of medical testing, and the demand for 13C in high abundance is fast increasing. Using carbon tetrafluoride (CF4) as separation medium, study on centrifugal separation of carbon isotopes was carried out. Single-centrifuge experiments were done based on modified domestic gas centrifuges. As a result, the separation factor and single-centrifuge separative power under different working conditions were obtained. Based on the results of single-centrifuge separation experiments, cascade calculation of the enrichment of 13C isotope was conducted by ideal cascade. According to calculation results, through two cascade separations, 13C isotope could be enriched from 30% to above 99% in abundance. The study laid a good basement for production of 13C isotope in high abundance.
- Published
- 2020
39. The Valence States of Copernicium and Flerovium
- Author
-
Abhik Ghosh and Jeanet Conradie
- Subjects
chemistry.chemical_classification ,Valence (chemistry) ,010405 organic chemistry ,Chemistry ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Chloride ,0104 chemical sciences ,Divalent ,Inorganic Chemistry ,chemistry.chemical_compound ,Flerovium ,Xenon ,Computational chemistry ,Chemical physics ,Tetrafluoride ,medicine ,Copernicium ,medicine.drug - Abstract
Compared with its lighter congener HgF4, copernicium tetrafluoride, CnF4, is predicted to be significantly more stable with respect to decomposition to the elements. Tetravalent flerovium on the other hand is unlikely to be experimentally accessible, except possibly as FlF4. Because of the large 7p1/2–3/2 energy splitting, many divalent flerovium compounds are also expected to be thermodynamically unstable. The two dihalides FlF2 and FlCl2, however, are predicted to be thermodynamically stable; flerovium thus is not quite as noble as xenon, which is not known to form a chloride.
- Published
- 2016
40. Composition and method to remove asbestos
- Author
-
Block, Jacob [Rockville, MD]
- Published
- 1998
41. Synthesis and complex study of cerium(IV) fluoride hydrate
- Author
-
A. S. Parshakov, V. I. Privalov, E. G. Tarakanova, Lyudmila V. Goeva, N. P. Simonenko, L.D. Iskhakova, and E. G. Il’in
- Subjects
Aqueous solution ,010405 organic chemistry ,Organic Chemistry ,chemistry.chemical_element ,010402 general chemistry ,01 natural sciences ,Biochemistry ,0104 chemical sciences ,Inorganic Chemistry ,chemistry.chemical_compound ,Cerium ,Hydrofluoric acid ,chemistry ,Tetrafluoride ,Fluorine ,Environmental Chemistry ,Physical chemistry ,Physical and Theoretical Chemistry ,Hydrate ,Fluoride ,Powder diffraction - Abstract
By precipitating from an aqueous solution of Ce(SO4)2·4H2O with 40 % hydrofluoric acid obtained a nanosized powder of cerium tetrafluoride hydrate with a composition close to CeF4*0.95 H2O. According to the results of x-ray phase analysis, the crystalline phase has a cubic lattice similar to lattice of PuF4·1.6H2O. The hydrate nanopowder is characterized by XRD, TEM, 1H and 19F{1H}NMR and IR - spectroscopy. Quantum chemical calculations of the IR- spectra of models of the possible interaction of water molecules with a fluorine ions have been carried out. The temperature behavior of the CeF4*0.95 H2O powder was studied by using X-ray powder diffraction analysis up to 300 °C and thermogravimetrically up to 200 °C.
- Published
- 2020
42. The resistance of titanium tetrafluoride-treated human enamel to strong hydrochloric acid.
- Author
-
Büyükyilmaz, Tamer, Øgaard, Bjorn, and Røha, Gunnar
- Subjects
- *
DENTAL enamel , *MOLARS , *SCANNING electron microscopy , *TOOTH erosion , *MICROHARDNESS , *DENTAL care - Abstract
The acid resistance of TiF4-treated enamel was investigated to establish a possible treatment modality for endogenous dental erosion. Enamel slabs were prepared from human molars and treated with solutions of TiF4. Scanning electron microscopy (SEM) and microhardness testing were used to examine the effects of the exposure of the treated enamel to strong acid. SEM micrographs showed the presence of heavy deposits on enamel, surfaces. The surface coating, formed following TiF4 application, appeared to be resistant to severe acid attacks, Microhardness measurements showed that TiF4 treatment inhibited enamel softening. It is concluded that topical TiF4 application may be effective in prevention of dental erosion caused by hydrochloric acid from the stomach in patients with frequent vomiting or gastroesophageal reflux. [ABSTRACT FROM AUTHOR]
- Published
- 1997
43. Chromium Oxide Tetrafluoride and Its Reactions with Xenon Hexafluoride; the [XeF5]+ and [Xe2F11]+ Salts of the [Cr(VI)OF5]–, [Cr(IV)F6]2–, [Cr(V)OF5]2–, and [Cr(V)2O2F8]2– Anions
- Author
-
Daniel G. Stuart, Mark R. Bortolus, James Goettel, Hélène P. A. Mercier, and Gary Schrobilgen
- Subjects
Materials science ,Xenon hexafluoride ,Crystal structure ,Hydrogen fluoride ,chemistry.chemical_compound ,symbols.namesake ,chemistry ,Tetrafluoride ,X-ray crystallography ,Anhydrous ,Chromium oxide ,symbols ,Physical chemistry ,Raman spectroscopy - Abstract
Molten mixtures of XeF6 and CrVIOF4 in 1:1 and 1:2 molar ratios undergo reduction to Cr(V) and Cr(IV) by means of F2 elimination to form [XeF5][Xe2F11][CrVOF5]∙2CrVIOF4 and [XeF5]2[CrIVF6]∙2CrVIOF4, respectively, as shown by low-temperature (LT) single-crystal X-ray diffraction (SCXRD). A LT Raman spectroscopic study of an equimolar mixture of solid XeF6 and CrOF4 and its melt showed that [CrVIOF5]– is formed as an intermediate. Reaction of [XeF5]2[CrIVF6]∙2CrVIOF4 with XeF6 in a melt gave [Xe2F11]2[CrIVF6] and [XeF5]2[CrV2O2F8]. Their LT crystal structures revealed that [XeF5]+ and [Xe2F11]+ are coordinated to their respective [CrF6]2− and [Cr2O2F8]2− anions by means of Xe---F–Cr bridges to form infinite chain structures. The reactions of a 1:1 molar ratio of XeF6 and CrOF4 in anhydrous hydrogen fluoride (aHF) and in mixed CFCl3/aHF solvents yielded [XeF5]2[CrV2O2F8]∙2HF and a mixture of [XeF5]2[CrV2O2F8]∙2HF and [XeF5]2[CrV2O2F8]∙2XeOF4, respectively. The SCXRD structures of the latter and aforementioned salts provide the first X-ray structures of [CrOF5]2– and [Cr2O2F8]2–. The [XeF5]2[CrV2O2F8]∙2XeOF4 and [XeF5][Xe2F11][CrVOF5]∙2CrVIOF4 salts were also characterized by LT Raman spectroscopy. Quantum-chemical calculations were carried out to obtain the energy-minimized, gas-phase geometries and vibrational frequencies for [CrVIOF5]–, [XeF5]2[CrV2O2F8]∙2XeOF4, [CrV2O2F8]2–, [XeF5][Xe2F11][CrVOF5]∙2CrVIOF4, [CrVOF5]2–, and to aid in the assignments of their vibrational frequencies.
- Published
- 2018
44. Enhancement on the Surface Hydrophobicity and Oleophobicity of an Organosilicon Film by Conformity Deposition and Surface Fluorination Etching
- Author
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Jin-How Chang, Tai-Hong Chen, Tsung-Hsin Lee, Zheng-Wen Xu, Day-Shan Liu, Yu-Kai Zhang, and Pei-Yu Li
- Subjects
Materials science ,conformity deposition ,Nanoparticle ,02 engineering and technology ,010402 general chemistry ,01 natural sciences ,lcsh:Technology ,Article ,Contact angle ,chemistry.chemical_compound ,silver seed layer ,Etching (microfabrication) ,General Materials Science ,oleophobicity ,fluorination etching ,lcsh:Microscopy ,Deposition (law) ,Organosilicon ,lcsh:QC120-168.85 ,hydrophobicity ,Glow discharge ,lcsh:QH201-278.5 ,lcsh:T ,021001 nanoscience & nanotechnology ,0104 chemical sciences ,chemistry ,Chemical engineering ,lcsh:TA1-2040 ,organosilicon film ,Tetrafluoride ,lcsh:Descriptive and experimental mechanics ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,0210 nano-technology ,lcsh:Engineering (General). Civil engineering (General) ,Layer (electronics) ,lcsh:TK1-9971 - Abstract
In this work, the surface morphology of a hydrophobic organosilicon film was modified as it was deposited onto a silver seed layer with nanoparticles. The surface hydrophobicity evaluated by the water contact angle was significantly increased from 100°, to 128°, originating from the surface of the organosilicon film becoming roughened, and was deeply relevant to the Ag seed layer conform deposition. In addition, the organosilicon film became surface oleophobic and the surface hydrophobicity was improved due to the formation of the inactive C-F chemical on the surface after the carbon tetrafluoride glow discharge etching. The surface hydrophobicity and oleophobicity of the organosilicon film could be further optimized with water and oleic contact angles of about 138°, and 61°, respectively, after an adequate fluorination etching.
- Published
- 2018
45. Experimental ion mobility measurements in Xe-CF4 mixtures
- Author
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P.N.B. Neves, C.A.N. Conde, Rob Veenhof, F.I.G.M. Borges, M.A.G. Santos, A.F.V. Cortez, M.A. Kaja, J. Escada, and F.P. Santos
- Subjects
Range (particle radiation) ,Materials science ,010308 nuclear & particles physics ,Analytical chemistry ,chemistry.chemical_element ,01 natural sciences ,Spectral line ,Ion ,chemistry.chemical_compound ,Xenon ,chemistry ,Electric field ,Torr ,0103 physical sciences ,Tetrafluoride ,Detectors and Experimental Techniques ,010306 general physics ,Instrumentation ,Carbon ,Mathematical Physics - Abstract
In this paper we present the results of the ion mobility measurements made in gaseous mixtures of xenon with carbon tetrafluoride (Xe-CF$_{4}$) for pressures ranging from 6 to 10 Torr (8-10.6 mbar) and for low reduced electric fields in the 10 to 25 Td range (2.4-6.1 kV⋅cm$^{−1}$⋅bar$^{−1}$), at room temperature. The time-of-arrival spectra revealed one or two peaks depending on the gas relative abundances, which were attributed to CF$_{3}^{+}$ and to Xe$_{2}^{+}$ ions. However, for Xe concentrations above 60%, only one peak remains (Xe$_{2}^{+}$). The reduced mobilities obtained from the peak centroid of the time-of-arrival spectra are presented for Xe concentrations in the 5%-95% range.
- Published
- 2018
46. Synthesis of new coordination complexes of MF5(M = Nb, Ta), and insights into the Ta(V) reduction
- Author
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Tiziana Funaioli, Mohammad Hayatifar, Stefano Zacchini, Giulio Bresciani, Guido Pampaloni, Fabio Marchetti, Bresciani, Giulio, Funaioli, Tiziana, Zacchini, Stefano, Hayatifar, Mohammad, Marchetti, Fabio, and Pampaloni, Guido
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010405 organic chemistry ,Niobium ,Tantalum ,Cobaltocene ,chemistry.chemical_element ,Nuclear magnetic resonance spectroscopy ,010402 general chemistry ,01 natural sciences ,0104 chemical sciences ,Adduct ,Inorganic Chemistry ,chemistry.chemical_compound ,Crystallography ,chemistry ,Tetrafluoride ,Materials Chemistry ,Benzophenone ,Electrochemistry ,Physical and Theoretical Chemistry ,Fluoride ,Dichloromethane ,Reduction - Abstract
The pentafluorides of niobium and tantalum reacted with benzophenone (Ph2CO), (2-diphenylphosphino)phenol (DPPPh) and 4-fluorobenzonitrile affording adducts corresponding to the asymmetric (Ph2CO and DPPPh) and symmetric (4-fluorobenzonitrile) cleavage of the tetranuclear structure of MF5. The products were characterized by elemental analysis, IR and multinuclear NMR spectroscopy. A selection of Ta(V) complexes was investigated in the attempt to obtain tantalum tetrafluoride derivatives, which are almost unknown in the literature. The reactions with cobaltocene in dichloromethane afforded unidentified paramagnetic materials and [CoCp2][TaF6], characterized by X-ray diffraction.
- Published
- 2018
47. Syntheses and Crystal Structures of Sodium Hydrogen Fluorides NaF·nHF (n = 2, 3, 4)
- Author
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Martin J. Mühlbauer, Antti J. Karttunen, Andreas Kornath, Florian Kraus, Sergei I. Ivlev, Theresa Soltner, University of Marburg, Ludwig Maximilian University of Munich, Department of Chemistry and Materials Science, Technical University of Munich, Aalto-yliopisto, and Aalto University
- Subjects
Hydrogen ,010405 organic chemistry ,Hydrogen bond ,Sodium ,Crystal structure ,Neutron diffraction ,chemistry.chemical_element ,Infrared spectroscopy ,010402 general chemistry ,Sodium hydrogen fluorides ,01 natural sciences ,0104 chemical sciences ,Hydrogen bonds ,Inorganic Chemistry ,Crystallography ,chemistry.chemical_compound ,Trifluoride ,Density functional calculations ,chemistry ,IR spectroscopy ,Tetrafluoride ,ta116 - Abstract
A series of higher sodium hydrogen fluorides were synthesized and structurally characterized. Sodium tetrahydrogen pentafluoride, NaH4F5, crystallizes in space group type I4(1)/a with cell parameters a = 6.0275(4), c = 11.6208(13) angstrom, V = 422.19(7) angstrom(3), Z = 4 at 100 K. Sodium trihydrogen tetrafluoride, NaH3F4, crystallizes in space group type R (3) over bar with cell parameters a = 6.5139(4), c = 13.4040(15) angstrom, V = 492.55(8) angstrom(3), Z = 6 at 100 K. Sodium dihydrogen trifluoride, NaH2F3, crystallizes in space group type Pnma with cell parameters a = 7.9276(9), b = 3.4514(3), c = 9.6937(10) angstrom, V = 265.23(5) angstrom(3), Z = 4 at 100 K. The investigations were complemented by IR spectroscopy and theoretical calculations. NaH2F3 was additionally characterized by means of powder neutron diffraction. All observed F-H center dot center dot center dot F hydrogen bonds are unsymmetric, close to linearity and can be considered as strong hydrogen bonds.
- Published
- 2017
48. A theoretical approach to the sublimation separation of zirconium and hafnium in the tetrafluoride form
- Author
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Philippus L. Crouse and H.F. Niemand
- Subjects
Zirconium ,Aqueous solution ,Zirconium alloy ,Inorganic chemistry ,Metals and Alloys ,chemistry.chemical_element ,Geotechnical Engineering and Engineering Geology ,Chloride ,Hafnium ,chemistry.chemical_compound ,chemistry ,Tetrafluoride ,Materials Chemistry ,medicine ,Sublimation (phase transition) ,Inert gas ,medicine.drug - Abstract
Synopsis The separation of zirconium and hafnium is essential in the nuclear industry, since zirconium alloys for this application require hafnium concentrations of less than 100 ppm. The separation is, however, very difficult due to the numerous similarities in the chemical and physical properties of these two elements. Traditional methods for separation of zirconium and hafnium rely predominantly on wet chemical techniques, e.g. solvent extraction. In contrast to the traditional aqueous chloride systems, the AMI zirconium metal process developed by Necsa focuses on dry fluoride-based processes. Dry processes have the advantage of producing much less hazardous chemical waste. In the proposed AMI process, separation is effected by selective sublimation of the two tetrafluorides in an inert atmosphere under controlled conditions, and subsequent selective desublimation. Estimates are made for the sublimation rates of the two tetrafluorides based on the equilibrium vapour pressures. A sublimation model, based on the sublimation rates, was developed to determine if the concept of separation by sublimation and subsequent desublimation is theoretically possible.
- Published
- 2015
49. Solid-Phase Interaction of Depleted Uranium Tetrafluoride with Different History of Production with Silica
- Author
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O. M. Klimenko, A. V. Zhukov, G. D. Polenov, Eldar P. Magomedbekov, and S. V. Chizhevskaya
- Subjects
inorganic chemicals ,Inert ,Inorganic chemistry ,Radiochemistry ,technology, industry, and agriculture ,chemistry.chemical_element ,Uranium tetrafluoride ,Uranium ,complex mixtures ,chemistry.chemical_compound ,Hexafluoride ,Nuclear Energy and Engineering ,chemistry ,Halogen ,Depleted uranium ,Tetrafluoride ,Uranium oxide - Abstract
The characteristics and behavior of depleted uranium tetrafluoride obtained by different methods in the process of solid-phase conversion into uranium oxides using mechano-activated crystalline and x-ray amorphous silica in oxygen-containing and inert media in the absence of mixing of the components are compared. It is found that the reactivity of depleted uranium tetrafluoride obtained by the reduction of depleted uranium hexafluoride by unsaturated organic halogen derivatives and hydrogen in a fluorohydrogen flame is actually no different, and the solid-phase reaction products UO2 and U3O8 inherit the morphological features of the initial uranium tetrafluoride.
- Published
- 2015
50. Real-Time Fab-Wise Airborne Molecular Contaminant (AMC) Monitoring System Using Multiple Fourier Transform Infrared (FTIR) Spectrometers in a Semiconductor Plant
- Author
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Shin-Yu Chen, Yaw-Huei Hwang, Yung-Chieh Tsao, and Pao-Erh Chang
- Subjects
inorganic chemicals ,Pollutant ,chemistry.chemical_element ,Nitrous oxide ,equipment and supplies ,Pollution ,Methane ,Sulfur hexafluoride ,chemistry.chemical_compound ,chemistry ,Environmental chemistry ,Tetrafluoride ,Environmental Chemistry ,Fourier transform infrared spectroscopy ,Carbon ,Carbon monoxide - Abstract
The objective of this study was to investigate the airborne pollutant emission sources and fluctuations around the indoor and outdoor environments of a semiconductor manufacturing plant using monitoring data that were collected over 4 consecutive days via three Fourier transform infrared (FTIR) spectrometers located near an outdoor make-up air unit and an indoor Fab and sub Fab. Based on a total of 1,032 five-minute-interval records, fourteen chemicals were detected. Six of these chemicals, namely, carbon tetrafluoride, nitrous oxide, carbon monoxide, silane, sulfur hexafluoride, and methane, had significant concentration correlations between the indoor and outdoor environments. With the exception of silane and sulfur hexafluoride, the percentage of indoor/outdoor concentration ratios that were greater than one ranged from 62.2% to 73.1%, indicating that the indoor chemical concentrations were typically higher than the outdoor concentrations. Based on the regression models derived for the indoor and outdoor nitrous oxide concentrations, the nitrous oxide was believed to be originally emitted from the sub Fab vented to the outdoors and then partially returned to the Fab. It was estimated that for one ppb of nitrous oxide detected in the Fab, 2.58 ppb of nitrous oxide could be detected at the make-up air unit, which might result from the sub Fab emission being at a high level of 6.60 ppb. Furthermore, elevated outdoor concentrations of chemicals, such as carbon tetrafluoride, nitrous oxide and carbon monoxide, were observed without previous indoor emission peaks, indicating that these chemicals might accumulate in the outdoor surrounding area. This study successfully illustrated the dynamically changing relationship between indoor and outdoor chemical concentrations in a semiconductor clean room. These results can be used to prevent subtle and potential adverse impacts of airborne molecular contaminant (AMC) in various manufacturing facilities of technological industries, including the semiconductor and optoelectronics industries.
- Published
- 2015
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