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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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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

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 (

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.

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.

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.

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.

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&deg, to 128&deg, 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&deg, and 61&deg, respectively, after an adequate fluorination etching.

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.

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.

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.

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.

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.

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.