Search Results (147)

Phosphogypsum (PG) is a byproduct of wet-process phosphoric acid production and contains soluble phosphorus (P), fluorine (F), and other harmful impurities in addition to calcium sulfate. Its acidic leachate enriched with P and F poses long-term risks to soil and surrounding water bodies. Owing to the incorporation of soluble P and F within calcium sulfate crystal interlayers, these contaminants are gradually released during storage, making it difficult to achieve an economically efficient and environmentally benign treatment of PG at an industrial scale. In this study, a low-cost and sustainable process for the effective and long-term immobilization of soluble P and F in PG was developed using sulfuric acid-activated red mud (RM), an industrial waste rich in Fe and Al. After pulping PG with water, activated RM was added, followed by pH adjustment with Ca(OH)₂, leading to the in situ formation of amorphous calcium aluminate and calcium ferrite polymers with strong adsorption affinity toward soluble P and F. The immobilization mechanism and phase evolution were systematically investigated using inductively coupled plasma optical emission spectroscopy (ICP-OES, PS-6PLASMA SPECTROVAC, BAIRD, USA), on a Rigaku Miniflex diffractometer (Rigaku Corporation, Tokyo, Japan), scanning electron microscopy coupled with energy-dispersive spectroscopy (SEM-EDS), and zeta potential analysis. The leachate of PG treated with activated RM and Ca(OH)₂ contained P < 0.5 mg/L and F < 10 mg/L at pH 8.5–9.0, meeting environmental requirements (pH = 6–9, P ≤ 0.5 mg/L, F ≤ 10 mg/L). Moreover, the immobilized P and F exhibited enhanced stability during long-term stacking, indicating the formation of durable immobilization products. This study demonstrates an effective “treating waste with waste” strategy for the large-scale, environmentally safe utilization of phosphogypsum. Full article

We demonstrate the fabrication of air gaps in a PECVD SiN interlayer through lateral recess by employing two consecutive plasma etch steps on an AlN/SiN/Al₂O₃ stack. This approach enables the preservation of sub-100 nm openings in Al₂O₃, offering a potential optimization for the GaN-HEMT gate stack in RF applications while retaining low gate foot dimensions. A low-power, SF₆-based plasma etch is introduced, and time-dependent etch profiles reveal the formation of a skirt-like profile. The process exhibits excellent selectivity between SiN and Al₂O₃ etch rates. Furthermore, low-power SF₆ plasma produces a small self-bias voltage, and surface fluorine contamination which can subsequently be eliminated by annealing. Full article

Plasma-enhanced atomic layer deposition (PEALD) is used to grow high-quality aluminum fluoride (AlF₃) antireflective coatings via a safe, HF-free route using trimethylaluminum and SF₆ plasma. In situ diagnostics reveal a reaction pathway mediated by a hydrogen-terminated fluorinated surface (s-FH). By systematically varying the plasma pulse duration, a critical process window is identified that balances efficient ligand removal against ion-induced structural damage. Within this optimized window, the films achieve ultra-low impurity levels and an atomically smooth morphology, increasing the optical transmittance of glass to (97.6 ± 0.5)%. This study establishes a clear link between fundamental plasma kinetics and functional optical performance, providing a robust, non-corrosive strategy for the rational design of metal–fluoride PEALD coatings. Full article

Natural fibers are increasingly used as sustainable, lightweight, and low-cost alternatives to glass fibers in polymer composites. However, their inherent hydrophilicity and surface polarity limit compatibility with non-polar polymer matrices. Both gas/solid and plasma fluorination modify only the surface of lignocellulosic materials. Mild conditions are mild, with reactivity governed by fluorine concentration, temperature, and material composition. Surface energy is typically assessed through contact-angle measurements and surface analytical techniques that quantify changes in hydrophobicity and chemical functionalities. In wood, fluorination proceeds preferentially in lignin-rich regions, making lignin a key component controlling reactivity and the spatial distribution of fluorinated groups. Natural fibers follow the same logic as for flax, which is a representative example of lignin content. Applications of fluorinated bio-based materials include improved moisture resistance, enhanced compatibility in composites, and functional surfaces with tailored wetting properties. Scalability depends on safety, cost, and process control, especially for direct fluorination. Durability of the treatment varies with depth of modification, and environmental considerations include the potential release of fluorinated species during use or disposal. Full article

We demonstrate high-performance MOSFETs on β-Ga₂O₃ films grown by plasma-assisted molecular beam epitaxy (PA-MBE). The high crystalline quality of the β-Ga₂O₃ epilayer was confirmed by X-ray diffraction and atomic force microscopy. An optimized CF₄-plasma treatment was employed to introduce fluorine (F) into the near-surface region, effectively suppressing donor-like states. The resulting devices exhibit an ultralow off-state current of 1 × 10⁻⁹ mA/mm and a stable on/off ratio of 10⁵. A controllable positive threshold voltage shift up to +12.4 V was achieved by adjusting the plasma duration. X-ray photoelectron spectroscopy indicates that incorporated F atoms form F–Ga-related bonds and compensate oxygen-related donor defects. Sentaurus TCAD simulations reveal reduced near-surface charge and a widened depletion region, providing a physical explanation for the experimentally observed increase in breakdown voltage from 453 V to 859 V. These results clarify the role of fluorine in modulating surface defect states in PA-MBE β-Ga₂O₃ and demonstrate an effective route for threshold-voltage engineering and leakage suppression in Ga₂O₃ power devices. Full article

Background/Objectives: Leucine-rich repeat kinase 2 (LRRK2) is an enzyme implicated in Parkinson’s disease (PD) and a potential therapeutic target. LRRK2 PET radioligands could therefore function as imaging biomarkers for PD and as tools to measure enzyme occupancy of novel therapeutic candidates. This study aimed at developing novel radioligands for imaging using positron emission tomography (PET). Specific objectives were to synthesize fluorine-18-labeled pyrrolopyridine 1 ([¹⁸F]1), pyrrolo-pyrimidine 2 ([¹⁸F]2), as well as carbon-11-labeled pyrrolo-pyrimidine 3 ([¹¹C]3), and examine their binding specificity, using in vitro autoradiography (ARG) and in vivo positron emission tomography (PET) imaging in non-human primates (NHPs). Methods: Radiolabeling was achieved either by classical one-step fluorine-18 nucleophilic substitution reaction or by methylation using carbon-11 methane. [¹⁸F]1 and [¹⁸F]2 were tested in NHP and human whole-hemisphere ARG experiments. PET imaging was performed in cynomolgus monkeys. Radiometabolites were measured in monkey plasma using gradient HPLC. Results: The results demonstrated successful radiolabeling of all three ligands. In ARG studies, both [¹⁸F]1 and [¹⁸F]2 displayed binding in brain slices from NHP and human samples. The binding of [¹⁸F]1 was blocked by cold Compound 1 and structurally distinct Compound 3, but not by the structurally distinct LRRK2 inhibitor PFE-360. On the other hand, the binding of [¹⁸F]2 was blocked by PFE-360 in certain regions of the brain, indicating some level of specific binding to LRRK2. All three ligands showed relevant brain uptake (>3%ID), with highest uptake being observed for [¹⁸F]1, particularly in the thalamus. In contrast, brain uptake of [¹⁸F]2 and [¹¹C]3 was evenly distributed across all brain regions. No blocking effect of [¹⁸F]1 was observed after pretreatment with the structurally distinct LRRK2 inhibitors PFE-360 (0.5 mg/kg, iv) and GEN-7915 (40 mg/kg). Conclusions: PET imaging indicated a low in vivo specific binding of the radioligands in the cynomolgus monkey brain, suggesting that the radioligands are not suitable for LRRK2 imaging in vivo with PET. This study emphasizes the challenges in the development of PET radioligands for imaging LRRK2 and the need for additional work to achieve this goal. Full article

The fabrication of semiconductor devices with three-dimensional architectures imposes unprecedented demands on advanced plasma dry etching processes. These include the simultaneous requirements of high throughput, high material selectivity, and precise profile control. In conventional reactive ion etching (RIE), fluorocarbon plasma provides both accelerated ion species and reactive neutrals that etch the feature front, while the CF_x radicals promote polymerization that protects sidewalls and enhance selectivity to the amorphous carbon layer (ACL) mask. In this work, we present computational results on the role of CF₄ addition to hydrogen fluoride (HF) plasma for next-generation RIE, specifically cryogenic etching. Simulations were performed by varying the CF₄ concentration in the HF plasma to evaluate its influence on ion densities, neutral species concentration, and electron density. The results show that the densities of CF_x (x = 1–3) ions and radicals increase significantly with CF₄ addition (up to 20%), while the overall plasma density and the excited HF species remain nearly unchanged. The results of plasma density and atomic fluorine density are consistent with the experimental observations of the HF/CF₄ plasma using an absorption probe and the actimetry method. It was verified that the gas-phase reaction model proposed in this study can accurately reproduce the plasma characteristics of the HF/CF₄ system. The coupling of HF-based etchants with CF_x radicals enables polymerization that preserves SiO₂ etching throughput while significantly enhancing etch selectivity against the ACL mask from 1.86 to 5.07, with only a small fraction (~10%) of fluorocarbon gas added. The plasma simulation provides new insights into enhancing the etching performance of HF-based cryogenic plasma etching by controlling the CF₂ radicals and HF reactants through the addition of fluorocarbon gases. Full article

In semiconductor manufacturing, fluorinated gases such as CHF₃ and CH₂F₂ are widely used as process gases for plasma etching and cleaning. However, their decomposition within the plasma environment leads to the formation of secondary fluorinated by-products with high global warming potential (GWP). Understanding how plasma intensity affects the generation characteristics of these by-products under realistic process conditions is essential for developing country-specific emission factors and improving inventory accuracy. This study analyzes the by-product formation behavior of CHF₃ and CH₂F₂ under three plasma power conditions (500 W, 600 W, and 700 W), based on process data representative of domestic semiconductor facilities. The quantitative analysis revealed distinct reaction trends between the two gas systems. In the CHF₃ process, a reaction-pathway bifurcation was observed at 700 W, where the formation of high-GWP perfluorocarbons (PFCs, e.g., CF₄, C₂F₆) decreased, while the production of low-GWP fluorinated compounds such as C₄F₆ increased, resulting in an overall 18% reduction in CO₂eq. emissions. Conversely, CH₂F₂ showed a continuous increase in fluoromethane (CH₃F) generation with higher plasma power due to the higher hydrogen content in its molecular structure, leading to an 18.4% net reduction in total GWP emissions. These results provide scientific evidence for understanding the relationship between plasma intensity and by-product formation in fluorinated gas systems under conditions relevant to the Korean semiconductor industry, and offer a foundation for improving national F-gas emission factor development. Full article

The SiGe/Si multilayer is a critical component for fabricating stacked Si channel structures for next-generation three-dimensional (3D) logic and 3D dynamic random-access memory (3D-DRAM) devices. Achieving these structures necessitates highly selective SiGe etching. Herein, CF₄/O₂ and CF₄/N₂ gas chemistries were employed to elucidate and enhance the selective etching mechanism. To clarify the contribution of radicals to the etching process, a nonconducting plate (roof) was placed just above the samples in the plasma chamber to block ion bombardment on the sample surface. The CF₄/N₂ gas chemistries demonstrated superior etch selectivity and profile performance compared with the CF₄/O₂ gas chemistries. When etching was performed using CF₄/O₂ chemistry, the SiGe etch rate decreased compared to that obtained with pure CF₄. This reduction is attributed to surface oxidation induced by O₂, which suppressed the etch rate. By minimizing the ion collisions on the samples with the roof, higher selectivity, and a better etch profile were obtained even in the CF₄/N₂ gas chemistries. Under high-N₂-flow conditions, X-ray photoelectron spectroscopy revealed increased surface concentrations of GeF_x species and confirmed the presence of Si–N bond, which inhibited Si etching by fluorine radicals. A higher concentration of GeF_x species enhanced SiGe layer etching, whereas Si–N bonds inhibited etching on the Si layer. The passivation of the Si layer and the promotion of adhesion of etching species such as F on the SiGe layer are crucial for highly selective etching in addition to etching with pure radicals. This study provides valuable insights into the mechanisms governing selective SiGe etching, offering practical guidance for optimizing fabrication processes of next-generation Si channel and complementary field-effect transistor (CFET) devices. Full article

Surface-enhanced Raman Scattering (SERS) enables ultrasensitive detection but is often hindered by biocompatibility and sustainability concerns due to its reliance on noble metal substrates. To overcome these limitations, we develop a semiconductor-based SERS platform utilizing ultrathin tungsten trioxide (WO₃) nanofilms synthesized via a facile annealing process on fluorine-doped tin oxide (FTO). This system achieves an impressive Raman enhancement factor of 1.36 × 10⁶, enabling ultrasensitive detection of rhodamine 6G (R6G) and methylene blue (MB) at ultralow concentrations, surpassing conventional metal-based SERS platforms. It is further suggested that this is a substrate that can be easily coupled to other metals. An application for the detection of adenine molecules is realized through layered WO₃-Au NPs composites, where embedded gold nanoparticles act as plasma “hot spots” to amplify the sensitivity. Density functional theory (DFT) calculations and band structure analysis confirm that synergistic interface charge transfer and naturally formed oxygen vacancies enhance performance. By combining semiconductor compatibility with other metal amplification, this WO₃-based SERS platform offers a sustainable and high-performance alternative to conventional substrates, paving the way for environmentally friendly and scalable Raman sensing technologies. Full article

Theoretical studies have indicated that borophene is a promising two-dimensional material characterized by remarkable chemical, mechanical, and electrical properties. Nonetheless, its practical applications in areas such as catalysis and gas sensing are hindered by the limited density of reactive sites in its pristine form. To address this limitation, the present study explores the controlled fluorination of borophene nanoflakes as a strategy to modify their surface chemistry and enhance the availability of active sites. Furthermore, it is anticipated that surface fluorination will improve hydrophobicity, which is crucial for reducing humidity-related interference in sensing applications. In this study, we report the successful functionalization of borophene nanoflakes with fluorine using a plasma arc discharge technique for the first time. Borophene nanolayers were synthesized via a sonochemical-assisted exfoliation method, yielding nanosheets with an average lateral dimension of approximately 100 nm. The fluorinated samples were characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM). A systematic investigation of plasma exposure durations demonstrated that fluorine was effectively introduced as a dopant while maintaining the crystallinity of the borophene lattice. Full article

With the rapid progression of global industrialization and urbanization, emerging contaminants (ECs) have become pervasive in environmental media, posing considerable risks to ecosystems and human health. While multidisciplinary evidence continues to accumulate regarding their environmental persistence and bioaccumulative hazards, critical knowledge gaps persist in understanding their spatiotemporal distribution, cross-media migration mechanisms, and cascading ecotoxicological consequences. This review systematically investigates the global distribution patterns of ECs in aquatic environments over the past five years and evaluates their potential ecological risks. Furthermore, it examines the performance of various treatment technologies, focusing on economic cost, efficiency, and environmental sustainability. Methodologically aligned with PRISMA 2020 guidelines, this study implements dual independent screening protocols, stringent inclusion–exclusion criteria (n = 327 studies). Key findings reveal the following: (1) Occurrences of ECs show geographical clustering in highly industrialized river basins, particularly in Asia (37.05%), Europe (24.31%), and North America (14.01%), where agricultural pharmaceuticals and fluorinated compounds contribute disproportionately to environmental loading. (2) Complex transboundary pollutant transport through atmospheric deposition and oceanic currents, coupled with compound-specific partitioning behaviors across water–sediment–air interfaces. (3) Emerging hybrid treatment systems (e.g., catalytic membrane bioreactors, plasma-assisted advanced oxidation) achieve > 90% removal for recalcitrant ECs, though requiring 15–40% cost reductions for scalable implementation. This work provides actionable insights for developing adaptive regulatory frameworks and advancing green chemistry principles in environmental engineering practice. Full article

Plasma electrolytic fluorination (PEF) of AZ31 magnesium alloy was carried out by adding different ratios of water to the ethylene glycol-ammonium fluoride electrolyte. The structural composition of the coatings was characterized using SEM, XRD, and EDS, and the effects of water content on the microstructure and corrosion resistance of the PEF coatings were analyzed. The results showed that the addition of water promoted the ionization of ammonium fluoride and increased the conductivity of the glycol electrolyte, which led to a decrease in the termination voltage. However, the coating thickness was not changed by the addition of water. The O element in water was not enough to compete with the F element in the electrolyte and had a small effect on the PEF coating composition, which was still dominated by MgF₂. The addition of water had an effect on the structure of the coating: with an increase in water content, the number of coating penetration holes decreases, and the continuity is enhanced. The pores on the surface of the coating tended to be levelled off and transitioned to the typical coating structure of PEO (plasma electrolytic oxidation). The addition of water to the glycol electrolyte was conducive to improving the corrosion resistance of the coatings. The corrosion resistance of PEF coatings in neutral NaCl corrosive medium firstly increased and then decreased, and the strongest corrosion resistance was obtained when the ratio of glycol and water is 6:4. Full article

Ultra-high-molecular-weight polyethylene (UHMWPE) fabric is widely used in many fields due to its excellent properties such as high modulus, high strength, and impact resistance. However, its high flammability prevents its application in high-temperature environments. Therefore, it is important to develop multifunctional UHMWPE fabric to meet its different requirements in firefighting, military, and other scenarios. Here, we have prepared a durable flame-retardant superhydrophobic UHMWPE fabric by a simple coating method. A polyurethane solution mixed with decabromodiphenylethane and antimony trioxide is scraped on the surface of the fabric to form a coating, which endows the fabric with flame retardancy. The sprayed fluorinated hydrophobic agent provides superhydrophobic properties to the fabric. It is worth mentioning that plasma pretreatment greatly improves the adhesion properties of the coating by stimulating the active groups on the surface of the fabric. Tests have shown that the adhesion between the coating and the surface of the plasma-treated UHMWPE fabric has been greatly improved. The limiting oxygen index value of the coating UHMWPE fabric has increased by 90%, and it immediately extinguishes after leaving the flame, demonstrating excellent flame retardancy. The contact angle between its surface and water reaches 156°, exhibiting excellent superhydrophobicity and self-cleaning properties. This study provides a simple, convenient, and effective method for the development of multifunctional UHMWPE fabric, greatly expanding its application scenarios and providing ideas for future development. Full article

In this study, hydrophobic poly(hexafluorobutyl acrylate) (PHFBA) thin films were successfully deposited over a large area of 25 × 50 cm using plasma-enhanced chemical vapor deposition (PECVD). Key parameters, including plasma power and the distance between the plasma antenna and the substrate, were optimized to achieve the highest deposition rate while ensuring uniformity and defect-free coatings. The optimal conditions were determined as 5 W plasma power and a 9 cm antenna–substrate distance, yielding a maximum deposition rate of 11.3 nm/min. PHFBA’s low fluorine content makes it a more environmentally and biologically friendly alternative compared to heavily fluorinated polymers, addressing concerns about toxicity and environmental impact. The coatings were applied to a flexible and wetting-sensitive paper towel substrate, which was successfully coated without any visible defects. The contact angle measurements confirmed the hydrophobic nature of the films, with a maximum water contact angle of 131.9° after the deposition of PHFBA. This study highlights the potential of PECVD as an efficient and scalable method for producing hydrophobic coatings, combining high-performance properties with improved environmental considerations. The results not only validate PECVD as a scalable and precise method for thin film fabrication but also open new possibilities for its use in applications requiring durable and functional surface modifications. Full article