Search Results (2,164)

Three zinc(II) complexes based on 1-phenyl-3-methyl-4-acyl-5-pyrazolone were synthesized and characterized by elemental analysis, by X-ray crystallography and spectroscopy (UV-vis, fluorescence and IR). Crystallographic studies reveal that the complexes have a mononuclear structure in the solid state; however, intermolecular interactions combine the complexes into a 1D polymer chain. The complexes exhibit weak luminescence in the polycrystalline state and moderate emission in solutions and thin amorphous films. Thin films of the studied compounds were deposited on a glass substrate using thermal vacuum spraying, spin coating, and Langmuir-Blodgett technology and were studied using atomic force microscopy (AFM), X-ray spectroscopy, and fluorescence spectroscopy. Full article

Flexible pressure sensors serve as core sensing components for wearable health monitoring systems, electronic skins for soft robots, and flexible human–machine interaction devices. Benefiting from the interfacial electric double-layer polarization effect, iontronic sensing delivers far higher pressure response sensitivity than conventional parallel-plate capacitive sensors, endowing it with distinctive advantages in the detection of weak physiological signals. Nevertheless, current dense ionic thin-film dielectric layers suffer from limited deformation space under compression and poor low-pressure sensing capability. Mainstream high-precision micropillar arrays are fabricated via photolithography, 3D printing, and metal etching molds, which require costly equipment and complicated fabrication procedures, making large-area mass production unfeasible. Random frosted concave-convex microstructures feature disordered dimensions, leading to severe device hysteresis and narrow linear ranges, which fail to achieve ultrahigh sensitivity alongside a wide pressure detection range simultaneously. To address the aforementioned multiple bottlenecks, this paper proposes a low-cost resin template replication process to fabricate TPU-based ionic thin-film dielectric layers with ordered micropillar array microstructures. Combined with inkjet-printed silver conductive PI flexible electrodes, an iontronic flexible pressure sensor with a sandwich layered structure is constructed. Multi-dimensional investigations including microscopic morphology characterization, electromechanical sensing performance calibration, and human wearable application tests are systematically implemented to thoroughly elucidate the synergistic enhancement mechanism of the arrayed micropillars. Test results demonstrate that the effective pressure detection range of the sensor spans 0–1038 kPa, accommodating ultra-low pressures such as pulse signals as well as medium-to-high-pressure loads including joint bending. The sensitivity reaches 23.27 kPa⁻¹ within the low-pressure range of 0–200 kPa and remains stable at 3.52 kPa⁻¹ in the high-pressure range of 200–1038 kPa, with piecewise linear fitting correlation coefficients of 0.93 and 0.96 respectively. Both the response time and recovery time of the device are 40 ms, and the hysteresis error throughout the loading-unloading cycle is merely 2.62%. After 20,000 consecutive cyclic loading-unloading tests, the peak capacitance output only decays by 5.1%, verifying outstanding mechanical fatigue resistance and electrical stability. Validations in multi-scenario applications prove that the sensor can accurately capture human physiological and motion signals including radial artery pulses, laryngeal deformation induced by multi-syllable vocalization, and multi-angle bending of fingers and elbow joints, suitable for home-based health monitoring, quantitative rehabilitation training, flexible tactile interaction and other scenarios. The entire fabrication process eliminates high-precision micro-nano processing equipment such as photolithography systems, plasma etchers and 3D printers; only general chemical raw materials and conventional laboratory instruments are adopted. The reusable templates enable low manufacturing costs and large-area coating forming, offering a novel low-cost technical solution for the engineering implementation and industrialization of high-performance iontronic flexible pressure sensors. Full article

Infrared-selective stealth films, which concurrently offer high visible transmittance, suppressed infrared emission, and selective thermal dissipation, have emerged as compelling candidates for infrared protection and thermal-target stealth. However, traditional multilayer architectures are predominantly designed through empirical trial-and-error protocols, which inherently hinder the synergistic optimisation of multiband spectral performance and yield suboptimal parameter-tuning efficiency. To circumvent this bottleneck, we introduce a reinforcement learning (RL)-driven multi-objective optimisation framework that automates the design of composite thin-film configurations. The optimised multilayer film structure consists of TiO₂/ITO/Ag/ZnO/SiO₂, with layer thicknesses of 180, 656, 10, 33.75 and 50 nm, respectively. Spectral characterisation reveals a weighted average visible transmittance of 79.77% over the 0.38–0.78 μm range, alongside blackbody-weighted average emissivities of 33.93%, 72.93%, and 19.94% in the 3–5, 5–8, and 8–14 μm bands, respectively. Consequently, the spectral profile exhibits high visible transparency, deep suppression of emissivity within the atmospheric windows (3–5 and 8–14 μm), and markedly elevated emissivity in the non-atmospheric band (5–8 μm). Analysis of the electromagnetic field distribution and power-loss density along the thickness direction reveals that the energy transmission and dissipation behaviours across distinct bands are synergistically governed by multilayer interference, interfacial multiple reflections, and lossy interlayer coupling mechanisms. Furthermore, angle-resolved infrared-emissivity analysis calibrated against the normal-incidence FDTD spectrum confirms that the structure retains robust polarisation adaptability and pronounced spectral selectivity at incidence angles up to 80°. The above results demonstrate the effectiveness of the reinforcement learning-driven optimisation framework for the automated co-design of multiband spectral responses. Moreover, the uncovered multilayer interference and loss-coupling mechanisms furnish a solid physical foundation for further performance refinement and rational design of transparent stealth coatings. Full article

High-entropy alloys (HEAs) are a unique metallic alloy that was initially recognized for the possibility of stabilizing simple solid-solution phases through high configurational entropy. Research over the past two decades, however, has shown that their behavior is far more complex. Phase formation, microstructural evolution, and surface performance arise from the combined influence of composition, atomic interactions, processing history, and the surrounding environment. This paper reviews the connections between these aspects moving from the bulk alloy to the surface. The thermodynamic and empirical criteria utilized for prediction of phase formation and reasons behind ignoring the factors such as ordering, segregation, metastability, and processing defects are described. Further, the influence of casting, rapid solidification, coating deposition, and thin-film processing on the microstructure that will interact with catalytic or corrosive environment is reviewed. Electrocatalysis and corrosion resistance are considered as two strongly coupled surface phenomena rather than separate fields of application. Quantitative comparison of exemplary high-entropy alloy systems shows the influence of the alloying approach and surface development on the catalytic properties, surface reconstruction, selective dissolution, passive film formation, and localized corrosion. The potential of CALPHAD modeling, density functional theory, machine learning, and multi-objective optimization for a better alloy selection in the field of high-entropy alloys is reviewed as well. We identified that the success of HEA design is not only in choosing the right composition but rather in controlling the phases, defects, interfaces, and surface of the HEA. Full article

Environmental pollution, particularly water contamination, requires the continuous development of robust, effective monitoring technologies. While chemical optical sensors offer significant advantages for environmental monitoring, many traditional devices rely on complex combinations of chemical dyes with specific acid dissociation constants. To overcome these limitations, this study presents a dye-free approach centered on a fiber-optic pH sensor based on a TiO₂ thin film. The protective coating of multimode optical fibers was successfully removed using a controlled hydrofluoric acid (HF) treatment, enabling deposition of TiO₂ films via a low-cost sol–gel dip-coating method. Structural characterizations through X-ray diffraction (XRD) and Raman spectroscopy confirmed the preferential growth and high purity of the anatase phase. Furthermore, energy-dispersive X-ray spectroscopy (EDS) confirmed the presence and relatively uniform distribution of Ti on the fiber surface. The optical performance of the sensor was evaluated using a 940 nm light source over a broad pH range (4–14), where the device exhibited distinguishable stepped optical-power responses at four pH conditions spanning pH 4–14. A preliminary analysis yielded an apparent average slope of 0.40 µW/pH. These results support the feasibility of using sol–gel derived TiO₂ coatings in the preliminary development of dye-free optical devices for aqueous pH monitoring. Full article

Structural colors, generated by the physical interaction of light with micro- and nanostructured architectures, have emerged as an important platform in nanophotonics owing to their high color saturation, exceptional photostability, and long-term color durability. This review provides a comprehensive overview of recent advances in structural colors and establishes a unified classification framework based on their macroscopic angular optical responses. The intrinsic angular characteristics of four fundamental color-generation mechanisms are first distinguished, providing the physical basis for classifying structural colors into iridescent and non-iridescent systems. Representative iridescent architectures, including thin films, one-dimensional (1D) to three-dimensional (3D) photonic crystals, and diffraction gratings, are systematically reviewed, together with non-iridescent strategies based on independent plasmonic and dielectric resonators, quasi-amorphous structures, and engineered metasurfaces. Strategies for enhancing structural color visibility and saturation through absorption management are further discussed, particularly for suppressing undesired broadband and multiple-scattering backgrounds. Additionally, this review systematically summarizes quantitative methodologies for evaluating structural colors, including spectral metrics, CIE 1931 and CIE1976 color spaces, CIEDE2000 color difference, quantitative angular-response metrics, spatial resolution and pixel limits, and structural-order characterization using orientation parameters and two-dimensional fast Fourier transform (2D FFT) analysis. Particular attention is given to the quantitative assessment of angular stability through wavelength shifts and perceptual color differences, while recognizing that a universally accepted numerical boundary between iridescent and non-iridescent coloration has not yet been established. Representative functional applications are also reviewed, including self-cleaning coatings, passive daytime radiative cooling, label-free chemical and gas sensing, reflectometric interference spectroscopy (RIfS), surface-enhanced Raman scattering (SERS), and anti-counterfeiting. By integrating color-generation mechanisms, angular optical responses, quantitative evaluation methods, and functional applications, this review provides a unified framework for objectively comparing structural color platforms and highlights key trade-offs among color quality, angular stability, structural precision, durability, scalability, and multifunctionality, thereby providing design guidance for next-generation optical materials and devices. Full article

Silver (Ag)-based conductive coatings are widely used in electrical contacts due to their excellent electrical conductivity, low contact resistance, good thermal stability and oxidation resistance, although their susceptibility to sulfidation and environmental corrosion is a concern under certain service conditions. In recent years, significant progress has been achieved in both the manufacture and performance optimization of Ag-based coatings to satisfy the demanding requirements of modern electrical and electronic systems. This review summarizes recent advances in fabrication techniques and processing parameters for Ag-based coatings, including electroplating, electroless deposition, magnetron sputtering, electrospark deposition, thermal spraying, and electrical explosion spraying on metallic substrates, particularly on copper and steel substrates. More attention is given to microstructural design strategies, such as the incorporation and homogeneous dispersion of reinforcement or solid lubricant phases within the Ag matrix, to enhance contact reliability and operational endurance. The performance of Ag-based coatings is analyzed in terms of their physical, chemical and mechanical properties, electrical contact resistance, friction and wear behavior, arc erosion resistance, and environmental durability under different service conditions. Key challenges, including coating degradation under high electrical loads, mechanical wear, and corrosive environments, are highlighted. Future research directions are outlined, focusing on multifunctional coating structures that enhance surface performance and ensure the long-term durability of electrical contacts. Full article

Low-emissivity (low-E) coatings are among the most effective thin-film technologies for reducing radiative heat losses and controlling solar heat gain in buildings, which account for approximately 30–40% of global primary energy consumption. This expanded review follows the technological evolution of low-E glazing from early transparent-conductor “heat mirrors” to modern multi-silver dielectric/metal/dielectric (D/M/D) architectures and emerging functional coatings. Four complementary perspectives are addressed: (i) the materials employed, from silver-based multilayers and transparent conducting oxides (ITO, FTO, AZO, GZO) to seed, blocker, and protective dielectric layers; (ii) the deposition systems, contrasting on-line pyrolytic/CVD “hard” coatings with off-line magnetron-sputtered “soft” coatings, together with ALD, sol–gel, and evaporation routes; (iii) the methods of analysis used to correlate microstructure, composition. and interfaces with optical, electrical, and thermal behaviour (XRD, XRR, SEM/TEM, AFM, XPS, SIMS, spectrophotometry, ellipsometry, emissivity, and U-value metrology according to EN 410/EN 673 and ISO 9050); and (iv) the functional performance of low-E stacks in insulating glass units, vacuum glazing, retrofit films, and smart-window systems across climate zones. Persistent research gaps are identified in long-term durability and ageing, indium-free scalable materials, standardized accelerated testing, and multi-objective design of thinner, more selective, and more robust stacks. Full article

Copper and its alloys are indispensable for electronics, communications, new energy systems, and aerospace engineering due to their exceptional electrical conductivity and mechanical properties. However, the thin cuprous oxide (Cu₂O) layer that naturally forms on copper and its alloys is prone to failure under elevated temperatures and high humidity, particularly in chloride-rich environments, leading to accelerated localized corrosion. While conventional chromate-based passivation has long been the industrial standard for preventing corrosion, its use has been increasingly restricted by global regulations (such as RoHS and REACH) due to its severe toxicity and health risks. To address the conflict between environmental compliance and protective performance, this review systematically evaluates recent advances in environmentally friendly, chromium-free anti-corrosion coatings in the present review. These alternative coatings are critically analyzed and categorized into four mechanistic groups: (i) inorganic conversion coatings (including molybdate, tungstate, rare earth, and phosphate systems); (ii) organic films formed via chemical or physical adsorption (such as organic inhibitors, thiol-based monolayers, and organosilane self-assembled films); (iii) conversion coatings engineered through covalent bonding, coordination chemistry, and microstructural tailoring; and (iv) multifunctional coatings that integrate self-healing capability with high electrical conductivity. Beyond providing a technical summary, this review explored how the swift progression of electronic information technology, new energy infrastructure, and robotics has imposed more exacting, multifunctional demands on copper components. This review provides a strategic roadmap for future research and prioritizes the creation of protection strategies that operate robustly in multi-physics coupling environments—integrating high conductivity, autonomous self-healing, and long-term chemical stability to ensure the reliability of next-generation infrastructure. Full article

This study focuses on the deposition of nickel thin-films onto glass fiber fabric via DC magnetron sputtering and explores their potential for broadband microwave absorption applications. A total of twelve laminate samples were prepared by integrating the coated fabrics with epoxy resin, with sputtering powers ranging from 0.5 to 2 kW and deposition times ranging from 10 to 90 min. The microstructure, surface resistance, electromagnetic parameters, and microwave absorption performance were systematically characterized using SEM, XRD, four-point probe measurements, and vector network analysis, supplemented by the Lorentz model fitting and simulation validation. The results indicate that the nickel coatings exhibit a non-uniform arc-like morphology, with preferential growth along the (111) crystallographic plane, while the (200) and (220) planes form under specific conditions. The surface resistance reaches up to 10⁸ Ω·m, suggesting the absence of a continuous conductive network. Electromagnetic parameter analysis reveals that the laminates display dielectric-loss-dominated microwave absorption, and the Lorentz fitting identifies double resonance peaks under prolonged or high-power sputtering. The addition of a dielectric matching layer further enhances the absorption performance. All samples achieve wideband absorption within the Ku-band. Notably, the samples prepared at 1 kW for 30 min and at 1 kW for 90 min both exhibit a reflectivity of ≤−10 dB across the entire 8–18 GHz frequency range. The experimental results are in good agreement with simulations. The bulk density of the laminates is approximately 1.8 g/cm³. These findings confirm that magnetron-sputtered nickel-coated continuous glass fiber fabrics hold considerable promise for wideband microwave absorption applications. Full article

Atmospheric carbon dioxide (CO₂) has reached an unprecedented 430 ppm, warming the planet by 50% compared with pre-industrial times and prompting a search for a quick and effective solution to control CO₂ emissions. As a robust, renewable, biodegradable, and sustainable material, nanocellulose can serve as a strong support for many active molecules. Nanocellulose, whether in suspension, aerogel, or membrane form, is not sufficient for efficient CO₂ capture and separation; hence, active molecules, such as silanes, amines, zeolites, and metal–organic frameworks (MOFs), are introduced via chemical modification, such as grafting, or via physical mixing as fillers or additives to make nanocellulose effective for CO₂ capture and separation. Introducing amine or silane molecules into nanocellulose has proven to be an effective strategy for achieving a satisfactory CO₂ absorption capacity exceeding 6 mmol/g. Nanocellulose membranes, when fabricated with MOFs or zeolites and used as a coating with polyvinyl alcohol (PVA) to create a thin-film composite membrane (TFC), can achieve CO₂ permeance of more than 600 GPU for CO₂ separation from flue gas, with CO₂/N₂ selectivity close to 40. This review provides an overview of nanocellulose-based CO₂ capture and separation materials developed over the last 10 years, along with the related challenges that must be overcome to meet current performance and demand. To facilitate readability, the author has provided a brief introduction to the origin, performance, and scale-up developments of nanocellulose at the start of this review. Full article

The rapid development of implantable medical electronics requires robust biocompatible coatings capable of ensuring long-term stability in aggressive physiological environments. Although Grade 1 titanium is widely used for its excellent mechanical properties and corrosion resistance, active implants require defect-free insulating coatings to prevent electrical leakage and metal ion release. This study presents a systematic evaluation of Parylene C (P-C) thin films deposited by the Gorham chemical vapor deposition (CVD) process onto implant-grade titanium substrates. Four coating thicknesses (1, 5, 10, and 20 µm) were deposited and characterized using complementary chemical, morphological, optical, and mechanical techniques. Contact-angle measurements confirmed uniform hydrophobicity (90.56 ± 1.86°), while FTIR and EDX verified the characteristic chemical composition of P-C. Reflectometry, ellipsometry, and interferometry demonstrated excellent thickness control and deposition reproducibility. Pull-off testing showed high initial mechanical integrity, with detachment forces ranging from 52 to 73 N. However, accelerated PBS ageing (21 days at 90 °C) induced significant degradation, particularly for thicker coatings, reducing pull-off forces to 19–42 N. Likewise, thermal-shock cycling (−80 °C to +220 °C) caused severe interfacial damage, decreasing the required detachment force to approximately 5.5 N for 20 µm coatings because of extensive cracking and delamination. These results demonstrate that Parylene C provides excellent conformal coverage and chemical stability on titanium but that its durability is significantly affected by prolonged hydrothermal ageing and extreme thermal loading. This study provides practical guidelines for the design of reliable encapsulation systems for active implantable medical devices and highlights the need for improved interfacial engineering through optimized adhesion-promoting layers or hybrid protective architectures. Full article

In the present work, thin TiO₂ films were obtained by the sol–gel spin-coating method on glass and ITO-covered glass substrates. The crystallization evolution of the thin films was studied by the X-ray Diffraction (XRD) technique. The results indicate that the films’ crystalline structure was greatly affected by substrate type. X-ray photoelectron spectroscopy (XPS) revealed the chemical states of the TiO₂ films and proved the formation of TiO₂ on ITO substrates. Field Emission Scanning Electron Microscopy (FESEM) showed that the TiO₂ films deposited on the ITO glass possessed a uniform and homogeneous surface morphology. The influence of optical properties (transmittance, reflectance, and optical band gap) on substrate type, the number of layers and annealing temperatures was determined. Spectroscopic data confirmed high transparency of the TiO₂ films obtained on ITO substrates as the transmittance in the visible spectral range was close to 85%. The obtained results reveal that thin TiO₂ films on ITO substrates can be an excellent candidate for photovoltaic and optoelectronic applications. Full article

In the Western Anti-Atlas, the stratiform copper mineralisations of the Tabia Member are distinctly hosted within sedimentary rocks, forming deposits comparable to the sediment-hosted stratabound copper (SSC) type. In Tizert, Ouarmdaz, and Talat n’Ouamane, the sandstones and clays host primary sulphides as disseminations and copper carbonates occurring as small continuous or lenticular beds, small geodes, and coatings on clay laminations. In Tiferki, the conglomerates are more mineralised; sulphides are represented by chalcopyrite and bornite, locally altered into chalcocite. Copper carbonates appear as malachite and azurite coating pebbles and deeply impregnate the granular matrix. From a sedimentological and sequence-stratigraphic perspective, the conglomeratic level at Tiferki represents a low-sea-level prism (LST) formed during a stage of maximum platform exposure allowing erosion products to accumulate at the base of the slope. By contrast, the silty–sandy complex known as the “Talat n’ Ouamane level” corresponds to a prograding sedimentary sequence (Highstand Systems Tract, HST) that developed after a relative regression where the platform was only partially exposed. In both cases, relative sea-level fall promoted the emergence of the hinterland and active erosion, supplying the depositional environment with coarse detrital during the maximum drops in sea level and sandy-to-micro-conglomeratic deposits during less pronounced regressions. This detrital supply probably brought copper in the form of grains and especially dissolved copper, which is largely deposited at the bottom of slopes and in marine environments where microbial communities contribute to the precipitation of copper. The selective distribution of sulphides within the Tabia Member shows that only the low-sea-level and high-sea-level prisms are enriched in stratiform copper, while the transgressive and maximum flooding systems tracts lack significant mineralisation. This suggests that sea-level variations played a controlling role in copper deposition. The regressive trend of the high sea-level suite continued until emergence, reflected by the invasion of the environment by red or ochre siltstones from the alluvial plain. The emergence at the transition from sandstones to dolomites, and the “Red Beds”-type mineralisation embedded in these subaerial facies, support the syngenetic origin of the sulphides in the Tabia Member. After this main emplacement of stratiform copper, the sulphides would have undergone remobilisation and alteration during a significant episode of vertical water escape that deformed the host facies and enhanced mineral concentration within permeable sandstones. Even the clays were delaminated and coated with a thin films of copper carbonates on their surfaces. In the Tamjout dolomites, carbonates are percolated by acidic solutions, contributing to the brecciation and silicification of the stromatolitic layers. Copper mineralisation accompanies this silicification and fills the karstification pockets. Full article

The development of flexible thin-film transistors (TFTs) is crucial for the advancement of wearable electronics, bendable displays, and the Internet of Things (IoT). A key challenge in this field is the fabrication of high-performance gate dielectric layers that combine excellent electrical properties with mechanical robustness and low-temperature processability. In this work, we report flexible TFTs based on CdS and hybrid PVPh/PMMA-ZrO₂ as semiconductor and gate dielectric layers, respectively. The hybrid gate dielectric films were deposited on flexible PEN substrates via a facile spin-coating process at a low temperature of 150 °C. On the other hand, CdS layers were deposited through photo-assisted chemical bath deposition at room temperature. Both correspond to deposition methods in solutions, fulfilling the low-temperature condition. The electrical properties of the hybrid gate dielectric layers were characterized by using metal–insulator–metal (MIM) capacitors, which presented excellent insulating properties, low leakage current density and suitable gate capacitance for transistor operation. From the analysis of the electrical response of flexible TFTs, reliable device characteristics and key electrical metrics were extracted. Furthermore, the MIM and TFTs were tested under mechanical bending, demonstrating stable performance. The MIM capacitors showed outstanding mechanical stability, retaining low leakage and stable capacitance after 1000 bending cycles, with changes attributed to reversible interfacial charge redistribution rather than bulk degradation. Meanwhile the TFTs kept full electrical functionality under repeated bending and tight bending radii (down to 0.6 cm), demonstrating reasonable mechanical durability. These results validate the solution-processed PVPh/PMMA-ZrO₂/CdS system as a promising, mechanically robust platform for flexible electronics. Full article