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A novel atomic layer method for encapsulating individual micro‐ and nano‐particles with thin (sub‐10‐nm) dielectric films is presented. This method leverages the diffusion of vapor‐phase precursors through an underlying inert polymer film to achieve growth of a metal oxide film on all sides of the particle simultaneously, even on the side that is in contact with the substrate. Crucially, the deposition is performed on stationary particles and does not require an agitation mechanism or a special reaction chamber. Here, conformal coatings of alumina are shown to improve stability in aqueous environments for two optically relevant particles: compound semiconductor laser microparticles and lead halide perovskite nanocrystals. [ABSTRACT FROM AUTHOR]

Superconducting junctions are widely used in a multitude of applications ranging from quantum information science and sensing to solid-state cooling. Traditionally, such devices must be fabricated on flat substrates using standard lithographic techniques. In this study, we demonstrate a highly versatile method that allows for superconducting junctions to be fabricated on a more complex topography. It is based on maskless direct laser writing and two-photon lithography, which allows writing in 3D space. We show that high-quality normal metal–insulator–superconductor tunnel junctions can be fabricated on top of a 20-μm-tall three-dimensional topography. Combined with conformal resist coating methods, this technique could allow sub-micron device fabrication on almost any type of topography in the future. [ABSTRACT FROM AUTHOR]

A conformal coating is a protective chemical material that can be applied as a thin layer on printed circuit board assemblies (PCBAs). The purpose of conformal coating is to prevent the interaction between external environmental factors and the electrical assembly. However, since conformal coating materials have different mechanical properties than electronic components, their use may induce additional mechanical stresses on the board. This study focuses on the effect of having a different coefficient of thermal expansion (CTE) for the conformal coating material from the solder joints of ball grid array (BGA) packages on printed circuit boards (PCBs). Typical lead-free solders have a CTE of less than 25 ppm/°C, while coating materials have a much higher CTE. For example, polyurethane has a CTE around 193 ppm/°C. This CTE mismatch generates stresses in different directions on the solder joints, especially when the assembly is subjected to temperature cycling during its service. In this effort, four samples of PCB assemblies that have BGAs were used in temperature cycling tests. The sample size is nine modules, with each module having at least 272 exposed BGA joints. Three of the samples were coated by a layer of polyurethane and one baseline sample was not coated. Coating thickness was selected to be the experimental design factor. Thus, these three samples, which had different thicknesses (30, 80, and $130~\mu \text{m}$), were evaluated and compared against each other and against the noncoated sample. By comparing the four samples, it was found that a thick coating material significantly reduced the lifetime for BGA solder balls by initiating early solder cracks, which propagated and caused complete separation in the solder joint. [ABSTRACT FROM AUTHOR]

Silica optical microspheres often exhibit ultra-high quality factors, yet their group velocity dispersion, which is crucial for nonlinear optics applications, can only be coarsely tuned. We experimentally demonstrate that group-velocity dispersion of a silica microsphere can be engineered by coating it with conformal nanometric layers of alumina yet preserving its ultra-high optical quality factors (~107) at telecom wavelengths. Using the atomic layer deposition technique for the dielectric coating, which ensures nm-level thickness control, we not only achieve a fine dispersion tailoring but also maintain a low surface roughness and material absorption to ensure a low optical loss. Numerical simulations supporting our experimental results show that the alumina layer thickness is a promising technique for precise tuning of groupvelocity dispersion. As an application, we demonstrate the generation of Kerr optical frequency combs, showing that the alumina coatings can also sustain the high optical intensities necessary for nonlinear optical phenomena. [ABSTRACT FROM AUTHOR]

The WLEDs configuration with remote phosphor layers has higher luminescent performance than WLEDs with dispense coating or conformal coating and is applied for many modern devices. However, managing the chromatic performance of lighting structure with remote phosphor materials is a challenging objective that demands more research. This has inspired many research in recent years to use remote phosphor structures to improve color quality including remote structures with two or three phosphor materials separated into distinct layers. The results of this manuscript can support the manufacturers in choosing between the two structures so that multi-chip white LEDs (WLEDs) products obtain highest index in color rendering index (CRI), color quality scale (CQS), light output and color homogeneity. The simulated model used in the experments is 6500 K CCT WLEDs, which results show the triple-layers structure is more favorable in terms of color quality and light output. Besides, a notable reduction occurs in color deviation means that chromatic stability is also enhanced in WLEDs with three phosphor layers. These conclusions were verified by using the Mie theory to analyze the scattering characteristics of phosphor layers. This makes research results reliable and a useful information source to produce better WLEDs. [ABSTRACT FROM AUTHOR]

Transition‐metal phosphides (TMP) prepared by atomic layer deposition (ALD) are reported for the first time. Ultrathin Co‐P films were deposited by using PH3 plasma as the phosphorus source and an extra H2 plasma step to remove excess P in the growing films. The optimized ALD process proceeded by self‐limited layer‐by‐layer growth, and the deposited Co‐P films were highly pure and smooth. The Co‐P films deposited via ALD exhibited better electrochemical and photoelectrochemical hydrogen evolution reaction (HER) activities than similar Co‐P films prepared by the traditional post‐phosphorization method. Moreover, the deposition of ultrathin Co‐P films on periodic trenches was demonstrated, which highlights the broad and promising potential application of this ALD process for a conformal coating of TMP films on complex three‐dimensional (3D) architectures. [ABSTRACT FROM AUTHOR]

The susceptibility of self‐assembled materials to changes of environmental conditions and mechanical forces often limits their utility for many applications. In this work, the surface of nanofibers formed by β‐sheet peptide self‐assemblies were coated by polydopamine (PDA) deposition. This conformal coating process rendered the nanofiber dimensions and internal π‐stacking chirality impervious to changes in pH, temperature, and physical processing by spin‐coating onto a silicon wafer. Whereas sonication‐induced shearing of the dopamine/naphthalenediimide–dilysine (DA/NDI–KK) composite irreversibly shortened the nanofibers into 100–200 nm segments, the uncoated nanofibers unraveled into single strands upon similar treatment. Additionally, the PDA‐coated nanofibers could be wrapped by an additional layer comprised of a positively charged polyelectrolyte polymer. [ABSTRACT FROM AUTHOR]

The hydrophobilization of aerogels is critical for their long‐term application due to their highly open‐porous structures, while the hydrophobilization strategies for polyimide (PI) aerogels are limited. In the present work, a feasible strategy to synthesize superhydrophobic PI aerogels is proposed via a conformal‐coating process. The resulting PI aerogels (F‐PI) exhibit high contact angles up to 156°. Impressively, the F‐PI aerogels show excellent water‐resistant capacity not only in the ambient condition but also in the high‐pressure water up to 0.5 MPa, where the liquid cannot or only partially permeate into the aerogel's open pores. Besides, the F‐PI aerogels possess high Brunauer–Emmett–Teller surfaces areas (185 m2 g−1), high Young's modulus (3 MPa), low thermal conductivity (0.056 W m−1·k−1), and variable densities. All these parameters are found to be well preserved after high pressure (0.1–0.2 MPa) water treatment, further indicating the excellent water‐resistant performance of the F‐PI aerogels. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48849. [ABSTRACT FROM AUTHOR]

As an ultrathin film preparation method, atomic layer deposition (ALD) has recently found versatile applications in fields beyond semiconductors, such as energy, environment, catalysis and so on. The design, preparation and characterization of thin film applied in the emerging fields have attracted great interests. The development of ALD technique on particles opens up a broad horizon in the advanced nanofabrication. Pioneering applications are exploring conformal coating, porous coating and selective surface modification of nanoparticles. Conformal encapsulation of particles is a major application to protect materials with ultrathin films from being eroded by the external environment while keeping the original properties of the primary particles. Porous coating has been developed to simultaneously expose the particles' surface and provide nanopores, which is another important method that demonstrates its advantages in modification of electrode materials, catalysis and energy applications, etc. Selective ALD takes the method forward in order to precisely control the directionality of decoration sites on the particles and selectively passivate undesired facets, sites, or defects. Such methods provide practical strategies for atomic scale and precise surface functionalization on particles and greatly expand its potential applications. [ABSTRACT FROM AUTHOR]

Objectives: We evaluated the effect of the different carrier systems on early vascular response through histological analysis and scanning electron microscopy using a porcine model.Background: Although Synergy™ and Promus PREMIER™ share an identical stent material and drug elution (everolimus), they use different drug carrier systems: biodegradable abluminal coating polymer or durable conformal coating polymer, respectively. However, data regarding the impact of the different coating systems on vessel healing are currently limited.Methods: Twelve Synergy™ and Promus PREMIER™ were implanted in 12 swine. Histopathological analysis of the stented segments was performed on the 2nd and 14th days after implantation. Morphometric analysis of the inflammation and intimal fibrin content was also performed.Results: On the 2nd day, neointimal thickness, percentage of neointimal area, and inflammatory and intimal fibrin content scores were not significantly different between the two groups. On the 14th day, the inflammatory and intimal fibrin content scores were significantly lower in Synergy™ versus those observed in Promus PREMIER™. In Synergy™, smooth muscle cells were found and the neointimal layers were smooth. In contrast, inflammatory cells were observed surrounding the struts of Promus PREMIER™.Conclusions: These results demonstrate that termination of reactive inflammation is accelerated after abluminal coating stent versus implantation of conformal coating stent. [ABSTRACT FROM AUTHOR]

• This is the first long-term investigation of fungal degradation in space. • A significant increase in oxalic acid accumulation was observed in Aspergillus brasiliensis in space. • The Aspergillus brasiliensis forms mature biofilms in space that significantly affect the degradation of polyurethane coatings. Polyurethane (PU) is a commonly used conformal coating for printed circuit boards (PCBs). Filamentous fungi present in the space station environment are capable of degrading PU coatings, thereby posing a threat to the safety of electronic components. Therefore, we conducted a 90-day interaction test between Aspergillus brasiliensis and PU-coated PCBs in the China Space Station (CSS) and a controlled environment on the ground. This research aimed to investigate the alterations in the physiological properties of A. brasiliensis on PCB surfaces and the deterioration behavior of PU coating systems in the space microgravity environment. The results show that many fungal parameters, such as growth, morphology, cell ultrastructure, and low molecular weight organic acids (LMWOA) accumulation showed strong changes after spaceflight compared to ground controls. Distinct corrosion morphological features were found in the internal coatings by FIB/SEM analysis, suggesting the existence of a particular deterioration mechanism in the microgravity environment, which requires further investigation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Reactions of bis(cyclopentadienyl) ruthenium (ruthenocene, RuCp 2) and cyclopentadienyl pyrrolyl ruthenium (RuCpPy) on the hydroxylated surface were explored by density functional theory calculations. • Ru precursors, such as bis(pyrrolyl) ruthenium (RuPy 2), were designed for H 2 O-based atomic layer deposition of RuO 2 · x H 2 O. • New cascade mechanism of H 2 O-based atomic layer deposition of RuO 2 · x H 2 O was proposed. As the unique nanofabrication technique, atomic layer deposition (ALD) can be used to deposit high-quality, uniform, and conformal nanoparticle coatings. Ru and its oxides (RuO x) are important materials in the fields of microelectronics and catalysis. In this work, the reaction of Ru precursors with different ligands on the hydroxylated surfaces were explored. The elimination of the pyrrolyl (Py) ligand is easier than that of the cyclopentadienyl (Py) ligand on the hydroxylated surface. The reaction involved in RuO 2 · x H 2 O ALD using RuPy 2 and H 2 O as precursors was further investigated. During the RuPy 2 reaction, the pyrrolyl ligand is eliminated by the substitution reaction with a surface hydroxyl group. However, the desorption of the pyrrole molecule is difficult due to the strong adsorption between the pyrrole molecule and Ru surface. During the H 2 O reaction, the H 2 O molecules further help the elimination of pyrrolyl ligands from the surface and the dissociative desorption of pyrrole molecules This unique reaction mechanism involved in the ALD of RuO 2 with the assistance of H 2 O can be termed new cascade mechanism. These findings provide theoretical guidance for precursor design and ALD growth of metal oxides. [ABSTRACT FROM AUTHOR]

The continuous development of sustainable food-active packaging materials and practices with high performance is a response to the increasing challenges posed by microbial food safety and environmental contamination. In this study, a multifunctional bio-nanocomposite composed primarily of chitosan, cellulose nanomaterials and carvacrol was proposed as a conformal coating for fruit preservation. The coating exhibits excellent antioxidant and antibacterial activities owing to the incorporation of the carvacrol. The inhibition rate of the coating on E. coli and S. aureus is enhanced by 57.13 % and 62.18 %, respectively. And its antioxidant activities is also improved by 77.45 %. In addition, the oxygen permeability (OP) and water vapor permeability (WVP) of this CS/CNC coating are significantly lowered by 67 % and 46 %, respectively, comparing with the CS coating. The coating exhibited excellent biosafety and cytocompatibility because of over 90 % of the HepG2 cells remained alive in each concentration of the coating after 24 h incubation. Additionally, the efficacy of the coating in prolonging the freshness and visual appeal of perishable fruits is substantiated by the experiment involving two fruit specimens. Furthermore, the coating's ease of production, ingestibility, washability, and utilization of cost-effective and easily accessible biomaterials, including renewable waste materials, indicate its potential as a viable economic substitute for commercially accessible fruit coatings. [ABSTRACT FROM AUTHOR]

[Display omitted] • Compressed Li 3 PS 4 films demonstrate significant resistance to hydrolysis during exposure to an industrial-type dry room. • The infiltration of surface-absorbed hydroxyl groups into the Li 3 PS 4 films is a primary cause of electrolyte failure. • Atomic layer deposition (ALD) effectively eliminates surface-absorbed hydroxyl groups and surface cracks. • ALD coated Li 3 PS 4 films show improved resistance to dry room conditions while maintaining their original ionic conductivity. The susceptibility of sulfide solid electrolytes (SSEs) to rapid hydrolysis upon exposure to moist air significantly hinders their application, underscoring the necessity for effective protective strategies. This study countered initial expectations by demonstrating that Li 3 PS 4 (LPS) films compressed at 400 MPa and subjected to an industrial-type dry room environment (4 % relative humidity at room temperature) for a specific period (e.g., 2 h) exhibit limited surface hydrolysis. This phenomenon was accompanied by a substantial accumulation of hydroxyls from hydration, predominantly affecting the topmost 100 nm of the film surface. Furthermore, upon prolonged exposure in a dry room, these surface hydroxyls were observed to progressively penetrate deeper into the films through inevitable surface cracks, thereby exacerbating hydrolysis and leading to the dislocation of the compressed LPS films. These findings indicate that these detrimental hydroxyls can be effectively harnessed as reactants in atomic layer deposition (ALD) with trimethylaluminum. This ALD technique successfully achieved two key objectives: the thorough removal of hydroxyl groups through the ALD coating process and the simultaneous creation of conformal Al 2 O 3 layers on the surface and in cracks, which significantly enhanced the surface robustness of the compressed LPS films. Further experimental examination revealed that precise control over the thickness of the ALD-applied Al 2 O 3 layer, particularly a 30-nm coating, substantially improved the air stability of the LPS films while concurrently maintaining their ionic conductivity. [ABSTRACT FROM AUTHOR]

As polymer applications and popularity grow in various contemporary industries, they are also being developed as matrices for high atomic number (Z) fillers in the field of radiation protection. Before a specific composite material can be a feasible radiation shield, it must first have defined and validated radiation shielding properties. This allows expected performance levels to be incorporated into material selection and design. The primary metric of photon shielding worth is mass attenuation coefficient. This report provides mass attenuation coefficients for two attractive metal oxide polymer composite options for energies ranging from 123 keV to 1.2 MeV, based on high Z and availability with low cost. The addition of tungsten oxide filler shows an effective way to improve X Ray shielding worth by multiple factors at the 123–247 keV energy range versus pure polyurethane coating or versus Aluminum. Similarly, gadolinium oxide infusion also effectively improves X Ray shielding worth in this energy regime. These samples featured exceptional homogeneity that allowed for performance levels to match theoretical calculations. With the low cost of the metal oxide powder and polyurethane coating, these materials show promise as cost-effective radiation shielding for various applications. [ABSTRACT FROM AUTHOR]

In the past years, the conformal coating on the printed circuit board has been widely used because it offers several advantages in terms of protection and reliability of electronic circuits. However, the coating is a dielectric material, which can impact on the performance of radio-frequency components such as microstrip filters. Hence, the coating characterisation from the dielectric point of view is essential in order to design filters that meet prefixed requirements. Although the dielectric properties of commercial conformal coatings are well known, specific analyses on the effect of the coating on devices performance for space applications are not present in the literature and the coating manufactures do not often provide an appropriate characterisation of dielectric properties, making the analysis and the design of the microstrip filters difficult. The authors discuss numerical and experimental results regarding the performance of a coupled microstrip filter and show that the presence of CV-1152 coating causes a significant shift of the S-parameters. Moreover, a new configuration of the filter based on a fractal shape is proposed, which is characterised by more compact size and an optimised bandwidth.

• SPH model of the flow in a device for pancreatic islets conformal coating. • Encapsulation process suitably reproduced while assuring phase conservation. • Simulation of jet fragmentation and surface tension effects on islet coating process. • Evaluation of influence of process parameters on the shape of encapsulated islets. The paper discusses a Smoothed Particle Hydrodynamics (SPH) model for the analysis of the multiphase flow occurring in an experimental microfluidic device for conformal coating of pancreatic islets with a biocompatible and permeable polymer. The proposed numerical model, based on a weakly-compressible SPH approach, accurately mimics the encapsulation process while assuring phase conservation, thus overcoming potential limitations of grid-based models. The proposed SPH model is a triphasic multi-phase model that allows one: (i) to reproduce the physics of islet conformal coating, including the effects of surface tension at the interface of the involved fluids and of the islet diameter; and (ii) to evaluate how modulation of process parameters influences the fluid dynamics within the microfluidic device and the resulting coating characteristics. This model can represent a valuable, time- and cost-effective tool for the definition of optimized encapsulation conditions through in silico screening of novel combinations of conformal coating parameters, including polymeric coating blends, size range of insulin-secreting cell clusters, utilized chemical reagents, device geometry and scale. [ABSTRACT FROM AUTHOR]

Hierarchical core–shell (C–S) heterostructures composed of a NiO shell deposited onto stacked‐cup carbon nanotubes (SCCNTs) are synthesized by atomic layer deposition (ALD). A film of NiO particles (0.80–21.8 nm in thickness) is uniformly deposited onto the inner and outer walls of the SCCNTs. The electrical resistance of the samples is found to increase of many orders of magnitude with the increasing of the NiO thickness. The response of NiO–SCCNT sensors toward low concentrations of acetone and ethanol at 200 °C is studied. The sensing mechanism is based on the modulation of the hole‐accumulation region in the NiO shell layer upon chemisorption of the reducing gas molecules. The electrical conduction mechanism is further studied by the incorporation of an Al2O3 dielectric layer at NiO and SCCNT interfaces. The investigations on NiO–Al2O3–SCCNT, Al2O3–SCCNT, and NiO–SCCNT coaxial heterostructures reveal that the sensing mechanism is strictly related to the NiO shell layer. The remarkable performance of the NiO–SCCNT sensors toward acetone and ethanol benefits from the conformal coating by ALD, large surface area of the SCCNTs, and the optimized p‐NiO shell layer thickness followed by the radial modulation of the space‐charge region. [ABSTRACT FROM AUTHOR]

• GaAs nanowires are combined with conformal coating of P3HT for enhancing light. • harvesting capability. • Parametric Optimization is done using 3D finite-difference time-domain (FDTD) • method. • Maximum short circuit current density (Jsc) of 41.01 mA/cm2 is achievable with the proposed structure. • The proposed structure yields PCE of 27.85% which is ~10% higher than its planar counterpart. The implications of using the combination of inorganic and organic materials in the active layer of solar cells have motivated researchers to find a new pathway for flexible, low cost, and highly efficient future generation solar cells. III-V material based nanowires (NWs) with subwavelength scale diameters have shown excellent light harvesting and charge transport properties and can be easily combined with organic polymer materials and thin substrates to design hybrid solar cells (HSCs). To obtain optimum design requirements for GaAs nanowire array (NWA) HSCs, an optical simulation of poly(3-hexylthiophene) P3HT/ GaAs (NWA) hybrid solar cell is investigated using finite-difference-time-domain (FDTD) method. In comparison to planar substrate, P3HT coated NWA have shown superior optical properties owing to its intrinsic anti-reflection, broad absorption spectra, and efficient excitation of resonance modes. A steady improvement in light absorption of P3HT/GaAs NWA HSCs is observed as the polymer coating thickness increased up to a certain limit and beyond which there is a significant degradation in the exciton generation. The geometrical parameters like diameter (D) of NW and filling ratio or periodicity are also optimized to achieve superior light absorption and maximum short circuit current density (J sc). Under AM1.5G illumination, maximum photocurrent obtained for optimized structure with conformal coating of P3HT is almost 12% and 15% higher than its fully infiltrated and uncoated counterparts respectively [ABSTRACT FROM AUTHOR]

Although non-toxic solution processing offers a scalable approach for growth of Cu 2 ZnSnS 4 (CZTS) thin films, it must suppress the formation of secondary phases and yield facile conformal large grained films with minimum process steps. While growing CZTS films from environment-friendly ethanol based solutions, here we demonstrate how precursor concentration and post sulfurization critically affect the reaction pathway and morphology of the films. Deposition from lower ionic concentration precursor solution and sulfurization with nominal sulfur amount yielded phase-pure films. However, the thickness and grain size of these films were far lower than that desired for solar cell application, thus necessitating overlay depositions to achieve desired thickness and grain size. This issue was alleviated by increasing the ionic concentration in the precursor solution and the sulfur amount during sulfurization. It was found that coating from 1 M Cu-solution in just two dipping cycles followed by sulfurization at 500 °C yielded phase pure kesterite CZTS films of ~850 nm thickness. In addition, differently with the reported bilayered structure, the films exhibit a uniform microstructure with reasonably large grains. The resulting films showed the bandgap of 1.42 eV and very high photosensitivity upon illumination of white light. Unlabelled Image • Facile growth of phase pure CZTS films from non-toxic solutions without any chelating agent is reported. • Influence of molar concentration of reagent solutions and sulfurization ambience on film properties have been examined. • Resulting films had a conformal microstructure with reasonably large grains. • Films have a bandgap of 1.42 eV and showed very high photosensitivity upon illumination of white light. [ABSTRACT FROM AUTHOR]

The use of quad flat no-leads (QFNs) in high-reliability applications is receiving increased interest. To address concerns of harsh working environments, conformal coatings are used to protect the components and associated printed circuit board (PCB). However, using conformal coatings can pose a reliability risk for the components on the PCB. This paper details an investigation into the effect of conformal coatings on the reliability of QFN second-level solder interconnections. Five QFN package types and two types of conformal coatings were investigated. In the experiments, a large population of QFN assemblies coated with conformal coatings were subjected to a thermal cycling test condition. These components, designed with daisy-chain connections, were monitored during the thermal cycling tests, and the exact time for failure to occur for each component was recorded and analyzed. Detailed finite-element models for the tested QFN assemblies were developed; the inelastic strain energy density was used as the damage indicator to evaluate the impact of conformal coating on the solder joint reliability. Modeling results reveal that the conformal coating plays an intricate role in QFN solder joint reliability. The presence of conformal coating results in a reduction in the shear stress in the solder joint and plays a positive role in solder reliability. However, it also induces more stress in the solder joint in the out-of-plane direction and plays a negative role. These two mechanisms are competing, and their relative magnitude will determine the overall effect of conformal coating on solder joint reliability. [ABSTRACT FROM AUTHOR]

Tin whisker growth, which may lead to short circuits and current leakage, is a serious issue in electronics components. Polyurethane-based conformal coatings have been seen as an effective candidate to mitigate the tin whisker growth. To better understand the effect of such coatings, this study exposed the tin-plated copper coupons coated with i) moisture cured polyurethane (PU) and ii) dual UV/moisture cured polyurethane acrylate (PUA), for long-term (up to 5000 h) high-temperature and high-humidity (HTHH) storage (85 °C and 85%RH, respectively). After HTHH storage, microstructural developments in the tin layer, coating degradation, tin surface reaction, and coating adhesion to tin surface were analyzed to compare the tin whisker mitigation behavior. In order to improve the coating adhesion, tin surface was also treated with a silane adhesion promoter before coating was applied. Furthermore, the effect of electron beam irradiation was investigated as it degraded the coating properties and adhesion. The results show that maintaining good adhesion and suppressing the degradation of mechanical properties of conformal coatings during various environmental exposures are essential for enhanced tin whisker mitigation. • Two types of polyurethane-based conformal coatings are evaluated for tin whisker mitigation capacity. • Tin whisker growth mechanism under the protection of an overlying conformal coating is discussed. • Conformal coatings are degraded during the extended thermal and humid aging conditions (85 °C/85%RH, up to 5000 h). • Coating adhesion is improved on tin surface via its silane treatment that provides long-term protection from tin whiskers. • Effect of the electron beam irradiation on conformal coatings is evaluated for their tin whisker mitigation capacity. [ABSTRACT FROM AUTHOR]

Abstract Engineering and preparation of nanostructured ferroferric oxide/carbon composites (Fe 3 O 4 /C) have been extensively considered as enabling Fe 3 O 4 -based anode materials for improvement in lithium storage performance. However, the general synthesis strategies for nanostructured Fe 3 O 4 /C composites are involved in hydrothermal treatment and application of various raw materials containing reagents and solvents, which are not conducive to environmental protection and energy conservation. Herein, a characteristic Fe 3 O 4 /C anode material with a superior electrochemical performance has been constructed by a extremely simple and relatively green route. It consists of smaller secondary nanoparticles and conformal carbon coating, and are full of pores. Consequently, the as-constructed Fe 3 O 4 /C shows an outstanding cycling stability as well as high specific capacities, releasing 896.4 mAh g−1 after 300 cycles at 200 mA g−1 as well as 455.3 mAh g−1 after even 500 cycles at 1000 mA g−1. Thus, the as-constructed Fe 3 O 4 /C may be a prospective candidate for high performance anode materials of lithium-ion batteries. Graphical abstract A high performance of Fe 3 O 4 /C composite anode material has been successfully prepared by an extremely facile and relatively green strategy, and exhibits superior lithium storage performance. Image 1 Highlights • A high-performance Fe 3 O 4 /C anode had been prepared by a relatively green and facile way. • The as-prepared Fe 3 O 4 /C anode exhibited outstanding lithium storage performance. • The as-prepared Fe 3 O 4 /C anode delivered a high capacity of 896.4 mAh g−1 after even 300 cycles. [ABSTRACT FROM AUTHOR]

Atomic layer deposition (ALD) relies on alternated, self-limiting reactions between gaseous reactants and an exposed solid surface to deposit highly conformal coatings with a thickness controlled at the submonolayer level. These advantages have rendered ALD a mainstream technique in microelectronics and have triggered growing interest in ALD for a variety of nanotechnology applications, including energy technologies. Often, the choice for ALD is related to the need for a conformal coating on a 3D nanostructured surface, making the conformality of ALD processes a key factor in actual applications. In this work, we aim to review the current status of knowledge about the conformality of ALD processes. We describe the basic concepts related to the conformality of ALD, including an overview of relevant gas transport regimes, definitions of exposure and sticking probability, and a distinction between different ALD growth types observed in high aspect ratio structures. In addition, aiming for a more standardized and direct comparison of reported results concerning the conformality of ALD processes, we propose a new concept, Equivalent Aspect Ratio (EAR), to describe 3D substrates and introduce standard ways to express thin film conformality. Other than the conventional aspect ratio, the EAR provides a measure for the ease of coatability by referring to a cylindrical hole as the reference structure. The different types of high aspect ratio structures and characterization approaches that have been used for quantifying the conformality of ALD processes are reviewed. The published experimental data on the conformality of thermal, plasma-enhanced, and ozone-based ALD processes are tabulated and discussed. Besides discussing the experimental results of conformality of ALD, we will also give an overview of the reported models for simulating the conformality of ALD. The different classes of models are discussed with special attention for the key assumptions typically used in the different modelling approaches. The influence of certain assumptions on simulated deposition thickness profiles is illustrated and discussed with the aim of shedding light on how deposition thickness profiles can provide insights into factors governing the surface chemistry of ALD processes. We hope that this review can serve as a starting point and reference work for new and expert researchers interested in the conformality of ALD and, at the same time, will trigger new research to further improve our understanding of this famous characteristic of ALD processes. [ABSTRACT FROM AUTHOR]

In the past years, the conformal coating on the printed circuit board has been widely used because it offers several advantages in terms of protection and reliability of electronic circuits. However, the coating is a dielectric material, which can impact on the performance of radio-frequency components such as microstrip filters. Hence, the coating characterisation from the dielectric point of view is essential in order to design filters that meet prefixed requirements. Although the dielectric properties of commercial conformal coatings are well known, specific analyses on the effect of the coating on devices performance for space applications are not present in the literature and the coating manufactures do not often provide an appropriate characterisation of dielectric properties, making the analysis and the design of the microstrip filters difficult. The authors discuss numerical and experimental results regarding the performance of a coupled microstrip filter and show that the presence of CV-1152 coating causes a significant shift of the S-parameters. Moreover, a new configuration of the filter based on a fractal shape is proposed, which is characterised by more compact size and an optimised bandwidth. [ABSTRACT FROM AUTHOR]

In this paper the aptitude of a distributed antenna array (DAA) microwave system composed of planar matrix sources for the NanoCrystalline Diamond (NCD) film conformal coating of complex-shape 3D substrates is investigated using H 2 /CH 4 /CO 2 gas mixture at low pressure and low temperature (<500 °C). First, NCD films are synthesized on 2- and 4-in. silicon wafers aligned perpendicularly (vertical samples) with respect to the plan of plasma sources. A strong heterogeneity of the layer thickness and microstructure along the vertical direction is observed but can be improved by decreasing the working pressure down to 0.25 mbar. At this pressure, NCD films synthesized on 4-in. silicon wafer at a substrate holder temperature of 400 °C show a homogeneous thickness with deviation below 15% on 3 cm along the vertical direction, which highlights the ability of the DAA reactor to treat three-dimensional substrates of a few centimeters size. A first concretization is then presented by coating a cylindrical-shape titanium implant of 6.3 mm height for biomedical applications with NCD films characterized by satisfactory purity and uniformity. Unlabelled Image • Conformal low temperature growth of nanocrystalline diamond films is investigated. • Vertical thickness homogeneity is improved on 2-in. Si samples. • Vertical thickness deviation below 15% is obtained over 3 cm on 4-in. Si samples. • Three dimensional growth is successfully achieved on cylindrical titanium implant. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) have revolutionized the world of portable power, enabling the proliferation of electronics, electric vehicles, and renewable energy systems. However, these remarkable energy storage devices are not without their challenges, ranging from safety concerns to capacity degradation. Conformal coatings have emerged as a transformative technology to address these issues by providing a protective and uniform layer over critical battery components, such as the anode, cathode, and separator. The innovations in technologies relating to multifunctional conformal coatings have taken their application a step ahead of only providing safety. Multifunctional coatings have enhanced battery performance, developed solid-state battery technology, and allowed 3D and nano-architectured LIBs to be easily fabricated. Materials like conductive polymers, polymer electrolytes, and graphene are leading the research for multifunctional coatings for high-performance LIBs, increasing their conductivity, cycling capacity, and more. This comprehensive review aims to provide a detailed understanding of the recent innovations in the field in the realms of varied materials and methods utilized for the conformal coating of LIBs. [Display omitted] • Materials for conformal coating of Lithium-ion batteries • Characteristics of conformal coatings • Multifunctional conformal coatings for high-performance lithium-ion batteries • Conformal Coatings Techniques [ABSTRACT FROM AUTHOR]

A new strategy for preparing flexible and semi-transparent gas-barrier coatings was developed using tailored self-assembly of montmorillonite (MMT)/polyvinylpyrrolidone (PVP) nanocomposites assisted by aqueous liquid crystalline (LC) scaffolds. First, we established a composition wherein aqueous MMT exhibited the LC phase in the presence of polyethyleneimine (PEI) and hydrochloric acid (HCl). The viscoelastic rheological features of MMT LC enable the formation of uniform and conformal MMT coatings on various types of substrates, including flat or topographically featured surfaces. Moreover, the MMT LC serves as a structural scaffold that enables the rapid transport of PVP within the inner gallery space of the MMT LC, resulting in the formation of stacked MMT/PVP nanosheets after drying. Owing to its highly aligned layered structure, MMT/PVP exhibited flexible mechanical properties with enhanced hardness and modulus compared to neat MMT. Furthermore, the MMT/PVP can suppress gas permeation, as demonstrated by 0.1 Barrer of H 2 permeability for the best coating conditions (containing 63 wt% MMT and 37 wt% PVP), while maintaining semi-transparent optical properties. Considering the aforementioned properties and that all components in MMT/PVP are bio-safe materials, this coating system has potential applications as a gas-barrier coating in conventional packaging materials, food packaging, and H 2 storage tanks. [Display omitted] • Free-flowing liquid-crystalline viscoelastic gel of montmorillonite (MMT) can form with PEI and HCl. • Highly ordered nanocomposite layers of MMT/PVP (polyvinylpyrrolidone) can be coated on various types of substrates. • Hirarchically architecture MMT/PVP nanocomposite coating effectively hinders H 2 permeation. • The barrier coating is flexible and semi-transparent due to its highly ordered nanosheet structure. [ABSTRACT FROM AUTHOR]

The rising interest in binder-free electrode supercapacitors can be attributed to their outstanding electrochemical performance and seamless compatibility with a diverse range of electronic devices. This study show cases the successful development of a binder-free electrode, facilitating the direct growth of Ni 3 S 2 nanostructures on Ni foam substrate, resulting in the development of high-performance supercapacitors. The formation of 0.5@Ni 3 S 2 , 1@Ni 3 S 2 , 2@Ni 3 S 2 , and 3@Ni 3 S 2 with a heazle-woodite-phase structure was confirmed through X-ray diffraction, grown by the direct sulfurization of the Nickel foam surface into Ni 3 S 2 using a straightforward one-step hydrothermal process with varying quantities of sulfur source. Field emission scanning electron microscopy (FESEM) was employed to visualize the continuous porous micro-networks on Ni foam surface. In a three-electrode system, the supercapacitor exhibited a capacitance of 418.46 F/g at 2 A/g. Furthermore, the Ni 3 S 2 //AC asymmetric supercapacitor device demonstrated remarkable performance with a specific capacitance of 192.24 F/g, an energy density of 65.42 Wh/kg, and a power density of 2966.14 W/kg @ 1 A/g. Impressively, even after undergoing 8000 charge-discharge cycles, these devices retained 51% of their initial capacitance. • Direct sulfurization of Nickel foam surface into Ni 3 S 2 via a facile one-step hydrothermal. • Supercapacitor in three electrodes system resulted the capacitance of 418.46 F/g at 2A/g. • 0.5@ Ni 3 S 2 had better result because of better conformal coating of the active material and low agglomeration. • The fabricated devices showed ∼51% capacitive retention even after 8000 charge discharge cycles. [ABSTRACT FROM AUTHOR]

Atomic layer deposition (ALD) of chalcogenide amorphous films has attracted attention, thanks to its ability to deposit highly conformal and uniform thin films on three-dimensional structures; these film properties are critical for the development of ultrahigh-density integrated electronic circuits such as nanoscale 3D cross-point memory stacks. Control over the composition of chalcogenide compounds is indispensable for fabricating functional electronic devices. In this work, the authors used trichlorogermane (HGeCl3) and bis(trimethylsilyl)telluride [(Me3Si)2Te] as ALD precursors to develop conformal and uniform germanium telluride (GeTe) films at low temperature (60 °C). The growth of GeTe resulted in moderately Ge rich films independently of the ALD precursor injection time and the use of single or discrete (Me3Si)2Te doses. To achieve control over the GeTe film composition, the authors developed a unique ALD of elemental tellurium (Te) using tellurium ethoxide [Te(OEt)4] and (Me3Si)2Te as precursors. Combining GeTe and elemental Te in an ALD supercycle fashion, they obtained GeTex films with a controllable Te content showing a uniform and conformal morphology on high aspect ratio trench structures. A detailed analysis of the variations in Ge and Te contents upon exposure of GeTex films to Te(OEt)4 revealed that an interfacial replacement of Ge atoms to form volatile Ge(OEt)2 takes place and produces a decrease in Ge and an increase in Te content. The ALD studies of GeTe and Te films described in this work provide a facile route for deposition of GeTe with controllable composition. This material system is important for the development of ovonic threshold switching selectors and phase change memories. [ABSTRACT FROM AUTHOR]

Abstract A comparative theoretical analysis of the atomic-layer deposition is implemented for trenches and cylindrical holes. The precursor insertion duration necessary for the conformal coating of the walls of three-dimensional structures is studied at different values of the structure aspect ratio and the sticking coefficient of the precursor molecules. The critical duration (the minimum time required for a conformal surface coating) has been estimated on the basis of the kinetic model of particle flows to the walls of the microstructure. Analytical expressions have been derived, which allow estimate the critical duration as a function of the parameters of the technological process (pressure, temperature). Highlights • Atomic layer deposition model into nanoscale trenches and holes is developed • Step coverage parameter as function of aspect ratio is estimated • Impact of sticking coefficient is discussed • Two asymptotic regimes for shallow and deep structures is identified • The analytical expression for minimal dosage time is obtained [ABSTRACT FROM AUTHOR]

Exploring efficient photocatalysts for water oxidation is highly demanded because of their significant role in artificial photosynthesis. The research of metal-organic frameworks (MOFs) based photoelectrochemical (PEC) water splitting is promising but still in its infancy due to the challenge to fabricate high-quality MOFs photoelectrode. Here an Fe 2 O 3 /Fe-based MOF core/shell nanorod is prepared for efficient PEC water oxidation via a facile surfactant-assisted solvothermal method. With polyvinylpyrrolidone (PVP) molecules as intermedia, an ultrathin MOF shell of several nanometers thick can be controllably grown on the surface of Fe 2 O 3 nanorod. Charge dynamical behaviors study by ultrafast transient absorption spectroscopy (TAS) and photoelectrochemical impedance spectroscopy (PEIS), reveal that the ultrathin MOF shell is crucial to promote the charge separation by providing a cascade band level, but also accelerate the hole injection efficiency via exposing more accessible Fe-oxo cluster active sites. Accompanied with good visible-light response, the Ti-doped Fe 2 O 3 /NH 2 -MIL-101(Fe) photoanode delivers a boosted photocurrent density of 2.27 mA cm −2 at 1.23 V vs. RHE, which is about 2.3 folds of that of pristine Fe 2 O 3 . This study provides new insights into the rational design of semiconductor/MOFs hybrid materials for photo/photoelectrochemical catalysis. [ABSTRACT FROM AUTHOR]

The Through-Silicon (Si) Via (TSV) is the integration technology for three-dimensional integrated-circuit packaging. The layer-by-layer (LbL) technique has been used to deposit flexible poly(allylamine) hydrochloride (PAH)/polystyrene sulfonate (PSS) multilayers inside scalloped Si trenches of a high aspect ratio, fabricated by the Bosch-etching process. An outstanding control of the thickness and the conformality of the polymer layers, along with a significantly improved planarization, was achieved due to the LbL-technique self-termination effects. In addition, the basic properties of the polymer layers have been characterized: diffusion-barrier properties, adhesion, density, and elastic modulus. The results of this study demonstrate the feasibility of LbL multilayers regarding the TSV liner for the vertical interconnect accesses with a high aspect ratio of highly scalloped surface walls. [ABSTRACT FROM AUTHOR]

Expanded perlite particles were surface functionalized using poly(hydroxyethyl methacrylate) (PHEMA) thin film under radio frequency (RF) plasma conditions in a rotating-bed plasma enhanced chemical vapor deposition (PECVD) system. Using a rotating-bed system allowed effective agitation and mixing of the particles during depositions, which ensure uniform surface coating of highly porous and particulate materials. The effects of plasma power and plasma operation mode, namely pulsed and continuous modes on the deposition rates, structure, wettability and water holding capacities of expanded perlite particles were investigated. Chemical and morphological properties of uncoated and coated expanded perlites were determined by SEM, FTIR, contact angle, and BET analyses. Observed deposition rates changed between 10 and 35 nm/min., which were dependent on the deposition conditions. It was found that pulsing the discharge helped to minimize undesirable monomer fragmentation while providing better film structure. The most hydrophilic PHEMA thin films were fabricated at 50 W plasma power and under pulsed-plasma mode. When the expanded perlite was modified with PHEMA under suitable experimental conditions, the water holding capacity of untreated particles is increased by more than twenty percent. [ABSTRACT FROM AUTHOR]

Here, we concisely review the nonminimal coupling dynamics of a single scalar field in the context of purely affine gravity and extend the study to multifield dynamics. The coupling is performed via an affine connection and its associated curvature without referring to any metric tensor. The latter arises a posteriori and it may gain an emergent character like the scale of gravity. What is remarkable in affine gravity is the transition from nonminimal to minimal couplings which is realized by only field redefinition of the scalar fields. Consequently, the inflationary models gain a unique description in this context where the observed parameters, like the scalar tilt and the tensor-to-scalar ratio, are invariant under field reparametrization. Overall, gravity in its affine approach is expected to reveal interesting and rich phenomenology in cosmology and astroparticle physics. [ABSTRACT FROM AUTHOR]

The efficiency of impregnation methods for making Cu-based solid oxide fuel cells (SOFCs) is qualitatively characterized for the first time through a conformal coating model. It is found that the low-efficiency results from the uneven distribution of Cu instead of the small loading. Most of the Cu deposits form isolated islands, e.g., in a 20.4 vol.% Cu-loaded anode, 81% Cu is isolated from each other. In order to address the limited impregnation efficiency, two different procedures are adopted to fabricate the practical Cu/CeO2 anodes, namely, simultaneous and sequential impregnation procedures. It is found that CeO2 works as a solid dispersant, improving the Cu distribution drastically. Compared to the Cu-only anode, more than a threefold improvement of impregnation efficiency is achieved by both methods. The anode made by the sequential impregnation yields the best performance in CH4 at 700 °C, 170 mW cm−2, which represents an 18% enhancement over that of the simultaneous impregnation, or 340% over the Cu-only anode. These findings demonstrate that it is of importance to optimize the Cu impregnation to yield a highly active anode, and the sequential impregnation method is a promising procedure to break the efficiency-limiting factor and produce a high-performance anode with minimized fabrication effort. [ABSTRACT FROM AUTHOR]

The internal charging effect is one of the most important factors threatening satellite’s life in the space environment. In this paper, a semi-insulating conformal coating is prepared on the circuit board surface by spray method aimed to eliminate the charging. The coating is composed of two layers. A polymethyl methacrylate (PMMA) base layer followed by top layer made of PMMA matrix polyaniline (PANI) composite with a surface resistivity of 1.49 × 1011 Ω. The structure and morphology of PANI were investigated by FTIR, XRD, and TEM. Anti-internal charge testing of PANI/PMMA conformal coating is performed by the internal charging simulation device. The results showed that the coating can prevent the discharge phenomenon effectively. [ABSTRACT FROM AUTHOR]