Layers Of Different Thicknesses Research Articles

Preparation of New Hybrid Materials SiO2@Melamine-Cyanurate as Precursors of Graphite-Like Carbon Nitride

This work describes the use of silica particles obtained by sol-gel method as a templat for deposition of supramolecular complexes of melamine cyanurate. To obtain SiO2@melamine-cyanurate (SiO2@MCA) material, the method of covalent modification of silica surface by melamine molecules (SiO2-mel) was applied and the method of its further functionalization by hydrogen-bonded organic framework of melamine-cyanurate (HOF, MCA) was proposed. One of the promising directions of using SiO2@melamine-cyanurate is obtaining SiO2@g-C3N4 material on its basis. Control of the amount of applied melamine-cyanurate allows to potentially obtain g-C3N4 layers of different thicknesses on the silica surface.

Optimization of the polyaniline solid contact in potentiometric sensors for detection of paralytic shellfish toxins in mussels

The present study optimized the properties of the electropolymerized polyaniline (PANI) solid inner contact for a potentiometric chemical sensor by varying the thickness of the polymer layer. A potentiometric sensor for detecting one of the paralytic shellfish toxins, decarbamoyl saxitoxin (dcSTX), in mussel extracts was selected as a case study. The plasticized PVC membrane composition, developed in previous work for the detection of this toxin, was used. The structure and electrical properties of PANI layers of different thicknesses were studied using scanning electron microscopy and electrochemical impedance spectroscopy. The effect of PANI solid contact thickness on the characteristics of the potentiometric sensor, including sensitivity, detection limit, and selectivity to dcSTX in buffer solutions and mussel extracts, was evaluated. The formation of a water layer at the inner solid contact and PVC membrane interface was investigated using electrochemical impedance spectroscopy and a water test. PANI layer thickness 1.1 µm was found to be optimal for solid inner contact for potentiometric sensor with PVC membrane providing highest sensitivity and selectivity.

On the intrusiveness of phosphor thermometry for metal surface temperature measurements in reciprocating engines: an experimental and heat conduction modeling study

Abstract Lifetime-based phosphor thermometry has been applied in a wide variety of surface temperature measurement applications due to its relative ease of implementation and robustness to background interference when compared to other optical temperature measurement methods. It is often assumed that the technique is minimally intrusive if the thickness of the applied phosphor coating is < 20 µm. To evaluate this assumption, high-speed phosphor surface temperature and thermocouple measurements were performed on 4140 steel substrates installed in the cylinder head of an optically-accessible internal-combustion engine for four operating conditions. For phosphor thermometry measurements, four substrates were studied, each coated with a phosphor layer of different thickness ranging between 6 µm and 47 µm. The phosphor thermometry measured temperature swings during combustion were shown to be heavily impacted by the presence of the phosphor coatings, increasing by roughly a factor of 2 - 2.5 when increasing the thickness from 6 µm to 30 µm. A technique was implemented which utilizes the temperature data in combination with a heat conduction model to provide estimates of the temperature swing and heat transfer flux in the absence of the phosphor coating. It was shown that even the 6 µm phosphor coating could lead to an order of magnitude increase in the temperature swing relative to the uncoated 4140 steel substrate. Despite the intrusiveness of phosphor thermometry for the surface temperature measurements, reasonable agreement was demonstrated between heat flux estimates determined with the heat transfer modeling technique and those deduced from temperature-swing measurements using two different high-speed thermocouples. The results indicate that phosphor surface thermometry can be a reliable surface temperature and heat flux diagnostic for transient high heat flux environments, as long as proper care is taken to account for the impact of the phosphor layer on the measurement.

Effect of Sb2S3 sacrificial layer thickness on structural, optical and electrical properties of CuSbS2 films and investigation of diode parameters of CuSbS2/CdS heterojunctions

The ternary copper chalcogenides CuSbS2 (CAS) is found to have appealing optical and photovoltaic properties to be used as absorber layer in thin film solar cells. However, the difficulty to grow good quality CuSbS2 layer of micrometer thickness by chemical bath deposition method holds a big challenge. In this work, we reported the effect of incorporating Sb2S3 sacrificial layer of different thickness on structural, optical and electrical properties of CAS films. The X-ray diffraction results and Raman spectroscopic analysis confirm the formation of single-phase orthorhombic crystal structure for CuSbS2. The increase of Sb content in CAS films with the increase in deposition time of Sb2S3 layer has been reflected in the change in relative intensity ratio of characteristic Raman peaks as well as in diffraction peak profiles. The magnitude of defect states in terms of Urbach energy is decreased drastically by increasing Sb percentage in the films. A clear improvement in electrical properties of CAS films is observed with the decrease in Cu/Sb ratio. The carrier density is increased by one order of magnitude from 1016 to 1017 cm−3 and hole mobility increases from 1.14 to 4.87 cm2/Vs. The impact of Sb concentration on Scottky diode parameters of CAS/CdS heterojunction was studied by using thermionic emission model. Both the ideality factor and series resistance are decreased with the increase in Sb content. The J-V measurements reveal that the integration of Sb2S3 sacrificial layer improves the PV parameters such as fill factor, open circuit voltage, photocurrent and efficiency. The overall improvement in diode parameters can be ascribed to decrease in defect states, better film quality, absorber layer thickness and improved stoichiometry of CAS films.

Strain in Hybrid Organic-Inorganic Metal Halide Perovskites Microstructures by Numerical Simulations.

Hybrid organic-inorganic metal halide perovskites (HOIPs) are promising materials for optoelectronics applications. Their optical and electrical properties can be controlled by strain engineering, that results from application of local elastic deformation or deposition on pre-patterned substrates acquiring a conformal 3D shape. Most interesting, their mechanical properties depend on their crystal structure, composition and dimensionality. We explore by numerical simulations the deformation of a selection of HOIPs comprising a broad range of elastic properties. We consider an axial symmetry with the formation of microdomes on flakes. Radial and vertical forces are considered, finding that the radial force is more effective to obtain large deformation. Large vertical displacement and strain is obtained for HOIPs with low stiffness. The layered nature of HOIPs, that are formed by inorganic layers of different thickness and organic spacers, is also investigated, revealing a non-monotonous trend with the proportion of inorganic to organic part.

Transfer of High-Temperature-Sputtered BiFeO3 Thin Films onto Flexible Substrates Using α-MoO3 Layers.

Inducing external strains on highly oriented thin films transferred onto mechanically deformable substrates enables a drastic enhancement of their ferroelectric, magnetic, and electronic performances, which cannot be achieved in films on rigid single crystals. Herein, the growth and diffusion behaviors of BiFeO3 thin films grown at various temperatures is reported on α-MoO3 layers of different thicknesses using sputtering. When the BiFeO3 thin films are deposited at a high temperature, significant diffusion of Fe into α-MoO3 occurs, producing the Fe1.89Mo4.11O7 phase and suppressing the maintenance of the 2D structure of the α-MoO3 layers. Although lowering the deposition temperature alleviates the diffusion yielding the survival of the α-MoO3 layer, enabling exfoliation, the BiFeO3 is amorphous and the formation of the Fe1.89Mo4.11O7 phase cannot be suppressed at the crystallization temperature. High-temperature-grown BiFeO3 thin films are successfully transferred onto flexible substrates via mechanical exfoliation by introducing a blocking layer of Au and measured the ferroelectric properties of the transferred films.

Effect of Impregnation of PEDOT:PSS in Etched Aluminium Electrodes on the Performance of Solid State Electrolytic Capacitors

Electrolytic capacitors store larger amounts of energy thanks to their thin dielectric layers and enlarged surface area. However, the benefits of using a liquid electrolyte are at the expense of the possibility of leakage, evaporation, or rupture of the device over time. As a solution, solid electrolytes, such as conductive polymers, substitute the liquid ones decreasing the internal resistance and enlarging the lifetime of these devices. PEDOT:PSS is a widely used conductive polymer in the formation of solid electrolytic capacitors. However, using the enlarged surface of the porous electrodes efficiently requires industrial processes, the efficacy of which has not been explored. In this work, porous aluminium electrodes with dielectric layers of different thicknesses were coated with PEDOT:PSS at different levels of doping in order to study the efficiency of the production of solid electrolytic capacitors in industry. The combination of odd random phase electrochemical impedance spectroscopy (ORP-EIS) with surface characterization techniques (SEM-EDX, GDOES) formed a methodology that allowed the study of both the electrical properties and the level of impregnation for these model systems. All samples consisting of a porous aluminium electrode with an amount of PEDOT:PSS deposited on top resulted in an inefficient degree of penetration between the two electrodes. However, the electrochemical analysis proved that the use of dopants produces systems with the highest capacitive properties. Consequently, the evolution towards better solid electrolytic capacitors does not rely solely on the proper coverage of the porous electrodes, but on the proper electrical properties of the PEDOT:PSS within the pores.

Demonstration of 0−π transition in Josephson junctions containing unbalanced synthetic antiferromagnets

Josephson junctions containing ferromagnetic (F) materials have been the subject of intense study over the past two decades. The ground state of such junctions oscillates between 0 and π as the thickness of the ferromagnetic layer increases. For some applications, it might be beneficial to replace a very thin F layer with an unbalanced synthetic antiferromagnet (SAF) consisting of two F layers of different thicknesses whose magnetizations are coupled antiparallel to each other. According to theory, such a system should behave similarly to a single F layer whose thickness is equal to the difference of the two F-layer thicknesses in the SAF. We test that theoretical prediction with Josephson junctions containing unbalanced Ni/Ru/Ni SAFs, keeping the thickness of one layer fixed at 2.0 nm and varying the thickness of the other layer between 2.0 and 5.0 nm. We observe the first 0−π transition at a thickness difference of 0.86 nm, which closely matches the position of the transition observed previously using single Ni layers.

The effect of sand-crumb rubber mixture treatment on the seismic response of a low-rise building located on liquefiable soil

One of the most effective measures to reduce earthquake risks in high-seismic areas is to reduce the input forces caused by earthquakes to the structure. The properties of rubber materials in geotechnical projects are energy absorption, dynamic deformation change as well as damping of latent energy in loads, high shear modulus and damping ratio, easy access and their economic nature. In this research, with finite difference modeling, the effect of using sand- crumb rubber layer on the seismic behavior of the model has been obtained. In the following, by changing the thickness and depth of the sand-crumb rubber layer, the seismic behavior such as floor displacement and internal forces have been investigated. This research numerically models liquefaction (UBCsand with FLAC) and predicts the effects of the sand-crumb rubber layer of different thicknesses (as % weight of the mixture) under the foundation and evaluates the structure's damage and settlement interacting with the soil by validating the numerical model with the laboratory model and calibrating it with different ratios. The results show that liquefaction, pore water pressure excess ratio and soil settlement will be significantly reduced with the presence of sand-crumb rubber layer, and also the base shear has shown an increase, but the structural damage is reduced.Graphical

Optimal permeance ratio, flux direction and layer distribution in composite asymmetric membranes composed of sequences of layers obeying real-power flux laws

In this study, the optimal permeance ratio and layers distribution in multilayer membranes and thin films in which each layer obeys the following real-power law: Flux=πi(P1,ini−P2,ini) are determined for any positive real values of ni. Such an exponent has a physical meaning in several cases, such as: diffusion-controlled permeation of hydrogen in metal membranes i) under infinite-dilution conditions (n = 0.5), and ii) under higher-concentration ones (0.5 < n < 1.5), iii) desorption-limited permeation (n = 1) in the same type of membranes, Knudsen-type diffusional mechanism (n = 1) and viscous flow (n = 2) in microporous membranes. Furthermore, n is equal to 4 in radiation-driven thermal flux. The work considers two generic layers of different thicknesses and exponents, for which it is proven the existence of a general optimal permeance ratio π1/π2 maximising the flux ratio, which is found to be equal to the inverse of the ratio between the respective maximum theoretical driving forces that can be established in each layer. Such an optimal permeance ratio is also proven to be a global optimum. Afterwards, we provide a theoretical generalisation of this optimality to whatever types of driving forces. Then, we provide a demonstration that the highest species permeating flux is always established when feeding it from the layer side with the highest exponent independently of the permeance ratio. As an important consequence, to maximise flux, a multilayer membrane/thin film should be fabricated by depositing the layers in cascade according to the ascending or descending exponents, and should be used in a configuration in which the flux flows from the layer with the highest pressure exponent to the layer with the lowest one. It is also shown that there exists an optimal value of the lower exponent n1 that maximizes the flux ratio keeping constant the other parameters. Finally, we showed that a virial-type linear combination of polynomial driving forces can be approximated by the empirical flux law investigated. Overall, our results are valid not only for whatever type of composite membranes and thin films (metallic, ceramic, polymeric and hybrid ones), but also for any sequential system involving a flux of whatever physical entity obeying the aforementioned law, such as heat transfer in the presence of radiation, non-linear electrical resistances and possible others.

Influence of surface texture and coating thickness on adhesion of nickel plated coatings to aluminium substrate

Adhesion of coating to substrate has been a challenge due to the hybrid effects induced by surface roughness. In this study, the adhesion of electroplated nickel and electroless NiP layers of different thicknesses ranging from 5 to 20 μm, as metal coatings, applied to aluminium substrates of different surface conditions, has been evaluated. Different processes including grinding, polishing, sandblasting and laser surface texturing were used to produce a series of roughness/surface textures on the substrate coupons. Adhesion of the coatings was assessed by bending test qualitatively as well as semi-quantitatively. It was found that surface texture isotropy/anisotropy (value of <0.1 and >0.8) and skewness significantly affect the delamination of plated coatings. With the increase in layer thickness, it was realized that the coating cracks and delamination increased and adhesion strength decreased by 14 % on average.

Toward Tectonic-Type and Global 1D Seismic Models of the Upper Mantle Constrained by Broadband Surface Waves

ABSTRACT The unprecedentedly dense current sampling of the upper mantle with seismic data offers an opportunity for determining representative seismic velocity models for the Earth’s main tectonic environments. Here, we use over 1.17 million Rayleigh- and 300,000 Love-wave, fundamental-mode, phase-velocity curves measured with multimode waveform inversion of data available since the 1990s, and compute phase-velocity maps in a 17–310 s period range. We then compute phase-velocity curves averaged over the globe and eight tectonic environments, and invert them for 1D seismic velocity profiles of the upper mantle. The averaged curves are smooth and fit by VS models with very small misfits, under 0.1%, at most periods. For phase-velocity curves extending up to 310 s, Rayleigh waves resolve VSV structure down to the shallow lower mantle. Love-wave sampling is shallower, and VSH and, thus, radial anisotropy profiles are resolved down to 375–400 km depth. The uncertainty of the VS models is dominated by the trade-offs of VS at neighboring depths. Using the model-space-projection approach, we quantify the uncertainty of VS in layers of different thickness and at different depths, and show how it decreases with the increasing thickness of the layers. Example 1D VS models that fit the data display the expected increase of the lithospheric seismic velocity with the age of the oceanic lithosphere and with the average age of the continental tectonic type. Radial anisotropy in the global and most tectonic-type models show a flip of the sign from positive (VSH&amp;gt;VSV) to negative at 200–300 km depth. Negative anisotropy is also observed in the shallow mantle lithosphere beneath oceans down to 45–55 km depth. We also compute a global model with the minimal structural complexity, which fits the data worse than the best-fitting one but does not include a sublithospheric low-velocity zone, providing a simple reference for seismic studies.

Formation of Highly Tunable Periodic Plasmonic Structures on Gold Films Using Direct Laser Writing

AbstractDirect laser writing method is a promising technique for the large‐scale and cost‐effective fabrication of periodic nanostructure arrays exciting hybrid lattice plasmons. This type of electromagnetic mode manifests a narrow and deep resonance peak with a high dispersion whose precise controllability is crucial for practical applications in photonic devices. Here, the formation of differently shaped gold nanostructures using the direct laser writing method on Au layers of different thicknesses is presented. The resonance peak is demonstrated to be highly dependent on the shape of the structures in the array, thus its position in the spectra, as well as the quality, can be additionally modulated by changing the morphology. The shape of the structure and the resonance itself pertain not only on the laser pulse energy but also on the grating period. This overlapping effect occurring at distances smaller than the diameter of the focused laser beam is studied in detail. By taking advantage of the highly controllable plasmonic resonance, the fabricated gratings open up new opportunities for applications in sensing.

Numerical Modelling of Bearing Strength of Concrete Strengthening with Carbon Fibre Reinforced Polymers (CFRP) Wrapping for Different Thickness of CFRP Sheet

The bearing strength of concrete plays an important role in transmitting the bearing force into the structural supports, especially for buildings and infrastructure such as concrete footings, concrete bridges, column corbels and concrete connections. The structural behaviour of the concrete bearing is related to the confinement effect, in which the load is transmitted to the concrete surface through the contact interaction between the steel bearing plate. However, extreme penetration on the contact surface of the concrete blocks by the steel bearing plate leads to failure modes on the concrete block. This research study focuses on the performance of the bearing strength of the concrete when it is wrapped with carbon fiber-reinforced polymers (CFRP) as the strengthening method. This research also examines the bearing strength of concrete when it is wrapped with a single layer of different thicknesses of CFRP sheet, which range from 1mm to 4mm thick. In order to understand the concrete bearing performance, a finite element model (FEM) using ABAQUS/CAE software is developed. An optimum meshing with a size 12.5mm is used for the further nonlinear analysis of the concrete model to discuss the results, such as the model validation by comparing the bearing strength results from the FE model with the Australian Standard, the comparison of the load-displacement curve for different thicknesses of CFRP wrapping, as well as the structural response or visualization of the concrete model. From the results, it shows that the different thicknesses of the CFRP wrapping significantly have a positive impact on the bearing capacity of the concrete, where the bearing strength of the concrete increases up to 26.16% as the thickness of the CFRP wrapping increases to 4mm for the optimum meshing size of 12.5mm. The FE visualization also shows various structural responses of the concrete bearing in the context of the deformation shape, vertical displacement, vertical stress distribution and max and minimum principal stress distribution of the concrete bearing, which are further discussed in this report

Titanium adhesion layer influence on the formation of hybrid lattice plasmon structures via laser-direct writing

The field of nanotechnology is attracting increasing attention due to the successful use of nanostructures in sensor fabrication and the development of new optical devices. Various lithography techniques can be employed to produce nanostructures, but the most recent technique, laser-direct writing, provides efficient and precise control over structural parameters, which is crucial for achieving and optimizing optimal plasmonic properties. In this work, plasmonic structures were formed on a thin gold surface using adhesive titanium layers of different thicknesses, which improve the adhesion between the gold coating and the substrate. The plasmonic properties of the formed structures were assessed to determine the influence of the titanium layer on the quality of plasmonic resonance. The plasmonic structures formed with the titanium adhesion-enhancing layer exhibited high-quality values of plasmonic resonances comparable to those of the structures without the adhesion layer. This property is particularly relevant for the development of plasmonic sensors, as increased adhesion of laser-induced structures increases the durability of this type of sensors.

Seismic Failure Mechanisms of Concrete Pile Groups in Layered Soft Soil Profiles

So far, little attention has been paid to the investigation on the seismic failure mechanisms of flexible concrete pile groups embedded in the layered soft soil profiles considering the material non-linearities of soil and concrete piles. The purpose of this study is to investigate seismic failure mechanism models of flexible concrete piles with varied groups in silt layered loose sand profiles under horizontal strong ground motions. Three-dimensional finite element models of the pile–soil interaction systems, which include nonlinearities of soil and concrete piles as well as coupling interactions between the piles and soil, were created for Models I, II, and III of the soil domains, encompassing 1x1, 2x2, and 3x3 flexible pile groups with diameters of 0.80 m and 1.0 m. Model I consists of a homogenous sand layer and a bedrock, Models II and III are composed of a five-layered domain with homogeneous sand and silt soil layers of different thicknesses. The linear elastic perfectly plastic constitutive model with a Mohr–Coulomb failure criterion is considered to represent the behavior of the soil layers, and the Concrete Damage Plasticity (CDP) model is used for the nonlinear behavior of the concrete piles. The interactions between the soil and the pile surfaces are modeled by defining tangential and normal contact behaviors. The models were analyzed for the scaled acceleration records of the 1999 Düzce and Kocaeli earthquakes, considering peak ground accelerations of 0.25 g, 0.50 g, and 0.75 g. The numerical results indicated that failure mechanisms of flexible concrete groups occur near the silt layers, and the silt layers have led to a significant increase in the spread area of the damaged zone and the number of damaged elements.

Microstructure and physical properties of black-aluminum antireflective films.

The microstructure and physical properties of reflective and black aluminum were compared for layers of different thicknesses deposited by magnetron sputtering on fused silica substrates. Reflective Al layers followed the Volmer-Weber growth mechanism classically observed for polycrystalline metal films. On the contrary, the extra nitrogen gas used to deposit the black aluminum layers modified the growth mechanism and changed the film morphologies. Nitrogen cumulated in the grain boundaries, favoring the pinning effect and stopping crystallite growth. High defect concentration, especially vacancies, led to strong columnar growth. Properties reported for black aluminum tend to be promising for sensors and emissivity applications.

Fire and Explosion Hazard Aspects for Bucket Elevators

Technological installations for the vertical transport of cereal products, are affected by the presence of combustible dusts that can be mixed with air, in suspension, or in the form of dust layers of different thicknesses. The presence of these combustible dusts is a constant danger of fires or even explosions. In combustible dusts are swirled in the air in concentrations in their explosive range and there is also an ignition source, the dusts can burn quickly and even give rise to explosions, in which case the force and pressure developed is considerable. Since, in most cases, following a fire and especially a combustible dust explosion, the damage caused is quantified by immeasurable material damage and even by recording human losses, special attention must be paid to how they are identified and implemented protection and prevention measures to prevent fires and combustible dust explosions. In this paper, the principles and main factors that must be considered when quantifying the risk of fire and/or explosion for a bucket elevator used for the vertical transport of cereal products are highlighted. A number of recommendations for the safe use of these lifts are also presented.

Investigating ultra-thin Ag and Au layers using spectrophotometry and AFM imaging

A spectrophotometric method is demonstrated for refractive index and thickness determination of thin and ultrathin metallic films. The method involves a three-layer stack where the metallic layer of interest is deposited on an opaque Si wafer coated with SiO2. This stack creates oscillations in the reflectance spectrum, which are highly sensitive to the index of the metallic film, allowing precise determination of the index of layers down to 1 nm. Experimental index values are given for Ag and Au over the wavelength range of 370–835 nm. These results are correlated with Atomic force microscopy (AFM) images of the films, which reveal dramatic changes in structure for layers of different thickness.

Multilayered Inhomogeneous Beams under Torsion and Bending: An Analytical Study of Energy Dissipation

The present theoretical paper is devoted to the problem of energy dissipation in multilayered inhomogeneous beam structures of visoelastic behaviour. In particular, our attention is concentrated on studying the energy dissipation for the case of a beam that is loaded simultaneously in torsion and bending. Both torsion and bending moments which are applied on the beam change with time so that the angles of twist and rotation of the beam end vary continuously with time. The viscoelastic mechanical behaviour of the beam under torsion is treated by a viscoelastic model that has two linear springs and a linear dashpot. The model is under time-dependent shear stress. The viscoelastic behaviour of the beam under bending is modelled in a similar way. An analytical approach of deriving the energy dissipation is applied. The approach treats a multilayered beam that has an arbitrary number of layers of different thicknesses and material properties. The layers are longitudinally inhomogeneous. An investigation of the energy dissipation is carried-out to clarify the effect of the parameters of the time-dependent bending and torsion moments, the material inhomogeneity and the beam size on the energy dissipation.