Single Layer Thickness Research Articles

A New Method for Measuring Multilayer Thickness Using a Chromatic Confocal Sensor

Multilayer transparent plates play a crucial role in industrial fields, such as optical lenses, electrodes, and solar panels, because of their superior optical and electrical properties. The thickness and uniformity of such plates are decisive for the quality of the final product. However, traditional contact measurement methods are inadequate in accuracy and pose the risk of damaging the plates, making nondestructive measurement of multilayer transparent plate thickness rather challenging. A new measurement technology is urgently needed. This study proposes a new method for the thickness measurement of multilayer transparent plates based on chromatic confocal sensor technology. First, we investigated the dispersive behavior of light in various media layers and derived theoretical measurement models for single-layer and multilayer transparent plate thicknesses. Subsequently, we designed and constructed a measurement system using a C-series chromatic confocal sensor and optical instruments and prepared a five-layer transparent sample consisting of quartz and air layers to confirm the feasibility of the method. The results of the experiment show that the proposed method can accurately measure the thickness of the five-layer sample with a maximum absolute error within 13 µm and a maximum relative error of 4.27%, thus proving its validity, precision, and stability. The results further indicate the high practicality and reliability of this technology in production environments, theoretically enabling the simultaneous measurement of up to 18 layers of the plate and offering broad application prospects in the industry.

Quasi-brittle fracture criterion of CFRP with shallow surface scratch based on boundary effect model

This study investigates the quasi-brittle fracture parameters of carbon fiber composites with shallow surface scratches by considering single-layer prepreg thickness as the characteristic composite microstructure. Three-point bending fracture tests were conducted on single-edge notched specimens of various-sized carbon fiber composites. The boundary effect model was employed to establish the relationship between the microstructure and macroscopic mechanical characteristics of carbon fiber composites. The maximum fracture load was used to determine the quasi-brittle fracture characteristics. By employing normal distribution analysis, the tensile strength and fracture toughness of each specimens were determined asft = 453.28 MPa andKIC = 22.2 MPa √ m, respectively. The analysis results exhibited an error of only 0.39 % compared to the least-squares fit, and encompassed almost all discrete points of the specimens within a 95 % reliability range. Using standard laboratory dimensions, fracture intervals for different notched depths at the same thickness can be predicted. Furthermore, the fracture parameters demonstrated an increasing trend within a certain range as the crack-thickness ratio increases, which aligns with the theoretical findings.

Optical properties of transparent TiO2 films by sintering anatase nanoparticles with a CO2 laser

A novel CO2 laser additive manufacturing technique is reported in this paper for depositing transparent TiO2 films on quartz substrates using anatase TiO2 nanoparticles (NPs). Single- and double-layers of TiO2 films were prepared in two stages: (i) wet deposition using the spin-coating technique, and (ii) laser-assisted both drying of the wet layer and then sintering of the dried NPs to form a film. A theoretical model is presented to select and optimize the laser processing parameters. Scanning electron microscopy (SEM) revealed that the laser heating induces necking and coalescence of TiO2 NPs without cracking the sintered films or damaging the quartz substrate. An anti-reflection coating (ARC) model is utilized to select the film material and film thickness, aiming to reduce the reflectance and enhance the transmittance at certain wavelengths. UV/Vis spectrophotometry showed transmittance above ∼90% in the visible (Vis) range. The effect of laser power on the enhancement of transmittance is presented in this paper. Different concentrations of TiO2 NPs were used to optimize the film thickness. Single layer (∼110nm thick) and double layer films of the same total thickness as the single layer were analyzed to infer the effects of interface on the transmittance of TiO2 films. The transmittance of the single layer is higher, same as that of the double layer. Therefore, the difference in the transmittance of the single- and double-layer may be due to the effect of interface. The optical properties of the anti-reflection TiO2 coating in the UV–Vis ranges were investigated. X-ray diffraction (XRD) analysis showed that the thickness affects the crystallinity of the sintered TiO2 films.

Effects of highly-textured and untextured polycrystalline layers on deformation mechanisms in amorphous submicron-layered materials

Amorphous alloys have high strength, but softening can lead to room temperature brittleness, limiting their applications. Typically, soft means low hardness and yield strength, and the lower the yield stress, the higher the fracture toughness. Two amorphous/crystalline multilayer samples with submicron single layer thickness were prepared. The crystalline layer of one sample is composed of highly-textured (111) nanocrystalline grains, and the other sample is untextured. Indentation experiments proved that the samples were plastically deformed, while the amorphous layer did not form shear bands with decreased layer thickness. The thickness reduction of the amorphous layer in the sample with highly-textured crystalline layers is greater than in the sample with untextured crystalline layers. The strain-hardening ability of the textured crystalline layer is higher, while the corresponding amorphous layer is deformed more severely with free volume annihilation and greater flow with more compact atoms. The amorphous layer corresponding to the untextured crystalline layer absorbs dislocations, and activates shear transformation zones (STZs), increasing the free volume near the interface. The annihilation of the free volume is less than the sample with highly-textured crystalline layers.

Geopolymer-based radiative cooling coating: Tailoring surface hydrophobic properties while retaining optical characteristics

The longevity of geopolymer-based radiative cooling coatings is questionable due to their hydrophilic nature. This study used four hydrophobic agents - sodium methyl silicate (SMS), polydimethylsiloxane (PDMS), polytetrafluoroethylene (PTFE), and triethoxyoctylsilane (TEOS) - to modify the surface hydrophobicity of geopolymer while maintaining its optical properties. The optimal agent contents were determined by optical performance and water contact angle: 5 % for SMS, 10 % for 50 cP viscosity PDMS, and a single-layer thickness for PTFE and TEOS (60 °C). The agents' working mechanisms were analyzed using FTIR and XRD characterization: SMS forms a hydrophobic alkylsilanol layer by reacting with the geopolymer's silanol group; PDMS lowers the geopolymer's surface energy with its hydrophobic methyl groups; PTFE's low electric polarizability is due to its fluorine content; and TEOS replaces the geopolymer surface's hydroxyl groups with hydrophobic octyl groups. The long-term durability of these modified coatings was evaluated through outdoor exposure tests, resulting in total solar reflectance losses of 0.74 %, 1.9 %, 3.9 %, and 0.05 % respectively. A slight reduction in the water contact angle confirmed their enduring hydrophobic characteristics. These modification methods open up possibilities for the practical use of hydrophobic geopolymer radiative cooling coatings.

Discovery and petroleum geological significance of delta in the third member of Oligocene Lingshui Formation in southern Baodao Sag, Qiongdongnan Basin, South China Sea

Based on the 3D seismic data and the analysis and test data of lithology, electricity, thin sections and chronology obtained from drilling of the Qiongdongnan Basin, the characteristics and the quantitative analysis of the source-sink system are studied of the third member of the Upper Oligocene Lingshui Formation (Ling 3 Member) in the southern fault step zone of the Baodao Sag. First, the YL10 denudation area of the Ling 3 Member mainly developed two fluvial systems in the east and west, resulting in the formation of two dominant sand transport channels and two delta lobes in southern Baodao Sag, which are generally large in the west and small in the east. The evolution of the delta has experienced four stages: initiation, prosperity, intermittence and rejuvenation. Second, the source-sink coupled quantitative calculation is performed depending on the parameters of the delta sand bodies, including development phases, distribution area, flattening thickness, area of different parent rocks, and sand-forming coefficient, showing that the study area has the material basis for the formation of large-scale reservoir. Third, the drilling reveals that the delta of the Ling 3 Member is dominated by fine sandstone, with total sandstone thickness of 109–138 m, maximum single-layer sandstone thickness of 15.5–30.0 m, and sand-to-strata ratio of 43.7%–73.0%, but the physical properties are different among the fault steps. Fourth, the large delta development model of the small source area in the step fault zone with multi-stage uplift is established. It suggests that the episodic uplift provides sufficient sediments, the fluvial system and watershed area control the scale of the sand body, the multi-step active fault steps dominate the sand body transport channel, and local fault troughs decide the lateral propulsion direction of the sand body. The delta of the Ling 3 Member is coupled with fault blocks to form diverse traps, which are critical exploration targets in southern Baodao Sag.

Influence of 2D CuxAl(100−x) electrodes on the CuxAl(100−x)/Cu21(SiO2)79/W memristive device

In recent years, 2D metal nanomaterials have emerged as a novel class of 2D materials owing to their unique physiochemical properties. In this paper, memristive devices ([Formula: see text](BE)/[Formula: see text]/W(TE)) were fabricated utilizing 2D [Formula: see text] materials with different compositions as electrodes. After exfoliation by sonication, the minimum thickness of the freestanding single layer of 2D [Formula: see text] was only 1.5 nm. Furthermore, the distribution of SET thresholds was determined by the composition of the 2D [Formula: see text] materials. The results suggest that the SET and RESET thresholds can be adjusted according to the composition of the 2D [Formula: see text] materials. The application of 2D metals as electrodes is promising for miniature memristive devices.

Optimization design of surface optical characteristics of space solar cells based on transfer matrix method

The antireflection coating (ARC) can improve the photoelectric conversion efficiency of photovoltaic (PV) cells. In this paper, the influence of film thickness and refractive index of single-layer and double-layer ARC on solar light absorption under different spectral conditions is simulated by the transfer matrix method. The optimum values of ARC film thickness and refractive index are obtained. To optimize it at AM 0 (air mass 0) solar irradiance, a 66 nm thick SiN x ARC with a refractive index of 2.0 was used. The PV cell’s maximum power density is 89.87. The maximum power density of the PV cell with double-layer SiN x as ARC is 90.94. This work provides a theoretical basis for the application of ARC in ground PV power generation systems and space solar power systems.

A-Si/SiO2 nanolaminates for tuning the complex refractive index and band gap in optical interference coatings.

A-S i/S i O 2 nanolaminates are deposited by magnetron sputtering and show a decreasing absorption when the a-Si single-layer thickness is reduced from 2.4n m to 0.7n m. Moreover, an increase of the Tauc band gap by 0.18e V is measured. Experimental Tauc band gaps are compared to calculated effective band gaps, utilizing a numerical Schrödinger solver. Further, it is demonstrated that the refractive index can be controlled by adjusting the a-Si and S i O 2 single-layer thicknesses in the nanolaminates. The nanolaminates are optically characterized by spectroscopic ellipsometry, transmittance, and reflectance measurements. Additionally, TEM images reveal uniform, well-separated layers, and EDX measurements show the silicon and oxygen distribution in the nanolaminates.

Blast effect on layered polyurethane foam

The shock wave interaction with solids has been a classical problem of interest for a long time in various domains due to its diverse applications. One such application is energy dissipation using polymeric foam. Since the mechanical compression of polymeric foam exhibits an extended plateau region, it is a primary choice of interest in any form of energy dissipation, particularly blast wave energy. Density-based layered foam has a higher chance of more blast energy absorption compared to a single layer of the same density. Hence, in this study, the response of the blast-induced compression of three different polyurethane (PU) foam densities such as 29.201 kg/m3, 59.692 kg/m3, and 107.720 kg/m3, say D1, D2, and D3, respectively, are carried as single layer and bilayer of the same thickness using a Blast Wave Simulator (BWS). Here, we experimentally record the incident and reflected blast pressure near the blast-hitting face and the reaction force at the rear face of the foam. The full-field displacement of PU foam because of the blast wave is measured using a 2D DIC method. In the bilayer PU foam B2 (D2/D1←, the arrow represents the blast direction), the peak displacement of 10.478 mm, the reaction force, FT of 3.75 kN, reflection coefficient, Cr of 1.99, and energy absorption Eabs of 18.68 J was observed. The increase in energy absorption of the bilayer B3 (D2/D1←) compared to a single layer D1 is 83.03 %, and for the bilayer B1 (D1/D2←) it is 18.90 %. This observation helps to utilize the foam for the blast and shock-prone zone more effectively. The force exerted on the reaction wall of the PU foam helps in deciding the type of material to be used as the blast barrier wall. Also, this study proposes an outline to examine the material’s response in a uni-directional compression because of blast wave impact.

Characteristic Plasmon Energies for 2D In2Se3 Phase Identification at Nanoscale.

Two-dimensional (2D) materials with competing polymorphs offer remarkable potential to switch the associated 2D functionalities for novel device applications. Probing their phase transition and competition mechanisms requires nanoscale characterization techniques that can sensitively detect the nucleation of secondary phases down to single-layer thickness. Here we demonstrate nanoscale phase identification on 2D In2Se3 polymorphs, utilizing their distinct plasmon energies that can be distinguished by electron energy-loss spectroscopy (EELS). The characteristic plasmon energies of In2Se3 polymorphs have been validated by first-principles calculations, and also been successfully applied to reveal phase transitions using in situ EELS. Correlating with in situ X-ray diffraction, we further derive a subtle difference in the valence electron density of In2Se3 polymorphs, consistent with their disparate electronic properties. The nanometer resolution and independence of orientation make plasmon-energy mapping a versatile technique for nanoscale phase identification on 2D materials.

The application of graphene material in the negative electrode of lithium battery

With the development of science and technology, the massive consumption of traditional fossil fuels not only brings serious environmental pollution but also causes an energy crisis. As an indispensable new energy in today’s world, Lithium batteries have many advantages that other types of batteries do not have, such as high energy density, long life, low self-discharge rate advantages, green and environmental protection, etc., and widely used in various fields, such as automotive, medical, aerospace and so on. However, the drawbacks such as low specific capacity and high side reaction of graphite material in traditional lithium batteries limit the application of lithium batteries. Graphene, as a two-dimensional material composed of carbon atoms in a single layer thickness, possesses the advantages of huge surface area, high strength and hardness, good electrical and thermal conductivity, flexibility, and transparency, and has great potential for application in lithium batteries. In this paper, for graphene as the anode material of lithium batteries, its effects on the performance of lithium batteries, including cycling performance, charge/discharge rate, and energy density, are discussed respectively. In addition, this paper also summarizes the latest progress on the application of graphene anode materials in lithium batteries.

Low-temperature grown MnAs/InAs/MnAs double heterostructure on GaAs (111)B by molecular beam epitaxy

We used MBE to grow a double heterostructure of MnAs/InAs/MnAs on GaAs(111)B at low temperature for vertical spin FET applications. To confirm the ideal development environment, we primarily prepared single InAs thick layer (∼1.2 μm) at low growth temperature (∼250 °C) with varied V/III ratio (As/In = 2, 10, 20) due to the challenge of growing InAs at much lower temperature than its usual growth temperature (∼480 °C). We measured their structural and electrical properties and found an optimum condition at V/III ratio of 10. Afterwards, we prepared the double heterostructure at low temperature (∼250 °C), again varying the As/In beam equivalent pressure ratio to find its influence on the overall quality of the structure. Using atomic force microscopy, we observed the surface roughness variation corresponding to V/III ratio variation of InAs. We confirmed the growth of three individual thick layers of MnAs and InAs by cross-sectional analysis using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Using a superconducting quantum interference device magnetometer, we found in-plane easy magnetization and observed the effect of top and bottom MnAs layers on the hysteresis curve. We also found the existence of ferromagnetic behavior of MnAs layers at RT MH measurements. The MnAs/InAs/MnAs double heterostructure on GaAs(111)B, in our opinion, has potential as a structure for spin FETs.

High thermostability in CoFeB/MgO/Ta multilayers by {Pt(t)/Ta(t)}n superlattice buffer layers

Ta/CoFeB/MgO/Ta multilayer known as the fundamental building block for magnetic tunneling junctions, has been studied for decades. However, its thermostability is normally less than 300 °C, which cannot meet the requirements for subsequent semiconductor processes. In this study, buffer layers of {Pt(t)/Ta(t)}n superlattices were introduced into CoFeB/MgO/Ta multilayers grown by magnetron sputtering. The growth period n and the single layer thickness t in the superlattice have been systematically explored. And it is found that the sample can maintain distinct perpendicular magnetic anisotropy (PMA) even after a 440 °C post-annealing treatment at n = 3 and t = 1.5 nm. This has been attributed to that the superlattice buffer layer might serve as a diffusion barrier, reducing Ta atoms from diffusing into the CoFeB/MgO interface. Less Ta at the interface results more FeOx formed and enhances the hybridization of Fe 2p and O 3d orbitals which increases the thermostability of PMA. This suggests that superlattice buffer layer provides a new approach to improve the materials’ thermostability.

Enhanced adsorption of phenol using graphene oxide-bentonite nanocomposites: Synthesis, characterisation, and optimisation

Wastewater treatment is crucial because it causes harm to the environment of human beings. Adsorbents are faulted by low adsorption capacity and difficult recovery due to organic pollutants. This study aims to improve adsorption capacities using bentonite and other environmentally friendly and economically feasible adsorbents. To do this, using Hammer's approach, bentonite was subjected to an acidic treatment (1.5 M H2SO4) and then hybridized with synthetic graphene oxide (GO). Integrating GO nanosheets within the interlayer of acid-activated bentonite and depositing them onto the exterior surface using a simple ultrasonic-assisted method successfully created a graphene oxide-bentonite nanocomposite. GO, and its composites (at 5 and 10 wt%) were characterized using ATR-FTIR, BET, XRD, FE-SEM, and AFM studies. The results demonstrated that GO with a single-layer thickness of 0.618 nm could be successfully fabricated. We employed energy-dispersive X-ray spectroscopy (EDX) to detect changes in chemical composition before and after phenol adsorption. It was thoroughly studied how essential factors, including adsorbent dosage, pH, agitation period, and beginning phenol concentration, affected adsorption behavior. An obvious increases of the adsorption capacities from 30.69 to 46.43 mg/g were achieved under ideal circumstances of pH 6, an 8-hour contact duration, and doses of 0.3 g and 0.2 g for GO-MB5 and GO-MB10 composites, respectively. The pseudo-second-order kinetic and Langmuir equilibrium isotherm models efficiently described the adsorption process. More notably, the synthesized adsorbents could be successfully regenerated and used without major capacity losses after six cycles. This study highlights the effectiveness of GO-bentonite nanocomposites as effective adsorbents for environmental treatment.

Principle & application of energy storage based on 2D material: Evidence from graphene

The development of new energy and related industries has raised higher requirements for energy storage devices. Graphene, a 2-D carbon material with a single atomic layer thickness, possesses excellent mechanical properties, thermal conductivity, SSA, optical transparency, and rapid electron migration, among other unique physical and chemical properties. The addition of graphene is predicted to enhance the rate performance, durability and energy density of electrochemical energy storage devices. This study summarizes the recent research in the production and application of graphene in electrochemical energy storage devices, primarily focusing on supercapacitors and the positive and negative electrode of lithium-ion batteries. The main roles of graphene include serving as an ultrathin support and buffering material, an active substance, and a conductive material. In addition, the limitations of graphene due to its production technologies and the potential brought by its super flexibility and lightweight properties are discussed. Finally, a brief outlook in the field of graphene is provided.

Influences of shale microstructure on mechanical properties and bedding fractures distribution

The difference in microstructure leads to the diversity of shale mechanical properties and bedding fractures distribution patterns. In this paper, the microstructure and mechanical properties of Longmaxi marine shale and Qingshankou continental shale were studied by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM) with mineral analysis system, and nanoindentation. Additionally, the typical bedding layers area was properly stratified using Focused Ion Beam (FIB), and the effects of microstructure and mechanical properties on the distribution patterns of bedding fractures were analyzed. The results show that the Longmaxi marine shale sample contains more clay mineral grains, while the Qingshankou continental shale sample contains more hard brittle mineral grains such as feldspar. For Longmaxi marine shale sample, hard brittle minerals with grain sizes larger than 20 μm is 18.24% and those with grain sizes smaller than 20 μm is 16.22%. For Qingshankou continental shale sample, hard brittle minerals with grain sizes larger than 20 μm is 40.7% and those with grain sizes smaller than 20 μm is 11.82%. In comparison to the Qingshankou continental shale sample, the Longmaxi marine shale sample has a lower modulus, hardness, and heterogeneity. Laminated shales are formed by alternating coarse-grained and fine-grained layers during deposition. The average single-layer thickness of Longmaxi marine shale sample is greater than Qingshankou continental shale sample. The two types of shale have similar bedding fractures distribution patterns and fractures tend to occur in the transition zone from coarse-grained to fine-grained deposition. The orientation of the fracture is usually parallel to the bedding plane and detour occurs in the presence of hard brittle grains. The fracture distribution density of the Longmaxi marine shale sample is lower than that of the Qingshankou continental shale sample due to the strong heterogeneity of the Qingshankou continental shale. The current research provides guidelines for the effective development of shale reservoirs in various sedimentary environments.

Facile Fabrication and Characterization of Oriented and Multilayer Thin Films of Solution Processable Conjugated Polymer

Fabrication of multilayer thin films of solution‐processable organic semiconductors has great potential in organic electronics, but adopting existing thin‐film techniques to attain this is highly cumbersome. Herein, a unique unidirectional floating film transfer method has been utilized, which allows the facile fabrication of large area and oriented thin films of conjugated polymers. This method has successfully fabricated and characterized multilayer and oriented thin films of regioregular poly(3‐hexylthiophene) without having any adverse effect on the underlying layers. Optical characterizations reveal that fabricated thin films are anisotropic with a dichroic ratio of 2.2 having a single layer thickness of 14.5 nm. X‐ray diffraction results demonstrate uniformity in the crystallinity of the multilayered thin film with comparable crystallite size and interplanar spacing with purely edge‐on molecular orientation. The organic field effect transistor fabricates using multilayer thin films and also exhibits a uniform and saturated charge carrier mobility of about 0.1 cm2 V−1 s−1.

Peculiar Structural Phase of a Single-Atom-Thick Layer of Antimony.

Using molecular beam epitaxy, a new structural phase of a single atom thick antimony layer has been synthesized on the W(110) surface. Scanning tunneling microscopy measurements reveal an atomically resolved structure with a perfectly flat surface and unusually large unit cell. The structure forms a well-ordered continuous film with a lateral size in the range of several millimeters, as revealed by low energy electron microscopy and diffraction experiments. The results of density functional theory calculations confirm the formation of a new phase of single-atom-thick antimony film without the buckling characteristic for the known phases of antimonene. The presented results demonstrate a substrate-tuned approach in the preparation of new structural phases of 2D materials.

Thickness, Adhesion and Microscopic Analysis of the Surface Structure of Single-Layer and Multi-Layer Metakaolin-Based Geopolymer Coatings

This work is focused on creating coating layers made of a metakaolin-based geopolymer suspensions (GP)-formed Al matrix modified using H3PO4 acid with Al(OH)3 in isopropyl alcohol, named GP suspension I, and H3PO4 acid with nano Al2O3 in isopropyl alcohol, named GP suspension J. The selected GP suspensions were applied on aluminum and steel underlying substrates as single-layer coatings and multi-layer coatings, where multi-layer coatings included three and five layers that were polymerized by a curing process. Curing was divided into two types with every layer curing process and final layer curing process. For both GP suspensions I and J, the effect of the number of layers and the type of substrate on adhesion was investigated. The prepared samples on underlying substrates were characterized on the microscopy analysis including SEM for high-resolution images and 3D laser confocal microscopy (CLSM) for the 3D visualization of the coatings structure. Microscopy analysis showed structural defects such as porosity, cracks and peeling, which increase with a greater number of applied layers. However, these defects were only evident on a micro scale and did not seem to be fatal for the performance of the surface stability. The EDS mapping of the prepared layer showed inhomogeneity in the distribution of elements caused by the brush application. A grid test and thickness measurement were performed to complete the microscopy analysis. The grid test confirmed a very high adhesion of GP coatings on the aluminum substrate with a rating of one (only in one case was there a rating of two) and a lower adhesion on the steel substrate with the most frequent rating of three (in one case, there were ratings of two and one). The thickness measurement proved a noticeably thicker thickness of the prepared layer on the Fe substrate compared to the Al substrate by 20%–30% in the case of suspension I and by 70%–10% in the case of suspension J. The thickness of the layer also showed a dependence on the method of application and curing, as a thicker layer was always achieved when curing after the final layer of the GP suspension, compared to curing after each applied layer. The resulting single-layer and multi-layer thicknesses ranged from approx. 7 to 30 µm for suspension I and from approx. 3 to 11 µm for suspension J. A non-linear increase in thickness was also evident from the thickness measurement data.