Layers Of Different Thicknesses Research Articles

Influence of combined electromechanical processing modes of 40Kh steel on its structure and hardness

The paper considers the effect of combined electromechanical processing in three different modes on the structure and hardness of the surface layers of 40Kh steel, which was in a normalized state (the original structure). The modes differ from each other by the different applied load and the number of pulses. The applied load in modes 1 and 2 (current strength 39 kA, pulse time 0.02 s, number of pulses 1) is 100 and 250 MPa, respectively. A distinctive feature of mode 3 compared to mode 2 is a greater number of pulses (two). Metallographically it was established that in all three cases a hardened surface layer of different thickness (from 300 to 1200 μm) with a hardness of 593 – 598 HV is formed, consisting of two zones (a surface zone with a structure of fine-needle martensite; a transition zone smoothly transitioning into the initial ferrite structure). The transition zone (treatment according to mode 1) in its structure contains martensite and ferrite. The transition zone (mode 2 processing) consists of a Widemannstett structure. A more substantial surface heating zone according to this mode (700 μm) in comparison with the processing according to mode 1 (300 μm) in combination with intensive heat removal contributed to the formation of a Widmanstett structure, which is defective and unacceptable for operation. The transition zone with the processing according to mode 3 has the structure of martensite and ferrite. The formation of a defective Widmanstett structure in the transition zone does not occur, since 2 times more pulses are used during processing than in mode 2. This contributes to the heating of the surface layer to a greater depth (1200 μm), and, consequently, the structure formation in the transition zone occurs from the intercritical interval Ag3 – Ag1 .

Effect of Carbon Layer Thickness on the Electrocatalytic Oxidation of Glucose in a Ni/BDD Composite Electrode.

High-performance non-enzymatic glucose sensor composite electrodes were prepared by loading Ni onto a boron-doped diamond (BDD) film surface through a thermal catalytic etching method. A carbon precipitate with a desired thickness could be formed on the Ni/BDD composite electrode surface by tuning the processing conditions. A systematic study regarding the influence of the precipitated carbon layer thickness on the electrocatalytic oxidation of glucose was conducted. While an oxygen plasma was used to etch the precipitated carbon, Ni/BDD-based composite electrodes with the precipitated carbon layers of different thicknesses could be obtained by controlling the oxygen plasma power. These Ni/BDD electrodes were characterized by SEM microscopies, Raman and XPS spectroscopies, and electrochemical tests. The results showed that the carbon layer thickness exerted a significant impact on the resulting electrocatalytic performance. The electrode etched under 200 W power exhibited the best performance, followed by the untreated electrode and the electrode etched under 400 W power with the worst performance. Specifically, the electrode etched under 200 W was demonstrated to possess the highest sensitivity of 1443.75 μA cm-2 mM-1 and the lowest detection limit of 0.5 μM.

Magnetoelectric response in laminated BaFe12O19/Pb(Zr,Ti)O3 composites

The magnetoelectric (ME) response of laminated composites consisting of BaFe12O19 and Pb(Zr,Ti)O3 ceramics is systematically investigated. A butterfly-shaped curve of a magnetoelectric coefficient emerges in both three-layer and multilayer composites. We show that the appearance of a 7 ppm residual strain in the BaFe12O19 layer after magnetization is the main reason for this special curve. We also observe the self-biasing effect of the composites and a maximum ME response from 0.6 to 5 mV/(Oe cm) in laminated composites with magnetic and ferroelectric layers of different thicknesses that can be measured at a zero-bias magnetic field. The repeatable and stable maximum and minimum values of the magnetoelectric coefficient can be obtained under periodically applied biasing magnetic fields, which is important for a practical device application. An electric-field control of ferromagnetism, evidenced by a 17%–19% enhancement in the magnetization of the BaFe12O19 layer after Pb(Zr,Ti)O3 is polarized, is observed in the composites, implying potential applications in memory devices for the composites. Our work indicates that both magnetic field-controlled polarization and electric-field-controlled magnetization exist in BaFe12O19/Pb(Zr,Ti)O3 laminated composites.

Интерпретация археологических памятников на основе сегментации данных многозональной аэрофотосъемки

Comprehensive study of a large territory is necessary for a reliable assessment of the boundaries of archaeological sites, the territory of which has been used as agricultural land for a long time. Multispectral remote sensing data are an effective tool for identifying areas of the cultural layer of different thickness and structure. The considered algorithm of multispectral data processing includes three main stages

Investigation of DC and RF characteristics of spacer layer thickness engineered recessed gate and field‐plated III‐nitride nano‐HEMT on β‐Ga2O3 substrate

AbstractIn this work, a field plated recessed gate III‐nitride HEMT on β‐Ga2O3 substrate is proposed using AlN spacer between AlGaN and GaN layers. The two‐dimensional electron gas (2DEG) transport characteristics, input/output, and RF characteristics of the proposed HEMT with AlN spacer layer of different thickness (1, 2, 3, 4, and 5 nm) are numerically simulated and compared with HEMT without spacer layer. The 2DEG, which is created at the junction of AlGaN/GaN, plays a crucial role in the operation of GaN HEMTs. With the help of AlN as spacer layer between AlGaN and GaN, an augmented 2DEG concentration is accomplished owing to its large conduction band offset, high polarization effect, and higher barrier. Additionally, the inclusion of AlN spacer layer shifts the 2DEG density away from interface, resulting minimized interface scattering which results into greater mobility. The HEMT exhibited a mobility of 1261 cm2/Vs, threshold voltage of −0.45 V, drain current of 1.12 A/mm, breakdown voltage of 149 V, and excellent RF characteristics, that is, cut‐off frequency (maximum oscillation frequency) of 384 GHz (546 GHz) using 2‐nm AlN spacer layer. The proposed III‐nitride HEMT on β‐Ga2O3 substrate with 2‐nm AlN spacer can be used for RF/microwave and high‐power nanoelectronics applications.

Tree seedling growth allocation of Castanopsis kawakamii is determined by seed-relative positions.

Plants allocate growth to different organs as a strategy to obtain limiting resources in different environments. Tree seeds that fall from a mother tree settle on, within, or below the forest floor and litter layer, and their relative positions can determine seedling biomass and nutrient allocation and ultimately affect survival to the sapling stage. However, how emerged seedling biomass and nutrients of each organ are affected by seeds in different positions is not yet completely understood in subtropical forests. Therefore, an experiment was conducted with seeds positioned above the litter layers of different thicknesses, on the forest floor, and beneath the litter layer, and the influences of seed position on biomass allocation and nutrient use efficiency of emerged seedlings of Castanopsis kawakamii was examined. The aim of the study was to determine the optimal seed position to promote regeneration. Allocation strategies were well coordinated in the emerged seedlings from different seed positions. Seedlings from seeds positioned above litter layers of different thicknesses (~40 and 80 g of litter) allocated growth to leaf tissue at the expense of root tissue (lower root mass fraction) and increased nitrogen (N) and phosphorus (P) accumulation and nutrient use efficiency. Seedlings from seeds positioned beneath a deep litter layer allocated most growth to roots (high root: shoot ratio, root mass fraction) to capture available resources at the expense of leaf growth. Seedlings from seeds positioned on the forest floor allocated most growth to roots to obtain limiting resources. Further, we also found that these traits were clustered into three groups based on trait similarity, and the cumulative interpretation rate was 74.2%. Thus, seed relative positions significantly affected seedling growth by altering the allocation of resources to different organs. The different strategies indicated that root N:P ratios (entropy weight vector was 0.078) and P nutrient use efficiency were essential factors affecting seedling growth in the subtropical forest. Of the seed positions analyzed, beneath a moderate litter layer (~40 g of litter) was the most suitable position for the growth and survival of Castanopsis seedlings. In future studies, field and lab experiments will be combined to reveal the mechanisms underlying forest regeneration.

Effect of thickness and uniformity of LiNbO3-coated layer on LiNi0.5Co0.2Mn0.3O2 cathode material on enhancement of cycle performance of full-cell sulfide-based all-solid-state batteries

Although LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode active material (CAM) is considered to have application potential in sulfide-based all-solid-state batteries (ASSBs), CAM/solid electrolyte interfacial instability remains a significant limiting factor. To effectively improve the interfacial stability and long-term cycling performance, NCM523 cathode material was coated with LiNbO3 layers of different thicknesses and uniformity. As a result, the cycle performance was greatly enhanced by increasing the thickness and uniformity of the LiNbO3-coated layer. Our findings further demonstrate that a thick (≥9 nm) and uniform coated layer (surface without uncoated area) displays outstanding electrochemical performance, especially cycle stability (capacity retention of 85.1% after 300 cycles at 60 °C), indicating that this strategy is very effective for constructing high-performance NCM cathodes for sulfide-based ASSBs. Moreover, the performance improvement mechanism was investigated by electrochemical impedance spectroscopy (EIS) combined with XPS and TEM-EDX analysis. The findings reveal that controlling the thickness and uniformity of the coating material plays a crucial role in the effective suppression of interface side reactions and resultant performance degradation in NCM cathodes.

On-chip digital holographic interferometry for measuring wavefront deformation in transparent samples.

This paper describes on-chip digital holographic interferometry for measuring the wavefront deformation of transparent samples. The interferometer is based on a Mach-Zehnder arrangement with a waveguide in the reference arm, which allows for a compact on-chip arrangement. The method thus exploits the sensitivity of digital holographic interferometry and the advantages of the on-chip approach, which provides high spatial resolution over a large area, simplicity, and compactness of the system. The method's performance is demonstrated by measuring a model glass sample fabricated by depositing SiO2 layers of different thicknesses on a planar glass substrate and visualizing the domain structure in periodically poled lithium niobate. Finally, the results of the measurement made with the on-chip digital holographic interferometer were compared with those made with a conventional Mach-Zehnder type digital holographic interferometer with lens and with a commercial white light interferometer. The comparison of the obtained results indicates that the on-chip digital holographic interferometer provides accuracy comparable to conventional methods while offering the benefits of a large field of view and simplicity.

Impact of autoclavation on baked-on siliconized containers for biologics

Many pharmaceutical manufacturing units utilize pre-sterilized ready-to fill primary containers for parenterals. The containers may have been sterilized by the supplier via autoclavation. This process can change the physicochemical properties of the material and the subsequent product stability. We studied the impact of autoclavation on baked on siliconized glass containers for biopharmaceuticals. We characterized the container layers of different thickness before and after autoclavation for 15 min at 121 °C and 130 °C. Furthermore, we analyzed the adsorption of a mAb to the silicone layer and subjected filled containers to 12 weeks storage at 40 °C monitoring functionality and subvisible particle formation of the product. Autoclavation turned the initially homogenous silicone coating into an incoherent surface with uneven microstructure, changed surface roughness and energy, and increased protein adsorption. The effect was more pronounced at higher sterilization temperatures. We did not observe an effect of autoclavation on stability. Our results did not indicate any concerns for autoclavation at 121 °C for safety and stability of drug/device combination products using baked-on siliconized glass containers.

High versus low energy ion irradiation impact on functional properties of PLD-grown alumina coatings

It is well known that ion irradiation can be successfully used to reproduce microstructural features triggered by neutron irradiation. Even though the irradiation process brings many benefits, it is also associated with several drawbacks. For example, the penetration depth of the ion in the material is very limited. This is particularly important for energies below MeV, ultimately reducing the number of available irradiation facilities. In addition to that, extracting information exclusively from the modified volume may be challenging. Therefore, extreme caution must be taken when interpreting obtained data. Our work aims to compare the findings of nanomechanical studies already conducted separately on thin amorphous ceramic coatings irradiated with ions of different energies, hence layers of different thicknesses. In this work, we show that in some instances, the 10% rule may be obeyed. In order to prove our finding, we compared results obtained for ion irradiated (with two energies: 0.25 and 1.2 MeV up to 25dpa) alumina coating system. Mechanical properties of pristine and ion-irradiated specimens were studied by nanoindentation technique. Interestingly, the qualitative relationship between nanohardness and irradiation damage level is very similar, regardless of the energy used. The presented work proves that for some materials (e.g., hard coatings), the qualitative assessment of the mechanical changes using nanoindentation might be feasible even for shallow implantation depths.

THEORETICAL ASPECTS OF AVOIDING DELAMINATION OF COMPOSITE MATERIALS DURING STRENGTHENING OF REINFORCED CONCRETE STRUCTURES

The scientific work is devoted to the improvement of the calculation methodology of reinforced concrete elements, using verification of the FRP delamination prevention, during structures strengthening with a system of composite materials (SCM) from various fibers types. During strengthening of reinforced concrete elements with composite material systems, the role of adhesion between concrete and FRP is of great importance due to the fragility of the failure mechanism due to delamination (loss of adhesion). The adhesion strength is generally much higher than the tensile strength of the concrete, so delamination always starts in concrete itself with the separation of FRP layer of different thickness. According to the load-bearing capacity requirements, such a failure mechanism should not precede the failure of the strengthened element during bending or shear. To solve the problem of possible strengthening delamination of composite materials systems, it is necessary to consider different failure modes of FRP. Due to imperfection of domestic building codes, a detailed analysis of the solution to the problem of FRP delamination was carried out in accordance with the recommendations of a number of foreign regulatory documents (ACI, CNR, FIB). The main failure modes, with subsequent initiation of delamination of FRP material from concrete base, are systematized, namely: FRP delamination due to surface irregularities, separation of FRP due to shear cracks, longitudinal shear stresses in the yield zone, excessive deformations in FRP material (FRP rupture), longitudinal shear stresses near the FRP edges, failure in anchoring (fixing) zone of FRP material. Six criterions are proposed that need to be verified during design of structures strengthening systems with FRP materials. During formulation of specified criterions, the main theoretical aspects necessary for application in structural calculations of the studied connection are given. The results of research can be used in future during the design of structures joints strengthening with systems of composite materials based on carbon fibers, glass, aramid. Keywords: system of composite materials, external reinforcement, FRP strengthening, reinforced concrete, failure mode, calculation, delamination.

Application of nano-patterned InGaN fabricated by self-assembled Ni nano-masks in green InGaN/GaN multiple quantum wells

The nano-patterned InGaN film was used in green InGaN/GaN multiple quantum wells (MQWs) structure, to relieve the unpleasantly existing mismatch between high indium content InGaN and GaN, as well as to enhance the light output. The different self-assembled nano-masks were formed on InGaN by annealing thin Ni layers of different thicknesses. Whereafter, the InGaN films were etched into nano-patterned films. Compared with the green MQWs structure grown on untreated InGaN film, which on nano-patterned InGaN had better luminous performance. Among them the MQWs performed best when 3 nm thick Ni film was used as mask, because that optimally balanced the effects of nano-patterned InGaN on the crystal quality and the light output.

Researching Characteristics of the Interaction between Sound Waves and Water Layers with Different Thickness

Effects of water layers of different thickness and different frequencies of sound for sound transmission intensity have been analyzed by calculations of sound waves propagating in air and water layer. The results have showed that, when water layer thickness is less than 5mm, the changes of thickness have a powerful effect on sound waves, while it is more than 5mm, there is nearly no effect with different thickness, however, frequency of sound waves play a decisive role, especially when the sound wave frequency is less than 100Hz.

Fabrication of Cu oxide/TiO2 p–n nanojunctions by stress-induced migration

Many Cu oxide/TiO2 p–n nanojunctions were fabricated by introducing the concept of using n-type TiO2 layers to the fabrication method of p-type Cu oxide nanowires by stress-induced migration. Cu oxide/TiO2 nanojunctions were formed along with nanowire growth by heating a Cu thin film with TiO2 passivation layers of different thicknesses. The presence of p–n nanojunctions at the Cu oxide/TiO2 interface was analyzed by current–voltage and electrochemical impedance measurements. The sheet resistance of the samples decreased as the TiO2 thickness increased from 0 to 20 nm and then increased with increasing TiO2 thickness. The shapes of Nyquist plots consisted of two semicircles, one distorted semicircle, and two distorted semicircles for samples without a TiO2 layer, with 2 or 20 nm TiO2 layer, and with 100 or 200 nm TiO2 layer, respectively. The TiO2 thickness dependence of these electrical characteristics suggests that electrical conduction in the sample heated with a TiO2 passivation layer was through the Cu oxide grain surface, Cu oxide/TiO2 interface, and Cu oxide nanowires. In the equivalent circuit representing this electrical conduction, the capacitance values at the Cu oxide/TiO2 interface decreased with increasing TiO2 thickness. These results suggest that a thicker TiO2 passivation layer led to the formation of more p–n nanojunctions at the Cu oxide/TiO2 interface.

Influence of Laser Beam Power on the Temperature Distribution and Dimensions of the Molten-Pool Formed during Laser Boriding of Nimonic 80A-Alloy

Laser boriding is a surface treatment that involves the simultaneous re-melting and mixing of the alloying material, containing amorphous boron blended with diluted polyvinyl alcohol, with the substrate material (Nimonic 80A-alloy). As a result of high cooling rates, the boride layer is formed from a solidifying molten pool. The thickness of the produced layer depends on the laser treatment parameters, e.g., power of the laser beam, scanning rate, and laser beam radius. These parameters influence the temperature distribution on the cross-section of laser tracks and, thus, directly determine the size of the molten pool, from which the boride layer is formed after crystallization. In the present study, laser borided layers were produced on Nimonic 80A alloy using a CO2 molecular laser. Differences in the laser beam power used resulted in the formation of layers of different thicknesses, which resulted directly from the differences in the temperature distribution in the treated material. The amount of boron in the molten pool directly influenced the obtained hardness of the laser borided layer. It was found that the lower laser beam power had an advantageous effect on the hardness due to the higher percentage of nickel borides and chromium borides in the layer. The reasons for this situation are discussed in detail.

Research on nano-scale AlN nucleation layer growth and GaN HEMT characteristics based on MOCVD technology

The AlN nucleation layers of different thicknesses were grown on a 100 mm 4H-SiC substrate in a low-pressure MOCVD. By using in-situ high-temperature etching of the substrate steps, the AlN nucleation layer could achieve layered growth as soon as possible, and finally achieve 11.6 nm. The complete AlN film was prepared, and the surface morphology and interface quality of AlN were analyzed with atomic force microscope and transmission electron microscope. A 1.8 μm thick GaN HEMT epitaxial material was prepared based on the ultra-thin AlN nucleation layer. The (002) and (102) plane rocking curves of GaN had a FWHM of 138arcsec and 231arcsec, and the electrons mobility of the heterojunction two-dimensional electron gas reached 2200 cm2/V·s. The AlN interface thermal resistance measured by the high-precision 3ω method was reduced to 5.53 × 10−9 m2K/W.

Disentangling the magneto-optic Kerr effect of manganite epitaxial heterostructures

The magneto-optic Kerr effect can probe the process of magnetization reversal in ferromagnetic thin films and can, thus, be used as an alternative to magnetometry. The Kerr effect is wavelength-dependent and the Kerr rotation can reverse sign, vanishing at particular wavelengths. We investigate the epitaxial heterostructures of ferromagnetic manganite, La0.7Sr0.3Mn0.9Ru0.1O3, by using the polar Kerr effect and magnetometry. The manganite layers are separated by or interfaced with a layer of nickelate, NdNiO3. The Kerr rotation hysteresis loops of trilayers, with two manganite layers of different thicknesses separated by a nickelate layer, have intriguing humplike features when measured with light of 400 nm wavelength. By investigating additional reference samples, we disentangle the contributions of the individual layers to the loops: we show that the humps originate from the opposite sense of the Kerr rotation of the two different ferromagnetic layers, combined with the additive behavior of the Kerr signal. The change of sign of the Kerr rotation for the thinner manganite layer is most likely caused by optical interference.

A Multi-Plasmonic Approach for Simultaneous Measurements based on a D-Shaped Photonic Crystal Fiber Sensor: from Temperature to Optical Dispersion

The growing demand for multiparameter sensors includes compact devices accompanied by simple calibration processes to distinguish the outputs from each other. This paper evaluates a scheme to determine multiple parameters of a medium using localized surface plasmon resonances (SPR) excited on a Dshaped photonic crystal fiber (PCF) partially covered by two gold layers of different thicknesses. We demonstrate that the proposed sensing platform, once customized to characterize the possible dispersive profiles of the refractive index of the analyte, also allows interrogating the temperature of a sample from a linear relationship. Since the plasmonic resonances are excited at separated and low crosstalk spectral channels, different sensing responses can be obtained simultaneously in the same location of the D-shaped PCF. These features turn out the SPR sensor a suitable tool for simultaneous monitoring of optical dispersion and temperature.

Domain wall chirality reversal by interfacial engineering in Pt/Co/Pt based perpendicularly magnetized systems

Heavy metal/ferromagnet interfaces in systems with perpendicular magnetic anisotropy (PMA) hosts chiral Néel wall with the assistance of interfacial Dzyaloshinskii–Moriya interaction (iDMI). We have investigated field induced domain wall motion in the creep regime to estimate the effective iDMI strength, Deff of sputter-deposited Ta/Pt/Co/Pt and Ta/Pt/Co/Au/Pt thin films that exhibit PMA. Two similar Pt/Co interfaces on either side of the Co layer in the Ta/Pt/Co/Pt system lead to a small Deff with a negative sign that supports the Néel type domain wall of right-handed chirality. Ultrathin Au layers of different thicknesses have been deposited at the top Co/Pt interface to introduce asymmetry around the Co layer and control the Deff. Here, two interfaces (Pt/Co and Au/Co) of opposite iDMI polarity have been chosen to invert the domain wall chirality to the left-handed chirality instead of the right-handed chirality found in the Ta/Pt/Co/Pt system.

Variation in the properties of chernozems in the Priob Plateau within the boundaries of the key site “Volodarka” (Altai Territory, Russia)

The aim of the study. To assess spatial heterogeneity of the chemical properties of the chernozems of the Near-Ob Plateau within the boundaries of the key site “Volodarka” and explain the reasons that determined the variation of the studied soil properties. Location and time of the study. Steppe zone of the northeastern part of the Near-Ob Plateau within the boundaries of the key site “Volodarka” (52°41-42' N and 83°38'E); the results of the long-term research (2007–2019) are discussed. Objects of the study. Chernozems that formed under the dry-steppe vegetation on loess deposits, as well as on different horizons of paleosols of Middle Pleistocene origin that reached surface. Methodology. Soil samples were collected to a depth of 40 cm in a continuous column at an increment of 2 to 10 cm, taking into account the visible boundaries of genetic horizons. To characterize soil chemical properties, the methods commonly used in Russian soil science studies were used. Specifically, soil organic carbon content was determined by dichromate digestion method. Results. The studied properties of chernozems, currently functioning in the same environmental conditions of the key area located on the territory of the Altai Territory, showed significant variation, as can be judged by comparing their means and coefficients of variation. The greatest fluctuations in all soil properties in all soil profiles were observed, as a rule, in the 10–20 or 20–40 cm layers, whereas in the 0–10 cm layer they changed less significantly. It was revealed that the degree of humification and humus reserves, as well as nitrogen reserves and the nitrogen enrichment of humic substances in the 0-40 cm layer, can be regarded as significant; they displayed the greatest variation in the 20–40 cm layer. Conclusions. The heterogeneity of the main properties of chernozems located in the same natural conditions of the Priob Plateau within the boundaries of the key site “Volodarka”, even within 0-40 cm layer, is most likely due to the currently present features of ancient pedogenesis. Those features do not correspond to the combination of modern soil formation conditions of the dry-steppe type: it is confirmed by the presence and extent of clearly visible Middle Pleistocene pedocomplexes in the coastal outcrops of the Ob River. Different horizons of those pedocomplexes reached the surface and had been overlayed by products of modern soil formation in layers of different thicknesses. The combination of heterogeneity of soil profiles in terms of properties, position in the coastal outcrop and their visual differentiation allowed us to conclude that the variation in the compositional characteristics and properties of the studied soils resulted from the history of the territory development, which determined the surfacing of the buried paleosols. The knowledge of the heterogeneity of soil profiles makes it possible to use the studied soil properties and characteristics of their composition for monitoring the state of modern soils, substantiating forecasts of their behavior under changing ecological conditions, as well as for identifying features of ancient pedogenesis in order to reconstruct the paleonatural environment.