Electrophysical Characteristics Research Articles

Facile Synthesis of Stable Nanosized Silver Clusters in Plasma Discharge Under Ultrasonic Cavitation

This work is devoted to the study of plasma-chemical processes determined by the combination of the effect of thermally nonequilibrium, low-temperature plasma and intensive ultrasonic vibrations in the regime of intensive cavitation on liquid-phase media. This method for the realization of plasma-chemical transformations has been proven to be of significant interest and to have advantages for the creation of new nano-sized materials with special properties because it allows for varying the electrophysical and acoustic characteristics of the process when carrying out plasma-chemical reactions and fusion reactions. In this work, a novel facile technique for the synthesis of nanosized silver clusters in plasma discharge under ultrasonic cavitation is reported. Such a type of plasma involves the simultaneous effect of high-intensity cavitation and steady electric discharge in a liquid phase between electrodes of desired material. As a result, stable tiny silver nanoclusters with around a 1-nm size and a relatively narrow particle size distribution were obtained using toluene as a liquid medium. The nanoclusters were characterized with dynamic light scattering, transmission electron microscopy, electron diffraction, and optical methods. The results confirmed the formation of nanoclusters with an absorbance peak around 300 nm and the absence of 400-nm peaks typical for silver nanoparticles. Fluorescence tests allowed for establishing the amorphous structure of the synthesized nanoclusters occupying the intermediate position between few-atom nanoclusters and nanoparticles. The nanoclusters obtained were proven to be stable for more than 3 months. The experiments also revealed the possibility of performing high-temperature plasma-chemical reactions that can be applied in fusion technology.

Effect of Ultrasonic Dispersion on Electrophysical Characteristics of Composites Based on Carbon Nanotubes

Effect of Ultrasonic Dispersion on Electrophysical Characteristics of Composites Based on Carbon Nanotubes

Temperature−Frequency Dependences of the Electrophysical Characteristics of Polyfunctional Compounds Using Guaiacol as an Example

Temperature−Frequency Dependences of the Electrophysical Characteristics of Polyfunctional Compounds Using Guaiacol as an Example

АВТОМАТИЗИРОВАННЫЕ ИССЛЕДОВАНИЯ ДИЭЛЕКТРИЧЕСКИХ ПАРАМЕТРОВ ПОЛИМЕРНЫХ МАТЕРИАЛОВ В СОСТАВЕ ТЕХНОЛОГИЧЕСКОЙ СМЕСИ

The use of high-quality polymer film as packaging makes it possible to maintain marketable quality and reduce losses during storage of agricultural products even without additional processing. An overview of the existing control systems for the electrophysical parameters of polymeric materials is presented, the use of which serves as the basis for selecting the correct processing modes with the use of high-frequency electrothermal processing. When measuring the electrophysical characteristics of polymeric materials in multicomponent mixtures using standard testing methods, significant errors occur. In this regard, it is necessary to improve laboratory methods and diagnostic tools to solve research problems by automating the process of accounting for air gaps and studying their influence on the process of controlling the electrophysical parameters of the technological mixture. (Research purpose) The research purpose is developing an automated control system for the installation to determine the electrophysical parameters of multicomponent polymeric materials and studying the effect on the dielectric loss and dielectric permittivity of existing air gaps. (Materials and methods) Considered a number of methods to establish the methodology for conducting experimental studies on finding the electrophysical parameters of technological systems with air. (Results and discussion) We have developed an automated installation for determining the parameters of materials, created on the basis of domestic equipment of the VM-560 model. Methods of hardware and algorithmic implementation of the developed system of automated control of the process of investigation and control of the dielectric losses and permittivity of granular polymeric materials were presented. Experimental studies of the effect of air gaps and insulating material on the electrophysical properties of polymeric materials were performed. Refined electrophysical parameters of multicomponent polymers used in the production of films for packaging materials resistant to ultraviolet radiation have been obtained. (Conclusions) It was shown that the developed control system allowed to increase the accuracy of measurement by 12 percent.

Macroscopic and Mesoscopic Inhomogeneities of Electrophysical, Optical, and Photoelectric Characteristics in Chromium Compensated Gallium Arsenide Wafers

Macroscopic and Mesoscopic Inhomogeneities of Electrophysical, Optical, and Photoelectric Characteristics in Chromium Compensated Gallium Arsenide Wafers

Technology for studying the electrophysical characteristics of sedimentary rocks of South Yakutia at the railway station Kyurgellyakh using the method of remote inductive probing

The possibilities of a new technology for applying the method of remote inductive sensing at a frequency of 1,125 and 0,281 MHz in the separation interval of the emitting and receiving antennas in terms of quantitative assessment of electrophysical characteristics in the rock foundation of engineering structures at the railway station Kyurgellyakh in South Yakutia are studied. In the strata of icy and clay deluvial-eluvial formations and sedimentary rocks (dolomites, limestones), a general increase in depth of the effective values of the electrical resistance and the real part of the complex relative permittivity, which is atypical in AC geoelectrics, has been established. The range of variability of resistivity and permeability is 600–1600 Ohm·m and 3–7 arb. units. According to a sharp change (from a smaller to a larger one) in the growth rate of resistance and permeability, two boundaries were found. The first structural boundary lies at a depth of about 10 m and corresponds to the lower boundary of the area of intense weathering. The second petrophysical boundary lies at a depth of about 20 m and characterizes the transition of the highly weathered and highly fractured upper part of the sedimentary rock mass into the lower consolidated solid part located in the area of thermal rest. The obtained results give grounds to recommend a proven technology for solving the problems of geomechanics and thermophysics of frozen soils in terms of determining their strength and depth of the lower boundary of the layer of annual heat exchanges.

Characterization of the electrical properties of MPS schottky structures incorporating Fe doped polyvinyl chloride (PVC)

This paper explores the effects of the organic interfacial layer on the electrophysical characteristics of Schottky barrier diodes (SBDs). Three types of SBDs were fabricated: Au-Si (referred to as MS), Au/PVC/Si (referred to as MPS1), and Au-/PVC:Fe/Si (referred to as MPS2). Fe nanopowders were subjected to analysis using XRD, SEM, and EDX techniques to investigate their structural and optical characteristics. To investigate the conduction mechanisms of these diodes, I-V characteristics were examined using thermionic-emission (TE), Cheung, and Norde functions. The surface-state density (N ss ) distribution of energy was determined by analyzing the current–voltage (IF-VF) curve under forward bias conditions. This analysis considered the voltage-dependent barrier height (BH) and ideality factor (n(V)). The results demonstrated that the polymeric interlayer without Fe nanoparticles reduced N ss by a factor of 7, while the presence of Fe nanoparticles led to a two-order magnitude decrease, resulting in improved efficiency in comparison with MS structures. The obtained results indicated that including a polymeric layer in MPS structure enhanced their electrophysical features compared to MS diodes, and significantly increased rectification by 15–45 times. In summary, the existence of an organic interfacial layer significantly altered the conduction mechanisms and electrophysical characteristics of MPS diodes. It was found that the addition of Fe nanoparticles in the interlayer resulted in substantial improvements in N ss , efficiency, rectification, and conduction characteristics compared to MS diodes.

Impact of the thickness of phthalocyanine films and its metal complexes on optical and electrical properties

The paper presents the results of a study of the structural, optical and electrophysical characteristics of phthalocyanine films and its metal complexes with different thicknesses. Films of phthalocyanine and its metal complexes were obtained on the conductive surface of the FTO by thermal evaporation in vacuum. It is shown that the observed broadening of the B and Q bands and the hypsochromic shift of the maxima in the absorption spectra are associated with the central atom. With a decrease in the thickness of MPc films, there is a decrease in the value of the half-width of the absorption spectra. The effect of the thickness of phthalocyanine films on the efficiency of generation and transport of charge carriers in the FTO/MPc/Al cell was studied. It is shown that the VAC increases almost 2.5 times compared to a photocell based on a metal-free phthalocyanine. From the obtained impedance measurement data, it was found that the electrophysical parameters of phthalocyanines depend on the values of optical density, broadening of absorption bands in the short-wave and visible spectral regions, which is consistent with the data of the volt-ampere characteristic.

Influence of silicon characteristics on the parameters of manufactured photonics cells

The paper investigates the influence of the electrophysical characteristics of silicon on the final parameters of photoelectronic elements using p-i-n photodiodes as an example. It has been found that photodiode samples made on the basis of silicon with a higher resistivity are more prone to the formation of inversion channels at the oxide-semiconductor interface. Also, the dark current and responsivity of such photodiodes reach saturation at a lower voltage. It has also been shown that silicon-based photodiodes with a longer lifetime of non-basic charge carriers have lower dark current values. It has been shown that products with crystallographic orientation [111] have a much lower density of surface dislocations after technological operations than in the case of silicon with orientation [100]. It was also found that materials with different crystallographic orientations have different phosphorus diffusion coefficients. It has been experimentally established that a silicon oxide film grows faster on the surface of crystallographic orientation silicon [111] than on the surface of crystallographic orientation silicon [100]. This is due to the difference in the surface density of silicon atoms inherent in different crystallographic planes.

Spectrum Modelling as a Method for Temperature Correction of Organic Light Emitting Diodes Based on Three-Component Structures

OLED technology is widely used in various displays, which operate in a wide range of temperatures. For such devices, it is necessary to maintain the luminance and chromaticity coordinates at the given level when the external temperature changes. In this work, a program was developed that, based on the electro-physical characteristics and electroluminescence spectra of a white OLED sample at different temperatures and currents, as well as the spectral characteristics of the coloured filters, allows for selection of currents in the range of (1–25) mA, applied to each subpixel in such a way as to converge the chromaticity coordinates to the specified values. Various chromaticity coordinates were tested in the process of program execution, including CIE sources of type A, type B, type C, and type D65. In each of these cases, the program significantly reduced the difference in chromaticity coordinate changes with temperature. The obtained results will be used for gamma correction of micro-displays produced at the Cyclone Research Institute during their operation at a wide range of temperatures.

THE METHOD OF ADJUSTING THE MULTI-FREQUENCY PROBING RADAR SIGNAL PARAMETERS AND THE TROPOSPHERIC RADIO WAVEGUIDE CHARACTERISTICS

Peculiarities of air circulation in the coastal zone of large reservoirs (large lakes or inland seas such as the Black and Azov Seas) can lead to a significant departure from the standard spatial distribution of meteorological and, accordingly, radiophysical characteristics of air.
 As a result, it is possible for regions of space with an abnormally low attenuation level of radio waves of certain frequency ranges to appear – tropospheric radio waveguides (TWG). The appearance of TWG leads to multi-beam propagation of radio waves and fluctuations of radar signals. Fluctuations of the radar signal lead to a decrease in the range of detection of aerial objects by radars. For single-frequency radar signals, it is only possible to estimate the degree of distortion and the amount of radar detection range loss. A paradoxical situation arises when, due to TWG, it is possible to increase the range of detection of aerial objects, but due to the distortion of the radar signal in TWG, the detection performance decreases. For multi-frequency signals, it is potentially possible to adjust the parameters of the radar signal with the parameters of the radar channel (in this case, the tropospheric radio waveguide).
 The adjustable parameters of a multifrequency signal include: the number of frequency components; bandwidth of the frequency component; average frequency of the frequency component; signal duration; period.
 The characteristics of TWG, on which the parameters of the multifrequency signal depend, include: the lower transmission frequency of TWG; the upper transmission frequency of TWG; the delay time of the rays in the TWG.
 The bandwidth and beam delay values can be obtained directly by emitting and receiving a test multi- frequency pilot signal, but this method requires the presence of a reference reflector in space, which is difficult to implement in practice.
 The electrophysical characteristics of the tropospheric waveguide can be determined from the data of meteorological observations. The method developed in the article allows, based on the known characteristics of the tropospheric waveguide, to determine and adjust the parameters of a multi-frequency signal, which reduces the fluctuations of the sounding signal and increases the aerial objects detection rang.

Calculation of Electrophysical Characteristics of Semiconductor Quantum Wire Device Structures with One-Dimensional Electron Gas

Calculation of Electrophysical Characteristics of Semiconductor Quantum Wire Device Structures with One-Dimensional Electron Gas

The Influence of Temperature on Electrophysical Characteristics of Carbon-Containing Polymer Composites

The Influence of Temperature on Electrophysical Characteristics of Carbon-Containing Polymer Composites

Analysis of the Electrophysical Characteristics of the RF MEMS Switch Taking into Account the Influence of the Substrate Material

Analysis of the Electrophysical Characteristics of the RF MEMS Switch Taking into Account the Influence of the Substrate Material

Basic Electrophysical Characteristics of Natural Three-Phase Dispersed System “A Storm Cloud−Earth”

The results of engineering calculation of basic electrophysical characteristics of a three-phase dispersed system of the Earth troposphere “storm cloud-earth”, in the cloud of which a bearing gaseous air phase contains fine liquid water drops and small solid dielectric particles, are present-ed. The indicated characteristics are as follows: the total electric charge qΣ concentrated in a storm cloud of a given spherical volume V0 with finely dispersed charged inclusions in the form of water droplets of the radius rw and solid dielectric particles of the radius rd with the given cor-responding average volume densities Nw and Nd, respectively; the electric potential φr in the spherical volume V0 of a storm cloud with a specified outer radius R0; the electrical energy W0 accumulated in the volume V0 of a storm cloud with finely dispersed inclusions ; and the amplitude and temporal parameters of the pulse current iL(t) of the lightning in the plasma channel of a long air spark electrical discharge from the storm cloud to the ground. It is shown that at rw ≈ rd ≈ 5 μm, Nw ≈ 108 m-3, Nd ≈ 5106 m-3, R0 ≈ 895 m and the height of the center of a spherical storm cloud (with its volume of V0 ≈ 3109 м3) H0 ≈ 3000 m above the ground level, the following numerical values (in modulus) of the sought parameters of the system under consideration could be obtained: the accumulated cloud charge of qΣ ≈ 43.8 C; the electric potential on the outer cloud surface of φR ≈ 439 MV; the electric energy of W0 ≈ 9.61 GJ; the amplitude of the lightning current of ImL ≈ 218.5 KА corresponding to the time tmL ≈ 11.1 μs. The obtained results are in a good agreement with known experimental data related to the atmospheric electricity. They will contribute to a possibility of predicting thunderstorm conditions in the Earth troposphere with the minimal initial meteorological information, the further development of the nature of the atmospheric electricity, the physics of the linear lightning and solving the problem of the lightning protection of air and ground facilities and their personnel.

Effect of phenol-formaldehyde resin on mechanical durability and structure of low-density polyethylene

Relevance. The development of technology for producing new polymer modifications with specific properties, which remain stable even when exposed to external factors, is a key area of focus for researchers in the field of high-molecular compounds. Purpose. The purpose of this study was to create new composite materials based on low-density polyethylene. Methodology. The extrusion blowing method on an industrial URP 1500 unit was used for processing low-density polyethylene (LDPE) and its modified films. Electron microscopic images of the surface were captured using a S-570 scanning microscope (Japan) at X1000 magnifications. Results. The composition and quantity of a low-molecular organic additive that alters the electrical characteristics of low-density polyethylene grade 10803-020 was ascertained. The modified low-density polyethylene is noteworthy for its minimal usage of additives and their compatibility with technology. Based on experimental data, it was found that the inclusion of 0.05 wt% phenol-formaldehyde resin in low-density polyethylene increases its mechanical strength to the highest level when compared to both the unaltered low-density polyethylene and low-density polyethylene with other additives. Furthermore, the study found that the addition of phenol-formaldehyde resin in small proportions (0.05 wt%) substantially enhances mechanical strength at varying temperatures. Conclusions. The electrophysical characteristics of low-density polyethylene and its modified versions were comprehensively investigated. The adequately altered low-density polyethylene exhibits considerably improved mechanical durability. It was indicated that the additives used, at optimal levels, influence the physical framework of low-density polyethylene, highlighting their technological compatibility differences

Underlying mechanism of atrial fibrillation–associated Nppa-I137T mutation and cardiac effect of potential drug therapy

BackgroundMore than a hundred genetic loci have been associated with atrial fibrillation (AF). But the exact mechanism remains unclear and the treatment needs to be improved. ObjectiveThis study aimed to investigate the mechanism and potential treatment of NPPA mutation–associated AF. MethodsNppa knock-in (KI, p.I137T) rats were generated, and cardiac function was evaluated. Blood pressure was recorded using a tail-cuff system. The expression levels were measured using real-time polymerase chain reaction, enzyme-linked immunosorbent assay or Western blot analysis, and RNA-sequence analysis. Programmed electrical stimulation, patch clamp, and multielectrode array were used to record the electrophysical characteristics. ResultsMutant rats displayed downregulated expression of atrial natriuretic peptide but elevated blood pressure and enlarged left atrial end-diastolic diameter. Further, gene topology analysis suggested that the majority of differently expressed genes in Nppa KI rats were related to inflammation, electrical remodeling, and structural remodeling. The expression levels of C-C chemokine ligand 5 and galectin-3 involved in remodeling were higher, while there were declined levels of Nav1.5, Cav1.2, and connexin 40. AF was more easily induced in KI rats. Electrical remodeling included abbreviated action potentials, effective refractory period, increased late sodium current, and reduced calcium current, giving rise to conduction abnormalities. These electrophysiological changes could be reversed by the late sodium current blocker ranolazine and the Nav1.8 blocker A-803467. ConclusionOur findings suggest that structural remodeling related to inflammation and fibrosis and electrical remodeling involved in late sodium current underly the major effects of the Nppa (p.I137T) variant to induce AF, which can be attenuated by the late sodium current blocker and Nav1.8 blocker.

Influence of the phthalimide on the process of electrical aging of the high-pressure polyethylene

Relevance. The use of polyolefins without additional processing methods, namely, the increase in their electrophysical characteristics, is an actual modern requirement. For this, it is necessary to use the mechanism of ionization ageing where the role of the modifying additive must be elucidated by the method of infrared spectroscopy in high-pressure polyethylene. Purpose. The research aims to study the effect of low molecular weight organic additives of phthalimide on molecular structural changes in polymers that occur under external action. Methodology. The impact of electrical discharges on polymer dielectrics was carried out in a test cell of an asymmetric type. Tested polymer film before and after pre-stretching was tightly stretched onto this plate following the research procedure. To create an air gap of constant thickness between the top electrode and the polymer film, 1.5 mm thick glass spacers were placed along the edges. Results. The electrical strength (lifetime) of high-pressure polyethene (LDPE) and its optimal modification before and after electrical ageing was investigated. Following experimental data, at the content of 0.05 wt. % LDPE its electrical strength reaches a maximum value compared to both the original LDPE and LDPE at other additive contents. The introduction of 0.05 wt.% phthalimide into high-pressure polyethene contributes to a noticeable decrease in the intensity of the formation of C=0 groups, which is the measure of the oxidative degradation of polymer chains. Conclusions. The optimal composition of the phthalimide was determined and their electrophysical properties were studied. It was found that composites with additions of 0.05 wt.% phthalimide significantly improve the electrophysical properties of LDPE.

Low-Voltage Logic Gates based on Vertical GAA Nanotransistors

The issues of numerical simulation of low-voltage logic gates based on silicon vertical surrounding gate CMOS nanotransistors with a conical working area circuits are discussed. Using the TCAD instrument process modeling program, numerical studies of conical prototypes have been performed. The electrophysical characteristics in the control voltage range from 0 to 0.6 V are characterized by a higher transistor current, a maximum Ion/Ioff current ratio, a low leakage current and a slope of the subthreshold characteristic close to the theoretical aisle. 3D TCAD models of three basic logic gates on vertically arranged transistors of n-and p-types have been developed for an optimized ratio of the diameters of the working area of 8.4/10 nm and the length of the working area of 22 nm. Their electro-physical characteristics are numerically investigated at control voltages of 0.6 V and a frequency of 20 GHz. The gate models demonstrate picosecond delays and low power consumption. The promising characteristics of the proposed transistors and valves based on them, such as a high degree of integration, high performance and low cost, open the way to the development of 3D integrated circuits of the next generation.

INVESTIGATION OF THE PHASE FORMATION PROCESS
 DURING THE SYNTHESIS OF CERAMIC MATERIALS
 BASED ON MODIFIED YTTRIUM MANGANITE

The aim of this work is to establish the nature and sequence of phase formation processes in the synthesis of ceramic
 materials based on yttrium manganite using different manganese oxides and structure modifiers. Differential scanning calorimetry,
 X-ray phase analysis, and scanning electron microscopy were used as research methods in the work. The physicochemical
 and electrophysical properties of the obtained samples were determined. Samples of modified yttrium manganite
 were obtained by solid-phase sintering of the initial components at various temperature-time parameters of heat treatment.
 The influence of Bi2O3, CoO and TeO2 additives on the physicochemical and electrophysical properties of prototypes was
 studied. Regularities of the structure formation processes and phase composition of ceramic materials are established in
 relation to the composition of raw materials and the technological parameters of the synthesis of modified yttrium manganite.
 It has been established that the addition of oxides of the RO type contributes to a decrease in the degree of crystallization
 of the samples, as evidenced by a decrease in the intensity of the diffraction peaks of the crystalline phases. In this case,
 the qualitative composition of the phases practically does not change, but the proportion of the amorphous component in the
 structure of the material increases. Bi2O3 has the most effective modifying effect in the synthesis of yttrium manganite.
 Its addition into the composition of the raw mixture intensifies the process of formation of the yttrium manganite phase with
 a crystal size of 2–4 μm, which is confirmed by the results of DSC, XRD, and electron microscopy. The intensification of the
 crystallization process due to the addition of bismuth oxide is explained by the developed mechanism of liquid-phase sintering
 and the formation of a significant number of crystallization centers. The developed ceramic materials based on modified
 yttrium manganite have a set of electrophysical characteristics that make it possible to recommend them for the manufacture
 of various elements of electronic technology.