bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Thin Films of Titanium Dioxide Deposited by Sputtering and Sol-Gel Methods for Waveguiding Applications
Authors: Brella M.  , Taabouche A.  , Gharbi B.  , Gheriani R.  , Bouachiba Y.  , Bouabellou A.  , Serrar H.  , Touil S.  , Laggoune K.  , Boudissa M.
Published: September 2022

In this work, TiO2 thin films were deposited onto glass substrate by two different techniques: sol-gel dip-coating (SG) and reactive DC magnetron sputtering (Sput). The prepared samples have been characterized by means of micro-Raman, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) measurements, scanning electron microscopy (SEM), UV-Visible spectrophotometry, and M-Lines spectroscopy (MLS). The micro-Raman results showed an amorphous TiO2-SG phase and the vibrational mode of TiO2-Sput is anatase phase. DSC-TGA analysis was used to investigate the thermal properties of the TiO2 material. SEM spectroscopy has shown that TiO2-SG has a disordered and more porous surface, TiO2-Sput sample is homogeneous and shows uniform distribution of densely packed well-defined grains. The obtained films have an optical transmittance varying from 60 to 88% in the visible region. The optical band gaps deduced from the transmittance are 3.48 and 3.53 eV for TiO2-SG and TiO2-Sput, respectively. The optical waveguiding measurements carried out on TiO2-SG and TiO2-Sput films show single guided modes behavior (TE0 and TM0). These measurements have allowed deducing the refractive index and thickness values that are 2.06 at 216 nm for TiO2-SG and 2.26 at 204 nm for TiO2-Sput thin films. The analysis of waveguiding properties indicates that amorphous TiO2 may prove to be more efficient in photonic device as compared to crystalline TiO2. Keywords: TiO2, thin films, sol-gel, sputtering, anatase, waveguiding.
Strip thermoelectric generator made of carbon fiber
Authors: Ivanov D. K.  , Ivanov K. G.  , Uryupin O. N.
Published: September 2022

A prototype of a thermoelectric generator based on p-n junctions of a strip carbon fiber modified by a pulsed current was created. Keywords: carbon fiber, thermoelectric Q-factor, p-n junction.
30a
Authors: Makarova E. S.  , Asach A. V.  , Tkhorzhevskiy I. L.  , Fomin V.E.  , Novotelnova A. V.  , Mitropov V.V.
Published: September 2022

The estimation of the deviation in the measurements of thermal conductivity by the laser flash method for materials with different thermal conductivity coefficients, arising due to the presence of a graphite coating on the sample and the small thickness of the sample, is carried out. A computer model of the method was created in the Comsol Multiphysics software environment. For bulk samples with a graphite coating thickness of 20 μm, the deviation is 5.5 %. The thickness of bulk samples does not affect the measurement results. For materials with low thermal conductivity, a sharp increase in the deviation is observed, reaching 60%. For thermally conductive materials, the deviation is 16-18%. For thin samples less than 10 μm thick, the thickness of the graphite coating does not affect the measurement results. The decisive factor is the duration of the laser pulse.
Influence of the ionic subsystem on the thermoelectric effect in colloidal solutions
Authors: Sidorov A. V.  , Grabov V. M.  , Zaitsev. A.A.  , Kuznetsov D.V.
Published: September 2022

The thermoelectric effect is investigated in mixtures of colloidal solutions with ionic electrolytes in the initial state, when the formation of concentration gradients under the influence of an inhomogeneous temperature field can be neglected. Based on experimental measurements in mixtures with different concentrations of colloidal particles and ions, the conditions under with the coefficient of thermoelectric EMF is determined by the ion subsystem and under which the main contribution to the value of the thermoelectric force is made by colloidal particles are determined. Keywords: colloidal solution, thermoelectric effect, ionic subsystem.
Effect of the presence of a sufficiently high phosphorus concentration on the concentration distribution of gallium in silicon
Authors: Bakhadirkhanov M. K.  , Zikrillaev N.F.  , Isamov S. B.  , Turekeev X. S.  , Valiev S. A.
Published: September 2022

It was found that the silicon preliminarily doped with a high concentration of phosphorus during the diffusion of gallium, there is a significant increase in the solubility of the gallium. The results obtained are explained by the interaction of gallium and phosphorus atoms, as a result of which quasi-neutral molecules [P+Ga-] are formed. It is assumed that the formation of such quasineutral molecules [P+Ga-] stimulates the formation of Si2GaP binary unit cells in the silicon lattice. It is shown that a sufficiently high concentration of such unit cells can lead to a significant change in the electrophysical parameters of silicon, i.e. the possibility of obtaining a new material based on silicon. Keywords: silicon, gallium, phosphorus, binary cell, diffusion.
Study of charge carrier mobility in PBS nanocrystal layers using field-effect transistors
Authors: Parfenov P. S.  , Bukhryakov N. V.  , Onishchuk D.A.  , Babaev A. A.  , Sokolova A. V.  , Litvin A. P.
Published: September 2022

The field-effect transistor method is used to study the mobility of charge carriers in layers of lead sulfide nanocrystals with ligands of tetrabutylammonium iodide and 1,2-ethanedithiol used to create solar cells. The difference between the operating of a transistor in ambient air and in an inert atmosphere is demonstrated. It is shown that, in the ambient air, the processes of charging nanocrystals are activated when current flows, and the influence of the polarization of the interface of nanocrystals and the insulator on the measurement of the mobility is analyzed. Different reactions of the layers with ligands to light have been demonstrated, showing a significant oxidation of the surface of nanocrystals treated with 1,2-ethanedithiol. Keywords: solar cells, trap states, photoconductivity.
Effect of ionizing irradiation on charge distribution and breakdown of MOSFETs
Authors: Alexandrov O. V.  , Tyapkin N. S.  , Mokrushina S. A.  , Fomin V. N.
Published: September 2022

The effect of ionizing radiation on the formation of charges at internal SiO2-Si (substrate) and external SiO2-Sips (gate) interfacial boundaries (IFB) and on the gate breakdown of MOSFETs is studied. It is shown that with an increase in the dose of ionizing radiation near the internal interfacial boundaries, a monotonous increase of positive charge in p-MOSFETs, and the accumulation of positive charges at first, and at doses above 105 rad the accumulation of negative charges in n-MOSFETs is observed. Near the external interfacial boundaries, at low radiation doses, positive charge accumulation is observed, and at doses >106 rad, negative charge in both p- and n-MOSFETs is observed. Up to a dose of 108 rad ionizing radiation dies not have a noticeable effect on the gate breakdown voltage in both p- and n-MOSFETs at both bias polarities. The absence of influence is explained by a breakdown by mechanism of anode hole injection. Keywords: ionizing radiation, MOSFETs, charge accumulation, gate breakdown.
9745
Authors: Kalinina E. V.  , Kudoyarov M. F.  , Nikitina I. P.  , Dementyeva E. V.  , Zabrodskii V.V .
Published: September 2022

Abstract. The results of the effect of irradiation with Ar ions
on the structural, electrophysical and optical characteristics of
the ultraviolet Cr/4H-SiC photodetectors in the spectral range
of 200−400 nm are presented. After a single irradiation with
53MeV Ar ions with a fluence of 1 · 1010 cm−2, the quantum
efficiency of the photodetectors practically remained at the level
of the initial samples due to the "gettering effect“ of simple
radiation defects by cluster formations. The observed effect
promoted a decrease in the number of simple radiation defects
of the vacancy type, an increase in the lifetime of current carriers,
and, as a consequence, unchanged values of the photoconductivity
of Cr/4H-SiC photodetectors. After repeated irradiation of the
photodetectors with Ar ions with a total fluence of 2 · 1010 cm−2,
the decay of clusters was observed, the formation of a significant
number of simple defect centers, which led to a decrease in the
lifetime of current carriers and, as a consequence, to a decrease in
photoconductivity of Cr/4H-SiC photodetectors.
15
Authors: Yapryntseva E. N.  , Ivanov O. N.  , Vasil’ev A. E.  , Yapryntsev M. N.
Published: September 2022

Single-phased samples of the medium-entropy
BiSbTe1.5Se1.5 (low-temperature thermoelectric with electron con-
ductivity) and PbSnTeSe (mid-temperature thermoelectric with
hole conductivity) compounds have been prepared by reactive
spark plasma sintering of powder mixtures consisting of relevant
elemental metals. The samples prepared are grained. Plate-
like grains with average grain size of ∼ 3.3 μm are observed
in BiSbTe1.5Se1.5, whereas irregularly-shaped grains with average
grain size of ∼ 18.9 μm are typical for PbSnTeSe. Highest value of
the thermoelectric figure-of-merit of the samples is equal to ∼ 0.43
(at 500 K for BiSbTe1.5Se1.5) and ∼ 0.35 (at 725 K for PbSnTeSe).
Effect of dendritic inhomogeneity on the thermoelectric properties of Bi-=SUB=-0.88-=/SUB=-Sb-=SUB=-0.12-=/SUB=- crystals
Authors: Grabov V. M.  , Uryupin O. N.
Published: September 2022

The effect of dendritic inhomogeneity in Bi0.88Sb0.12 crystals on the transport properties and thermoelectric Q-factor was studied by experiment. It was found that the thermoelectric Q-factor of dendritic Bi0.88Sb0.12 crystals grown at a molten zone displacement rate of 1 cm/h exceeds the Q-factor of homogeneous crystals of the same composition by up to 20%. Key words: bismuth, antimony, dendritic inhomogeneity, thermoelectric properties.
The increasing of charge carriers concentration in thin bismuth films
Authors: Demidov E. V.  , Grabov V. M.  , Komarov V. A.  , Suslov A. V.  , Gerega V. A.  , A. N. Krushelnitckii
Published: September 2022

The reasons for increasing the charge carriers concentration in thin bismuth films are discussed. The concentration was calculated on the basis of the measured electrical and galvanomagnetic coefficients at the temperature 77 K under the two-band approximation and the assumption that the charge carriers free path in the plane of the film is isotropic. Keywords: Bismuth, thin film, charge carriers concentration, surface.
MIS transistor based on PbSnTe : In film with an Al-=SUB=-2-=/SUB=-O-=SUB=-3-=/SUB=- gate dielectric-=SUP=-*-=/SUP=-
Authors: Klimov A. E.  , Golyashov V. A.  , Gorshkon D. V.  , Matyushenko E. V.  , Neizvestny I. G.  , Sidorov G. Yu.  , Paschin N. S.  , Suprun S. P.  , Tereshchenko O. E.
Published: September 2022

Results on the creation and properties of transistor-type MIS structures (MIST) with an Al2O3 thin-film gate dielectric based on PbSnTe : In films obtained by molecular beam epitaxy are presented. The source-drain current-voltage characteristics (CVC) and gate-controlled characteristics of the MIST at [BT=4.2 K have been investigated. It is shown that in MIST based on PbSnTe : In films with n~1017 cm-3 the modulation of the channel current reaches 7-8% in the range of gate voltages -10 V<Ugate<+10 V. The features of the source-drain CVC and the gate-controlled characteristics for a pulsed and sawtooth variation of Ugate are considered. Keywords: solid solution PbSnTe : In, field effect, MIS structure, Al2O3.
Effect of thermal history on the properties of efficient thermoelectric alloys Ge-=SUB=-0.86-=/SUB=-Pb-=SUB=-0.1-=/SUB=-Bi-=SUB=-0.04-=/SUB=-Te
Authors: Shabaldin A. A.  , Samunin A.Yu.  , Konstantinov P.P  , Novikov S.V.  , Burkov A.T.  , Bu Zhonglin  , Pei Yanzhong
Published: September 2022

In this work, we study thermoelectric properties of GeTei-based alloys, doped with bismuth, with partial substitution of lead for germanium: Ge0.86Pb0.1Bi0.04Te. The aim of the study is to explore the possibility of increasing the thermoelectric efficiency of a compound by combining optimal doping and isovalent substitution to improve the electronic properties with a simultaneous decrease of the lattice thermal conductivity. We studied alloy samples prepared in two different research laboratories using similar, but not completely identical procedures. It is shown that the electronic (thermoelectric power and electrical conductivity) properties of the samples of the two groups are in good agreement with each other. The properties of alloys depend on the thermal history of the samples due to the presence at temperatures of 600-800 K of a phase transition from a low-temperature rhombohedral to a high-temperature cubic structural modification and missibility gap in GeTe-PbTe quasibinary system below 870 K. The thermoelectric figure of merit of alloys reaches a maximum value of 1.5 at a temperature of about 750 K. Keywords: thermoelectric alloys, thermoelectric power, electrical conductivity, thermal conductivity
9758
Authors: Bessolov V. N.  , Konenkova E. V.  , Seredova N. V.  , Panteleev V. N.  , Scheglov M. E.
Published: September 2022

It has been reported the growth of nonpolar
GaN(11 ̄20) structures by hydride vapor phase epitaxy, which used
an AlN buffer layer synthesized by epitaxy from organometallic
compounds on an r-Al2O3 substrate. It has been shown that
the elastic stresses in the GaN(11 ̄20)/r-Al2O3 structure in the
direction of the ”c“and ”a“axes of the layer differ, correlate
with the values of the full width at half maximum of the X-ray
diffraction spectra in these directions and are due to the anisotropy
of the thermal expansion coefficients of the lattice, both the layer
and the substrate.
Growth of GaAs-=SUB=-1-x-=/SUB=-Bi-=SUB=-x-=/SUB=- layers by molecular-beam epitaxy
Authors: Semyagin B. R.  , Kolesnikov A. V.  , Putyato M. A.  , Preobrazhenskii V. V.  , Popova T. B.  , Ushanov V. I.  , Chaldyshev V. V.
Published: September 2022

By molecular-beam epitaxy we have grown epitaxial layers of GaAs1-xBix solid solutions with a bismuth content of 0<x<0.02. Structural and optical properties of the layers were investigated. We determine the influence of the bismuth flux and substrate temperature on the bismuth incorporation into the growing layers. Keywords: gallium arsenide, bismuth, molecular-beam epitaxy, bandgap.
9765
Authors: Shimanskii A.F.  , Kravtsova E.D.  , Kulakovskaya T.V  , Grigorovich A.P.  , Kopytkova S.A.  , Smirnov A.D.
Published: September 2022

The radial distribution of mechanical stress, optical inhomogeneity and oxygen concentration in Sb-doped germanium crystals grown by the Czochralski method with diameter of 200 mm and resistivity from 10.5 to 18.5 Ω·cm were studied. It was found that residual stress calculated from the data of X-ray structural analysis correlates with results of numerical simulation of thermoelastic stress and interrelates with optical inhomogeneity and concentration of oxygen presented in the atomically dispersed state in germanium.
Influence of the oxygen during the deposition of an indium tin oxide thin film by magnetron sputtering for heterojunction solar cells
Authors: Ivanov A. F.  , Egorov F. S.  , Platonov N. D.  , Matukhin V. L.  , Terukov E. I.
Published: September 2022

Optoelectronic properties of indium and tin oxide thin films depending on the oxygen content in the total gas flow were experimentally investigated during deposition of these films by DC magnetron target sputtering. Relationship of the heterojunction thin-film solar cell output parameters vs. oxygen partial pressure in a vacuum vessel was examined during indium and tin oxide layer deposition. The maximum photovoltaic conversion efficiency of the solar cell was achieved at an oxygen partial pressure in the vacuum vessel of ~6.5 Torr. Keywords: heterojunction thin-film solar element, indium and tin oxide, magnetron sputtering.
Insulating potential shape created by ultrathin silicon oxide layers
Authors: Goldman E. I.  , Chucheva G. V.  , Shusharin I. A.
Published: September 2022

A previously developed method for reconstructing the insulating potential pattern created by an ultrathin silicon oxide layer from the field dependences of the tunneling current has been modernized. Trapezoidal model potential parameters, that provide the dependence of the current-to-voltage logarithm derivative as close as possible to the experimental one, have been calculated. The approach to starting successive iterations of the potential has been changed in such a way that the functions calculated using the model shape are used rather than zeroing the first turning point coordinates in zero-order approximation. The modernized algorithm has been applied to the experimental field current dependences in n+-Si-SiO2-n-Si structures with an oxide thickness of 3.7 nm, that have a pronounced asymmetry of the tunneling current-voltage characteristics with respect to the external voltage polarity. The effective potential barrier reconstructed from the experimental data is always significantly thinner than the insulating layer, with its maximum shifted towards the contact with the polycrystalline material, and the effective mass of the tunneling electron is several times greater than the typical for thick silicon oxide. Keywords: degenerate polysilicon--silicon oxide--silicon, ultrathin oxide, tunneling current-voltage characteristics, potential pattern.
Low-temperature photoluminescence of WSe-=SUB=-2-=/SUB=- monolayer obtained by gold-assisted exfoliation
Authors: Nikolaev S. N.  , Bagaev V. S.  , Chernopitssky M. A.  , Usmanov I. I.  , Onishchenko E. E.  , Deeva A. A.  , Krivobok V. S.
Published: September 2022

We studied the optical properties of an atomically thin WSe2 film obtained by gold-assisted mechanical exfoliation. Raman scattering spectra, low-temperature photoluminescence, and micro-reflection from large-scale monolayer are investigated. At room temperature, the optical properties of such a film reproduce the properties of WSe2 monolayers obtained by regular mechanical exfoliation. It is shown that at low temperatures, the radiation spectra of the resulting film are determined by standard mechanisms of radiative recombination involving free excitons, bound excitons, and trions. However, in contrast to room temperatures, there is a significant difference in the spectral width and intensity of the lines compared to monolayers WSe2, obtained regular way from the same source material. The differences found, demonstrating a significant increase in background doping and structural disorder when using gold-assisted exfoliation, may be meaningful for a number of optoelectronic applications of atomically thin WSe2 films. Keywords: layered semiconductors, luminescence, monolayer, escitons.
Heterostructure of a 2.5 THz range quantum-cascade detector
Authors: Babichev A.V.  , Kolodeznyi E.S.  , Gladyshev A.G.  , Denisov D.V.  , Jollivet A.  , Quach P.  , Karachinsky L. Ya.  , Nevedomskiy V.N.  , Novikov I.I.  , Tchernycheva M.  , Julien F.H.  , Egorov A.Y.
Published: September 2022

The design of the heterostructure of a 2.5 THz range quantum-cascade detector is proposed and heterostructure is grown by molecular-beam epitaxy technique. To optimize the thicknesses of the layers of the heterostructure cascades, a numerical method for iterative solution of the Schrodinger--Poisson equation in the k· p formalism was used. The grown heterostructure of the quantum-cascade detector showed a high structural perfection, confirmed by the small values of the average FWHM of the high-order satellite peaks on the X-ray diffraction rocking curves, which were (8.3±0.5)n. Analysis of dark-field images obtained by transmission electron microscopy showed that the total thickness of the layers in the cascade is (137.3±6.9) nm, which corresponds to the calculated thickness of the layers in the cascade of the heterostructure of the quantum-cascade detector. Keywords: superlattices, quantum-cascade detector, epitaxy, gallium arsenide
Thermoelectric and memristive features of the Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-/Sb-=SUB=-2-=/SUB=-S-=SUB=-3-=/SUB=-/Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=- and Ag/Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-/Ag structures
Authors: Papikyan A. K  , Harutyunyan S. R.  , Aghamalyan N. R.  , Hovsepyan R. K.  , Khachaturova A.  , Petrosyan S. I.  , Badalyan G. R.  , Kafadaryan Y. A.
Published: September 2022

Single-layer Sb2Te3 films and three-layer Sb2Te3/Sb2S3/Sb2Te3 structures are obtained by thermal vacuum deposition. Their thermoelectric characteristics have been investigated in a wide temperature range (5-350 K). It is shown that the conductivity of Sb2Te3/Sb2S3/Sb2Te3 has a semiconductor behavior, the resistivity is an order of magnitude higher than the resistivity of the Sb2Te3 film; the Seebeck coefficient of Sb2Te3/Sb2S3/Sb2Te3 is 1.5 and 3 times higher than the Seebeck coefficient of the film and single-crystal Sb2Te3, respectively. The current--voltage characteristics of the Sb2Te3 film exhibit memristive properties with unipolar resistive switching, whereas Sb2Te3/Sb2S3/Sb2Te3 can be considered as a memristor with a parallel connected capacitance. Keywords: Sb2S3, Sb2Te3, films, volt-ampere characteristic, Seebeck coefficient, memristor.
9774
Authors: Malevskaya A. V.  , Il'inskaya N. D.  , Malevskii D. A.  , Pokrovskii P. V.
Published: September 2022

Investigations and modeling of ohmic contacts electrochemical deposition process in postgrowth technology of photovoltaic converters fabrication have been carried out. The technology of Ag/Au contact system galvanic deposition at vertical and horizontal position of heterostructure and anode in the electrolyte has been developed. The increase of contact system deposition uniformity up to ∼ 95% at the thickness of contact bus-bars ∼ 5 µm on the heterostructure area with 4 inch diameter has been archived.
Phase transformations in single-component multiphase systems: phase-field approach
Authors: Lebedev V. G.
Published: September 2022

The problems of constructing a multiphase model of the phase field for the processes of phase transitions of the first kind are considered. Based on the Gibbs energy of the complete system expressed in terms of antisymmetrized combinations of phase fields, it is shown that the equations of dissipative dynamics of a locally nonequilibrium system follow from the condition of its monotonic decrease, preserving the normalization of the sum of variables by one and the following properties of the previously known two-phase model. Keywords: multiphase systems, phase transformations, locally nonequilibrium processes, dissipative systems with constraints.
Influence of external electric field on optical breakdown in high-speed flow
Authors: Zudov V.N.  , Tupikin A. V.
Published: September 2022

The influence of an electric field on the plasma of an optical discharge in subsonic and supersonic air flows has been studied experimentally. The presence of a weak electric field practically does not affect the size of the plasma formation, but, regardless of the configuration of the field lines and the polarity of the applied voltage, it leads to a decrease in the probability of optical breakdown. The experiment has shown that the plasma created by focused laser radiation is very sensitive to the presence of an electric field. When a voltage exceeding 22 kV was applied to the ring electrodes, powerful quasi-stationary streamers were formed in the flow. The presence of an optical discharge plasma made it possible to create an electric discharge in fields with an intensity below the breakdown threshold of the medium. The effect of quenching and the processes of development of an optical discharge were studied depending on the speed and characteristics of the electric field. Quenching of the optical discharge was observed when a voltage of 22 kV and higher was applied. Despite the preservation of the geometric dimensions of the optical discharge, the high-temperature region in the flow can be increased by using electric streamers. This leads to an increase in the energy supplied to the flow, and thus allows combustion to be initiated and flame stabilized at higher flow rates. Keywords: experimental modeling, laser radiation, optical breakdown, electric field, electric discharge, sub- and supersonic air flow.
Fluctuation-dissipation theorem and frequency moments of response functions of a dense plasma to an electromagnetic field
Authors: Pavlov G. A.
Published: September 2022

The fluctuation-dissipative theorem and frequency moments for quadratic functions of the reaction of a dense plasma in a constant magnetic field to an electromagnetic field are considered. The frequency moments of the corresponding correlation functions are studied. A model approach is proposed to calculate quadratic reaction functions that determine nonlinear phenomena caused by the quadratic interaction of electromagnetic waves in a dense charged medium (Coulomb systems, plasma) in a constant magnetic field. Keywords: dense plasma, nonlinear fluctuation-dissipative theorem, quadratic reaction functions, nonlinear phenomena. Keywords: dense plasma, nonlinear fluctuation-dissipation theorem, quadratic response functions, nonlinear phenomena.
High temperature superconducting magnetic system for neuron activity researches
Authors: Diev D.N.  , Kovalev I.A.  , Makarenko M.N.  , Naumov A.V.  , Polyakov A.V  , Surin M.I.  , Shutova D.I.  , Shcherbakov V.I.
Published: September 2022

The paper describes a high-temperature superconducting magnetic system (HTS SMS) to equip an experimental stand intended for neuron activity researches under constant and low-frequency magnetic fields up to 1 T. The design of the magnetic system together with its electromagnetic and cryogenic parameters is briefly discussed. The test results of the preliminary experiments conducted in liquid nitrogen at 77 K for two interchangeable magnets are given. The first magnet was manufactured in the form of a double pancake coil wound with 4 mm high HTS tape. The second magnet was made of pure copper wire with no frame and was impregnated with a thermally conducting epoxy resin. The advantages of the HTS pancake coil were demonstrated in comparison with the cryo-resistive solenoid. Low energy consumption of the HTS magnetic system will allow conducting continuous non-invasive monitoring of biological objects in a magnetic field. Keywords: superconductivity, high-temperature superconductor, REBCO tape, cryogen magnetic system, magnetic field, neuron activity.
Prethreshold effects, when copper and its alloys were impacted to ultraviolet laser pulses
Authors: Malinskiy N. V.  , Rogalin V. E.
Published: September 2022

The prethreshold processes on the surface of copper and its alloys are investigated. In the absence of obvious traces of melting, while preserving the metal in a condensed state, under a nanosecond ultraviolet laser radiation energy density of 0.1-1.0 J/sm2, manifestations of high-temperature plastic deformation were observed. These are sliding and cracking along grain boundaries, within which crystallographic slipping was observed. A microprotrusion was formed on the surface of the irradiated zone, which was outwardly similar the distribution of laser radiation in the spot. The height of the microprotrusion reached 1 μm, and sometimes even more. An increase in the number of impacting impulses led to the accumulation of damage. The data obtained are in many ways similar to the acoustoplastic, electroplastic, and magnetoplastic effects. By analogy, we consider it possible to call the discovered effect optoplastic. Keywords: plastic deformation, optoplastic effect, crystallographic slip, laser.
A variational approach to the determination of the dynamic strength of a material
Authors: Evstifeev A.D.  , Volkov G.A.
Published: September 2022

The problem of the determination of material strength properties through the Kolsky experimental technique is considered. Small size specimens of M1 copper alloy are tested on a split Hopkinson pressure bars equipment. The experimental data of tensile tests observed under both dynamic and quasi-static conditions are analysed within the framework of the incubation time criterion and the Sign-Perturbed Sums method. It is shown that the influence of a test performance error is considered in the data treatment procedure based on the developed method. Keywords: Dynamic strength, incubation time criterion, Kolsky bar system, Sign-Perturbed Sums method.
Magnetic impedance of film nanostructures for stray magnetic field evaluation of microparticles in magnetic composites
Authors: Melnikov G. Yu.  , Lepalovskij V. N.  , Kurlyandskaya G. V.
Published: September 2022

Longitudinal giant magnetoimpedance effect of [Fe21Ni79/Cu]5/Cu/[Fe21Ni79/Cu]5 film element was investigated depends on stray magnetic field of epoxy magnetic composite with 30% weight concentration of iron oxide magnetic microparticles. Configuration of an experiment was a model of thrombus detection in a blood vessel. Stray magnetic field was varied by movement of a magnetic composite above the element perpendicular to the long side. Composite was either magnetized or not to the state of remanence. As the magnetic composite approaches the GMI element, MI ratio curves are smoothed and shifted along the field axis and maximum value of the MI ratio decreases. Magnetic properties of magnetic composite and film element were investigated as well. Keywords: Magnetoimpedance effect, multilayered film nanostructures, composite materials, biodetection.
Simulation of the ultracold neutron source at the reactor PIK
Authors: Fomin A. K.  , Serebrov A. P.
Published: September 2022

The paper presents the simulation of a complex of reserch with ultracold neutrons at the reactor PIK (Gatchina, Russia). The complex is being built on the basis of a high-intensity source of ultracold neutrons at the channel GEK-4. A Monte Carlo model has been developed, which includes a source, a neutron guide system and an experimental setup for search for the electric dipole moment of a neutron, taking into account their real location in the main hall of the reactor. Using the developed computer model the density of ultracold neutrons in the setup was obtained, which is 200 cm-3. It is 50 times higher than at the source at the Institut Laue-Langevin (Grenoble, France). This density will allow to achieve a sensitivity of measurements in the experiment of 1·10-27 e· cm/year. Keywords: ultracold neutrons, high intensity source, superfluid helium.
Change in the normal spectral emissivity during melting of elements
Authors: Kosenkov D.V.  , Sagadeev V.V.
Published: September 2022

An experimental and computational study of the normal spectral emissivity during melting of various metals was carried out, the installation scheme and the method of conducting experiments were given. The possibilities of the electromagnetic theory for describing the dependence of the behavior of the normal spectral emissivity of metals and semimetals are evaluated. Keywords: normal spectral emissivity, wavelength, metal, electromagnetic theory.
Formation of the microchannel structure of a spark discharge in air in the gap spike-plane
Authors: A.A. Tren’kin  , K.I. Almazova  , A.N. Belonogov  , V.V. Borovkov  , E.V. Gorelov  , I.V. Morozov  , S.Yu. Kharitonov
Published: September 2022

The formation of the microchannel structure of a spark discharge in the gap spike (cathode)-plane of 1.5 mm length in the air of atmospheric pressure was studied by the method of shadow photography. The images with the concurrent descent of microchannel diameter sand the number of microchannel increase in the cathode region on the time interval of 5 ns were recorded. The obtained data are explained in the frames of the microstructure formation mechanism at the expense of the front instability of the ionization wave. The parameters characterizing the process of the microstructure formation are estimated, and they agree with the experimental data. Keywords: spark discharge, ionization wave, ionization instability, microstructure, method of shadow photography.
Full-wave 2D modeling of helicons propagation and absorption in thespherical tokamak Globus-M2
Authors: Irzak M. A.  , Nechaev S. A.
Published: September 2022

Numerical modeling of propagation and absorption of fast waves(helicons) with frequency 200 MHz in 2D inhomogeneous plasma of thespherical tokamak Globus-M2 was carried out with 2D full-wave code. Toroidal effects, poloidal magnetic field and the actual shape of the fluxsurfaces were taken into account. The full wave electric field and RF powerabsorption profiles were computed by solving plasma wave equation withelectron Landau damping term. The modeling demonstrated a fairly highefficiency of helicons absorption in the bulk plasma within a wide range ofexperimental parameters. The waves propagate to the inner regions of theplasma column and are mainly absorbed there; less than 20% of RF energyreturns back to the plasma periphery. Keywords: high temperature plasma, nuclear fusion, tokamak, high frequency plasma waves, helicons, plasma wave equation, full-wave code.\
Microwave diagnostics of electrical discharges in an artificial cloud of charged water drops
Authors: Bogatov  N. A.  , Syssoev V.S.  , Sukharevsky  D. I.  , Naumova  M. Yu.
Published: September 2022

The microwave diagnostics of discharges occurring in an artificial cloud of charged water droplets created in an open air simulating the environment of thunderclouds is implemented. An artificial cloud with a droplet size of about 1 microns is opaque in the visible range, so intra-cloud discharges are not available for investigation by traditional methods in the spark discharge physics based on the registration of visible discharge radiation. Microwaves pass through such a cloud without noticeable attenuation, they interact only with the plasma of discharges occurring in the cloud. The probing microwave radiation had a wavelength of 8 mm. The attenuation of microwaves passed through the cloud was measured with temporary resolution of about 10 ns. The temporal characteristics of intra-cloud discharges were investigated. Keywords: spark, leader, streamer, electromagnetic wave.
Experimental and Theoretical Study of high-velocity penetration of long rod projectiles into sand
Authors: S.I. Gerasimov  , Yu.F. Travov  , A.G. Ioilev  , V.V. Pisetsky  , N.N. Travova  , A.P. Kalmykov  , S.A. Kapinos  , N.V. Lapichev  , Yu.I. Faikov
Published: September 2022

Results of computations with the use of improved modified Alekseevskii-Tate theory (IMATT) are compared to experimental data on high-velocity penetration of long rod projectiles into sand in the impact velocity range of V_0=0.5-3.5 km/s. Projectiles were made of three different metals: M1 copper, WNZh tungsten heavy alloy and 30KhGSA steel. The value of hardening coefficient k in the linear dependence of the projectile material yield on pressure could be determined using IMATT and experimental data on dependence of differential penetration coefficient K on the penetration velocity. At penetration in regime of the hydrodynamic erosion of projectile, differential penetration coefficient K could be approximated just by dependence on the ratio of the impact velocity of penetration to the value of the critical velocity, above which the projectile deforms plastically during penetration. The values of the critical velocity may differ for specific projectile material properties as well as the density and the humidity of sand. Keywords: high-velocity penetration, plastic deforming, yield, hydrodynamic erosion, Alekseevskii-Tate theory, experiment.
Critical current in a long Josephson contact with weak pinning in an external magnetic field
Authors: M.A.Zelikman
Published: September 2022

The analysis of possible current distributions when passing current through a periodically modulated long Josephson contact located in an external magnetic field is carried out. An approach based on the analysis of continuous configuration modification proceeding in the direction of Gibbs potential reduction is used for the calculation. The case when the pinning parameter is less than the critical value is considered. It is shown that at any value of the external magnetic field, there is a critical value of the transport current, when exceeded, the situation ceases to be stationary, as a result of which energy passes into radiation and heat, i.e. currents cease to be persistent. The value of the critical current is determined by the value of the magnetic field at which the vortices begin to fill the entire length of the contact. With an increase in the external magnetic field, the critical value of the current decreases. Keywords: high-temperature superconductors, pinning, Josephson contacts.
Effect of nanotubes on the electrical and mechanical properties of chitosan films
Authors: Kamalov A. M.  , Kodolova-Chukhontseva V. V.  , Dresvyanina E.N.  , Maslennikova T. P.  , Dobrovolskaya I. P.  , Ivan'kova E. M.  , Popova E. N.  , Smirnova V. E.  , Yudin V. E.
Published: September 2022

Using the methods of X-ray diffraction and scanning electron microscopy, the structure of composite films based on chitosan and single-wall carbon tubes has been studied. It is shown that the introduction of carbon nanotubes leads to the ordering of the chitosan structure. Increase in concentration of nanotubes (from 0 to 3%) causes rise in the value of storage modulus from 3 to 4 GPa (DMA data), increase in electrical conductivity of samples (from 10-11 to 102 S/m), and some changes in their dielectric permittivity (from 5.5. to 26 at an electrical field frequency of 1 kHz). Data on the ionic and electronic components of the conductivity of the composite film are presented. Keywords: chitosan, electrical conductivity, nanotubes, dielectric constant, composite.
Application of uncooled microbolometers for detecting pulsed terahertz and infrared radiation
Authors: Dem'yanenko M. A.  , Startsev V. V.
Published: September 2022

Analytical relations for temperature response of the bolometer to periodic radiation pulses are obtained. It is theoretically shown and experimentally confirmed by the example of infrared bolometers that when detecting short radiation pulses, in contrast to the case of constant radiation, increasing the thermal conductivity of the bolometer and, accordingly, decreasing its thermal relaxation time, it is possible to significantly increase the response rate of the receiver, practically without reducing its sensitivity. The possibility of effective registration of pulsed terahertz radiation by microbolometers with a resistively coupled, thermally non-isolated antenna is considered. It is shown that such bolometers, which have increased thermal conductivity and, accordingly, reduced sensitivity to continuous-wave radiation, can be highly effective when detecting pulsed radiation with a duration shorter than the thermal relaxation time of the bolometer. On their basis, uncooled matrix detectors of pulsed terahertz radiation, characterized by a minimum detectable energy of less than 1·10-12 J and a frame rate of up to 1000 Hz, can be developed. Keywords: microbolometer, pulsed terahertz radiation, antenna.
Temperature modes and mechanical stresses in photovoltaic converters of concentrated sunlight
Authors: Panchak A. N.  , Shvarts M. Z.
Published: September 2022

In photovoltaic converters of concentrated sunlight, the thermal flow is directed from the photoactive region (p-n junction) to a heat-spreading basement through the substrate. The heat sink transfers the excess thermal to the environment by convection or cooled by a liquid carrier. Reducing the thickness of the substrate makes it possible to reduce the thermal resistance of the crystal and lower the operating temperature of the photoactive region. However, in this case, the mechanical stresses in it increase. This work discusses the balance between the mechanical strength of the sample and the decrease in its operating temperature. Keywords: photovoltaic converters, heat sink, temperature regime, mechanical stress.
Radar absorbing and shielding characteristics in ferrite-polymer composites Mn-Zn ferrite/P (TFE-VDF)
Authors: Shakirzyanov R.I.  , Isaev I.M.  , Kostishin V.G.  , Kayumova A.R.  , Olitsky V. K.  , Salogub D.V.
Published: September 2022

The article discusses the electromagnetic absorbing and shielding properties of ferrite-polymer composites of the composition Mn-Zn ferrite/fluoroplast-42, obtained by pressing a mixture of powders with heating. The measurement of the complex magnetic and dielectric permittivity spectra, as well as the reflection coefficient spectra was carried out in the frequency range 0.1-7 GHz. Using the obtained spectra, a comprehensive analysis of the absorbing characteristics of the composites was carried out, and the factors responsible for the absorption were determined. Fitting of the composites magnetic permeability spectra show that the process of natural ferromagnetic resonance prevails over the resonance of domain walls, and a decrease in the concentration of ferrite inclusions leads to a significant shift in the frequency of natural ferromagnetic resonance to high frequencies. It was found that for composites with a thickness of 5-10 mm, compositions with a mass fraction of ferrite ≤0.4 show radio-absorbing properties, while compositions with a fraction of ≥0.6 show shielding properties. Keywords: polymer composite, magnetic properties, radio absorption, feromagnetic resonance, polyvinylidene fluoride, manganese-zinc ferrite.
Microwave Resonant Spectroscopy of Semiconductors with MicrometerResolution
Authors: Reznik A. N.  , Vostokov N. V.
Published: September 2022

We have proposed and experimentally verified a local method ofmicrowave resonant spectroscopy of semiconductors. The microwave circuit ofthe spectrometer based on the Cascade Microtech probe station is equippedwith a coaxial resonator of special geometry. As result, the measurementaccuracy of the previously developed volt-impedance spectroscopy method wasgreatly increased. A technique for spectrometer calibration and resonantmeasurements of the complex impedance of the probe-sample system has beendeveloped. We have measured the impedance of test structures with Schottkycontacts of 30-60 μm in diameter on a single-crystal GaAs wafer at severaldiscrete frequencies in the range of 50-250 MHz . The nontrivial resistiveproperties of the structures are studied, which consist of the excessresistance that is 1-2 orders higher than the spreading resistance for thealternating current in the unperturbed region of the semiconductor. Thediscovered effect is presumably associated with the a.c. charge modulationon deep levels of the semiconductor. A model calculation of the impedancespectrum has been performed, which demonstrates a good agreement with theexperimental spectra. Keywords: Microwave microscope, near field, probe, resonator, impedance, semiconductor.\
The features of the layers growth in stressed InAs/GaSb superlattices
Authors: Levin R.V.  , Nevedomskiy V. N.  , Sokura L.A.
Published: September 2022

The paper presents the results of a study of factors affecting the thickness of transition (interface) layers in stressed InAs/GaSb superlattices during growth by MOCVD method. It is shown that the thicknesses of the interface layers between InAs and GaSb are practically independent of the growth temperature. The thickness of the interface layers is influenced by the direction of switching the layer growth. The smallest thickness of 1.2-1.4 nm of the interface layer InAs/GaSb was obtained for the direction of growth switching from GaSb to InAs. Keywords: MOCVD, stressed superlattice, InAs/GaSb, interface layer, transmission electron microscopy.
Magnetc states in the surface dimer model for adsorption
Authors: Davydov S. Yu.  , Posrednik O. V.
Published: September 2022

For the electrons of surface dimer formed by adsorbed particle and substrate atom effects of the intra- and interatomic Coulomb interactions are taken into account. Two cases are considered: adsorption of magnetic particle on nonmagnetic substrate and adsorption of nonmagnetic particle on magnetic substrate. Analytical expressions for the surface dimer magnetization are obtained for the regimes of weak and strong dimer --- substrate coupling. Keywords: adsorbate, substrate, occupation number, magnetization
Bending test of nanoscale consoles in atomic force microscope
Authors: Ankudinov A. V.  , Khalisov M. M.
Published: September 2022

Consoles and bridges of MgNi2Si2O5(OH)4 nanoscrolls were tested for bending in atomic force microscope. Using test data, we analyze how the consoles or bridges were fixed, and took this information into account when calculating the Young's modulus of the nanoscrolls. The results on the consoles are in good agreement with the results on the bridges when modeling the latter as three-span beams, and the former as beams on an elastic foundation with a suspended console. Keywords: AFM, nanoscroll, bending, Young's modulus, Krylov's functions.
The intermolecular interaction influence on non-linear optical properties in COANP-carbon nanoparticles system
Authors: Likhomanova S.V.  , Kamanina N.V.
Published: September 2022

The main results of non-linear optical, spectral and current-voltage characteristics research of pyridine organic conjugated molecule-carbon nanoparticles combined system have been presented. The perspective of these materials further study in global trends of modern search of materials for optical limiting has been demonstrated also in the present paper. Keywords: fullerenes, charge transfer complex, optical limiting, organic conjugated molecules
Distribution of mechanical properties in annual growth rings of deciduous trees measured using scanning naation
Authors: Golovin Yu. I.  , Tyurin A. I.  , Gusev A. A.  , Matveev S. M.  , Golovin D. Yu.  , Vasyukova I. A.
Published: September 2022

The paper presents the results of mechanical properties scanning by means of naation across the annual growth rings of deciduous trees wood, small-leaved lime (Tilia cordata) and common oak (Quercus robur) in particular. Significant variations in microhardness H and Young's modulus E radial dependencies have been found for any of the studied species. Results can be useful 1) to amend the understanding the nature of macromechanical properties of various wood species and to reveal the details of their formation depending upon microstructural characteristics, 2) to optimize the technologies of growing, reinforcement and subsequent usage of the wood, 3) to develop new independent methods in dendrochronology and dendroclimatology Keywords: nanocomposites, naation, nano-/microhardness and Young's modulus scanning, tree annual growth rings, dendrochronology
Investigation of the parameters of a self-focused electron beam outputted behind the anode of a vacuum diode
Authors: Oleshko V.I.  , Nguyen V. V.
Published: September 2022

The parameters of a high-current electron beam extracted from the self-focusing zone through a hole in the anode into a vacuum chamber are investigated. The beam parameters were determined from the measurement of the spatial distribution of destruction and glow arising in polymethyl methacrylate samples installed at different distances from the anode (electron beam autographs). The formation of two electron beams --- a self-focused with a high energy density, propagating along the axis of the cone facing the base to the anode with an apex angle of ~ 7o and a high-energy beam of low density, propagating in a hollow truncated cone and surrounding self-focused, was found. The oscillograms of the current and the energy of the electron beams were measured. Keywords: vacuum diode, electron beam, filamentation, self-focusing, polymethyl methacrylate, destruction, glow, high current pulsed electron beam