Journal of Physics and Electronics

3-8

Authors: O.A. Borisenko, V.V. Skalozub

In SU(2) gluodynamics, the Debye gluon contribution WD(A0) to the effective action of the temporal gauge field component (we consider A0 = const) in the background Rξext is calculated at high temperaturegauge. It is shown that at A0 ≠ 0 the standard definition k0 = 0 , |k| → 0 corresponds to long distance correlations for the longitudinal in internal space gluons. The transversal gluons become screened by the A0 background field. Therefore, they give zero contributions and have to be excluded from the correlation corrections. The total effective action accounting for the one-loop, two-loop, and correct WD(A0) satisfies Nielsen’s identity that proves gauge invariance of the A0 condensation phenomenon.

17-28

Authors: S.F. Lyagushyn, A.I. Sokolovsky, S.A. Sokolovsky

Kinetics of electromagnetic field in noneqilibrim medium of atoms is studied on the basis of the Dicke model. The field is described by average electric and magnetic fields and their binary correlations. The atoms are considered in two-level approximation and assumed to be fixed in the space. States of the medium are described by the energy density. Nonresonant atom-field interaction is accounted phenomenologically. The theory is built on the Bogolyubov idea of the functional hypothesis that is the basis of his method of the reduced description of nonequilibrium processes. The investigation of the system is carried out in the framework of the Peletminsky–Yatsenko model. Atom-field interaction is assumed to be small and is taken into account up to the second contributions in the interaction included. Average electric and magnetic fields satisfy the Maxwell equations. Material equations for them express average current and charge densities through the average field. Evolution equations for the binary correlation of the field are constructed. Material equations for these equations express correlations field-current trough correlations field-field. The time equation for energy density of the medium is obtained. Density evolution is governed by the average field and field correlations. All material coefficients of the system are found.

37-42

Authors: A.N. Galdina

The supercritical transitions are widely occurring. They include the supercritical transitions in the liquid-vapor system, ferromagnetic transitions, transitions in polymers, many transitions in liquid crystals, and some structural transitions. In the paper it is emphasized that the nature of the critical and supercritical transitions is the same – these are continuous fluctuation transitions. Above the critical temperature the system passes through a region of lowered stability, which leads to increase of fluctuations of energy and external parameters of the system. From the point of view of thermodynamic stability this indicates the existence of a continuous supercritical transition between supercritical mesophases. Knowing the basic stability characteristics of a system, we derive the equation of these mesophase transitions. Depending on a thermal equation type, we can get one or several such equations, which may not coincide. This approves the fact that a supercritical transition occurs in a certain interval of thermodynamic forces. In the paper the relations between the critical exponents of thermodynamic parameters of the system are obtained and the conditions of continuous conjugation of the lowered stability line to subcritical coexistence line are investigated. The results are applied to the Curie–Weiss and van der Waals models: we obtain the quasi-spinodal equation for these systems and analyze the critical and supercritical behavior of the stability characteristics.

47-50

Authors: V.F. Bashev, N.A. Kutseva, O.I. Kushnerov, S.I. Ryabtsev, O.V. Yelina, O.O. Veres

Using the modernized three-electrode ion-plasma sputtering method, homogeneous thin films of FePt and Fe (Pt/Bi) were obtained. Films were deposited on NaCl and glass-ceramic substrates. The film thickness was 120-530 nm. In this case, the calculated cooling rate reached ~ 1012–1014 K/s. The structure of the FePt and Fe (Pt/Bi) films was investigated using X-ray diffraction and electron microscopy methods. It was established that metastable phases were formed in freshly sputtered films, including a supersaturated solid solution, a nanocrystalline and amorphous phases. It was determined that the obtained metastable structures are stable when heated to 540-880 K, depending on the composition. It was established that Bi additives significantly reduce the coercive force of films in the as-sputtered state. It was shown that a heat treatment increased the coercive force up to 36 kA/m in FePt films and up to 10 kA/m in Fe (Pt/Bi) films. The composition of Fe (Pt/Bi) films with a small value of the temperature coefficient of resistance (TCR ~3·10-5 K-1) was determined.

55-60

Authors: L.I. Fedorenkova, G.P. Fedina

The work is devoted to the research of influence of the electrolysis on the saturating ability of the electrolyte, which is a borax melt. To establish regularity when the saturating medium activity changes, which influences the intensification of saturation process, the structure and properties of borax during electrolysis were investigated. The change in the saturating medium activity was estimated by a relative value equal to the ratio of the boride layer depth obtained by non-electrolysis borating to the layer depth obtained by electrolysis borating. When comparing the real and theoretical saturating abilities, their convergence was observed. It was found that the saturation ability of the borax melt increases with increasing electrolyte runtime, which is due to a change in the structural components of the borax melt. A quantum-chemical calculation of the borax molecule structure was carried out using the non-empirical method of molecular orbitals in the theory of the density functional (DFT) with the three-parameter exchange-correlation functional B3LYP. Calculations show that two main structures are characteristic of a borax molecule: non-coplanar, with two mutually perpendicular 4-membered boron-oxygen cycles and flat linear. An increase in the saturation ability of the borax melt during electrolysis allows the development of new low-energy borating processes.

65-68

Authors: N.A. Kutseva, V.F. Bashev, S.I. Ryabtsev, O.S. Krapivina-Soloviova

Effect of geometrical parameters (metallic core diameter, glass cover thickness) on the structure and magnetic properties of glass-coated Fe-Si-B-Nb-Cu microwires is investigated. The structure of as-prepared Fe73.8Cu1Nb3.1Si13B9.1 microwire is nanocrystalline, consisting of α-Fe(Si) crystallites in a residual amorphous matrix. It is shown that great residual stresses arising at the manufacturing processes greatly influence the microstresses and crystallite sizes of α-Fe(Si) crystals. An increasing of stress magnitude results to structure refinement. The size of α-Fe(Si) crystals and crystallized volume fraction decrease from approximately 105 nm and 71 % to 9 nm and 34 %, respectively, with glass cover thickness increasing. Grain size refinement of α-Fe(Si) leads to the considerable decrease of coercivity of microwires from 1800 A/m to 160 A/m.

77-80

Authors: Y. Syetov

Lattice vibrations are studied theoretically by density-functional based tight-binding methods for the model structure of 2-(2'-hydroxyphenyl)benzoxazole crystal with defects. 2-(2'-hydroxyphenyl)benzoxazole is a photoreactive compound that exhibits excited state intramolecular proton transfer in the structure with an OH...N hydrogen bond. The unit cell of the model structure consists of two crystal unit cells where the molecules have the structure with intramolecular hydrogen bonds OH...N and one molecule is supposed to have a different orientation of the whole molecule or its fragment. The different orientation of the fragment forms the structure with an intramolecular hydrogen bond OH...O. It is calculated that defect caused by the different orientation of the molecule have a lower energy than the defect caused by the different orientation of the fragment. In the frequency region where the contribution of external vibrations of the molecules is significant, the vibrations mainly involve several molecules in the cell. In the region of internal vibrations there are modes, which are local vibrations of the defects. These local vibrations involve mainly motion of the atoms constituting the defect molecule. The number of local vibrations is larger for the defect that corresponds to the formation of the structure with the OH...O hydrogen bond than for the defect that corresponds to the different orientation of the whole molecule with the OH...N hydrogen bond. The internal vibrations of the defect molecule formed by the different orientation of phenol fragment in the lattice undergoes frequency shift in relation to the frequency of the modes of isolated molecule.

85-88

Authors: T.V. Panchenko, L.M. Karpova

The temperature-frequency dependences of the complex dielectric permittivity ε and the voltage-farad characteristics of undoped and aluminum doped Bi12SiO20 crystals are studied before and after their polarization. It is shown that Al ions in the Bi12SiO20 dielectric matrix provide a significant increase as well as nonlinearity of ε in the temperature range 300 – 800 K and electric field strengths Е = 103 – 104 V/cm. It is shown that polarization causes the appearance of dielectric hysteresis loops. Al impurity significantly affects the appearance and parameters of these loops. The role of Al ions in increasing the contribution of the quasi-dipole mechanism in the polarization processes is revealed.

93-98

Authors: A.I. Ivon, R.I. Lavrov

The current-voltage characteristics of various compositions of nonlinear varistor ceramics based on ZnO (ZOC) and SnO2 (TOC) are studied in a wide range of electric current. On the basis of obtained data were determined the parameters that allow finding the coefficients kprs and kprl, which define the protection levels against the switching surge and the lightning surge for surge suppressors on the basis of ZOC and TOC varistors. The lower the value of these coefficients are, the significantly higher the efficiency of surge protection is. A relationship between kprs, kprl, and the effective linear resistivity ρlin limiting the current of intergranular barriers in varistor ceramics are established. It is shown that the values of kprs and kprl increase with increasing ρlin, which value is determined by the bulk resistance of the ceramic grains. The studied TOC compositions have 2-3 times larger values of ρlin and more high values of kprs and kprl than ZOC. ZOC-based varistors with lower kprs and kprl values provide more effective surge protection than TOC-based varistors.

105-110

Authors: A.B. Gnilenko, S.V. Plaksin

Millimeter waves are now considered as an important part of 5G spectrum. Higher frequencies provide larger bandwidth giving the ability to support very high data rate, ultra high capacity and very low latency. The utilization of millimeter wave frequency bands for 5G mobile applications requires effective solutions in the design of antennas and antenna arrays which are the key parts of modern communication systems. In this paper a 4x4 microstrip patch antenna array sub-module is presented to be a part of 5G wireless communication system. The antenna array is designed and optimized to operate at a frequency of 85 GHz which corresponds to the middle of the second atmospheric transparency window. The antenna array is simulated using the time domain solver of the CST Microwave Studio software package. Simulation results are demonstrated and discussed for an optimized array. The designed patch antenna array provides good directivity characteristics with a main lobe magnitude of 16 dBi, angular width of 28 degree and can be applied as a part of a wireless communication system operating at a high frequency band of 5G frequency range.

3-8

Authors: V. D. Gladush

Analytical aspects of the classical geometrodynamics for the spherically-symmetric configuration of the electromagnetic and gravitational fields in GR are considered. The feature of such configurations is that they admit two motion integrals – the total mass and charge. The Einstein-Hilbert action for the configuration, after dimensional reduction, by means of the Legendre transformation is reduced to the Hamiltonian action. Using the conservation laws for the mass and charge, as well as the Hamiltonian constraint, the momenta are found as functions of configuration variables. The set of equations, which associate momenta and functional derivatives of the action in the configuration space (CS) is integrable. This allows us to obtain the action functional as a solution of the Einstein-Hamilton-Jacobi equation in functional derivatives. Variations of the action functional with respect to mass M and charge Q of the configuration lead to the motion trajectories in the CS. We note that the minisuperspace metric, which is induced by the kinetic part of the Lagrangian, does not coincide with the CS metric that arises when the function of lapse N is excluded from the action. The space-time metric for which the indicated metrics coincide in the T-region up to a coefficient are considered. The metric of CS is constructed and its geometry is studied. Under the trivial embedding of hypersurfaces of the foliation into a dynamical T-region, the CS is flat. It allows introducing pseudo-Cartesian coordinates in which the CS metric takes the Lorentz form.

19-26

Authors: A.N. Galdina

It is known that basic stability characteristics of a system are inversely proportional to fluctuations of external parameters. Above the critical point there is a region remaining homogeneous macroscopically, but becoming microheterogeneous within an interval of thermodynamic forces. Within this interval thermodynamic coefficients of stability pass finite non-zero minima. This corresponds to the considerable growth of fluctuations and indicates the occurrence of supercritical transition of continuous kind. The limit case of such continuous phase transitions is the critical state, which is also the limit point of some first-kind transitions (the limit point of phase equilibrium curve). In this paper we consider the relation between thermodynamic stability conditions and fluctuations of external parameters of the system. We study the behavior of a simple one-component thermodynamic system (liquid, magnet, and ferroelectric) in the supercritical region and derive the equation of the line of supercritical transition for this system.

31-36

Authors: N.Yu. Filonenko, A.N. Galdina

It is known that solubility of elements affects the phase composition of alloys that are formed in the solidification process. To predict the phase composition of alloys, it is necessary to determine the solubility limit in the phases. In the paper the structural properties of austenite of alloys in the system of Fe-B-C are studied and the solubility limit of boron and carbon is determined. The investigation is carried out for the specimens with carbon content of 0.0001–2.3 wt.% and boron content of 0.0001–1.0 wt.%, the rest is iron. To determine the physical properties of alloys, we use the microstructure analysis, X-ray microanalysis, X-ray structure analysis and differential thermal analysis. It is shown experimentally that the maximum shift of the eutectoid point is observed when boron content is up to 0.004 wt.%. When boron content of the alloy increases to 0.01 wt.%, the eutectoid point shifts to the left to 0.21 wt.%-carbon and the austenite area decreases. Further increase in the numerical value of boron content in the alloy is hardly caused the eutectoid point to shift. In this paper, the vertical section of the Fe-B-C system state diagram is obtained from experimental data. For the first time we obtain temperature dependence of the free energy of γ-iron solid solution, using the quasi-chemical method, and determine the solubility limit of carbon and boron. The maximum weight fraction of boron in the austenite can be up to 0.0136 wt.%, and that for carbon – up to 1.12 wt.%.

41-46

Authors: O.I. Kushnerov

The processes of melting and solidification of AlCoCuFeNi nanoparticle of about 10 nm is studied by molecular dynamics simulation at three different cooling rates (1∙1011 K/s, 1∙1012 K/s, and 1∙1013 K/s) using the embedded atom model (EAM) potential. The melting and crystallization of the nanoparticle are characterized by studying the temperature dependence of the potential energy. The adaptive common neighbor analysis (CNA) is performed and the radial distribution function (RDF) is calculated to determine the structure and lattice parameters of phases of the AlCoCuFeNi nanoparticle. It is shown that the final structure of the investigated nanoparticle changes from amorphous to crystalline with decreasing of the rate of cooling, and the temperature hysteresis takes place during the melting and crystallization of AlCoCuFeNi HEA nanoparticle.

51-56

Authors: O.V. Ohiienko, V.N. Moiseienko, M.D. Volnyanskij

The work is devoted to the study of photoluminescence spectra of weakly polar ferroelectric crystals Li2Ge7O15 and Li2O – 7GeO2 glasses. For all initial samples was observed the wide intensive luminescence band with maximum in the region of 525–550 nm. The spectral distribution of intensity and the position of the maximum of the band for a Li2Ge7O15 crystal depended on the excitation wavelength (λex=405 nm or 365nm were used). The spectral profile of the luminescence band was broadened in glass containing of 0.67% copper. The intensity of the luminescence band was decreased 6 times for glass doped with Cr3+ ions (0.01%) as compared with glass containing Cu2+ ions. The intense luminescence band of Cr3+ ions with λmax=659nm was appeared starting from 600. The assumption about the nature of the broad luminescence band observed in both nominally pure and doped glasses and crystals was made: the source of luminescence can be germanium - oxygen complexes [GeO4] and [GeO6] of the tetrahedral and octahedral configuration in the material structure.

63-70

Authors: V.S. Khandetskyi

A theoretical analysis of the interaction of the eddy current sensor field with powder particles makes it possible to calculate the particle conductivity using the measured value of the sensor added active resistance. Relative to its own reactance, the value of this resistance is proportional to powder density, frequency of the probing field, electrical conductivity of particles and square of their diameter. Particles of spherical shape and cylindrical shape, the height of which is equal to the diameter of the base, are considered. The analysis allows to explain the experimentally observed different character of the resistance frequency dependences for powder and corresponding solid material when measuring by the same sensor.

79-88

Authors: A.V. Ivanchenko, A.S. Tonkoshkur, S.V. Mazurik

The problems of reducing the cost of ensuring the safe operation of solar cells by using low-cost elements of solid-state electronics to protect against overvoltage photovoltaic cells of solar arrays are considered. The results of experimental studies of the use of a varistor-posistor structure based on a metal oxide varistor and PPTC fuses of the PolySwitch type being in thermal contact to prevent overvoltages in series connections of photovoltaic cells are presented. General schemes for using the considered solid-state structure to limit the indicated constant overvoltages are given and justified. The requirements to the parameters of this structure are determined and experimentally verified. It is shown that such a device makes it possible to limit the long-term constant overvoltages that occur in photovoltaic arrays at the level of photovoltaic cells in the case of their malfunction or shadowing, which can lead to fire hazard and other “abnormal” situations during the operation of solar electric energy sources.

95-100

Authors: V.V. Ovsyanikov, D.M. Svynarenko, O.R. Beznosova, L.Z. Tsypko

The article presents the results of theoretical and experimental studies of the current distribution, the values and coordinates of the load connection points, as well as the radiation patterns for two-band linear microwave antennas with quarter-wave two-wire shunts of the upper range and concentrated reactive loads. Such antennas are promising for use in two-band duplex mobile satellite systems for receiving and transmitting data, for example, GLOBALSTAR, IRIDIUM, ELLIPSO, GPS and others. Theoretical studies are carried out by the method of integral equation. It is found that with a constant length of a quarter-wave shunt and different sizes of the antenna, the antenna can acquire or lose the property of two frequencies. A method for eliminating this negative phenomenon is proposed.

3-6

Authors: M.G. Holovko, V.D. Gladush

The paper considers a spherically symmetric configuration of the gravitational and electromagnetic fields with allowance to the cosmological constant, and its quantization. After dimensional reduction, the original action is transformed to new variables in the R- and T-regions. The exclusion of the non-dynamic degree of freedom from the obtained action leads to an action for the geodesic in the configuration space, which proves to be conformally flat. We use the Gitman–Tyutin formalism for the obtained dynamical system, which Lagrange function is degenerate. After performing a suitable canonical transformation, the constraints found from the Lagrange function are reduced to the canonical form. Herewith the physical part of the Hamilton function vanishes. To construct quantum theory, we introduce additional physical quantities – charge and mass functions. Since Hamilton operator equals zero, it leads to the fact that the desired wave function of the system obeys only the eigenvalue equations for the mass and charge operators. The solution of these equations leads to continuous charge and mass spectra.

17-28

Authors: S.A. Sokolovsky, A.I. Sokolovsky, І. S. Kravchuk, O.A. Grinishin

On the basis of the Landau kinetic equation a generalized Lorentz model is proposed, which contrary to the standard model, considers ion system as an equilibrium one. For electron system kinetic equation of the Fokker-Planck type is obtained. In the Bogolyubov method of the reduced description, which is based on his idea of the functional hypothesis, basic equations for electron hydrodynamics construction with account for temperature and macroscopic velocity relaxation processes (kinetic modes of the system) is elaborated. The obtained equations are analyzed near the end of the relaxation processes when the theory has an additional small parameter. The main in small gradients approximation is studied in details, it corresponds to the description of relaxation processes in a spatially uniform case. The obtained equations are approximately solved by the method of truncated expansion in the Sonine polynomials. The velocity and temperature relaxation coefficients are discussed in one- and two-polynomial approximation. As a result the relaxation coefficients are calculated in one-polynomial approximation.

33-36

Authors: L.I. Fedorenkova

Copper and its alloy were treated in an electrolytic plasma formed in the boron-containing electrolyte under the action of discharge in order to obtain a diffusion coating with enhanced hardening characteristics and the structural changes in the surface layer of the metal that occur in this case were studied. As a result of processing in electrolytic plasma, characterized by high heating and cooling rates, a diffusion layer was formed on the surface of copper and an alloy based on it (brass). The layer contains nanosized inclusions of copper borides, ternary compounds Cu-B-H, Cu-B-O concentrated mainly along grain and phase boundaries and providing hardening of the metal surface. The action of the discharge provides structural and phase transformations in the metal, the deformation of the grains - elongation in the direction of the driving force (electric transfer) at a depth of 100 μm and the creation of metastable states in the surface layers. Moving vacancies and compressing atoms in the direction of the force create conditions for the rapid movement of boron atoms. With increase in current density and time of treating, the size of nanostructures decreases. Their size is of the order of 6-16 nm. Obtaining wear-resistant coatings on copper and its alloys, which include phases containing copper and boron, increases the strength characteristics of copper and its alloys by 1.5-2 times.

45-50

Authors: V.F. Bashev, S.I. Ryabtsev, S.N. Antropov, N.A. Kutseva, O.I. Kushnerov, E.S. Skorbyaschensky

The quantitative estimation of maximum level of cooling rates in the process of casting microwires in glass insulation is given. The shown possibility of nonequilibrium formation of microwire substance is due to the influence of an amorphous substrate in the form of glass insulation. The amorphous state in the case of thin microwires with cast iron vein Fe‒20 at.% C confirms the implementation of an increased (compared to splat-quenching) level of nonequilibrium formation of microwires in combination with updated rates of cooling and increased degree of supercooling of liquid microwire vein.

55-58

Authors: Y. Syetov

Two-photon absorption spectra of 2-(2'-hydroxyphenyl)benzoxazole, 2,5-bis(2-benzoxazolyl)phenol and 2,5-bis(2-benzoxazolyl)hydroquinone are modeled by time-dependent density functional theory calculations. In contrast to the linear absorption, where the transitions to the two lowest excited states are leading, the two-photon absorption cross sections are significant for the transitions to higher states which are weak in one-photon absorption spectra. The 2,5-bis(2-benzoxazolyl)phenol and 2,5-bis(2-benzoxazolyl)hydroquinone demonstrate the maximum cross section of about ten times larger than that of 2-(2'-hydroxyphenyl)benzoxazole. The largest value of the cross section is calculated for 2,5-bis(2- benzoxazolyl)hydroquinone to be about 1500 units of Goeppert-Mayer for excitation at 600 nm.

63-66

Authors: I.P. Volnyanskaya, M.P.Trubitsyn, D.M. Volnyanskii, D.S. Bondar

Electrical properties of Pb2MoO5 single crystal were studied in AC field (f=1 kHz) after irradiation with UV light (290 K). It was found that UV irradiation caused appearance of maximums on permittivity ε and conductivity σ temperature dependences, which were observed around 530 K. The anomalies of ε and σ vanished after annealing at 700 K and could be restored by subsequent UV irradiation performed at room temperature. The magnitude of ε and σ peaks increased for higher exposition time. Above 600 K conductivity σ was practically independent on irradiation. It is proposed that photoelectrons induced by UV light, are trapped by Mo located -within the oxygen tetrahedrons with vacancy VO in one of the vertexes. The dipole moments of (MoO3) groups reorient at VO hopping through the tetrahedron vertexes. Annealing at 700 K thermally decomposes (MoO3)- complexes. For T>600 K behavior of σ(T) is determined by conduction currents and nearly insensitive to UV irradiation. At high temperatures the photoelectrons do not contribute to conductivity since they are bound in (MoO3)- centers, recombine with holes or re-captured by more deep traps.

73-80

Authors: O.V. Kovalenko, S.М. Vovk, Ye.G. Plakhtii

The smoothing method for experimental photoluminescence spectra, which uses Tikhonov regularization method, is proposed. Smoothing problem statement is performed as a statement of the minimization problem based on the least squares criterion. The functional to be minimized is a compound of two terms. The first one is the basic term, which determines the quality of data approximation provided by smooth function. The second one is the regularization term, which sets a constraint on the energy by smooth function derivative of a given order. A solution of the smoothing problem is obtained in the closed form analytically. The solution can be implemented by a simple array of matrix operations; one of those is an operation of matrix inversion. The necessity of matrix inversion imposes constraints on the order of derivative used in the proposed method and on noise level. It is related to the increase of either the order of derivative at the given noise level in data or the noise level at the given order of derivative, that deteriorates the conditionality of a matrix to be inverted and limits the scope of the proposed method, accordingly. Efficiency comparison of the proposed smoothing method, the Savitzky-Golay method, and the moving average method was performed by the numerical simulation of two models of photoluminescence spectra. Their advantages, disadvantages, and also the scopes of applicability are noted. The best values of operating parameters of these methods for the different noise levels in data were obtained. The conditions, under which the potential capabilities of the proposed smoothing method excel the potential possibilities of Savitzky-Golay method, were indicated. The results of smoothing the experimental photoluminescence spectra obtained for ZnO:Mn nanocrystals and ZnS:Mn crystals are provided.

89-92

Authors: O.O. Drobakhin, O.V. Olevskyi

Applicability of inverse filtering with evolution control for reconstruction of images obtained by aperture synthesis technique is considered. A horn antenna, which is moved in the transversal direction, is used in order to obtain a 2-dimensional image. Scanned structure consists of one or two similar metaplates. In the latter case the plates are coplanar and their common plane is parallel to the aperture of the antenna. Regularisation coefficients are found with the help of trial and error method. The image of a single plate was used to tune the software. The Prony’s method is tested as a separate way of estimation of the distance between the plates. Both methods are tested for a range of different distances between the plates and between the plates’ common plane and aperture of the antenna. It is shown that inverse filtration tends to provide better results if the scanned object is situated further from the antenna. Said method was proven to be precise enough to distinguish closely-spaced plates. The Prony’s method was proven to provide reliable distance measurements if it was tuned correctly.

97-100

Authors: A.V. Ivanchenko, A.S. Tonkoshkur

Electrical characteristics of experimental two-layer structure based on layers of varistor ceramics and polymer nanocomposite with carbon filler being in thermal contact are studied. A layer of such polymer nanocomposite is used in PPTC fuses of the PolySwitch technology. The dependences of the output voltage on the varistor layer, current and temperature on the input voltage applied to the entire structure are analyzed. It is shown that with an increase in the input voltage, the output voltage reaches a certain value and does not change after that. It is concluded that the two-layer structure of varistor ceramics–PPTC nanocomposite type can be used as a limiter of constant electrical voltage and for protection of electrical circuits from long-term alternating electrical overvoltages.

3-10

Authors: I. A. Baranov, V. V. Skalozub

The presence of the A0 condensate in quark-gluon plasma leads to Z(3) symmetry breaking and Furry's theorem violation. Due to this phenomenon the color charges are induced and other even-number diagrams are allowed. We calculate the first diagram of this series – tadpole diagram with one gluon line and find induced color charges in the plasma. Next, quark polarization operator in presence is calculated and partially investigated.

19-28

Authors: K. M. Haponenko, A. I. Sokolovsky

The Landau definition of the effective Hamiltonian (of the nonequilibrium free energy) is realized in a microscopic theory. According to Landau remark, the consideration is based on classical statistical mechanics. In his approach nonequilibrium states coinciding with equilibrium fluctuations are taken into account (the Onsager principle). The definition leads to the exact fulfillment of the Boltzmann principle written in the form with the complete free energy. The considered system is assumed to consist of two subsystems. The first subsystem is an equilibrium one. The second subsystem is a nonequilibrium one and its state is described by quantities that are considered as order parameters. The effective Hamiltonian is calculated near equilibrium in the form of a series in powers of deviations of the order parameters from their equilibrium values. The coefficients of the series are expressed through equilibrium correlation functions of the order parameters. In the final approximation correlations of six and more order parameters are neglected and correlations of four parameters are assumed to be small that leads to the corresponding perturbation theory. The developed theory is compared with the phenomenological Landau theory of phase transitions of the second kind. The obtained results are concretized for paramagnetic-ferromagnetic system. The consideration is restricted by paramagnetic phase.

35-38

Authors: O. V. Sukhova, Yu. V. Syrovatko

The heat capacity of decagonal quasicrystals of the Al–Co–Cu or Al–Co–Ni alloys was calculated at the temperatures of 600, 700, and 900 K in this work. The expression for the heat capacity of the quasicrystals was obtained based on the Debye model. For the quasicrystals, the linear “excessive” heat capacity is observed in the range of temperatures between 400 to 600 К which means the deviation from the 3R Dulong-Petit value. The heat capacity at a temperature of 900 К is about 28.4 J/mol К which is higher than the Dulong-Petit value (~ 25 J/mol К). The “excessive” heat capacity relates to the peculiarities in the decagonal quasicrystal anisotropy. These crystals are quasiperiodic in the x and y directions, and periodic in the z direction. As a result, there is a difference in the dispersive laws in the different directions. The Debye temperature values have essential influence on the temperature dependencies of the heat capacity of the decagonal quasicrystals. Thus, the higher the Debye temperature and the larger “excessive” heat capacity, the more stable are considered the quasicrystals exposed to the temperature effects.

45-52

Authors: V. F. Bashev, N. A. Kutseva, О. I. Kushnerov, S. I. Ryabtsev, S. N. Antropov

The method of modernized ion-plasma sputtering produced metastable states, including nanocrystalline and amorphous phases in films of Fe-Ag, Fe-Bi, Fe-Ag-Bi, Fe-Co-Ag and Ni-Ag alloys whose components do not mixed in the liquid state. The periods of the crystal lattices and the dimensions of the crystallites of the nonequilibrium phases in the fresh-sputtered state and after the heating are determined. The temperatures of the beginning and the end of the decomposition of metastable phases are established when heated at a constant rate. The electric and hysteretic magnetic properties of films in freshly dusted and thermally processed states are measured. The compositions and conditions for obtaining films with low values of the temperature coefficient of electrical resistivity (~ 10-5 K-1) and high coercive force (HC ~ 150 kA/m) are established. Such films can be promising for use as thin-film precision resistors and magnetic information carriers with an increased recording density.

57-62

Authors: Y. Syetov

Structure and crystal lattice vibrations are calculated for 2-(2'-hydroxyphenyl)bezoxazole and bis-(2,5-benzoxazolyl)hydroquinone by density functional based tight-binding methods. Despite lowering of the molecular symmetry, structure parameters of the molecules in crystal and forms of the internal vibrations are similar to those of isolated molecules. Weak interaction between the molecules in the molecular crystals leads to appearance of the external vibrations, splitting and mixing of the vibrations of the isolated molecules into internal crystal vibrations. External and internal vibrations are not separated well; contribution of the translations and librations is noticeable in the region below 150 cm-1. The magnitude of the splitting does not exceed 4 cm-1 for the most vibrations. The internal vibrations that correspond to the out-of plane molecular vibrations demonstrate larger molecule-to-crystal frequency shift than in-plane modes, mostly to higher frequencies, whereas the modes involving torsion motion of the OH bond are shifted toward lower frequencies. Mixing occurs for the molecular vibrations with frequencies that are different by less than 16 cm-1. Calculations performed for model molecular clusters show that the defect caused by different molecule orientation has lower energy than the defect related to the formation of rotamers.

69-72

Authors: O. V. Kovalenko, M. F. Bulaniy, V. Y. Vorovskiy, O. V. Khmelenko

Nanocrystals of ZnO:Mn were obtained by ultrasonic spray pyrolysis and had dimensions of d ~ 36 nm. The changes of photoluminescence end EPR spectra of these nanocrystals in dependence of Mn admixture concentration ( 2–8 at. %) and also at heat treatment in air during 1 hour at T = 850 ̊C were investigated. It is shown that under short-term (7–10 s) nonequilibrium conditions of ZnO:Mn nanocrystals forming, they consist of a nuclens and shell surface, in which, predominantly, the Mn admixture is concentrated. After annealing, the Mn admixture diffuses into the nucleus of a nanocrystal.

77-82

Authors: A. V. Ivanchenko, A. S. Tonkoshkur, S. V. Mazurik

The results of experimental study of the transformation of the light current-voltage and volt-watt characteristics for the parallel connections of photovoltaic modules when using “PolySwitch” polymer resettable fuses are given. The conditions for selecting such fuses which allow their correctly triggering and minimize the current overload are formulated and experimentally verified. It is established that if resettable fuses are connected in series to the circuits of all photovoltaic modules, which are connected in parallel thus forming a unit, this prevents such a situation as the complete loss of electrical energy generated by this unit due to the short circuit of one of its modules. At the fuse triggering the total power loss of the unit of parallelly connected photovoltaic modules is mainly determined by the decrease of its current by the amount that is equal to the current of the disconnected photovoltaic module.

89-92

Authors: V. M. Morozov, V. I. Magro

The features of the use of finite waveguide antenna arrays in the structure of modern smart antenna systems are considered. The paper deals with the problem of diffraction of an electromagnetic wave on a finite waveguide antenna array scanning in the E-plane. Antenna array consists of five radiating elements. The open ends of the waveguides are surrounded by a metal screen. The resonator coupling region was chosen as matching elements. The solution of the problem is carried out by the integral equation method on the basis of the selection of overlapping regions. The problem reduces to solving the Fredholm integral equation of the second kind. An array of infinitely thin plates and that of waveguides with a finite wall thickness are considered. The main regularities for choosing the optimal geometric dimensions of the antenna array are established. Studies were carried out for arrays with a number of elements from five to fifteen. The analysis of edge effects in the final antenna array is carried out. It is shown that the introduction of a resonator region into a five-element lattice makes it possible to expand the sector of the radiation angles and avoid the effect of blinding. It is shown that this statement is valid not only for five-element lattices, but also for arrays with a large number of radiating elements. The radiation patterns are calculated. The coefficients of mutual coupling in an array with five elements are investigated. General recommendations for choosing optimal sizes of the resonator coupling region of radiators are considered.