Journal of Physics and Electronics

9-18

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

The process of self-ordering in the famous Dicke model was studied in the framework of eliminating the boson variables. But the reduced description method enables us to obtain also the picture of electromagnetic field evolution provided field amplitudes and correlation functions are included into the number of reduced description parameters. In the Dicke Hamiltonian structure the interaction term includes the operators of emitter dipole moments or dipole moment density (polarization) since a spatial system is under consideration. Thus operator evolution equations are based on using such operators and their derivatives. The chain of evolution equations for averaged field amplitudes and binary correlation functions are obtained with using the statistical operator calculated in a perturbation theory in quasispin-photon interaction assumed to be small. The problem of chain decoupling does not arise since at any step we have a closed set of equations. The sets should be solved on the basis of material equations for current density and their generalizations for more complicated correlation functions. The way to constructing such equations and estimating the material parameters which are necessary for the numerical modeling of the development of correlations is discussed in the paper.

27-30

Authors: S.I. Ryabtsev, O.V. Sukhova, V.A. Polonskyy

For the first time, quasicrystalline Al60Cu28Fe12 films with 260 nm thickness cooled at 1012–1014 K/s were produced by the modernized method of three-electrode ion-plasma sputtering. Films were deposited on NaCl substrate. The structure of as-sputtered films was investigated in comparison with that of as-cast specimens by methods of quantitative metallography, X-ray analysis, and scanning electron microscopy. Corrosion behavior in 5% NaCl aqueous solution was studied by potentiodynamic method and model tests. In the structure of the as-cast Al–Cu–Fe alloy, the quasicrystalline icosahedral i-phase was established to co-exist with λ -Al13Fe4 , τ-AlCu(Fe), η-AlCu, and θ-Al2Cu crystalline phases and occupy ~56 % of the alloy volume. The Al–Cu–Fe film contains dispersive quasicrystalline i-phase (~3 nm in size) that is stable up to 723 К. Corrosion of the as-sputtered Al–Cu–Fe film runs at the lower rate as compared with that of the as-cast alloy of the same composition. Model corrosion tests for 1, 2, 3, 4, 8 days with 5% NaCl solution at 293 K indicate that the investigated Al–Cu–Fe film remains virtually untouched by corrosion. No marks of pittings typical for as-cast Al–Cu–Fe alloys are observed on the film surface affected by saline solution.

37-40

Authors: T.V. Kruzina, S.A. Popov, Yu.N. Potapovich, A.S. Rutskyi

We report some peculiarities of behavior of domain structure and birefringence ∆n of Na0.5Bi0.5TiO3 crystals. Polarization-optical methods are used to study the domain structure and the birefringence ∆n in temperature interval 25°C÷520°C and axial pressure interval 2.5÷60 bar. Single domain state is achieved by application of axial pressure along [100] and [110] directions at temperature near 500°C. Application of axial pressure ~50 bar along [100] direction leads to switching of the samples into anisotropic single domain state. While application of axial pressure ~0.5 bar along [110] direction results in exposition of visually isotropic state and the state is preserved during a cooling process in temperature interval ~500°C÷240°C. In both cases the anisotropic single domain state is observed at room temperature. It is shown that f axial pressure (2.5÷25 bar) application along [110] direction at room temperature leads to a significant increase of the birefringence. It is supposed that both the peculiarities of Δn behavior and the linear behavior of Δn = f(p) are associated with presence of the nanoregions with various orientations of optical indicatrices and their involvement into the orientation process under the action of axial pressure.

47-50

Authors: Y. Syetov

Hyperpolarizability of molecules of 2-(2'-hydroxyphenyl)benzoxazole and 2,5-bis(2-benzoxazolyl)phenol is calculated by density functional theory quadratic response method for static electric field and hyper-Rayleigh scattering at 532 nm. It is found that 2,5-bis(2-benzoxazolyl)phenol demonstrates the hyperpolarizability about ten times larger than 2-(2'-hydroxyphenyl)benzoxazole. Dominant component of the hyperpolarizability tensor corresponds to the long axis of the molecule.

57-62

Authors: A.I. Ivon, V.R. Kolbunov

The results of studying the electrical conductivity σ for the glass-ceramic systems VO2 ‒vanadium-phosphate glass (VPG) and VO2‒VPG‒SnO2 with the additions of Cu and Cu2O are presented. It is found that the jump of conductivity at the temperature of metal-semiconductor phase transition (MSPT) in VO2 (Tt = 341K) takes place only for glass-ceramics containing not more than 5 wt% of these additives. When their content exceeds 5 wt%, the VO2 content decreases sharply according to the data of differential thermal analysis. The reason for this is the oxidation-reduction reactions in the liquid phase between Cu and VO2 at ceramics synthesis. These reactions result in the appearance of Magneli phases in glass‒ceramics composition. The phase transitions in Magneli phases V4O7, V5O9, and V6O13 are indicated by the temperature dependence of σ, as bends of the straight lines in coordinates log10σ ~ 1/T at the phase transition temperatures Tt of these phases: 240K, 150K, and 130K. The activation energy of σ for T> Tt is lower than for T

71-78

Authors: A.Yu. Lyashkov, A.S. Tonkoshkur, S.F. Lyagushyn

Experimental results of the development of self-healing fuses based on ceresin–nanocarbon composites are presented. The technical framework for the applicability of industrial resettable fuses based on polyethylene is justified. Good prospects of using composites based on ceresin to create low-temperature posistor elements with the aim of providing current protection for solar cells is shown.

89-94

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

The method of improving the interference protection of axisymmetric antennas is considered. An experimental study of the focusing properties of a zonal antenna is carried out in this work. Such a zonal antenna acts as a shading screen and is located in the aperture of an axisymmetric antenna. The combination of a shading screen with an axisymmetric antenna can significantly reduce the level of side lobes in the anterior semi-space, and as a result, significantly improve the immunity of the antenna system. A zonal antenna for 40 GHz frequency is manufactured. The field distribution along the axis of symmetry for different numbers of rings in the antenna is experimentally investigated. The number of rings varied from 1 to 5. The focusing properties of the zonal antenna are studied at the change of operating frequency. The position of the focus is investigated when the working frequency changes in relation to the calculated frequency. It is established that the experimentally found focal point does not coincide with the focal point found by geometric optics. For a zonal antenna with three rings, the difference between the experimentally found focus and the focus found by the law of geometric optics is 0.1%. The distribution of the field in planes perpendicular to the focal line is investigated. It is established that an increase in the number of rings in a zonal antenna to more than five leads to diffraction effects which impair the focusing properties of the zonal antenna. At the same time there is a "deliquescence" of the wave beam in the focus. These studies allow us to determine the boundaries of the working frequency of a complex antenna system.