Том 61, № 6 (2018)

The results of experimental studies of processes of the radiation defect formation under ion implantation of narrow-gap Cd_xHg_1-xTe solid solutions (MCT) are presented. The processes of formation of structural damages of the crystal and their effect on the electrophysical properties of ion-implanted bulk crystals and ptype heteroepitaxial structures grown by liquid-phase and molecular-beam epitaxy are considered. The results on the spatial distribution of implanted boron atoms and radiation donor centers in these materials are presented as a function of the mass, dose, and energy of ions being implanted and the implantation temperature. The processes and models of the formation of n⁺–n^-–p-structures during boron ion implantation in p-type MCT and their experimental proof are considered.

Significant influence of the defective structure, specific faceting, and special features of the surface morphology of metallic materials, in particular electrolytic copper, on its catalytic activity in the reaction of decomposition of formic acid is experimentally shown. It is established that, in turn, the structure of the crystals formed during the metal electrocrystallization is affected by the technology of their production. To obtain copper crystals with a defective structure, a developed surface, and a specific facet consisting of certain catalytically active crystallographic planes, a mechanical activation of crystals growing during electrocrystallization of the metal was used.

The paper presents investigations into thermophysical, rheological, and morphological properties of graphitized carbon nanotube/polyoxymethylene composites containing 30 wt.% graphite and 0.1 wt.% nanotubes. It is shown that thermal conductivity and thermal diffusivity of graphitized carbon nanotube/polyoxymethylene composites increase respectively by 8 and 11 times in comparison with the original polyoxymethylene. And their melt flow index reduces approximately by 3.5 times. In spite of the abrupt decrease in the melt flow index, graphitized carbon nanotube/polyoxymethylene composites can be used in extrusion, jet molding and three-dimensional printing.

An investigation of the structural features of TiNi-based porous materials, having terraced morphology of the pore-wall surfaces, manufactured by sintering is performed. Using liquid-phase diffusion sintering of a TiNibased powder, a porous alloy is manufactured where the fraction of the master phase TiNi is 78.6 wt.%. The distribution of the secondary phases Ti₂Ni, Ti₄Ni₂(О,N,С) and Ti₃Ni₄ in the porous materials is determined by the structure of the spongy and compact powder particles. The pore-wall surfaces of the resulting porous alloy exhibit terraced relief in all regions of the melt formation. The height of the steps is up to 0.25 μm for the width of the terraces 0.4–0.5 μm. The terraces are found on the areas free from the secondary-phase particles; they propagate across the curved pore-wall surface within one grain. In certain areas, there are hexagonal islands on the pore-wall surface, which measure from 1 to 2 μm. The terraced relief is formed as a result of volumeand surface diffusion during the interaction of the melt with the martensite B19′ crystals on the pore-wall surfaces. It is hypothesized that the mass transfer processes during the formation of terraces are affected by the phase content inhomogeneity and the creep deformation effect.

The paper studies the behavior of ceramic porous tungsten alloy with reinforcing agents under the shock-wave loading conditions. Penetrating capacity of tungsten kinetic energy projectiles is calculated and experimentally investigated during their high-speed impacts on steel plates. It is shown that the increased penetration depth of tungsten projectiles exceeds that of the prototype with relevant weight and size, made of tungsten-nickel-iron cast alloy. A mathematical model is developed together with the design technique of the behavior of tungstennickel-iron-cobalt metal foams alloyed with boron carbide, tungsten titanium carbide and tungsten carbide during the high-speed impact interaction. The composite ceramic material is described here as a porous medium. The matrix of this medium is a homogeneous two-phase mixture of the tungsten-nickel-iron-cobalt system and reinforcing agents added in the required proportions.

As a result of analysis of the experimental spectrum of the ¹²C₅H₄ molecule, the absolute intensities of some spectral absorption lines in the region 2900–3100 cm^–1 are determined.

In the isobaric model of photoproduction of η'-mesons on protons, reproducing well the experimental cross sections for photon energies from 1500 to 2500 MeV and the Σ-asymmetry of this reaction near its threshold, various polarization observables of this reaction have been calculated in the energy range near its threshold in order to stimulate future experiments.

Thanks to found radial solutions of polynomial partial differential equations, the uniqueness of the Stokes hydrodynamic solution has been proven for the problem of calculating the resistance force of a sphere in a viscous medium.

Analytical expressions are presented for the wave number, the characteristic wave impedance, and the refractive index of homogeneous longitudinal plane waves propagating in an acoustic metamaterial with dissipative losses. The metamaterial is characterized by the effective scalar material parameters: the complex density and the compressibility. To distinguish between the forward and backward waves, the wave type identifier is introduced.

The effect of increasing the electric strength of vacuum insulation of gaps with electrodes from contact CuCr (≅30% Cr) material widely used in vacuum switches subject to conditioning with an AC vacuum arc modulated by high-frequency oscillations is considered. The modulating component stimulates periodic arc interruption and its ignition in new places thereby promoting effective treatment of the entire surface of the electrode pair. In addition, when the high-frequency arc is burning, the voltage drop across the electrodes significantly increases, thereby leading to alternating treatment of both electrode surfaces by intense high-energy flows of charged particles. For such treatment, the special regime of cleaning and local surface melting is used leading to the effective increase of the electric strength of vacuum gaps.

A method for determining the crystal phase and estimating the crystal lattice deformations in H_xLi_1-xNbO₃ proton-exchanged optical waveguides from an analysis of the Raman light scattering spectra measured with high spatial resolution (the so-called method of micro-RS spectroscopy) is suggested.

Results of theoretical and experimental investigations of the stationary thermal regime of linear modules of filament light-emitting diode lamps are presented. It is demonstrated that the concentrated heat sources (lightemitting diode crystals) placed on a substrate form a non-planar temperature profile that negatively affects the stability of light characteristics of the filament lamps. The concept of localization function is introduced for a one-dimensional non-uniform distribution of crystals along the substrate. It is proved that when placing point heat sources, there exists a certain dichotomy coefficient at which the crystal localization function provides the least curvature of the temperature profile at a characteristic point x. Experimental investigations demonstrate that the localization of crystals whose dichotomy coefficient differs from unity allows the order of curvature of the profile for the sample of light-emitting diode linear module to be decreased by an order of magnitude in comparison with samples possessing equidistant distribution of heat sources.

Absolute intensities of the absorption lines of the deuterated modification of the ethylene C₂D₄ molecule, namely, the ν₇ band are measured for the first time.

A qualitative analysis of a cosmological model based on the asymmetric scalar doublet classical + phantom scalar field with minimal interaction is performed. It is shown that depending on the parameters of the model, the corresponding dynamical system can have 1, 3, or 9 stationary points corresponding to attractive or repulsive centers (1–5) and saddle points (0–4). A physical analysis of the model is performed.

Experimental and theoretical investigations of a breakdown of atmospheric-pressure air are performed in a strongly non-uniform electric field. Using an ICCD-camera, the dynamics of formation of streamer and diffuse discharges is studied. The data on the streamer characteristics (propagation velocity, plasma parameters, dynamics of the nitrogen emission band N₂(C–B) are obtained during the breakdown development in a non-uniform electric field.

The dependence of the characteristics of hydrogen sensors based on thin Pt/Pd/SnO₂:Sb, Ag, Y and Ag/SnO₂:Sb, Ag, Y films obtained by the method of magnetron sputtering at a direct current on the humidity level of the gas mixture during operation in thermal cyclic mode is investigated. The analysis of the experimental data was carried out using the expressions obtained on the basis of the dissociative adsorption model of hydrogen and water molecules on the SnO₂ surface, taking into account the presence of three types of adsorbed particles: O^–, OH, OН^–. The use of complex modifiers Pt/Pd, Ag on the surface and Ag + Y in the bulk of tin dioxide films allows to reduce the influence of humidity on the characteristics of sensors. The role of these modifying additives in the process of dissociative adsorption of hydrogen molecules on the surface of SnO₂ films in humid environment is established.