Vol 59, No 6 (2016)

We present the results of studying the capacitance-voltage and conductance-voltage characteristics of the GaxOy/GaAs-based metal – oxide – semiconductor structures obtained by thermal evaporation. Influence of the annealing temperature on the characteristics of the structures is established. It is found that at long-term storage in the room atmosphere, the structures do not change their properties, which is manifested in the stability of electrical characteristics.

A model is proposed for desorption of molecules via a precursor state in the presence of two distinct chemisorption states on the surface. Analytical expressions describing the temporal evolution of the concentration of molecules in chemisorbed states are obtained. It is shown that redistribution of molecules between the chemisorbed states can lead to a non-monotonic time dependence of the concentration of molecules in one of the states in the early stages of desorption, as well as to a significant change in the spectra of temperature programmed desorption.

The features of microstructure and phase composition of metastable austenitic steel subjected to thermomechanical treatment, including low-temperature processing accompanied by warm rolling deformation, are investigated. Direct (γ → α΄) and reverse strain-induced martensitic transformations are shown to take place, followed by the formation of submicrocrystalline states and 3–4-fold increase in the yield point values. The mechanisms of formation of submicrocrystalline states and the reasons for increased strength are discussed.

Methods of electron microprobe analysis, X-ray structure analysis and electron microscopy were used to study the element composition and features of the structure-phase, elastic stress state of nanocrystalline coatings of the Ti–Al–Si–Cu–N system with gradient of copper concentration across their thickness. The authors established the effects of element composition modification, non-monotonous behavior of the lattice constant of alloyed nitride and rise in the bending-torsion value of the crystalline lattice in individual nanocrystals to values of around 400 degrees/μm with increase in copper concentration, whereas the sizes of alloyed nitride crystals remained practically unchanged. Mechanical (hardness), adhesion and tribological properties of coatings were examined. Comparative analysis demonstrates higher values of adhesion characteristics in the case of gradient coatings of the Ti–Al–Si–Cu–N system than in the case of single-layer (with constant element concentration) analogues.

Energy spectrum of fullerene C₆₀ is calculated in the approximation of static fluctuations within the Hubbard model. Allowed optical transitions are chosen in the approximation of molecular orbitals, and the optical absorption spectrum is simulated. A good qualitative agreement with the available experimental data is obtained not only in the short-wavelength range, but also in the visible range. This demonstrates the correctness of the approach to the study of fullerenes as systems with strong correlations.

In the Duffin–Kemmer–Petiau formalism, on the basis of a covariant model taking account of the spin polarizabilities and gyrations of spin-one particles, relativistic-invariant phenomenological Lagrangians of the interaction of the electromagnetic field with these moments have been obtained. It is shown that in the proposed covariant model with cross symmetry, parity conservation laws, and gauge invariance taken into account, certain spin polarizabilities and gyrations of a spin-one particle contribute to the expansion of the Compton scattering amplitude, starting at the corresponding orders in the radiation frequency in agreement with low-energy theorems for this process.

The zitterbewegung (trembling motion) effect in the vicinity of a spherically-symmetric black hole is investigated. An analytical expression for the current density is obtained which describes the current caused by the motion of an electron wave packet. The intensity of dipole radiation in the vicinity of the black hole is calculated.

A theory of ion sputtering of metals in the form of neutral and charged clusters with their subsequent fragmentation into the stable state is developed. The theory is based on simple physical assumptions and is in good agreement with experiment. Results are presented in the form of formulas convenient for practical application. As an example, calculations of the total yield of stable neutral and charged clusters of silver, indium, and niobium are carried out.

The electrophysical approach is used to estimate conditions for effective pumping of the active medium of lasers on self-terminating metal atom transitions in gas-discharge tubes (GDT) with electrodes located in the hot zone of the discharge channel. It is demonstrated that in the laser discharge contour there are processes limiting the frequency and energy characteristics (FEC) of radiation. The mechanism of influence of these processes on the FEC of radiation, and technical methods of their neutralization are considered. It is demonstrated that the practical efficiency of a copper vapor laser can reach ~10% under conditions of neutralization of these processes. Conditions for forming the distributed GDT impedance when the active medium is pumped on the front of the fast ionization wave are determined.

A simulation of magnetic properties of nanosized manganese ferrite particles is performed. In the simulations, the Metropolis Monte Carlo algorithm is used. The particle parameters are selected taking into account true values of the exchange integrals and anisotropy constants, as well as particle size distribution in nanostructured manganese ferrite powder produced by the mechanochemical synthesis.

Properties of robust estimations of the scale parameter are studied. It is noted that the median of absolute deviations and the modified estimation of the average Gini differences have asymptotically normal distributions and bounded influence functions, are B-robust estimations, and hence, unlike the estimation of the standard deviation, are protected from the presence of outliers in the sample. Results of comparison of estimations of the scale parameter are given for a Gaussian model with contamination. An adaptive variant of the modified estimation of the average Gini differences is considered.

Supercapacitors are often characterized by responses measured by methods of impedance spectroscopy. In the frequency domain these responses have the form of power-law functions or their linear combinations. The inverse Fourier transform leads to relaxation equations with integro-differential operators of fractional order under assumption that the frequency response is independent of the working voltage. To compare long-term relaxation kinetics predicted by these equations with the observed one, charging-discharging of supercapacitors (with nominal capacitances of 0.22, 0.47, and 1.0 F) have been studied by means of registration of the current response to a step voltage signal. It is established that the reaction of devices under study to variations of the charging regime disagrees with the model of a homogeneous linear response. It is demonstrated that relaxation is well described by a fractional stretched exponent.

The three components of the tensor analyzing power of the exclusive π^– meson photoproduction reaction on deuterons measured simultaneously in the photon energy ranges 300–900 MeV and 50–210 MeV are presented. The experiment made use of an internal tensor-polarized deuterium-gas target of the VEPP-3 electron storage ring and the two-proton coincidence recording method. The results obtained are compared with theoretical predictions.

The joint effect of magnetic fields normal and tangential to the cathode surface and of short-pulse highfrequency bias potential of negative polarity on the accumulation of macroparticles on the potential target immersed in copper vacuum-arc plasma is studied. It is shown that the application of a vacuum-arc evaporator with the magnetic field tangential to the cathode surface reduces by 5 times generation of copper macroparticles in comparison with an axially symmetric vacuum-arc evaporator in which the magnetic field normal to the working cathode surface is used. It is established that the joint action of the tangential field and short-pulse high-frequency bias potential makes it possible to decrease by 2–3 orders of magnitude the density of copper macroparticles on the target surface.