Volume 61, Nº 7 (2018)

We present the results of studies of the effect of electron irradiation on the electrophysical parameters of (HgSe)₃(In₂Se₃) crystals, which are semimagnetic semiconductors with stoichiometric vacancies. It is shown that irradiation of (HgSe)₃(In₂Se₃) with high-energy electrons (E_e = 10 MeV, dose D = 10¹⁶ cm^–2) has little effect on the electrophysical and magnetic properties, which indicates their high radiation resistance.

Infrared photodetectors with germanium quantum dots on silicon are considered. Some characteristics of such detectors are calculated, namely: dark current and detectivity in the modes of limitation by background and generation-recombination noises. A comparison is also made of the performance of quantum-dot infrared detectors with the performance of HgCdTe detectors.

Experimental studies of the formation of a stepped surface structure during molecular-beam epitaxy of silicon on a Si (100) substrate have been carried out in wide ranges of variation of the substrate temperature and silicon growth rate. The conditions of the transition from a two-domain structure of the Si (100) surface to a single-domain structure associated with the formation of diatomic steps are determined using reflection high-energy electron diffraction. It is shown that the effect of an increase in the substrate temperature on the transition to a single-domain structure is non-monotonic: a single-domain surface forms in the region of relatively low temperatures, whereas a two-domain surface forms at high temperatures. The transition to a single-domain structure during the experiment is possible only, if the silicon growth rate is increased above a certain minimum value.

In this paper, the mathematical simulation is used to study the effect from the size of incoherent nanoparticles on thermal strength of heterophase aluminum alloy in materials with the similar volume fraction of the strengthening phase. It is shown that during the deformation process, the particle size affects the evolution of shear dislocations, prismatic dislocation loops and dislocation dipoles. It is found that if the volume fraction of incoherent particles is low, the behavior of the flow stress curves depends on the particle size. The paper identifies the variation range of scale parameters for thermal stability of dispersion-hardened materials.

A thermodynamic investigation of plasmochemical processes taking place in a magnetron during sputtering of the targets consisting of indium and dysprosium ions is performed, which allowed identifying the feasibility of forming under the given conditions certain amounts of the chemical compounds In₂O₃, Dy₂O₃, DyInO₃. In the thermodynamic analysis of the equilibrium compositions during magnetron sputtering of the films, a universal TERRA software program is used.

The paper deals with the synthesis of palladium-iron alloy thin film with the ordered L1₀ structure and presents results of its studies. The evolution of the thin film crystallinity is described at different stages of synthesis. Perpendicular magnetocrystalline anisotropy is confirmed by results of magnetometry and Mössbauer spectroscopy. Based on results, it is concluded that the obtained structure can be used as a medium for ultrahigh density magnetic recordings.

The IR spectrum of the ⁷³GeH₄ molecule is recorded with a Bruker IFS 125HR high-resolution Fourier spectrometer in the range 650–1100 cm^–1 and then analyzed; 1127 transitions with J^max = 19 are assigned to the ν₄ and ν₂ bands of the ⁷³GeH₄ molecule. The rotational and centrifugal parameters of tetrahedral splitting and the Coriolis interaction parameters for the (0100, E) ground and (0001, F₂) vibrational states are determined by varying positions of the experimental lines. The obtained set of the spectroscopic parameters reproduces the initial experimental data with the accuracy close to the experimental one.

Within the framework of the modified potential cluster model, the possibility of describing the available experimental data on the astrophysical S-factor for the p¹⁴N capture reaction to the first excited state of the ¹⁵O nucleus at 5.18 MeV for proton energies up to 1 MeV is considered. Under the assumption that this excited state is a D wave, we have successfully described the experimental data for the astrophysical S-factor.

Results obtained by measuring three components of the tensor analyzing power in the reaction of π- meson photoproduction on deuterons in the range of photon energies 300–800 MeV and proton energies 15–70 MeV are presented. The experiment was performed with an internal tensor-polarized deuterium target at the VEPP-3 electron storage ring, employing the method of recording two protons in coincidence. The obtained measurement results for the tensor analyzing power are compared with theoretical predictions.

The results of experimental investigations on plasma-immersion formation of ballistically focused beams of low-energy titanium ions with the pulse duration up to 30 μs are presented. The processes of neutralization of the space charge of high-intensity beams upon increasing the ion-current density by a few orders of magnitude during their focusing are addressed. The conditions of preliminary injection of the metal plasma, its parameters, the formation of the beam plasma during residual-gas ionization and secondary and thermionic emissions are shown to be of critical importance for an effective transport of these beams in the equi-potential drift space. It is demonstrated that the use of a disc electrode, preventing the macroparticles from penetrating the region of the ballistic beam focusing, increases the efficiency of long-pulse titanium ion beam transport and simultaneously reduces the probability of instability development.

Spectra of sixteen optical functions of Mg₂Ge at 77 K in the energy interval 0–11 eV are determined. The main features and the general patterns of behavior of the optical functions are established. They contain six maxima and shoulders caused by interband transitions and metastable excitons. The integral spectrum of the dielectric permittivity ε₂(E) at 77 K in the energy interval 2–5 eV comprising six maxima and shoulders is decomposed into sixteen elementary transition bands caused by exciton and interband transitions of transverse and longitudinal types. The supposed nature and the localization of transition bands in the optical spectra of magnesium germanide is proposed proceeding from the known results of theoretical calculations.

Special features of laser line generation upon high-energy diode pumping of Er:BaY₂F₈ crystals are investigated. The UV and visible laser lines are effectively formed via nonlinear self-addition of frequencies of induced Er³⁺ lines at 541 and 553 nm with the corresponding frequencies of IR Er³⁺ lines upon pumping of the Er:BaY₂F₈ crystals with a diode laser beam having a wavelength of 457 nm.

Electro-optical properties of the holographic and polarization holographic diffraction gratings formed in polymer-liquid crystal composites doped with Y₂O₃ nanoparticles are considered. The effect of impurities on the diffraction efficiency and operated electric field is shown. The diffraction efficiency of doped holographic diffraction gratings decreases, whereas the diffraction efficiency of polarization diffraction gratings increases. Doping with nanoparticles leads to a decrease in the operated electric field.

The semiclassical Thomas–Fermi method is extended to the case of two-dimensional (planar) multi-electron atoms. It is shown that within the framework of this model a two-dimensional multi-electron atom cannot exist, due to the impossibility of fulfilling the physical asymptotic limit φ(r)|_r→0 → (Ze)/r of the solution of the corresponding two-dimensional Thomas–Fermi equation.

There was a misprint in the second author’s name. It should read D. A. Goncharova instead of D. A. Goncharov.

The evolution of an anode spot is investigated in the course of burning of a high-current vacuum arc. The evolution process is recorded with a high-speed video camera at a rate of 180 thousand frames per second and with a high-speed 4-channel photo camera, which is equipped with a set of interference filters to register the distribution of Cr I (428 nm), Cu II (625 nm) and Cr I + Cu II (500 nm) in the gap. The arc is ignited between two CuCr-electrodes measuring 20 mm in diameter in a vacuum arc chute imitating the operation of a vacuum circuit breaker by switch opening at a constant rate.

The paper discusses the results of experimental research on air cavity capture by magnetic fluid and elasticity of the produced oscillatory system on an annular magnet segment with changing magnetic field sign. This research relied on analysis of magnetic and acoustic oscillograms. It was shown that using the magnetic field segment of an annular magnet with this distinctive feature expands the possibilities of managing the magnetic fluid when producing an isolated gas cavity with a reduced value of elasticity parameter.