卷 44, 编号 2 (2018)

The results of computer simulation of the influence of silicon impurities on the degree of tetragonality and on the interaction of carbon atoms in the body-centered cubic (BCC) lattice of iron by the molecular-dynamics method are reported. The influence of silicon on the martensite-lattice parameters has been established, as well as the dependence of the deformation interaction parameter λ₀ determining the critical temperature of the BCC–BCT (body-centered tetragonal) transition on the silicon concentration, is calculated on the basis of the Zener–Khachaturyan theory of ordering. It is found that the λ₀ parameter decreases by 18% from 5.2 to 4.2 eV/atom upon an increase in the silicon content up to 10 at %.

Multicomponent nanostructured coatings based on (TiZrNbAlYCr)N with a hardness as high as 47 GPa were obtained by cathodic arc deposition. The effect of partial nitrogen pressure P_N (with constant bias potential U_b =–200 V applied to the substrate) on the phase-composition variation, the size of crystallites, and their relation to the microstructure and hardness was investigated. An increase in the nitrogen pressure resulted in the formation of two phases with characteristic BCC (the lattice period is 0.342 nm) and FCC lattices with averaged nanocrystallite sizes of 15 and 2 nm. At a high pressure of 0.5 Pa, crystallites in the FCC phase with a lattice period of 0.437 nm grew in size to ~7 nm. The hardness of deposited coatings with larger (3.5 nm) FCC-phase crystallites and smaller (7 nm) BCC-phase crystallites was enhanced considerably.

The adsorption of CO, NO, NO₂, Н₂О, and NH₃ molecules on ideal graphene and graphene doped with aluminum is analyzed using simple models. The constants of electron–phonon coupling are evaluated with the Lennard-Jones 6–12 potential for ideal graphene and the 2–4 potential for doped graphene. It is demonstrated that the dimensionless electron–phonon-coupling constant for ideal graphene is ζ ≫ 1, while ζ ~ 1 corresponds to graphene doped with aluminum. Ways to use both types of graphene as a resistive gas sensor are discussed.

Results obtained in a study of the growth of InP/InAsP/InP nanowires on the Si (111) surface are presented. Using a special procedure of substrate preparation immediately before the growth made it possible to obtain a nanowire coherency with the substrate of nearly 100%. A high-intensity emission from nanostructures of this kind was observed at a wavelength of ~1.3 μm at room temperature.

Single crystals of L-histidine phosphite (L-Hist · H₃РО₃) have been grown from aqueous solution by slow cooling method. The results of elemental analysis, of X-ray-diffraction studies of the crystal structure, and the habitus of the obtained crystals are given. The elastic and piezoelectric coefficients have been measured on the plates with the (010) natural faces by the method of electromechanical resonance for stretching vibrations in the temperature range 295–340 K. Elastic compliance values s₃₃ and s₂₂ and the corresponding elastic-moduli values, piezoelectric coefficients d₂₃ and d₂₂, coefficients of electromechanical coupling, and temperature coefficient of the resonance frequency are obtained. A comparison is given with other crystals, which are compounds of amino acids with phosphorous or phosphoric acid.

Novel types of tandem solar cells (TSC) based on dye-sensitized (DSC) and perovskite (PSC) solar cells including DSC/DSC and DSC/PSC configurations with a common counter electrode were fabricated and investigated. The measurements of PV parameters for tandem solar cells under AM1.5 light intensity conditions have shown that the highest power conversion efficiency (PCE) of 14.5% was obtained for the DSC/DSC tandem configuration. At the same time, investigations of DSC/PSC tandem solar cells demonstrated the prospective benefits of this tandem system for obtaining high PCE values.

It is found that an electric field applied parallel to a substrate surface influences the adsorption of positively charged core–shell microcapsules on glass substrates. As a result, the amount of microcapsules adsorbed near negative contact is up to 2 times larger than the one absorbed near positive contact. It is also found that small concentration (less than 0.2 M) of salt in microcapsule suspension decreases this effect, while an increase in the concentration to 0.45 M results in enhancement of the effect.

We have studied the mechanical properties (Vickers microhardness H_V and fracture toughness K_C) of nanostructured CaO–ZrO₂–Al₂O₃ ceramic composites as dependent on the content of corundum (0 ≤ \(C_{Al_{2}O_{3}}\) ≤ 25%) and the temperature of sintering (1250°C ≤ T₁ ≤ 1500°C). Optimum value of the corundum content (\(C_{Al_{2}O_{3}}\) = 5%) and optimum regime (T₁ = 1300°C, 5 min; T₂ = 1200°C, 4 h) of two-stage sintering are established, which favor attaining the best mechanical characteristics of ceramic composites (H_V = 12.25 GPa, K_C = 8.47 MPa m^1/2).

We have studied the influence of growth conditions on the number of metallic indium clusters formed spontaneously in indium nitride (InN) layers grown by nitrogen plasma-assisted molecular-beam epitaxy (PAMBE). InN epilayers of N-and In-polarity were grown on c-sapphire substrates and GaN and AlN templates, respectively. N-polar layers were obtained in the standard PAMBE regime, while In-polar layers were grown using a three-stage regime including the stages of epitaxy with enhanced atomic migration and interruption of growth under nitrogen flow. A series of samples were prepared at various growth temperatures and relative In/N flow rates. Measurement of the magnetic-field dependences of the Hall-effect coefficient and its model approximation were used to determine the percentage content of In clusters in various InN layers and the minimum amount of such inclusions that can be achieved by varying the conditions of MBE growth.

The influence of ~300-ns pulsed sliding surface discharges on supersonic airflow with M = 1.2–1.5 past a thin wedge has been studied in a shock tube at 0.12–0.14 kg/m³ gas density. It is established that inhomogeneity of the airflow-density field near the wedge leads to changes in the discharge current geometry and the structure of surface-discharge glow. The dynamics of discharge-initiated shock waves disturbing the quasi-stationary flow past the wedge was studied by the method of shadow visualization. It is shown that shock waves from intense surface-discharge channels in front of the wedge and behind its rear part can produce nonstationary action on the flow past the wedge surface, which lasts for up to 120 μs after the discharge pulse.

Thermal characteristics of a direct-current plasma torch have been studied in the framework of numerical simulations of temperature fields in a plasma channel, cathode, and anode. It is established that the temperature of the operating cathode surface exceeds the melting temperature of the cathode material.

The problem of establishment of a chaotic synchronous response between two chaotic self-sustained oscillator systems under the conditions of phase filtration of the chaotic signal transferred via a channel from the master to slave system is considered. The characteristics of the phase filter are equivalent to those of a filter present in a communication channel with multipath propagation.

Desorption of cesium atoms from a rhenium point emitter in an electric field has been studied by method of field-desorption microscopy (FDM). Dependence of the desorbing field on degree of emitter surface coverage with Cs atoms is established. The heat of Cs-atom adsorption, which is dependent on the surface concentration of adsorbate and work function of the surface, is estimated in the framework of the model of mirror-image forces for field-induced desorption. Saturation of the rhenium emitter with carbon leads to changes in the character of desorption and in the distribution of desorption zones on the emitter surface.