The article contains a brief description of functioning principles of the device for creating ultradispersive powders of metals under the impact of electrically charged streams with power density about 10(8) W/cm(2). The results of atomic forced microscopy (AFM) measurements of surfaces of the electrodes exposed to dispergate the microdroplets, which allowed to study the droplets formation steps are presented. The results of AFM surfaces of the substrate surfaces to be inflicted by the dispergated droplets are presented. The dependency of the particles sizes on the distance between the electrode and substrate allows to consider the main mechanism of division the dispergated from the electrode surface droplets the Rayleigh instability.
The change in the structure of solid hydrogen upon compression along the isotherm of 100 K near the transition to the conducting state has been investigated within the density-functional theory. The dependences of pressure and electrical conductivity on the hydrogen density have been calculated. The pressure range from 602 to 836 GPa has been found where the first peak of the pair correlation function arises at a distance of 0.92 Å, which corresponds to the interatomic distance in the molecular H3+ ion. Notably, this distance does not change with an increase in density. A sharp increase in the electrical conductivity is also observed.
We propose and develop a classical density functional theory for the description of a minor amount of water dissolved in ionic liquid in the vicinity of an electrode. In addition to the electrostatic energy and lattice-gas mixing entropy terms, the utilised grand canonical potential contains several phenomenological terms/parameters that describe short-range interactions between ions of ionic liquid, water molecules and the electrode. Some of these have been earlier introduced in the theory of electrical double layer in pure ionic liquids. Based on this, we investigate the role of the remaining ’specific interaction’ parameters e those that characterize possible (i) specific interaction of ions and molecules with the electrode, which are responsible for their specific adsorption; and (ii) hydrophilicity/hydrophobicity of ions. As a result we obtain water electrosorption isotherms as a function of the potential drop across the electrical double layer, investigate its asymmetry with respect to the sign of electrode potential, and establish the relationship between the sign of this asymmetry and hydrophobicity/hydrophilicity of cations and anions. We also calculate the effect of water electrosorption on the double layer differential capacitance which brings clear new features to its voltage dependence, some of which have been already experimentally observed.
Thermoelements for thermoelectric coolers from fine-crystalline materials based on antimony and bismuth chalcogenide solid solutions of p- and n-type conductivities, obtained by hot pressing and extrusion from powders, made by melt spinning, were studied. Calculations of modules’ properties were performed in the range of 100−400K, taking into account temperature dependencies of thermoelectric parameters of legs, and the parameters of thermoelectric legs’ matching are estimated. The modules are produced and the experimental and calculated properties comparison is conducted.
A Vikhr plasma-beam device of the Dense Plasma Focus (DPF) type with an energy of ~5 kJ has been recently put into operation at the Baikov Institute of Metallurgy and Material Science. The device, the design of its components, and its parameters are described. The physical processes that occur in the DPF working chamber during generation of beams of fast electrons, ions, cumulative jets of a hot plasma, hard X rays, and neutrons (if deuterium is used as a working gas) are considered. Experiments have been conducted with the aim of testing energy-saving DPF circuits using a new power supply circuit of the DPF chamber, which contains a crowbar gap and an electronic delay circuit. The device is used for testing, diagnosing, and modifying the radiation-thermal resistance of various materials intended for use in the thermonuclear power engineering and aerospace engineering. The first experiments with this device in radiation testing of materials and aerospace materials science are described.
We report results of systematic measurements of charge transport properties of the 20.5-nm-wide HgTe-based quantum well in perpendicular magnetic field, performed under hydrostatic pressures up to 15.1 kbar. At ambient pressure, transport is well described by the two-band semiclassical model. In contrast, at elevated pressure, we observed nonmonotonic pressure dependence of resistivity at the “charge neutrality point.” For pressures lower than ≈9kbar, resistivity grows with pressure, in accord with expectations from the band structure calculations and the model incorporating effects of disorder on transport in two-dimensional (2D) semimetals with indirect band overlap. For higher pressures, the resistivity saturates and starts decreasing upon further increase of pressure. Above ≈14kbar the resistance value and the magnetoresistance character sharply change, which may indicate significant change of electronic structure due to new electronic phase formation or some structural transitions. The data also reveal strong influence of disorder on transport in 2D electron-hole system with a small band overlap.
In the paper, we propose a model describing a change of charge state of MIS structures and sensors based on them being under influence of both a radiation ionization and high-field injection of electrons from the semiconductor. The model proposed takes into account the interaction of injected electrons with holes generated by the radiation and high-field ionization and captured by traps in the SiO2 film at the interface with the semiconductor. Besides, the model takes into consideration the generation of the surface states at annihilation of a fraction of holes during their interaction with injected electrons. We demonstrate that MIS sensor, being under high-field injection of electrons into the dielectric film by constant current, can be utilized to control intensity of radiation by determining the current of radiation ionization using time dependence of voltage across the sensor using the model proposed. We have ascertained that in case the MIS sensor being under high-field injection of electrons, a significant raising of the dose sensitivity of MIS sensors of the absorbed dose has been possible. However, at that working life and dose range of MIS sensors could be significantly smaller.
In this paper, the results of tests on the roughness index of fibrous semi-finished products and paper intended for the production of mass types of products (packaging materials, printing publications) performed by direct (atomic force microscopy). This indicator was measured by direct (atomic force microscopy) and indirect methods (Bendsen method). It is shown that the use of atomic force microscopy provides an objective assessment of the surface topography of pulp and paper products for various purposes and has no limitations compared to standardized indirect methods for determining the roughness index.
The specific features of the structure in a polycrystalline anion-deficient strontium ferrite SrFeO3 – δ have been studied at different oxygen contents by the Mössbauer spectroscopy, X-ray diffraction, and scanning electron microscopy. Three compounds with different compositions have been prepared in the dependence on the condition of heat treatment. Within each of the structures, there are several nonequivalent positions of Fe corresponding to different valence states of Fe and different local oxygen environments, the relation and the degree of distortion of which are changed in the dependence on the oxygen content. Based on the Mössbauer data, the oxygen content in each of the structures is estimated. Yet another ideal Sr16Fe16O45 composition of the SrFeO3 – δ compound is proposed for an intermediate composition in addition to those available in the literature.
The article considers the principle of the load vector application on the garment during operation. On the basic of the analysis of products in operation, the article determines the loads application in nodes and zones for a different range of garments depending on the degree of loads in statics and dynamics. Moreover, it presents several factors influencing stability of garment design.
A method for constructing traveling wave type microwave device with a transverse interaction, forming a uniform temperature distribution over the volume of polymer composite rods is proposed. The results of theoretical and experimental studies of the temperature distribution of the rod material are presented. Advantages of microwave technologies of curing of polymeric composite materials in comparison with traditional methods are shown.