Piezoceramics based on the lead zirconate-titanate (PZT) system is the basis of most transducers operating on the piezoelectric effect and are used in various electronic devices operating in the sections of electrical and hydroacoustics, ultrasonic technology, etc. In turn, piezoceramic materials created in the last century have substantially exhausted their potential for use in modern devices, and it is rather difficult to develop new compositions and is not economically efficient. In connection with the above, an urgent task is to find modern ways to increase the parameters of piezoceramic materials.

Keywords: piezoceramics, piezophase, piezomaterial, ceramic technology, microstructure

The article presents the results of studying the effect of the loading of active metal on the physicochemical properties of cobalt catalysts for the Fischer-Tropsch synthesis on a silicate support, promoted with aluminum. Using the BET, XRF, TPR, TPD-H2 methods, it has been established that the optimum cobalt content is 15‒18 wt. %.

Keywords: Fischer-Tropsch synthesis, catalyst, cobalt, active component, loading

Concentration changes of refraction and frequency of raman spectrum in melts of salt systems of alkali metals containing nitrate and thiocyanate anions are shown. The change in molar refraction and frequency confirmed the concept of additivity and linearity of isotherms when changing composition.

Keywords: molten salt, nitrates and thiocyanates of alkali metals, refraction, raman-spectr

The article considers the effect of Al2O3 loading on the physical and chemical properties of cobalt catalysts. The loading of the alumina additive has a significant effect on both the phase and texture properties, as well as on the cobalt reduction process in the composition of the studied samples. It was found that with increasing loading of the additive, the specific surface area of the catalysts decreases, and the cobalt recovery process slows down.

Keywords: Fischer-Tropsch synthesis, catalyst, cobalt, alumina, promoter, temperature programmed reduction

The paper discusses the problems of predicting the growth regimes of quasi-one-dimensional electronic structures - quantum nanowires based on three-component compounds A3B5. It is shown that modeling of growth processes of threads based on the Monte Carlo method can be an effective solution. The formation of quantum nanowires is carried out due to the external flow of particles transferred in the first series of experiments perpendicular to the substrate, in the second series - at random angles. The constructed model allows us to evaluate the effect of the composition on the geometric parameters of the formed objects. The critical thickness of quasi-one-dimensional structures is calculated. Conclusions are drawn about the control factors of the processes of thread growth. It is shown that compositional variations are an effective parameter for controlling the processes of formation of three-component 1D structures.

Keywords: quantum nanowires, Monte Carlo method, growth on a substrate, adsorption, diffusion, one-dimensional structures

The paper studies the liquid-phase epitaxy processes of a new material of infrared optoelectronics - indium arsenide doped with bismuth using a stepwise thermal field. An analysis of the phase equilibrium during the growth of a solid solution is carried out. The possibility of the formation of a mesostructure (modulation of the composition along the growth coordinate) is shown. The problems of defect formation in composite layers grown from a melt are considered. Ways of decreasing the dislocations density in gradient layers are discussed. A relatively simple method for controlling the thermal field of temperature in the crystallization zone and a new technological procedure for the sequential crystallization of solid solutions with a mesostructure have been developed.

Keywords: solid solutions, liquid-phase epitaxy, indium arsenide, mesostructure, stepwise thermal field, dislocation generation

The theoretical aspects of crystallization of multicomponent solid solutions are discussed. Antimonoid heterosystems in which bismuth is present are considered, a component that largely determines the photoelectric properties of the studied materials. The features of establishing the equilibrium of the liquid and solid phases in the process of crystallization of these systems are considered. The laws of the thermodynamic behavior of heterosystems in the conditions of gradient liquid-phase epitaxy are established. The results of experimental studies on the growth of solid solutions of multicomponent bismuthides on InSb substrates are presented.

Keywords: solid solutions, migrating liquid phase, indium antimonide arsenide, gallium bismuthide, binary pair, recrystallization, quasicrystalline structure

In this work, we simulated the graphene-MnO composite structure based on minimizing the electron density functional. The analysis of the processes of rearrangement of the interface surface SLG (monolayer of graphene) - MnО (111). In this case, the interface was subjected to hydrogenation. The distribution of the effective charge on graphene is investigated. A decrease in the work function of the charge carriers during hydrogenation of the interface is established.

Keywords: effective charge, graphene, passivated surface, density functional, interface, work function, energy gap, band structure

In this work a breaking of interatomic bonds of kaolinite unit cell under a microwave irradiation was studied. Using density functional theory method (DFT), free energy of the unit cell was computed: without an external field created by the microwave radiation, with the field along (100), and (010) and (001) directions of the unit cell. It was shown that unit cell free energy differences are several kJ/mol. Computational results are backed up by a band structure computation. The conlcution is that there is no bond breaking in the caolinite unit cell caused by the microwave irradiation.

Keywords: kaolinite, microwave field, covalent bonds, discontinuity, ab inito, density functional theory, unit cell, free energy, electronic band structure, clay

hydroxyapatite, non-collagenous protein, implant, quantum-chemical analysis, molecular model, one-electron spectrum, vibrational mode, osseointegration.

Keywords: hydroxyapatite, non-collagenous protein, implant, quantum-chemical analysis, molecular model, one-electron spectrum, vibrational mode, osseointegration

The temperature dependence of the contact angle of wetting allows of Pb-Na of different concentrations on substrates of Co-Cr, Ni-Cr and stainless steel substrate 25X18H9C2 was studied by the method of a lying drop. Measurements were carried out by the method of a lying drop from 359°C to 800°C in an atmosphere of pure helium grade A. It is shown that the value of the wetting angle decreases with increasing temperature, wetting thresholds are observed.

Keywords: wetting angle polytherms, wetting threshold, Co-Cr, Ni-Cr, 25X18H9C2 substrates

Known mechanisms of relaxation of tension in the film at small misfit deformation: the formation of waviness on the initially flat free surface of the film (the instability of the Asaro-tiller-Grinfeld); nucleation of misfit dislocations at the interface film-substrate; a redistribution of atoms near the wavy surface of the film due to the reduction of elastic energy in napylenie on a substrate a semiconductor film; reducing surface energy of the film by increasing its thickness; formation of nanoscale isolated Islands on the surface of the film (Stransky-Krastanov growth); due to the formation of misfit twinning. This paper presents the results of calculations taking into account these factors for different values of the parameters of the film and Islands.The equilibrium conditions of a two-component elastic layer containing mismatch dislocations are investigated. A nanometer-thick SiGe film on a Si substrate and nanometer-sized SiGe Islands on a wetting layer are considered. The uneven distribution of Ge in the sample volume is taken into account. Three-dimensional models of a flat film with dislocation and Islands are constructed. The calculation of elastic deformations is performed using the finite element method. Approximating formulas and iterative algorithm are used to calculate the Ge distribution in the film. According to the results obtained, the uneven distribution of Ge provides relaxation of elastic energy in the alloy, and Ge atoms are concentrated on the protrusions of the disturbed surface of the film and in the vertices of the Islands. Taking into account the heterogeneity of the Ge distribution in the samples has a significant impact on the growth of islets (stable growth occurs with smaller islets) and undulation on the free surface.

Keywords: thin film, heteroepitaxy, Ge, SiGe, misfit dislocations, elastic energy density, finite element method

The article presents the results of research on the morphology of cobalt catalysts for Fischer-Tropsch synthesis on a silicate support with promoting additives of aluminum, manganese and chromium using scanning and transmission electron microscopy. The effect of additives on the surface structure and dimensional characteristics of metallic cobalt was determined.

Keywords: morphology, electron microscopy, catalysts, Fischer-Tropsch synthesis, promoters

The article presents the results of research of the physical and chemical properties of cobalt catalysts on a zeolite support. Methods of BET, thermoprogrammed reduction, thermoprogrammed hydrogen desorption and IR-spectroscopy were used for study. The influence of the support nature on the structural (specific surface area, dispersion of metallic cobalt, size of metal crystallites) and chemical (degree of cobalt reduction) properties of catalysts was established.

Keywords: Fischer-Tropsch synthesis, catalysts, zeolite, hydrocarbon synthesis, structural properties

The work is devoted to the structural characterization of carbon nanotubes by means of electronic combination scattering of light. Samples of double-walled carbon nanotubes with various electronic configurations of the layers have been synthesized, their study has been performed by means of high-resolution transmission electron microscopy, electron diffraction, Rayleigh spectroscopy, as well as spectroscopy of combination scattering of light. The structural characterization of the synthesized nanotubes has been carried out using electronic combination scattering of light, which can play the role of an additional criteria for nanotubes indexing, helping to clarify and verify the obtained results.

Keywords: carbon nanotubes, catalytic chemical vapor deposition, spectroscopy of combination scattering of light

The equations of spinodal decay in binary systems in which there is a phase transition-improper decay are obtained. For the first time, spinodal equations for a phase transition with one multicomponent order parameter (two one-component) are obtained.

Keywords: binary solutions, spinodal decay, structural phase transition

The article presents the results of studies of cobalt catalysts for the synthesis of hydrocarbons on a silicate support with promoting additives of aluminum, manganese and chromium. The influence of additives on the structural (specific surface area, dispersion of metallic cobalt, size of metal crystallites) and chemical (cobalt reduction degree) properties of catalysts was established.

Keywords: cobalt, catalysts, hydrocarbon synthesis, structural properties, promoters

The aim of this work is to estimate the density of the electron spectrum of objects with a dispersion bond, such as liquid helium, for example. The interest in its electronic properties is caused by the recently discovered dynamic polarization in the second sound wave, which made the study of its zone structure relevant. In this paper, the objects under study are modeled after born by a linear chain of coupled oscillators. The dispersion bond is considered on the basis of the quasi-classical London approximation, which takes into account the correlations of the oscillating dipole moments of atoms. The first part of the work is preparatory. A brief review of the new experimental data for helium II is given, and the problem statement is formulated. On simple examples (lines of two and three coupled oscillators) the research methodology is worked out. This section is of independent importance for rapid estimates of the density of the electron spectrum in dispersion coupling, and identifies trends in the change of spectrum parameters with an increase in the number of structural units. It is obtained, in particular, that the band width increases and the specific binding energy decreases slightly. In the second part, a long chain of coupled oscillators is investigated on the basis of the developed techniques. The density of the electron spectrum is calculated both for specific chains and in the thermodynamic limit. The results obtained in this work are planned to be used in the future for the development of dynamic polarization models for helium II

Keywords: dispersion forces, helium II, dipole moment, harmonic oscillator, coupled oscillations, normal mode, electron spectrum, density, narrow band, binding energy

The aim of this work is to estimate the density of the electron spectrum of objects with a dispersion bond, such as liquid helium, for example. The interest in its electronic properties is caused by the recently discovered dynamic polarization in the second sound wave, which made the study of its zone structure relevant. In this paper, the objects under study are modeled after born by a linear chain of coupled oscillators. The dispersion bond is considered on the basis of the quasi-classical London approximation, which takes into account the correlations of the oscillating dipole moments of atoms. The first part of the work is preparatory. A brief review of the new experimental data for helium II is given, and the problem statement is formulated. On simple examples (lines of two and three coupled oscillators) the research methodology is worked out. This section is of independent importance for rapid estimates of the density of the electron spectrum in dispersion coupling, and identifies trends in the change of spectrum parameters with an increase in the number of structural units. It is obtained, in particular, that the band width increases and the specific binding energy decreases slightly. In the second part, a long chain of coupled oscillators is investigated on the basis of the developed techniques. The density of the electron spectrum is calculated both for specific chains and in the thermodynamic limit. The results obtained in this work are planned to be used in the future for the development of dynamic polarization models for helium II

Keywords: dispersion forces, helium II, dipole moment, harmonic oscillator, coupled oscillations, normal mode, electron spectrum, density, narrow band, binding energy

The paper presents the results of studies of the effect of ion-argon bombardment in vacuum on the spectral distribution of the photoconductivity of CdS crystals in the region of the fundamental absorption edge and on the current-voltage characteristic of the semiconductor under study. In the course of research, characteristic changes were found in the spectral distribution of the photoconductivity of a CdS crystal in the edge region of the spectrum and in its current-voltage characteristic at room temperature. It was shown that low-dose ion-argon bombardment leads to an increase in photosensitivity, as well as to a change in the spectral distribution of the photocurrent beyond the absorption edge of a semiconductor. It was found that the exposure of the sample, after exposure to it with argon ions, leads to the relaxation of the photoconductivity spectra of CdS crystals in the direction of the initial distribution. The observed spectral changes are associated with a decrease in the surface concentration of the recombina-tion centers, as well as with an increase in the number of near-surface donor self-defective centers, caused by the action of argon ions on the surface of CdS crystals. Exposure of the CdS crystal under investigation in the air, after exposure to it with argon ions, leads to a reverse increase in the number of recombination centers on the sample sur-face due to the interaction of the surface of the semiconductor with oxygen contained in the air.

Keywords: ion-argon bombardment, photoconductivity spectra, CdS crystals, surface recombination, current-voltage characteristic

Biphasic composite materials were synthesized near the La0.7Sr0.3MnO3-based percolation threshold and the second phase, which is an inorganic or organic compound — polyvinyl acetate, paraffin, carboxymethylcellulose, sucrose, and ultrafine silver particles. For composites with an organic matrix, the magnetoresistance values ​​do not exceed 2%, and for composites with silver particles - 8%. The values ​​of isotropic negative magnetoresistance for ceramic samples of 80% LSMO / 20% GeO2 (mass%) reach 13% in a 15 kOu magnetic field with a sensitivity of about 1% / ke in the low-field region. High chemical and radiation stability of these glass composites should be noted. The magnetoresistive properties of such compounds slightly decreased after 60 days of being in water with a salinity of 35 ppm. Composites of 80% LSMO / 20% GeO2 were exposed to X-rays with a dose of 7 Sv from the Co57 source. The magnetoresistive properties and electrical resistance of these composites did not change after that.

Keywords: lanthanum strontium manganite, ceramic two-phase material, one-step synthesis, radiation exposure, magnetoresistance, percolation threshold, dielectric constant, barrier layer, spin-dependent tunneling, spin polarization

The structural properties of cobalt catalysts and their active component are studied. The influence of metal oxides on the specific surface area, pore volume and size, the average crystallite size and the active surface area of the catalyst Co-Al2O3/SiO2 was studied.

Keywords: Fischer-Tropsch synthesis, synthetic hydrocarbons, catalyst, cobalt, promoter, carrier, specific surface, porous structure, catalytic activity, degree of reduction, active surface area

Today, catalysts based on zeolites containing transition metal ions are being intensively developed, ensuring the selectivity of the reaction of direct oxidation of methane to methanol. In current work, the X-ray absorption spectroscopy complimented with the structural models obtained in frames of the density functional theory were used to study the dependence of the local atomic structure of copper centers in mordenite type zeolites synthesized by solid-phase ion exchange using CuCl and H-MOR, upon the annealing temperature at different stages of synthesis. The typical Cu – O interatomic distances and the corresponding coordination numbers are determined. The dependence of the fraction of copper ions on the zeolite on the annealing temperature was established.

Keywords: EXAFS, DFT, zeolites, solid-phase synthesis, methanol synthesis

The physical and chemical properties of cobalt catalysts promoted by manganese oxides for the synthesis of hydrocarbons by the Fischer-Tropsch method are studied. The influence of polymorphic modifications of the alumina carrier on the specific surface area, pore volume, degree of reduction, size of cobalt crystallites,catalytic activity, dispersion degree of catalyst reduction is considered.

Keywords: Synthesis of Fischer-Tropsch, synthetic hydrocarbons, the cobalt catalyst, promoter MnO2, the carrier of Al2O3, specific surface area, the degree of recovery of the catalytic activity, dispersion, and the crystallites of cobalt

It is found that a sufficiently high catalytic activity of the metal oxide electrode is due to the state of phase disordering of the coating surface due to the presence of highly dispersed spinel-like and rutile-like phases of solid solutions, as well as the nature of the distribution of these phases in the coating volume. The possibility of formation of disordered and partially ordered spinel-like phases of the form (Co,Mn)3-xO4 is analyzed

Keywords: structural-phase disorder, solid solutions, spinalator phase retinopathy phase coating