Abstracts archive – Issue 16 (2024)

1. EXPERIMENTAL STUDIES OF NANOPARTICLES, NANOSYSTEMS, AND NANOMATERIALS – page 7

Antonov A.S., Sdobnyakov N.Yu., Anofriev V.A., Afanasiev M.S., Semenova E.M., Makaev V.V.
Comprehensive approach to studying fractal structures on iron surfaces – page 7
Abstract: Nanoscale iron films of different thicknesses and at different spatial scales were studied using two alternative methods: atomic force microscopy and scanning tunneling microscopy. It was revealed that the surface morphology and fractal dimension depend not only on the film thickness but also on the deposition conditions and subsequent digital processing. It was concluded that the surface has a highly developed relief, which corresponds to high values of the fractal dimension. A hypothesis was put forward that the presence of iron oxides on the surface of the studied samples significantly affects their morphology, contributing to the formation of a complex and highly developed relief. These oxides lead to the formation of some structural inhomogeneities, which lead to the observation of agglomerates in a fairly wide range of fractal dimension values (from 2,49 to 2,94) on the film surface, i.e. oxides contribute to the aggregation of particles, creating a more complex surface structure. In addition, a method of separating agglomerates allowed us to record an increase in the value of the fractal dimension, which indicates the efficiency of separating and studying individual complex surface objects. Thus, for nanosized iron films, it becomes important to take into account the effects of oxidation and agglomeration of surface elements when analyzing them and choosing a method for obtaining them to identify structures with a certain value of the fractal dimension.
Keywords: atomic force microscopy, scanning tunneling microscopy, magnetron sputtering, fractal dimension, iron films.

Akhmatov Z.A., Khokonov A.Kh., Sergeev I.N., Ambartsumov M.G.
Study of potassium intercalated graphite by Raman spectroscopy – page 24
Abstract: In this paper, a study of a graphite intercalation compound by potassium was carried out using Raman spectroscopy. The purpose of the study was to determine the intercalation stage and study the influence of intercalated atoms on the vibrational properties of highly oriented pyrolytic graphite lattice. The intercalation of highly oriented pyrolytic graphite by potassium was performed using a two-zone method. Raman spectra were obtained for both pure and intercalated highly oriented pyrolytic graphite. The experiments carried out to identify the synthesized structures showed the formation of sixth stage graphite intercalation compound. Knowledge of the stage of the intercalated graphite compounds is important for its use as a superconducting material, as well as in supercapacitors. In addition, the intercalation stage is a key factor in obtaining graphene by chemical exfoliation of graphite intercalation compound, since the number of graphene layers will directly depend on the intercalation stage. In the obtained Raman spectra, the effect of G-peak splitting is observed, indicating a change in the vibrational properties of the graphite lattice during its intercalation due to the charge transfer from the intercalate to the carbon layers. The value of the transferred charge is determined using first-principles calculations.
Keywords: Raman spectroscopy, highly oriented pyrolytic graphite, alkali metals, intercalation, two- zone method, first-principles calculations.

Barabanova E.V., Ospelnikov N.M., Ivanova A.I.
Effect of Bi-doping on the electrophysical properties of sodium niobate solid solutions – page 33
Abstract: Introduction of dopants is a classic method for modifying the properties of materials, in particular, complex oxides of the perovskite family with the general formula ABO₃. Ions located in positions A and/or B are substituted. In this case, their valence can coincide with the valence of the basic ion (isovalent substitution) or differ (heterovalent substitution). Sodium niobate (NaNbO₃) is a convenient basis for producing ferroelectric solid solutions. Doping changes the properties of sodium niobate in a wide range, allowing the production of functional materials for various applications. In this paper, the effect of Bi³⁺ doping upon substitution of niobium ion Nb⁵⁺ on the structure and electrophysical properties of sodium niobate is studied. It has been shown that such compositions are characterized by a significant increase in electrical conductivity with increasing the doping concentration, a decrease in the Curie temperature, and a change in the grain structure. The dopant concentration is more than 10 mol. % leads to the formation of some secondary phases.
Keywords: ionic conductivity, ferroelectric solid solutions, sodium niobate, dielectric permittivity.

Bezverkhniy V.P., Gagarina A.Y., Muratova E.N., Maximov A.I., Moshnikov V.A.
Investigation of optical properties of metal-doped CsPbX3 perovskite nanocrystals – page 41
Abstract: As a part of the research work, inorganic lead-containing halide perovskite nanocrystals with the CsPbX₃ structure were obtained by the hot injection. The alloying of single crystals of perovskites was carried out by solution methods, zinc and indium ions acted as dopants. The photoluminescence spectra and optical density spectra of the obtained colloidal solutions were studied. Our studies have shown that doping of perovskite nanocrystals with metal ions leads to an increase in photoluminescence as well as to a shift in the maximum of photoluminescence relative to the reference composition by 4 and 12 nm for bromides and iodides, respectively. Also, it has been shown that the magnitude of the shift does not depend on the type of dopant. It is noted that within the framework of this work, doping does not lead to a change in the position of the edge of its own absorption.
Keywords: perovskites, solar energy, nanocrystals, alloying, optical properties.

Bobreva L.A., Titov R.A., Smirnov M.V., Biryukova I.V., Masloboeva S.M., Pyatyshev A.Yu., Sidorov N.V., Palatnikov M.N.
Comparative studies of structural features of LiNbO3:Er:Zn crystals of different genesis – page 48
Abstract: Comparative studies of double-doped LiNbO₃:Er:Zn crystals of different genesis have been carried out using infrared absorption spectroscopy (in the region of OH^–-group stretching vibrations) and Raman spectroscopy. A LiNbO₃:Er(0,53 mol.%):Zn(4,02 mol.%) crystal obtained by solid-phase doping and a LiNbO₃:Er(0,75 mol.%):Zn(3,82 mol.%) crystal obtained by homogeneous doping were used in the study. No significant changes have been recorded in the infrared absorption spectra and Raman spectra of crystals obtained using different technologies. Minor changes in the main parameters of the absorption bands with frequencies of 3483 and 3492 cm^-1 have been detected in the infrared absorption spectra. This may be due to the higher concentration of zinc dopant in the LiNbO₃:Er (0,53 mol.%):Zn(4,02 mol.%) crystal. Measuring the half-width parameter of the band with a frequency of 271 cm^-1 in the Raman spectra of the studied crystals helped to establish that the LiNbO₃:Er(0,53 mol.%):Zn(4,02 mol.%) crystal has a higher ordering of the structural units of the cation sublattice compared to the LiNbO₃:Er(0,75 mol.%):Zn(3,82 mol.%) crystal.
Keywords: lithium niobate, solid phase doping, homogeneous doping, erbium, zinc, double doping, Raman scattering, complex defects, infrared spectroscopy.

Bobreva L.A., Titov R.A., Smirnov M.V., Biryukova I.V., Masloboeva S.M., Pyatyshev A.Yu., Palatnikova O.V., Sidorov N.V., Palatnikov M.N.
Comparative studies of photoluminescent and optical properties, concentration of OH^– groups in double-doped LiNbO₃: Er:Zn crystals – page 60
Abstract: A comparative analysis of the photoluminescent properties, concentration of OH^–-groups and optical quality of double-doped crystals obtained from charges of different genesis has been performed. In a LiNbO₃:Er(0,53 mol.%):Zn(4,02 mol.%) crystal obtained by solid-phase doping, the content of OH^–-groups is higher than in a LiNbO₃:Er(0,75 mol.%):Zn(3,82 mol.%) crystal obtained by homogeneous doping. These changes occur as a result of the simultaneous formation of two types of complex defects in the LiNbO₃:Er (0,53 mol.%):Zn(4,02 mol.%) crystal structure: Zn_Nb^3--OH and V_Li- OH. It has been established that photoluminescence in the visible region is caused by radiative transitions of Er³⁺ without the manifestation of the host’s own luminescence in the studied crystals. For the LiNbO₃:Er:Zn crystal obtained by solid-phase doping, the luminescence intensity is 77% higher than in the crystal obtained by homogeneous doping. This may be due to the participation of OH^–-groups in the energy transfer between the host and the Er³⁺ ions.
Keywords: lithium niobate; double doping; photoluminescence; hydroxyl groups; rare earth and non- photorefractive dopant; point and complex defects.

Bolshakova N.N., Ivanova A.I., Druginina N.Yu., Semenova E.M., Schipilov S.S.
Switching processes in alanine doped triglycine sulfate crystals – page 72
Abstract: The paper presents the results of an experimental study of the dielectric and switching characteristics of some initial and annealed alanine-doped crystals of the triglycine sulfate group at room temperature. The results of measurements and calculations of the effective permittivity, switchable polarization, coercive and bias fields, unipolarity coefficient and dielectric loss tangent are presented. It was found that for most samples before and after annealing, the dielectric hysteresis loops are unipolar and shifted along the abscissa axis. This indicates a preferential orientation of domains and the presence of bias fields. As a result of annealing, the values of the coercive field and the unipolarity coefficient of the crystals decrease, and the switchable polarization increases. It is shown that the field dependences of the effective permittivity of the crystals before annealing have extrema lying in the field range of (5-7,5) ∙ 10⁴ V∙m^-1 and in the range (5-12) ∙ 10⁴ V∙m^-1 after their annealing.
Keywords: triglycine sulfate crystals, hysteresis, switching processes, permittivity.

Guseva A.M., Sinkevich A.I., Smetannikova S.D., Semenova E.M., Pastushenkov Yu.G.
Analysis of domain structure parameters of RFe₁₁Ti (R = Y, Gd, Ho, Er) single crystals based on magnetic force microscopy data – page 85
Abstract: The results of an experimental study of the magnetic domain structure on the basal plane of RFe₁₁Ti single crystals (R=Y, Gd, Ho, Er) by magnetic force microscopy are presented. At room temperature, the compounds are characterized by magnetocrystalline anisotropy of the «easy axis» type. Based on the magnetic force microscopy data, the sizes of domains on the basal plane of the samples were determined. Using the Bodenberger-Hubert method, the surface energy density of domain walls γ was determined for all compounds based on the magnetic force microscopy data: YFe₁₁Ti – 4,05 mJ/m², GdFe₁₁Ti – 5,93 mJ/m², HoFe₁₁Ti – 4,97 mJ/m², ErFe₁₁Ti – 2,98 mJ/m². The cube counting method was used to calculate the fractal dimension D_L of the stray fields of the domain structure at different heights from the surface (0,1 – 9 μm). D_L on the surface of the z(0) sections has values of 2,62 for compounds with R = Y, Gd, Ho and 2,72 for R=Er. For all samples, D_L has a maximum near the surface.
Keywords: rare earth intermetallic compounds, domain structure, magnetic force microscopy, fractal dimension.

Dunaeva G.G., Karpenkov A.Yu.
Towards the investigation of the magnetization processes of uniaxial magnetic materials by means of the analysis of transformation of their domain structure: experiment and computer modeling – page 96
Abstract: This paper presents the results of complex studies, including direct experiment and computer modeling, of the magnetization reversal processes of a SmCo₅ single crystal and a (GdBiLu)₃(FeGa)₅O₁₂ ferrite-garnet film. The analysis of images of the domain structure in the external magnetic field of both samples allowed us to construct the field dependences of magnetization. It was found that the field dependence of the magnetization of the ferrite-garnet film coincides with the magnetometry data. For the SmCo₅ single crystal the saturation field of the surface corresponds to the saturation field obtained from the measurements on a vibrating sample magnetometer, however, the view of the field dependence M(H) differs. Image analysis of the main domains of a single crystal in an external magnetic field and computer modeling have shown that the values of the domain structure disappearance fields on the surface of the film located above the single crystal are significantly less than the saturation fields according to magnetometry data. The application of an external magnetic field of 0,02 T leads to saturation of the entire volume of the ferrite-garnet film in the direction of the field, which does not allow further observation of the transformation of the main domain structure of the bulk sample and limits the applicability of the indicator film method.
Keywords: ferrite-garnet film, single crystal, magnetic domain structure, Kerr effect, magnetization reversal processes.

Zernitsa D.A., Shepelevich V.G.
Structural features and properties of the Sn-Zn-Si-Al system alloys obtained by the method of rapid solidification from the melt – page 110
Abstract: The article presents the results of studying the microstructure of rapidly solidified foil of Sn_55,18Zn_44,50Si_0,23Al_0,09 alloy. The phase composition of rapidly solidified foil was studied. A uniform distribution of alloying silicon and aluminum in tin in the form of a solid solution was established. The formation of the (100) texture of tin and (1010) of zinc was revealed, associated with the predominant growth of crystallites, in which the close-packed planes of tin and zinc are perpendicular to the direction of heat removal during crystallization. An analysis of the structure and properties of the foil during isothermal annealing and natural aging was performed, with a description of the processes occurring. Formation of a dispersed structure due to high degree of supercooling of liquid phase with increase of degree of dispersion of zinc during isothermal annealing (average chord d on sections of zinc phases is 1,24 μm before heat treatment and 0,42 μm after isothermal annealing for 170 min at 150°C) along with invariance of texture during heat treatment is established. Change of the microhardness of foil during natural aging, noticeable formation of large number of clusters of precipitations of tin and zinc phases due to their supersaturation, as well as reinforcing action of alloying elements (Si, Al) are explained. During heat treatment zinc dissolves in the matrix phase, with decrease of its volume, while share of softening phase of tin increases which leads to a decrease in the microhardness.
Keywords: rapidly solidified structures, multicomponent alloy, zinc, tin, supersaturated solution, structure, isothermal annealing, silicon, aluminum.

Zigert A.D., Kuz`min N.B., Semenova E.M., Karpenkov A.Yu., Ivanova A.I., Sdobnyakov N.Yu.
Correlation of magnetic characteristics and fractal dimension of magneto-optical images of permanent magnets – page 119
Abstract: The article continues a series of studies of permanent magnets with different magnetization reversal mechanisms (nucleation, domain boundary displacement). In this work, a correlation is established between magnetic characteristics of permanent magnets (Y25 and AlNiCo) and the fractal dimension of magneto-optical images of their stray fields. Bismuth-containing ferrite-garnet films were used as an indicator. It is shown that the limiting values of the fractal dimension: 1,76 for a ferrite magnet and 1,85 for an AlNiCo magnet, are consistent with the results obtained for NdFeB (grade N35) and SmCo (grade KC37) magnets, as is the behavior of the field dependence of the fractal dimension. The behavior of the field dependence of magnetization M_mo(H_rev) has similar features to a similar dependence recorded for a permanent magnet NdFeB (grade N35), but the values of the demagnetizing fields for the Y25 sample are much smaller. The paper discusses the relationship between the mechanisms of magnetization reversal of permanent magnets and the behavior of the M_mo(H_rev) dependence.
Keywords: permanent magnets, fractal dimension, magneto-optics, dM(Hrev)/dHrev dependence.

Ivanov V.I., Myagotin A.V.
Тhe holographic method for diagnostics of nanoparticles in dense nanosuspensions – page 128
Abstract: The efficiency of the recording dynamic holograms in dispersed liquid-phase media with a high concentration of nanoparticles is analyzed. The optical nonlinearity of the medium is due to the electrostriction forces acting on the particles of the dispersed phase in a gradient light field. Mass transfer is considered in the case of suprathermal radiation intensities, when the light-induced change in the concentration of nanoparticles is greater than the initial one and reaches saturation. It is shown that at high levels of the radiation intensity, the recording of a dynamic hologram is carried out in a significantly nonlinear mode, when the phase lattice becomes non-sinusoidal. At the same time, the amplitude of the first harmonic increases sharply with increasing intensity, which makes it possible to achieve a significant increase in the efficiency of the hologram recording. The results obtained are relevant for dynamic holography of dispersed liquid-phase media, as well as for optical diagnostics of such media.
Keywords: electrostriction, cubic nonlinearity, nanosuspension, dynamic holograms, suprathermal radiation intensity, optical diagnostics.

Ivanov V.I., Egorshin I.N.
A modulation method of light-induced pseudo-prism in nanosuspension – page 134
Abstract: In this paper, a modulation method for creating a pseudo-prism in a nanodispersed liquid-phase medium is proposed, based on using the light pressure of radiation. Usually, the pseudo-prism method is used to study a stationary sedimentation profile in a dispersed medium. For nanoparticles and macroscopic cell sizes, the typical equilibrium times are tens of hours. Even with significant light pressure forces that exceed gravitational pressures, the characteristic time of settling the sedimentation profile remains very long. Therefore, achieving an equilibrium distribution requires a long experiment, which places high demands on the stability of all conditions and is practically unrealizable due to the presence of convective flows. Modulation of the reference beam makes it possible to study the dynamics of the pseudo-prism at short times, which significantly increases the accuracy of the optical diagnostic method. The article presents a theoretical analysis of the process of light-induced mass transfer in a dispersed liquid-phase medium located in a homogeneous time-modulated light field. As a result of the analytical solution of the problem of light-induced mass transfer, an expression was obtained that makes it possible to determine the amplitude of the angle of deflection of the signal beam in a pseudo-prism.
Keywords: pseudoprism method, light pressure, nanofluids, optical diagnostics, separation, nanoparticles.

Ivanov Yu.F., Akhmadeev Yu.Kh., Klopotov A.A., Prokopenko N.A., Petrikova E.A., Krysina O.V., Shugurov V.V., Shmakov A.N., Lavrov V.Yu.
X-ray diffraction studies of the growth process of thin films of high-entropy TiNbZrTaHfCu alloy in situ using synchrotron radiation – page 140
Abstract: High-entropy alloys based on refractory metals, possessing an unusual combination of physical, mechanical, tribological, electrophysical, etc. properties, can be recommended for use in various fields of industry and medicine. The aim of the work is to study the growth process of high-entropy alloys films of the Ti-Nb-Zr-Ta-Hf-Cu system in real time by X-ray phase analysis using synchrotron radiation. Experiments on the deposition of multielement metal films were carried out on the VEIPS-1 setup developed at the Institute of high current electronics Siberian branch of the Russian academy of sciences for studying the processes of the film and coating formation on a synchrotron radiation source. The process of in situ thin film structure formation with high time resolution was studied using a synchrotron radiation source – the VEPP-3 electron storage ring, the Institute of nuclear physics, Siberian branch of the Russian academy of sciences. It is shown that the deposition of Ti-Nb-Zr-Ta-Hf-Cu plasma on a HG40 substrate is accompanied by the formation of an amorphous-crystalline state represented by phases of the composition (presumably) Ti-Nb-Zr-Ta-Hf-Cu, TiZr, NbZr, and CuTiZr, formed at different stages of film deposition. The main phase is the Ti-Nb-Zr-Ta-Hf-Cu composition.
Keywords: high-entropy alloy, refractory metals, synchrotron radiation, phase composition, copper alloying.

Ivanova A.I., Dudilovskaya A.V., Zhuravlev O.E., Kaphtanov A.D.
Application of ionic liquids in scanning electron microscopy studies of dielectric microstructure – page 154
Abstract: This article presents the results of studying non-conducting biological, crystalline objects, powders, and glass composite samples using an ionic liquid by scanning electron microscopy. Ionic liquids based on alkylpyridinium dicyanamides studied in the work were obtained by a metathesis reaction. A solution of ionic liquid in acetone was used as a conductive coating for dielectrics. It was found that the use of ionic liquid is an alternative to the methods of metal and carbon sputtering on dielectric samples. Scanning electron microscopy images of samples obtained by such microscopy methods as low vacuum mode, the use of metal sputtering (Pt) on samples, and a study of samples without a conductive coating are presented. A comparative analysis of the results obtained by traditional methods and the method of applying ionic liquid to samples is carried out. It is shown that the use of electrically conductive ionic liquids with the thermal and chemical stability makes it possible to obtain high-resolution electron microscopic images and also allows visualization of the topographic and compositional contrast of the studied dielectric samples.
Keywords: ionic liquid, sample preparation, dielectric samples, surface microstructure, scanning electron microscopy.

Kabirov Yu.V., Utoplov A.A., Lyanguzov N.V., Sidorenko E.N., Prutsakova N.V., Chebanova E.V.
Thermopower of magnetoresistive composites based on La_0,7Sr_0,3MnO₃ – page 164
Abstract: The paper studies the dependence of the magnetoresistance and Seebeck coefficient of the composite magnetoresistive composition near the percolation threshold of 80%La_0,7Sr_0,3MnO₃/20%GeO₂ on the constant magnetic field strength up to 3,8 kOe and temperature in the range from 25°C to 150°C. The 80%La_0,7Sr_0,3MnO₃/20%GeO₂ samples have the p-type conductivity, a the positive sign of the Seebeck coefficient and a dielectric character of the change in the electrical resistance with temperature. The activation energy of such compositions is of about 0,35 eV. The magnetoresistance of such a composition decreases with an increase in the temperature difference between the hot and cold edges and disappears in the region of the phase transition temperatures of 90°C. It was found that in a constant external magnetic field of 3,8 kOe, a decrease in the Seebeck coefficient of the 80%La_0,7Sr_0,3MnO₃/20%GeO₂ compositions by 11% is observed at a temperature difference of 10 K. The dependence of the Seebeck coefficient on the magnetic field decreases with an increase in the hot edge temperature and also disappears in the temperature range of 90°C, which is associated with the ferromagnetic-paramagnetic phase transition of lanthanum manganite La_0,7Sr_0,3MnO₃ and the suppression of spin-dependent electron tunneling.
Keywords: Seebeck coefficient, magnetoresistive composite, constant magnetic field, lanthanum- strontium manganite, percolation.

Kislova I.L., Kiselev D.A., Kholkin A.L., Solnyshkin A.V., Muhin O.A., Kolkov G.G.
Features of the dynamic pyroelectric response and the local domain structure in PZN-PT crystals – page 171
Abstract: In this work, the polarization distribution over the volume of (1-x)Pb(Zn_1/3Nb_2/3)O_3-xPbTiO₃ crystals of the directions [001] and [111] was studied by the method of dynamic pyroelectric response. It is established that the value of the pyroelectric coefficient in the samples of both directions is the same. The domain structure of the studied crystals was visualized by piezoresponse force microscopy. It is shown that on the surface of the initial single crystals of these directions there is a small-sized labyrinth-like domain structure from 50 to 500 nm, characteristic of ferroelectric relaxors. At a depth of 50 microns from the crystal surface, a larger domain structure with a characteristic micron-scale domain size is observed. To determine the average thickness of a layer with an inhomogeneous polarization distribution, a theoretical model was used that analytically describes the possibilities of a dynamic pyroelectric method for studying the near-surface layer of ferroelectric materials. Theoretical calculations have shown that this method allows us to obtain accurate data on the thickness of the layer and its polarization state. It has been experimentally established that in a single crystal 0,955Pb(Zn_1/3Nb_2/3)O_3-0,045PbTiO₃ of the direction [001], the secondary pyroelectric effect contributes to the overall pyroelectric response much more than for the direction [111] due to the large value of the piezoelectric coefficient.
Keywords: relaxors, pyroelectric effect, polarization, piezoelectric force microscopy, domain structure.

Kozhevnikova N.S., Bogdanova E.A., Skachkov V.M., Baklanova I.V., Tyutyunnik A.P., Buldakova L.Yu., Yanchenko M.Yu., Yushkov A.A.
Ex-situ modification of nanostructured hydroxyapatite by colloidal CdS particles – page 183
Abstract: The article discusses the possibility of obtaining functional composite materials with pronounced photocatalytic properties. A hybrid composite material based on nanoscale cadmium sulfide fixed on a matrix of hydroxyapatite obtained by precipitation from solution has been developed. The initial components and synthesized samples were certified using some modern physico-chemical analysis methods: X-ray phase analysis, energy dispersive X-ray analysis, Raman spectroscopy, scanning electron microscopy, the Brunauer-Emmett-Teller method. The functional characteristics of the developed composite material Ca₁₀(PO₄)₆(OH)_2-CdS, in particular, the photocatalytic activity under the action of ultraviolet or visible radiation, are investigated. The efficiency of using the developed composite material as a photocatalyst was evaluated by the rate of oxidation of p-dihydroxybenzene (hydroquinone). Based on experimental data obtained, the values of the constants of the reaction rate of photocatalytic oxidation of hydroquinone and the time of its half-conversion under various conditions (radiation, the presence of a catalyst) are calculated. It is proved that the developed composite material, which is a hydroxyapatite modified with colloidal CdS particles, has pronounced catalytic properties and is a promising material for use as a photocatalyst. A patent application has been filed for the developed composite material.
Keywords: cadmium sulfide, chemical condensation from aqueous solutions, hydroxyapatite, composite material, photocatalysis.

Kravchenko D.A., Kolosov A.Yu., Sokolov D.N., Nepsha N.I., Bogdanov S.S., Sdobnyakov N.Yu.
An integrated approach to studying the structure of ternary CoCrMo alloy: scanning electron microscopy and atomistic simulation – page 198
Abstract: A comparative study combining the experimental technique of scanning electron microscopy and atomistic simulation by (molecular dynamics) was carried out using of the ternary CoCrMo nanoalloy as an example. Employing the technology of selective laser melting based on the PR-KH28M6 powder, a sample was made for which a non-uniform surface composition with respect to the presence of cobalt and chromium was identified, i.e. areas were simultaneously enriched and depleted in these elements, which indicates the possibility of forming various intermetallic compounds based on them. In the process of atomistic simulation, three nanoparticles of the ternary CoCrMo nanoalloy with the number of 10000, 15000 and 30000 atoms were subjected to a sequential cycle of heating and cooling, including the identification of phase transitions corresponding to melting and crystallization, respectively. The corresponding temperatures of the beginning and end of the phase transition were determined. The regularities of structural and surface segregation in the ternary CoCrMo nanoalloy are described. It is noted that for nanoparticles containing 10000 atoms, only a shell of cobalt atoms is formed without forming a core, while for nanoparticles containing 15000 and 30,000 atoms, an onion-like structure is formed. Chromium atoms form either the core of the nanoparticle as at N=10000 or the peripheral region as at N=15000 and 30000. Molybdenum atoms behave indifferently, i.e. are distributed uniformly throughout the entire volume of the nanoparticles under study.
Keywords: ternary CoCrMo alloy, selective laser melting technology, surface microstructure, molecular dynamics method, structural and surface segregation.

Lapushkin M.N.
Adsorption of barium on surface of GaN(0001) – page 210
Abstract: For the first time, the adsorption of barium atoms on the surface of the (0001) face of GaN was calculated using the density functional method. The 2D GaN layer was modeled using a GaN(0001) 2×2 supercell containing 10 GaN bilayers. The electron density of state and the adsorption energy of the Ba atom were calculated for five adsorption sites of the Ba atom: in the hollow position, in the bridge position between the surface Ga (N) atoms, and above the surface Ga (N) atom. There was one Ba atom per 4 surface Ga atoms in the first GaN bilayer. The adsorption of the barium atom above the surface N atom was most preferable. The adsorption energy was 2,96 eV. The adsorption of Ba atoms resulted in an insignificant reconstruction of the GaN surface: the maximum shift of the Ga (N) atoms did not exceed 0,11 Å. The adsorption of Ba resulted in the formation of a surface band below the Fermi level.
Keywords: density functional method, electronic structure, interface, surface, adsorption, barium, GaN.

Mamaev D.V., Malyshkina O.V., Ivanova A.I.
Porous ceramics of sodium potassium niobate system – page 219
Abstract: In our work, we used the finely dispersed polystyrene to produce porous samples of the piezoelectric ceramics. Samples of the sodium potassium niobate ceramics with pore concentrations of the 10, 20, 25, 30 and 40 volume percent were produced. The structure was analyzed and the temperature and frequency dependences of the dielectric constant of the obtained samples were investigated. It has been established that the presence of polystyrene in the process of sintering piezoceramic samples plays the role of a binder, which evaporates during high-temperature processing. At the same time, the binder contributes to stabilization of the dielectric properties of the ceramics. In the porous samples, there are no fluctuations of the permittivity in the low-frequency region, and the frequency range in which the permittivity values are independent of the frequency increases. It was found that already 34 volume percent of the pores worsen the mechanical strength of the sample. It is shown that the use of a simple problem of percolation theory does not allow assessing the mechanical strength of porous samples depending on the pore concentration.
Keywords: piezoelectric ceramics, porous materials, potassium sodium niobate, permittivity, nanostructure, 3-3 composites.

Medyanik E.V., Malyavin F.F., Lapin V.A., Kravtsov A.A., Suprunchuk V.E., Tarala L.V.
Study of the influence of sintering additives and vacuum sintering conditions on optical properties of LuAG:Er (1 at.%) ceramics – page 229
Abstract: In this work, ceramic samples based on lutetium-aluminum garnet doped with erbium (content 1 at.%) were manufactured. In the manufacture of ceramic material, the chemical precipitation method was chosen. The influence of two types of sintering additives, MgO and CaO, on the microstructure and optical properties of ceramic samples obtained at vacuum sintering temperatures of 1800, 1850, 1875°C was studied. The article discusses in detail how the microstructure and optical transmission of ceramics with sintering additives MgO and CaO change at different vacuum sintering temperatures. It was found that magnesium oxide allows to achieve a higher optical transparency of ceramics (about 80%), while calcium oxide more effectively inhibits the grain growth. An increase in the sintering temperature for samples with MgO from 1800 to 1850°Ccontributed to an increase in the light transmission of samples from 10 to 80% and an increase in grain size from 1,80 to 3,03 microns. Earlier no such a phenomenon was not observed for samples with CaO, samples obtained at sintering temperatures of 1850 and 1875°C had approximately the same microstructure, containing some residual microporosity.
Keywords: lutetium-aluminum garnet doped with erbium, optical ceramics, sintering, light transmittance coefficient, luminescence.

Novik O.D., Gavrilova N.D., Malyshkina O.V.
Low-frequency impedance spectroscopy of polymers and crystals with a hydrogen-bond network. Quantum collective excitations of nuclei in molecules – page 239
Abstract: In this work, we present the results of our studies of temperature-frequency behaviour of dielectric permittivity ε, conductivity σ, relaxation time τ_μ, thermodepolarisation currents j, and pirocurrents γ in hydrophilic polymers and crystals with a hydrogen-bond network OH…O in the ranges of 0,01–10⁷ Hz and 20-140°С. Analysis of the obtained data has revealed temperature anomalies of ε(T), σ(T), τ_μ(T), j(T), and γ(T) around «threshold» points at 20, 36, 50, 65, and 85°С, where the destruction of water clusters (and, if above 100°С, of water molecule itself) takes place, and thereby the release of deep traps, the change of the charge carriers (Н₃O⁺, ОН^–, etc.) composition and of their trajectories in volume are observed. In this study, we draw an analogy between the temperature behaviour of ε, σ, τ_μ, j, and γ in «threshold» points having a characteristic single resonance peak and the dipole resonance of photoabsorption in clusters of Ag, Mg, and Sm metals, which is manifested in thebroadening of resonance, single peak splitting, and in the formation of single-domain ATGS+Cr³⁺ crystal (0,06 wt.% Cr). We also discuss a possible onset of collective nuclear excitements during irradiation with photons or an onset of internal electrical displacement field E_dp in a sudden sample cooling or warming. The entanglement of photons by polarization is also considered.
Keywords: giant dipole resonance, discrete energy levels of double-well potential, dielectric permittivity and conductivity, coherent collective excitements of nuclei, splitting of resonance maxima of ε, σ and of conductivity relaxation time τμ, spin probability field.

Rakunov P.A., Lyakhova M.B., Semenova E.M., Karpenkov A.Yu.
Magnetic properties and magnetic reversal processes of the Sm-Gd-Zr-Co-Cu-Fe alloys – page 258
Abstract: The results of experimental studies of magnetic properties and magnetization reversal processes of a series of alloys Sm-Gd-Zr-Co-Cu-Fe are presented. The studied samples were subjected to prolonged isothermal annealing for 24 hours, which made it possible to achieve the formation of a certain nanostructure that affects the hysteresis properties of the material and allows to achieve a high coercivity state. According to the magnetic measurements data obtained by the method of a vibrating magnetometer, the hysteresis loops are constructed, the dependence of the saturation magnetization, and the coercive force on chemical composition, and the values of the temperature coefficient of magnetization change depending on the relative content of Sm and Gd are determined. It is shown that the substitution of a part of samarium atoms for gadolinium atoms increases the effect of the mechanism of irreversible rotation of the spontaneous magnetization vector on the remagnetization of samples. Application of the studied samples in various devices puts serious demands on the stability of their magnetic properties at high temperatures. Our researches allow us to conclude that compounds with gadolinium concentration x=0,5 have the greatest coercive force, and compounds with gadolinium concentration in the range x=0,5-0,6 have the highest temperature stability.
Keywords: rare earth intermetallic compounds, hard magnetic materials, hysteresis, coercive force, magnetization, magnetization reversal processes.

Salomatina A.Yu., Fedotov A.Yu., Severyukhina O.Yu., Vinogradov F.A.
Study of Co-Fe nanocomposite magnetic properties – page 267
Abstract: In this paper, a comparative analysis of the characteristics, advantages and disadvantages of five different types of magnetoresistive random access memories has been carried out. An optimal mathematical model for investigation of composition and structure of materials for spintronics devices is selected. A review of the combined mathematical model consisting of the molecular dynamics method and the model of spin dynamics of particles with interatomic interaction potential based on a modified embedded atom method is presented. An analysis is performed of modeling of magnetic properties of cobalt and iron bilayer film under conditions of the uniform external magnetic field. The iron layer was characterized by the formation of skirmions, while regions with different magnetic domains were found in the cobalt nanofilms. The overall magnetization of the Co-Fe system was found to be low due to the lack of the priority direction of the magnetic moment. The magnetizationrates of cobalt, iron of different thicknesses and the Co-Fe system as a whole were compared separately.
Keywords: spintronics, magnetoresistive random access memory, mathematical modeling, molecular dynamics, spin dynamics, modified embedded atom method, LAMMPS, skirmions.

Sidorov N.V., Bobreva L.A., Palatnikov M.N., Pyatyshev A.Yu., Tarabrin M.K., Bushunov A.A.
Features of the defect structure of LiNbO3:Cu crystals and their manifestation in the IR absorption spectrum in the region of stretching vibrations of hydrogen atoms OН– -group – page 277
Abstract: LiNbO₃:Cu (0,005 wt.%), LiNbO₃:Cu (0,015 wt.%), LiNbO₃:Cu (0,022 wt.%), LiNbO₃:Cu (0,042 wt.%), LiNbO₃:Cu (0,46 wt.%) crystals were studied by IR absorption spectroscopy in the region of stretching vibrations of OH^–-groups. These crystals were grown by the Czochralski method using the technology of direct doping of a charge of congruent composition. It has been established that the recorded absorption bands in the infrared spectrum in the frequency range 3469-3490 cm^-1 are associated with a deviation in the composition of the LiNbO₃:Cu crystal from the stoichiometric one. Such changes occur due to a deficiency of Li⁺ cations in the crystal structure. The incorporation of Cu²⁺ dopant leads to disordering of the cation sublattice and noticeable deformation of oxygen octahedra. This occurs due to an increase in the O–O bond lengths. In this case, a newabsorption band with a frequency of 3487 cm^-1, corresponding to the V_Li-OH complex defect, is recorded in the IR spectrum. Calculation of the volume concentration of OH^–– groups showed the highest value for crystals ofLiNbO₃:Cu (0,005 wt.%), LiNbO₃:Cu (0,015 wt.%), LiNbO₃:Cu (0,022 wt.%). These changes occur due to the simultaneous formation of two types of complex defects in the crystal structure: Cu⁺-OH-Cu^3- and V_Li-OH. A change in the mechanism of entry of a doping impurity into the structure of a LiNbO₃:Cu crystal (0,042 wt.%) leads to a decrease in the concentration of OH^–– groups.
Keywords: lithium niobate, photorefractive impurity, point defects, complex defects, infrafed spectroscopy.

Staritsyn M.V., Pronin V.P., Khinich I.I., Krushelnitsky A.N., Senkevich S.V., Kaptelov E.Y., Pronin I.P.
Effect of electron channeling in the crystal lattice of radiant spherulites – page 289
Abstract: The paper presents the results of the microstructure study of spherulitic islands in thin films of lead zirconate titanate, characterized by either a non-uniform radial rotation of the crystal lattice (radiant microstructure) or a uniform rotation, which allows one to detect Kikuchi lines of electron channeling. Thin lead zirconate titanate films were obtained by a two-stage method of radio-frequency magnetron sputtering of a ceramic target: deposition onto a «cold» platinized silicon and glassceram substrates, followed by high-temperature annealing to obtain islands of the perovskite phase surrounded by a matrix of the low-temperature pyrochlore phase. To study the cross section, a lamella was prepared, the study of the microstructure of which showed that the rotation of the crystal lattice in the perovskite spherulite occurs uniformly throughout the entire thickness, and it is not a manifestation of some near-surface effects. It was found that the rate of rotation of the crystal lattice in spherulites with a radial-radiant structure is approximately two times less than in spherulites with a radiallyuniform rotation; a model of translational rotation of the crystal lattice with the formation of dislocations and partial relaxation of mechanical stresses is proposed; it is assumed that the lattice rotation velocity is limited by the elasticity limit of the thin film. It is assumed that the Kikuchi image in spherulitic islands consisting of crystalline grains is determined by both the identical growth texture and the orientational correlation of the grains in the plane of the film; an analysis and interpretation of Kikuchi electron channeling lines has been carried out, which makes it possible to determine the orientation of the crystal lattice planes and growth axes in thin films.
Keywords: thin films of lead zirconate titanate, spherulites, radially-radiant microstructure, electron Kikuchi channeling.

Teplyakova N.A., Sidorov N.V., Palatnikov M.N.
Clusters in the structure of non-stochiometric lithium niobate crystals – page 300
Abstract: This work examines the main reasons for the appearance of an «extra» band with a frequency of ~737 cm^-1 in the Raman spectra of lithium niobate crystals. The following stand out among the reasons: the presence of clusters (microstructures); the presence of microinclusions of impurity phases of other lithium niobates (LiNb₃O₈ and Li₃NbO₄); strong anharmonicity of some fundamental vibrations of the Raman spectrum. The structure of clusters differs from the structure of the crystalline matrix. It has been shown that the appearance of a line with a frequency of ~737 cm^-1 in the Raman spectrum cannot be unambiguously associated with the existence of regions with reduced symmetry in the structure of doped crystals. These regions are the result of uneven incorporation of dopants into the crystal. The existence of these areas is also not explained in terms of the photorefractive effect. The results of studying the features of the defect structure, stoichiometry, optical uniformity and photorefractive effect confirm a correlation between the band with a frequency of ~737 cm^-1 and Nb_Li defects in the structure of the lithium niobate crystal.
Keywords: lithium niobate, crystal, defects, clusters, Raman spectroscopy, anharmonicity of fundamental vibrations, «extra» lines.

Utoplov A.A., Prutsakova N.V., Rudskaya A.G., Nazarenko A.V., Belokobylsky M.V., Kabirov Yu.V.
Magnetoresistance of LSMO/(Cu2O, Ag) composites – page 307
Abstract: Electrical, structural and magnetoresistive properties of ceramic composites with different mass ratios of components were synthesized and studied: (Cu₂O+CuO)_x/(La_0,7Sr_0,3MnO₃)_1-x (x = 0,17; 0,22; 0,33; 0,43; 0,48; 0,53; 0,58; 0,63; 0,68; 0,72; 0,77; 0,82; 0,86; 0,91; 0,99), and Ag_y/(La_0,7Sr_0,3MnO₃)_1-y (y = 0; 0,02; 0,06; 0,08; 0,10; 0,12; 0,25; 0,50). The composites with copper oxides were synthesized using an original technology for sample preparation using dispersed copper and a pre-prepared ferromagnetic oxide with the perovskite structure La_0,7Sr_0,3MnO₃. Pressed mixtures with a copper content of less than 45% by weight were annealed at a temperature of 1050°C. At higher copper contents, annealing was performed at 1000°C. The compositions with silver nanoparticles were prepared by reduction from silver nitrate. The composites were synthesized using an original technology for sample preparation using dispersed copper and La_0,7Sr_0,3MnO₃ manganite with annealing at 1000-1050°C. It was shown that the synthesized composites with a mass ratio of components (Cu₂O+CuO)_0,43/(La_0,7Sr_0,3MnO₃)_0,57 exhibit the highest magnetoresistance values of about 7% in a constant magnetic field of 14 kOe at room temperature. The maximum magnetoresistance correlates with a special region of change in the dependence of electrical resistance on the component ratio in these compositions. In the Ag_0,08/(LSMO)_0,92 composition, the magnetoresistance values reach 5,5%.
Keywords: ceramic composites, magnetoresistance, lanthanum-strontium manganite, copper oxides, silver nanoparticles, percolation.

2. THE THEORY OF NANOSYSTEMS – page 318

Apekov A.M., Shebzukhova I.G., Khamukova L.A.
Interphace energy of aluminum crystals at the boundary with nonpolar organic liquids – page 318
Abstract: Understanding the energy characteristics at the metal-organic interface is of great importance for the development of equipment and technologies in various industries. In this regard, there is a great interest in studying the processes occurring at this interface. Particularly noteworthy is the rapid growth of studies on the properties of metal-organic framework structures, which is associated with the possibility of synthesizing these structures with the desired properties by varying the lengths of the organic molecules connecting the atoms of metals or their oxides, as well as by selecting the chemical composition. In this paper, the values of the interfacial energy at the boundaries of the faces of an aluminum crystal with organic liquids are obtained within the framework of the electron-statistical method, taking into account the polarization of metal ions and molecules of the organic liquid, as well as the dispersion interaction of Wigner-Seitz cells on the interface. The dependence of the interfacial energy and corrections to the interfacial energy on the permittivity of the liquid and the orientation of the metal crystal is obtained. It is found that the dispersion correction makes a positive contribution while the polarization correction reduces the interfacial energy.
Keywords: interphase energy, polarization correction, dispersion correction, electronic statistical method, nonpolar organic liquid, aluminum.

Belavin V.O., Brylkin Yu.V., Zaletaev S.V., Kusov A.L., Pavlikov V.V., Potapov A.A., Tsarkova V.A.
Problems of quantitative assessment of the friction couple contact area – page 327
Abstract: The results of our research of the surface of steel disks before and after friction are presented. Problems of the friction couple contact area estimation were under consideration. The results of searching a universal criterion of the friction couple contact area quantitative estimation are discussed. Using optical and scanning tunneling microscopy allows studying the surface profile at the micro- and nanoscales. An approach for determination of the contact area between bodies is proposed on the basis of the fractals theory. Such an approach allows to describe the heat transfer between bodies (conductive at contacts and radiant in pores heat exchange), to define the dependence of the friction force on the applied external force. The offered technique for the quantitative estimation of the surface structure at the micro- and nanoscales by means of the fractal theory will allow improving the accuracy of the spacecrafts thermal modes calculation as well as parameters of the knots of friction in them. This, in turn, will positively affect reliability and durability of the future spacecrafts. Improvement of methods in our further work will be aimed at studying tribological properties of the robotic products under the influence of the space factors and validation of the numerical modeling of the friction and heat exchange between mobile knots using results of experiments.
Keywords: tribology, thermal modes, robotics, steel surface, microscopy, fractal analysis, friction couple.

Belyaeva I.N., Korsunov N.I., Chekanov N.A., Chekanov A.N.
Calculation of the spectrum of a gallium arsenide semiconductor with a triangular potential function by the power series method – page 337
Abstract: The paper investigates the quantum characteristics of the widely used semiconductor gallium arsenide in the modern promising field of microelectronics. For the energy levels in a triangular potential well, analytical expressions are obtained using the zeros of the Airy function. In addition, the corresponding Schrödinger equation with this potential function is solved by the power series method and both the energy spectrum of the lower levels and the corresponding wave functions are calculated. Satisfactory agreement between the values of the energy levels obtained in both approaches is found, but the prospects of calculating the quantum characteristics directly using the Schrödinger equation are noted. The solution of the Schrödinger equation is sought as a linear combination of two linearly independent solutions in the form of power series. The coefficients of this linear combination depend on the total energy as a parameter. Taking into account the boundaryconditions on the boundary of the integration segment leads to a linear algebraic system of equations. Nontrivial solutions of this system determine both the energy spectrum and the corresponding wave functions. Due to the sharp dependence of the energy levels on the type of wave functions, a careful choice of boundary points is necessary, as well as the number of terms in the series of wave functions. Optimal values of the specified fitting parameters allow us to obtain the values of the energy levels with the desired high accuracy.
Keywords: heterostructures, computer modeling, Schrödinger equation, gallium arsenide, energy spectrum, wave functions, power series method, Airy function.

Golov D.O., Petrov N.A., Tsirulev A.N.
Variational quantum algorithm for low-dimensional systems in the Pauli basis – page 343
Abstract: In the last decade, variational quantum algorithms implemented on modern quantum computers have successfully solved practical problems of optimization, quantum chemistry, and machine learning. We propose new variational quantum algorithm based on a Monte Carlo scheme that uses a random selection of the generators for a unitary transformation, and also uses optimization of the objective functional employing the annealing or Metropolis-Hastings algorithm. The states of the quantum system in the form of a density operator and its model Hamiltonian are represented by expansions in the Pauli basis. In the algorithm, the state of the system is changed by means of a random choice of the Pauli generator that determines the unitary transformation of the state. The efficiency of the annealing algorithm directly depends on the equiprobable choice of the transition from one state to the second, so the work uses a compromise version of the uniform distribution of operators on the SU(2ⁿ) group – the direct product of the SU(2) group, where n is the number of qubits in the system. The random choice of a single-qubit operator (consistent with the Haar measure on SU(2)) is implemented in Hopf coordinates on the group manifold (the three-sphere). The results of testing the algorithm show that it can be effective for low-dimensional systems.
Keywords: variational quantum algorithm, annealing algorithm, unitary transformation, Pauli basis, Hamiltonian expansion, uniform distribution of a random variable on a three-dimensional sphere, Hopf coordinates.

Ionin V.V., Mikhalevsky V.A., Burtsev A.A., Kiselev A.V., Nevzorov A.A., Eliseev N.N., Lotin A.A.
Modelling of radiation propagation in a photonic integrated circuit based on a polymer waveguide and phasechange material nanoparticles – page 351
Abstract: This paper presents the results of numerical modelling of optical radiation propagation in a SU-8 polymer waveguide and signal modulation at different phase states of an array of nanoparticles of the phase-change material Ge₂Sb₂Te₅ (GST). It is shown how the transmitted radiation is modulated for different numbers of nanoparticles when placed on the top and at the edge of the waveguide. The simulation results show that in addition to the influence of the phase states (crystalline or amorphous) on the properties of the transmitted signal, in the case of nanoparticles not only reflection and absorption but also scattering of the material play a prominent role. The basic possibility of controlling the optical signal of telecommunication range passing through the interface by switching the optical active element based on nanoparticles of phase-change material is demonstrated. The concept of developing photonic integrated circuits proposed in this work is the cheapest of all known planar technologies of developing waveguide devices and allows realizing computing elements andarchitectures on its basis with a high degree of heterogeneous integration.
Keywords: photonic integrated circuits, optical waveguides, polymers, phase-change materials, chalcogenides, nanoparticles.

Kolosov A.Yu., Veresov S.A., Serov S.V., Sokolov D.N., Savina K.G., Grigoryev R.E., Sdobnyakov N.Yu.
Size effect in four-component Au-Cu-Pd-Pt nanoparticles and their stability – page 361
Abstract: The four-component Au-Cu-Pd-Pt nanosystems of different sizes with the stoichiometric composition Au₃CuPd₁₂Pt₄ were studied. The molecular dynamics method was used as a simulation method, the interatomic interaction was described by the tight-binding potential. Based on the results of a series of computer experiments, it was found that the four-component Au-Cu-Pd-Pt nanoparticles do not have a tendency to form a core-shell structure, even though gold atoms demonstrate an increased segregation to the surface. Melting and crystallization temperatures were determined for the studied Au-Cu-Pd-Pt nanoparticles. The dependence of the crystallization temperature on the cooling rate was also established. With an increase in the cooling rate, the crystallization temperature decreases, and the temperature range in which crystallization occurs increases, while the heating rate does not significantly affect the melting temperature. It is shown that the size effect and the effect of the temperature-changing rate make it possible to control the dominant presence of the fcc or hcp local structure, and also affect the temperature stability of the resulting crystalline phases.
Keywords: molecular dynamics method, tight-binding potential, four-component nanoparticles, structure formation, melting temperature, thermal stability.

Magomedov R.A., Akhmedov E.V.
Calculation of state equation isobars of carbon dioxide and methane in pressure interval from 2 to 20 MPa – page 373
Abstract: The paper presents the calculation results for the state equation isobars of carbon dioxide and methane in the pressure range from 2 to 20 MPa. The calculations have been performed by using the fractal equation of state and the Fract EOS software. It was previously shown that for carbon dioxide there is no temperature dependence of the fitting parameter α. For methane, it was found that the temperature dependence is not significant and weakens approaching to 1000 K. This allowed for considered substances to approximate the dependence of α on the density by a polynomial and use it in calculations at any temperature. Next, in order to apply the proposed model for calculating isobars, a set of isotherms with a small temperature step has been calculated. Then, a point with the required pressure was selected on each isotherm. The obtained results show a good agreement with experimental data. The proposed equation of state is suitable for studying industrially important substances such as carbon dioxide and methane.
Keywords: equation of state, integral-differentiation of fractional order, Maxwell relations, Helmholtz potential, partition function, carbon dioxide, methane, isobar, isotherm, thermophysical properties.

Malyshkin Yu.A.
Geometric preferential attachment with choice-based edge step – page 381
Abstract: We study the asymptotic behavior of the maximum degree in the geometric graph model with a preferential attachment choice-based edge step. Geometric graphs are natural models that describe some nanoscale systems, while preferential attachment provides a good description of complex networks, particularly different neural networks. The model is a recursively built sequence of graphs. We start with the initial graph on a single vertex and we add a new vertex and draw a few edges on each step. Each vertex is assigned a parameter that represents its location. The recursion step consists of two parts. First, we introduce a new vertex and draw edges to close enough vertices. This step represents the geometric part of the model. Then, we draw edges between vertices by preferential attachment with the choice rule. We prove that dependent on model parameters, the maximum degree could exhibit sublinear (similar to the standard preferential attachment) and linear (representing concentration effect) behavior.
Keywords: geometric graphs, complex networks, random graphs, preferential attachment, power of choice.

Samsonov V.M., Talyzin I.V., Zhigunov D.V.
Segregation of components as a necessary condition for the eutectic nature of an alloy and nanoalloy – page 387
Abstract: Employing results of our molecular dynamics experiments performed by using the LAMMPS program and embedded atom method, phase diagrams for binary Ag-Cu and Cu-Ni nanoalloys (binary nanoparticles containing 2000 and 5000 atoms) were constructed and analyzed. The concentration dependence of the melting temperature of nanoparticles was interpreted as the liquidus line. It was found that for the Ag-Cu nanoalloy, the phase diagram corresponds to the simple eutectic, and for the Cu-Ni nanoalloy, it corresponds to the phase diagram of an alloy with unlimited mutual solubility of components. The above results agree with the phase diagrams for the corresponding bulk alloys. It was found that the eutectic temperature decreases with decreasing nanoparticle size; and the value of the mole fraction corresponding to the eutectic point and equal to 0,4 coincides with the value corresponding to the bulk alloy. A hypothesis is put forward about the relationship between the surface segregation of one of the components of the binary alloy/nanoalloy and the eutectic type of the phase diagram. It is concluded that the surface segregation effect is a necessary condition for the eutectic behavior, but is not the sufficient condition.
Keywords: binary Ag-Cu and Cu-Ni nanoparticles, phase diagram, segregation ofcomponent, molecular dynamics.

Sdobnyakov N.Yu., Kolosov A.Yu., Sokolov D.N., Savina K.G., Nepsha N.I., Savel’ev Ya.P., Lomonosov G.D.
To the problem of tight binding potential parameters approbation: influence of the ratio between pair and many-body interaction on the process of the structure formation in binary Pd-Pt nanoparticles – page 399
Abstract: The reliability of the atomistic simulation is determined in terms of the correctness of the problem statement, including the choice of the interatomic interaction potential and its parameterization. In this paper, a detailed testing of the tight-binding potential parameters was carried out by means of studying the influence of the ratio between pair and many-body interactions on the process of the structure formation in binary Pd-Pt nanoparticles. Three parameterizations of the tight-binding potential for the cross parameters were selected: set (I) corresponded to the use of the Lorentz-Berthelot rule, sets (II) and (III) specified the scaling laws for the pair interaction parameters and the many-body interaction parameters, respectively. For sets (I) and (III), the surface segregation of palladium atoms was established, while the use of set (II) led to the formation of the Janus structure. In addition, differences in the formation of the local structure in binary Pd-Pt nanoparticles wereestablished. Set (III) predicts the dominance of the local bcc structure. Radial distributions of the local density of Pd and Pt atoms in the Pd-Pt nanoparticles at a final temperature of 300 K were also calculated.
Keywords: molecular dynamics method, tight-binding potential, pair interaction, many-body interaction, Pd-Pt nanoparticles, structure formation.

Tvardovskiy A.V.
Model prerequisites for derivation of the Dubinin-Radzhdkevich adsorption equation – page 409
Abstract: To date, a large number of different adsorption and absorption equations have been proposed, describing a variety of equilibrium situations on homogeneous and inhomogeneous surfaces of adsorbents, polymers, micro-, meso- and macroporous adsorbents. However, the most valuable works are those in which attempts are made to build a general theory of adsorption (and absorption). At least the well-known classical adsorption equations should follow from such a general equation as special cases. Thus, in [1] such an equation was proposed and it was shown that the classical Henry, Langmuir, and Brunauer – Emmett – Teller equations with constants having a clear physical meaning follow from it as special cases. Thus, the constant in the Henry equation is determined by the temperature as well as by the specific surface of the adsorbent, the size of the adsorbate molecules, the molar mass of the adsorbate, and the isosteric heat of adsorption (the energy of interaction of the adsorbate molecules with the surface of the adsorbent). In the derived Brunauer – Emmett – Teller partial equation, in contrast to its classical version, a clear dependence of the equation constant on the specific physical characteristics of the adsorption system is provided for the first time. The dependence in question is determined by the concentration of adsorbate molecules in the liquid phase at the temperature under consideration, the concentration of adsorbate molecules during the formation of a dense monolayer on the surface of the adsorbent, and by the energy of interaction of adsorbate molecules with the surface of the adsorbent and the heat of condensation. The presented approach can serve as a basis for modeling a variety of adsorption and absorption phenomena, including adsorption on microporous adsorbents. The Dubinin- Radzhdkevich adsorption equation, which is an empirical one, has been widely applied in adsorption science. In this paper, based on [1], a thermodynamic analysis of the Dubinin-Radushkevich equation is carried out and model prerequisites for the theoretical derivation of this equation in a wide temperature range (up to the critical temperature T_crit) are identified.
Keywords: adsorption, adsorbent, absorption, thermodynamics of phase equilibria, Henry equation, Langmuir equation, Brunauer – Emmett – Teller equation, Dubinin-Radushkevich equation.

Tvardovskiy A.V.
Equation of interphase adsorption equilibrium – page 419
Abstract: Despite intensive development of adsorption science, there are still many unresolved issues. In this regard, at least one of them can be highlighted in the present paper. As early as 1927 [1], it was established that solids change their dimensions during adsorption of gases and vapors. However, the development of research in this area was hampered for a long time by the lack of theoretical concepts and great experimental and methodological difficulties. Meanwhile, the study of the deformation of solids during adsorption is of great importance both for the development of adsorption thermodynamics and for practical purposes. In the theory of adsorption, a method for describing adsorption equilibrium is widely used, in which the role of a solid is reduced only to the creation of an adsorption force field in which the adsorbate is located. The adsorbent itself is considered thermodynamically inert. It is obvious that the analysis of a two-component system is replaced byconsideration of only one component – the adsorbate. However, the very fact of the existence of deformation of a solid during adsorption directly indicates the insufficient rigor of the description of adsorption equilibrium in the language of concepts of the one-component system, as was accepted in deriving, for example, the classical Henry, Langmuir or BET (Brunauer-Emmett-Teller) equations. Therefore, the greatest value is represented by those works in which attempts are made to construct a general theory of adsorption (and absorption), including phenomena on deformable adsorbents (absorbents). From such a general equation, as special cases, at least the known classical adsorption equations should follow. In work [2], such an equation was proposed and it was shown that from it, as special cases, follow the classical Henry, Langmuir and BET equations with constants that have a clear physical meaning. Thus, the constant in the Henry equation is determined by temperature, the specific surface area adsorbent, size of adsorbate molecules, molar mass of adsorbate, and the isosteric heat of adsorption (the energy of interaction of the adsorbate molecules with the adsorbent surface). In the derived particular BET equation, in contrast to the classical version, a clear dependence of the equation constant on specific physical characteristics of the adsorption system is indicated for the first time. It is determined by the concentration of adsorbate molecules in the liquid phase at temperature under consideration, concentration of adsorbate molecules during the formation of a dense monolayer on the adsorbent surface, the energy of interaction of adsorbate molecules with the adsorbent surface, and the heat of condensation. The approach presented in this work can serve as a basis for modeling a wide variety of adsorption and absorption phenomena, including adsorption on microporous adsorbents and deformable bodies. The present work continues the studies conducted. It is shown that particular cases of the equation presented in [2] are the well-known classical Fowler-Guggenheim, Temkin equations.
Keywords: adsorption, adsorbent, absorption, thermodynamics of phase equilibria, Henry equation, Langmuir equation, Brunauer-Emmett-Teller equation, Fowler-Guggenheim equation, Temkin equation.

Shishulin A.V., Shishulina A.V., Kuptsov A.V.
Several notes on the melting behavior of mesoporous materials – page 427
Abstract: In this paper, the melting temperature dependence on geometric characteristics (volume and shape) of pores distributed in the mesoporous material has been analyzed. The pore geometry has been determined in the framework of the fractal-geometry approach using the values of their effective diameter and fractal dimension. The obtained results demonstrate that the well-known effect (being characteristic of nanoscale particles), which consists in a significant dependence of the melting temperature on the size and shape of a particle, can also be realized in mesoporous materials (the pore size being from 5 up to 50 nm) while the mesoporous materials themselves can be of macroscopic dimensions. Using the example of mesoporous lead, it has been shown the reducing the pore size and «complicating» the pore shape result in a significant decrease in the melting temperature of a material. The results have been obtained using the cohesive energy-based model, being verified experimentally for lead nanoparticles.
Keywords: phase transitions, melting, mesoporous materials, fractal dimension, cohesion.

Shishulin A.V., Shishulina A.V., Kuptsov A.V.
Peculiarities of «liquid – solid» phase equilibria in Six-Ge1-x nanoparticles for various mutual arrangements of phases – page 437
Abstract: The application of 3D nanocrystalline materials obtained using the liquid-phase and solid-phase powder metallurgy technologies is one of the basic approaches to designing high-efficiency and low-cost thermoelectric energy converters. Nanostructured alloys of the Si_x–Ge_1-x system represent one of the most efficient high-temperature thermoelectric materials. Features of the equilibrium phase composition of Si_x–Ge_1-x nanoparticles with a core-shell structure and various fractions of Si have been simulated using the thermodynamic approach in the interval between the liquidus and solidus temperatures. It has been demonstrated that the temperature dependences of the equilibrium phase composition of co-existing liquid and solid phases in the heterogeneous region significantly depend on the mutual arrangement of these phases in the core-shell structure. The results are accompanied by analysis of the initial composition effect which consists in the fact that not only the volume fractions of co-existing phases but also their composition depend on the Si fraction of the parent particle. The «hysteresis effect» has been shown. A thermodynamic interpretation of the obtained results has also been given based on three mechanisms of reducing the free energy of the system.
Keywords: nanoparticles, solid solutions, chemical thermodynamics, liquidus, solidus, core-shell structure, germanium, silicon.

3. FIRST PRINCIPLES AND ATOMISTIC MODELING – page 448

Bespalov D.V., Golovanova O.A.
Quantum-chemical calculation of magnesium(II) compound with tryptophan: synthesis, structure, properties – page 448
Abstract: The synthesis of magnesium compound with tryptophan was carried out. The ratio of magnesium and amino acid in the obtained compound was determined by complexometric titration and formol titration according to the Serensen method. The infrared spectra of the synthesized compound measured in the range of 500-4000 cm^-1 are presented. The compound was analyzed by X- ray diffraction method. The diffractograms of the investigated compound are presented. The volume and unit cell parameters by dichotomy method, interplanar distances, average particle size by Selyakov-Scherrer method, Miller indices were calculated for the obtained compounds. A model of magnesium tryptophanate compound was constructed using quantum-chemical methods: Hartree-Fock and density functional (B3LYP) in the 6-31G(d,p) basis. The energy minimized, the normal vibrational frequencies of the infrared spectrum of the model infrared spectrum of the investigated compound were calculated. The calculated and experimental infrared spectra of the investigated compound were analyzed. The obtained data contribute to the development of the science of complex compounds, improvement of methods of synthesis of compounds of a given composition. The possibility of further use of such compounds as drugs is also discussed.
Keywords: synthesis, amino acids, magnesium complexes, tryptophan, density functional method, molecular simulation.

Gafner Yu.Ya., Ryzhkova D.A., Gafner S.L., Cherepovskaya A.A.
Determination of the size limit of stability of the fcc phase of Ag nanoparticles – page 457
Abstract: The main objective of the study was to find the size limit at which silver nanoclusters with different initial morphology spontaneously change their structure to the fcc structure inherent to the bulk silver. For this purpose, we have examined the data of high-resolution electron microscopy of the initial and annealed silver nanoparticles formed on a carbon substrate by vacuum-thermal evaporation. It was found that as a result of annealing, the number of small nanoparticles (D<3,5 nm) approximately twice decreased, and the proportion of nanoparticles with icosahedral and decahedral facets increased approximately 1,5 times. To evaluate the obtained results by the molecular dynamics method based on the second moment approximation of the tight-binding potential, an additional study of the stability limits of structural modifications of silver nanoclusters of similar diameters (D=2-10 nm) was carried out in order to determine the size limit of a possible thermally induced structural transition from the initial amorphous morphology to the fcc phase. The obtained data were compared with the results for Ag nanoparticles with the initial fcc structure. It was shown that the size limit at which the nanoclusters changed their initial amorphous structure to the fcc structure corresponds to a particle diameter of 8-10 nm.
Keywords: nanoclusters, silver, crystallization, structure, computer simulation, high-resolution transmission electron microscopy.

Karakeyan I.V., Puitov V.V., Talyzin I.V., Samsonov V.M.
Icosahedral metallic nanoclusters: low-temperature structures or pre-melting ones? – page 468
Abstract: Melting of cuboctahedral nanoclusters of fcc metals (Ag, Au, Cu, Ni, Pd and Pt) containing 561 atoms and a transition to icosahedral isomers preceding their melting were simulated using the isothermal molecular dynamics. The heating process was simulated in the NVT ensemble using the well-known open LAMMPS program, the Verlet velocity algorithm and the Nosé-Hoover thermostat. The interatomic interactions in metal nanoparticles were reproduced by employing the embedded atom method. At a relatively low for MD experiments heating rate of 0,15 K/ps, the cuboctahedron → icosahedron transition was observed in the face-centered cubic nanoparticles of all the above metals, except for Ag nanoparticles. However, an increase in the heating rate to 1,5 K/ps led to the fact that the cuboctahedron → icosahedron transition began to be observed in Ag nanoclusters as well. Unlike nanoparticles of other metals, the cuboctahedron → icosahedron transition in Pt nanoclusters occurs at a very low temperature, close to the initial temperature preceding the heating of the particles and equal to 10 K. In contrast, in Ni particles the cuboctahedron → icosahedron transition was observed at a temperature close to the melting point.
Keywords: metal nanoclusters, isomers, cuboctahedron-icosahedron transition, melting, molecular dynamics.

Komarov P.V., Malyshev M.D., Baburkin P.O.
Studying the interaction of polyacrylonitrile oligomer chains with carbon fillers – page 481
Abstract: The dependence of the adhesion energy of the polyacrylonitrile oligomeric chain on the surfaces of carbon nanoparticles such as carbon nanotubes and graphene is studied in the framework of full atomistic molecular mechanics simulation using the polymer consistent force field and the open part of the condensed-phase optimized molecular potentials for atomistic simulation studies force field. The length of the polyacrylonitrile oligomer chain, the number of layers in the graphene nanoparticle, the diameter of the carbon nanotube, and the type and density of the modifier molecules on the surface of the graphene are the main parameters of the calculations. The graphene nanoparticle is taken as a limiting case corresponding to the large-diameter carbon nanotube. N-(2-aminoethyl) carbamoyl, nitrocyclohexane, benzamide, and dinitrobiphenyl are selected as surface modifiers. It is shown that with an increase in the number of layers and diameter of carbon nanotubes, the adhesion energy of the polyacrylonitrile oligomer chain increases, which allows us to consider multiwalled carbon nanotube with large diameters as a preferred filler forpolyacrylonitrile. The estimates obtained also show that when surface modifiers are used, it is possible to increase the adhesion energy of polyacrylonitrile only in the case of low surface modifier densities.
Keywords: polyacrylonitrile, carbon fibers, carbon nanotubes, graphene, computer simulation.

Kotomkin A.V., Orlov Yu.D.
Structure – property relationship for the fluorinealcanes – page 493
Abstract: The enthalpy of formation (Δ_fH⁰) of molecules CH₃-(CH₂)_n-CH₂F, where 3≤n≤5, CH₃-(CH₂)_n-CHF₂(3≤n≤4), CH₂F-(CH₂)₃-CH₂F, CHF₂-(CH₂)₃-CHF₂, CF₃-(CH₂)₃-CHF₂, CF₃-(CH₂)₃-CF₃, CHF₂-(CH₂)₃-CH₂F, CF₃-(CH₂)₃-CH₂F, fluorinated isobutane C₄H_mF_k, where 0≤m≤9, k = 10-m, and neopentane C₅H_mF_k, where 0≤m≤11, k = 12-m has been calculated by the G4 method. Within the ΔH_f⁰ for molecules of fluoroethanes, fluorobutanes, and fluoropropanes this values has been formed learning sample, which totally includes 180 values. The calculation scheme for the enthalpy of formation of fluorine-containing molecules M have been proposed: ΔH_f⁰_add(M) = ΔH_f⁰(R) + a∙ΔH_f⁰(F-F)_1,2 + b∙ΔH_f⁰(F-F)_1,3 + c∙ΔH_f⁰(F-F)_1,4, where ΔH_f⁰(R) is contribution of group R into the enthalpy of formation (R = СH₃, CH₂, CH, С, CH₂F, CHF₂, CF₃, CHF, CF₂, CF), ΔH_f⁰(F-F)_1,2, ΔH_f⁰(F-F)_1,3, ΔH_f⁰(F-F)_1,4 are contributions of interaction of two fluorine atoms, which bounded with the carbon atoms from one, two and three С-С bounds, respectively, a, b, c are numbers of fluorine-fluorine interactions from one, two and three С-С bounds, respectively. All the group contributions have been computed. The comparison have been shown that new scheme is more effective than the simple group-additive methods.
Keywords: structure – property relationship, thermodynamic properties, additive model, electron structure, enthalpy of formation, quantum theory of atoms in molecules, electron density, fluorine alkanes, isobutene, neopentane.

Kuznetsov Yu.A., Lapushkin M.N.
Au adsorption on W(100): calculation – page 501
Abstract: The adsorption of gold atoms on the surface of the (100) tungsten face was calculated using the density functional method. A 2D layer of W atoms was used as a tungsten substrate. The 2D layer of W was modeled by a W(100) 2×2×2 supercell. The calculation was carried out for three sites of adsorption of the Au atom on the W(100) surface: in the hollow position, in the bridge position between the surface W atoms and on top the surface W atom. There was one Au atom per 8 surface W atoms. Adsorption of the Au atom in the bridge position is most preferable. The adsorption energy is 4,18 eV. Adsorption of Au atoms leads to the following reconstruction of the W surface: the shift of W atoms in the surface plane does not exceed 0,18 Å, and the shift of the upper layer of W atoms is 0,022 Å towards the volume of W. The valence band of the 2D W(100) layer is formed mainly W 5d electrons, with a minor contribution from W 6s electrons. Adsorption of gold leads to a change in the spectrum of the valence band of the tungsten surface layer.
Keywords: electronic structure, adsorption, interface, gold, tungsten.

Mikhailov G.P.
Calculation of the electronic absorption spectrum of a nanocluster (TiO2)15 doped with a nitrogen atom – page 510
Abstract: At the initial stage of the formation of titanium dioxide nanoparticles, clusters of (TiO₂)_n are formed, which, due to their unique electronic structures, may have an increased reactivity in comparison with large nanoparticles. The quantum chemical calculation of the equilibrium geometry of clusters (TiO₂)₁₅ and Ti₁₅O₂₉N₁ of the rutile modification was performed using the density functional theory methods. Using the nonstationary density functional theory in the TD DFT/B3LYP/6-31G(d) approximation, the electronic absorption spectra of clusters in vacuum and aqueous medium are calculated. The Ti₁₅O₂₉N₁ cluster doped with a nitrogen atom is characterized by the presence of absorption bands with wavelengths mainly in the visible region of the spectrum (430-780 nm) and a significant decrease in the E_gap energy gap between the lower vacant and higher occupied molecular orbitals in comparison with (TiO₂)₁₅. The influence of the position of the nitrogen atom in the central TiO₆ fragment of the Ti₁₅O₂₉N₁ cluster on the E_gap value, the shift of the electronic absorption spectrum and the maximum strength of the f_max oscillator among 30 electronic transitions is shown. It has been found that when taking into account the aquatic environment, the positions of the absorption bands in the electronic spectra shift to the region of shorter wavelengths. For transitions with the highest oscillator strength, the presence of an aqueous medium leads to a significant increase in the f_max value.
Keywords: cluster, titanium dioxide, density functional theory, energy gap, electronic absorption spectrum.

Nepsha N.I., Sokolov D.N., Kolosov A.Yu., Savina K.G., Grigoryev R.E., Sdobnyakov N.Yu.
On the problem of stability/instability in core-shell ternary Cu-Fe-Ni nanoparticles – page 517
Abstract: The article is devoted to the study of stability of ternary Cu-Fe-Ni nanoparticles (consisting of 5400 atoms) with a core-shell structure and its relationship with the surface segregation. The main focus is on modeling their structural formation using the LAMMPS software. The authors test the hypothesis that stability of nanoparticles depends on the spontaneous segregation of one of the components to the surface. Three configurations with different atomic distributions (configuration Cu₄₅Fe₄₅Ni₁₀ with random distribution of atoms, as well as configurations – Cu₂₅Fe₂₅@Ni₅₀ and Fe₂₅Ni₂₅@Cu₅₀) are considered, and numerical modeling is performed for each of them using molecular dynamics methods and applying the tight-binding and embedded atom method potentials. The analysis showed that copper tends to segregate to the surface, while nickel concentrates in the core, significantly affecting mechanical properties of the nanoparticles. Patterns of the defect formation and their impact on the strength of nanostructures were identified. The article emphasizes that the correct choice of shell and core can both stabilize and destabilize the nanoparticles, providing prospects for the practical application of these materials.
Keywords: molecular dynamics method, LAMMPS, embedded atom model, tight-binding potential, polyhedral template matching method, ternary nanoparticles, nickel, copper, iron, structural formation, caloric curve.

Savina K.G., Veselov A.D., Grigoryev R.E., Veresov S.A., Ershov P.M., Zorin D.R., Sdobnyakov N.Yu.
Structural transformations in binary Ti-V nanoparticles: size effect and effect of composition change – page 532
Abstract: The processes of the structure formation in Ti-V binary nanoparticles and the factors influencing the crystallization process are discussed. The objects of study were Ti-V binary nanoparticles containing N=200, 400, 800, 1520, 3000, and 5000 atoms with various compositions. The computer experiment was conducted using the molecular dynamics method. Interatomic interactions were described using the tight-binding potential. Based on a series of computer experiments, it was determined that the crystallization process of Ti-V binary nanoparticles is significantly dependent on both their size and component ratio. As the size of the nanoparticles increases, the crystallization temperature rises, and the component ratio has a substantial influence on the formation of crystalline phases. The lowest crystallization temperatures were observed at titanium-to-vanadium ratios of 25-75% and 50-50%. Larger nanoparticles also exhibit pronounced phase segregation, with FCC and HCP phases dominating depending on the titanium-to- vanadium ratio. The observed tendency to form a multilayered onion-like structure indicates a more complex structure formation process than surface segregation.
Keywords: molecular dynamics method, tight binding potential, binary nanoparticles, titanium, vanadium, melting, crystallization.

Sokolov D.N., Myasnichenko V.S., Polev O.V., Savina K.G., Sdobnyakov N.Yu.
On the stability and structure relaxation of metallic nanocages – page 543
Abstract: The problem of the thermal stability of mono- and binary metallic nanocages consisting of gold and silver atoms with the same nuclearity of 3000 atoms is considered. The initial configurations of nanocages were obtained in the ClusterEvolution software by cutting them out of a larger icosahedron. The heating process for studying the thermal stability/instability was simulated in the Metropolis software using the Monte Carlo method and the Metropolis scheme. The interatomic interaction was described by the tight-binding potential. The influence of the composition, characteristic dimensions (inner and outer radii), and the shape of the inner surface in the initial configuration on the thermal stability of nanocages was studied. The temperature of complete collapse of the internal cavity of nanocages was determined. The results of calculations of the temperature dependence of the average local density and the local density profiles at different temperatures corresponding to different initial configurations, as well as the temperature evolution of the fractions of crystalline structures in them, are presented and analyzed.
Keywords: atomistic simulation, Monte Carlo method, tight-binding potential, metal nanocages, thermal effects, stability/instability, local density, crystalline phases.

Cherepovskaya A.A., Gafner S.L., Gafner Yu.Ya., Ryzhkova D.A.
Analysis of thermal stability of the internal structure of Ag-Cu nanoparticles – page 557
Abstract: Binary nanoparticles of the copper-silver alloy of are of great practical interest due to the possibility of fine-tuning their physical and chemical properties by changing the composition, size, shape and structure ofnanoparticles. The processes of formation of the internal structure of Ag-Cu nanoparticles with a diameter from 2.0 to 8.0 nm during their crystallization with three different rates of thermal energy dissipation were studied by the molecular dynamics method. The features of this process were found to be dependent on the target chemical composition of nanoparticles, their size and the intensity of the thermal energy dissipation. The actual appearance and structure of the studied nanoparticles were determined using OVITO and xmakemol visualizers. It was shown that as a result of crystallization from the melt of binary Ag-Cu nanoparticles, metastable states that are sufficiently stable at room temperature (300 K), and the stability of such states after annealing at a temperature of 600 K is also evaluated.
Keywords: binary alloys, copper, silver, nanoparticles, structure, crystallization, metastable states, computer modeling, strong coupling.

4. PHYSICAL AND CHEMICAL BASES OF NANOTECHNOLOGIES – page 565

Akhmedov A.K., Asvarov A.Sh., Murliev E.K., Shomakhov Z.V.
High-mobility transparent conductive layers based on indium oxide doped with tungsten – page 565
Abstract: Increasing the conductivity of transparent conductive layers by increasing the mobility of free charge carriers is one of the most important tasks of transparent electronics, since its solution contributes not only to the reduction of heat losses in the layers, but also to the expansion of the spectrum of the radiation used towards the near infrared region. Currently, work in this area is being carried out in some routes, one of which is the search for new layer’s compositions that allow reducing the amount of impurity introduced while simultaneously increasing the efficiency of its ionization. In this paper, the influence of the oxygen content in the working gas and the deposition temperature on the morphology, microstructure, electrical, and optical characteristics of thin layers deposited by high-frequency magnetron sputtering of an ceramic target based on In₂O₃ with the addition of 1 wt.% WO₃ was investigated. It was found that the maximum mobility (59 cm²/V٠s) and minimum specific resistance (7,8×10^–4 Ohm٠cm) are achieved in layers synthesized at 300°C in the pure argon atmosphere. For comparison, layers based on a solid solution of indium and tin oxides, widely used in the formation of transparent electrodes in various optoelectronic applications, were obtained under identical conditions. It was shown that layers based on indium oxide doped with tungsten retain acceptable transparency in a wide spectral range, up to 2000 nm, and are, therefore, preferable for use in devices operating in the near infrared range, for example, in solar energy converters or night vision devices.
Keywords: transparent electrode, indium oxide, doping, magnetron sputtering, transparency, electrical conductivity.

Akhmedov A.K., Asvarov A.Sh., Murliev E.K., Shomakhov Z.V.
Some features of localization of Al, Ga and In impurities in ZnO layers – page 575
Abstract: Reducing the cost of the materials and technologies used to form functional films is one of the most pressing issues in the rapidly developing transparent electronics industry. In this regard, ZnO-based films deposited by magnetron sputtering are of particular interest, being considered as a real alternative to more expensive indium oxide films when forming transparent electrodes in various optoelectronic applications. However, the choice of optimal film’s compositions and formation modes for each specific application is complicated by the lack of systematic comparative data on these systems obtained under identical conditions. In this work, ZnO films doped with Al, Ga, and In at a level of 1 to 20 at.% were obtained under identical conditions by the magnetron sputtering method. The dependence of the structure and electrical characteristics of ZnO films on the dopant content and deposition temperature was studied. It has been established that the key factors determining the behavior of an impurity in a ZnO matrix are its chemical activity, solubility in the matrix, the ionic radius of the impurity metal in a given coordination, and the electrical characteristics of additional oxide phases of the doping element formed at grain boundaries.
Keywords: thin film, magnetron sputtering, transparent electrode, zinc oxide, doping, carrier transport, microstructure, grain boundary.

Bibanaeva S.A., Skachkov V.M., Sabirzyanov N.A.
Sorption purification of solutions with synthetic zeolites – page 584
Abstract: The work is devoted to studying the possibility of using synthetic zeolites (nanodispersed hydroxyapatite and mechanically activated hydroxyapatite-zeolite mixture in a ratio of 1:1) as sorbents of chromium and nickel ions from the acidic aqueous solutions. The chemical qualitative and quantitative composition, morphology of the initial reagents and the obtained solutions were studied. It was found that the synthetic zeolite and the hydroxyapatite-zeolite mixture exhibit high sorption activity and sorption capacity with respect to chromium ions (the extraction degree of 99,96%), while nanodispersed hydroxyapatite allows obtaining the extraction degree of 98,73. As for the sorption of nickel from a solution, it was shown that the maximum extraction degree is achieved using the hydroxyapatite-zeolite sorbent (63,83%). The conducted studies allow us to recommend the obtained samples for use as sorbents for cleaning industrial waste solutions from toxic impurities, as well as for further studies with the aim of introducing it not only for the extraction of various ions from aqueous solutions, but also for use in various industries.
Keywords: purification, synthetic zeolite, hydroxyapatite, sorption, heavy metals, aluminosilicate, nickel, chromium.

Bolotov A.N., Novikova O.O.
On the nature of anomalously high value of yield stress of nanostructured magnetic fluid – page 592
Abstract: Based on magnetic fluids, new effective technical devices have been implemented, such as magnetic fluid bearings, seals, and dampers. The magnetic-viscous effect inherent in magnetic fluids can not only improve the properties of magnetic fluid units, but significantly complicate their operation after a long stop. This refers to the so-called «stop effect», which occurs due to an abnormally high limiting shear stress in a structured liquid. It is shown that, based on the existing ideas about the thixotropic properties of a magnetic fluid, it is not possible to convincingly explain the experimental value of the yield strength. Estimations according to the known formulas obtained for the chain model give a significantly underestimated value of the yield strength of a real magnetic fluid. A hypothesis is proposed according to which the rheological properties of the carrier medium change in the process of structure formation in the magnetic fluid under the action of compressive stresses created by a network of dispersed particles. Experiments have confirmed an increase in the density of the magnetic fluid in the magnetic field under the influence of such stresses. It can be assumed that high values of the yield strength are due to the presence of the intrinsic yield strength of the dispersion medium, which is in a quasi-solid state.
Keywords: magnetic fluid, yield point, dispersed particles, magnetic interaction, chain model.

Burtsev A.A., Kiselev A.V., Mikhalevsky V.A., Ionin V.V., Nevzorov A.A., Eliseev N.N., Lotin A.A.
Kinetics of laser-induced crystallization of GeTe and Ge2Sb2Te5 chalcogenide phase-change material thin films – page 603
Abstract: The paper presents the results of theoretical analysis of crystallization of GeTe and Ge₂Sb₂Te₅ thin films under the influence of pulse laser radiation. The phase transformations and the fraction of the crystalline phase was estimated on basis of the change of the probe optical reflection coefficient from the film sample surface. The formalism based on the Kolmogorov-Johnson-Mehl-Avrami theory was used to evaluate the kinetic behaviors of the phase transformation under the action of laser radiation. On the basis of experimental data of reflection changes during crystallization process of the researched materials, graphs were plotted and Avrami constants were determined. It is shown that GeTe exhibits a single step crystallization process associated with a high rate of nucleation and crystallite growth in all directions. The Ge₂Sb₂Te₅ alloy is characterized by a two-step crystallization process with a change in the Avrami constant due to the influence of many factors such as the film geometry, sputtering characteristics, etc. Such type of crystallization is explained by the predominance of the high-stochastic nucleation.
Keywords: laser-induced crystallization, phase transitions, chalcogenides, phase-change materials, thin films, kinetics.

Burtsev A.A., Mikhalevsky V.A., Nevzorov A.A., Kiselev A.V., Konnikova M.R., Ionin V.V., Eliseev N.N., Lotin A.A.
Synthesis of phase-change material Ge2Sb2Te5 nanoparticles by laser-induced forward transfer techniques – page 612
Abstract: Experimental results on the synthesis of nanoparticles of Ge₂Sb₂Te₅ phase-change material by the direct laser-induced transfer method are presented. Thin films obtained by the thermal vacuum deposition were used as a donor material and silicon wafers as an acceptor. The laser-induced forward transfer was carried out using the sub-nanosecond pulsed laser irradiation. The morphology, topology, and size of the obtained nanoparticles were analyzed by scanning electron microscopy. Structural studies were performed by Raman scattering. A quasi-uniform distribution of nanoparticles on the substrate and a quasi-uniform size distribution were achieved. It was shown that it is possible to achieve a nanoparticle diameter of less than 100 nm. Raman spectra show that the nanoparticles obtained are in the crystalline state. The results show the possibility of creating an element based on nanoparticles with a specific distribution in size as a technological alternative to devices based on thin films. The use of nanoparticles will make it possible to achieve the energy efficiency, greater flexibility, and smoothness of switching as well as to realize neuromorphic and stochastic computation.
Keywords: chalcogenides, phase-change materials, nanoparticles, nanoclusters, laser-induced forward transfer, phase transitions.

Devitsky O.V.
Pulsed laser deposition OF III-V semiconductor thin films: review – page 621
Abstract: This review highlights the latest advancements in pulsed laser deposition of III-V semiconductor thin films on various substrates. The pulsed laser deposition method is shown to be highly effective and distinct from other thin film deposition techniques due to its discrete nature. Epitaxial growth of III-V thin films is crucial for developing new optoelectronic devices. The review presents experimental data on how various pulsed laser deposition parameters affect the structural, optical, and electrical properties as well as the stoichiometry of binary and multicomponent III-V thin films. It is demonstrated that achieving the highest structural quality in III-V thin films requires using femtosecond and nanosecond lasers with wavelengths ranging from 248 nm to 532 nm, a pulse energy density of no more than 3 J/cm^², and substrate temperatures between 300 and 400°C. Additionally, the target material should be monolithic and have the highest possible density.
Keywords: pulsed laser deposition, thin films, III-V compounds, substrate temperature, energy density, stoichiometry.

Devitsky O.V.
Methods for reducing droplet formation density on the surface of thin semiconductor films by pulse laser deposition: review – page 631
Abstract: The review discusses the most effective methods for reducing droplet density on the surface of thin films during pulsed laser deposition. This review highlights pulsed laser deposition as a promising technique for producing thin films from a wide range of materials. However, a significant challenge to its industrial application is the formation of droplets on the thin film surface. The primary causes of the droplet formation are identified, and a classification of methods to reduce the droplet density during pulsed laser deposition is provided. Completely eliminating droplets without compromising the quality or altering the stoichiometric composition of the thin films is exceedingly difficult, and no researchers have achieved this to date. The most effective strategy for reducing the droplet density involves optimizing the pulsed laser deposition parameters for specific material groups. Techniques such as using a segmented crystalline target, periodically rotating it at a specific speed, and employing excimer lasers at the energy densities slightly above the ablation threshold have been shown to reduce the droplet density on the thin film surface to as low as 10³ cm^-2. The physical and chemical processes occurring on the target surface have the greatest impact on the droplet formation. Among active methods, high-speed filtration is the most effective, capable of reducing droplet density to approximately 2 ⋅ 10³ cm^-2.
Keywords: pulsed laser deposition, thin films, droplet density, high-speed filtration, segmented target, dual-pulse laser deposition, laser energy density.

Izmailov V.V., Novoselova M.V.
On the profile characteristics of technical surfaces as applied to nanoroughness – page 643
Abstract: The parameters of the structure of a technical surface at the nanoscale level, determined by the profile method, are considered. The possibility of applying the parameters determined in accordance with domestic and international standards for the roughness profile (microscale level) to the characteristics of the surface at the nanoscale level, which goes beyond the standards, is shown. This possibility is provided by the model of the profile of a technical surface that underlies modern standards as an implementation of a broadband random normal process. An experimental verification of the normality of the process was carried out by comparing the experimental values of the integral probability distribution function of the profile ordinates with theoretical values that obey the normal distribution. The experimentally obtained values of the nine most important parameters, as well as their some relationships between them, are presented, confirming the reliability of the surface profile model as a normal random process. The use of standard surface profile parameters ensures to avoid errors and misunderstandings associated with ambiguous interpretation of one or another parameter.
Keywords: surface structure, nanoroughness, profile method, profile parameters, normal random process.

Kiselev A.V., Mikhalevsky V.A., Nevzorov A.A., Burtsev A.A., Ionin V.V., Eliseev N.N., Lotin A.A.
Modelling of adaptive phase-shifting filter cells with optical control based on multilayer structures of phasechange materials – page 651
Abstract: The paper presents the results of modelling the phase shift of a passing optical beam caused by the formation of a layered structure in a controllable cell made of the phase-change material Ge₂Sb₂Te₅ induced by the controlling influence of pulsed laser radiation of short and ultrashort duration. The crystallization of a thin film of Ge₂Sb₂Te₅ is analyzed on the basis of the thermokinetic approach, taking into account the kinetic properties of the material, the energy and duration of the applied laser radiation, the amorphization of the upper layers of the film during rapid heating and the temperature dependence of the kinetic properties. Graphs of the thickness of the crystalline layer in the film material were plotted for each influencing pulsed radiation. From the data on the position of the crystalline layer, the phase shift of the transmitted optical radiation is calculated. Based on the modelling data of the investigated cell, a phase shifter can be constructed to transform an optical beam of arbitrary aperture. The proposed method of controlling the optical beam front by changing the structural state of a thin film can be very promising when accurate and fast tuning of the optical phase transparency is required.
Keywords: phase shift, optical filters, chalcogenides, phase change materials, thin films, crystallization.

Korolkov O.E., Misochenko A.A., Stolyarov V.V.
Electrostimulated plasticity of titanium under tension – page 658
Abstract: The paper confirms the possibility of electrical stimulation of plasticity, previously discovered in ultrafine-grained titanium. The regimes of pulsed current during tension have been experimentally determined, which make it possible to significantly increase the elongation to failure in commercially pure coarse-grained titanium Grade 4. It is shown that the introduction of single current pulses with an amplitude density of 300-400 A/mm² with a variable duration from 100 to 1000 μs and a duty cycle from 1000 to 10000 during tension helps to reduce the ultimate tensile strength from 845 to 750 MPa and simultaneously increase the elongation from 10 to 21%. Structural studies using optical microscopy have shown that tension accompanied current does not affect the average grain size, but leads to reducing large particles and a partial dissolution of small inclusions. The results of structural studies, temperature measurements and features of deformation behavior when the current is turned off confirm the predominantly athermal nature of the increase in plasticity.
Keywords: electroplastic effect, tension, pulsed current, titanium, deformation behavior, plasticity, microstructure, stress relaxation.

Kul’kov V.G., Kul’kova V.V.
Internal friction at grain boundaries in nanocrystalline material with pores – page 670
Abstract: A mathematical model of the internal friction in a polycrystalline material with the nanoscale grain size is considered. Their boundaries contain pores, both in the triple joints of the grains and between them. Under the influence of the alternating normal boundary stresses, flat sections of the boundary are periodically active sources and sinks for vacancies. Due to the presence of these flows, the mutual displacement of adjacent grains is carried out. Depending on temperature, the diffusion length of the vacancies is smaller or compared with the distance between the pores. In the graph of the dependence of the internal friction on temperature, there is a break between the rectilinear sections. From the position of the fracture, the average size of the flat sections of the border can be estimated. The effective activation energy of the process in these cases depends on temperature and differs twice. At temperatures when the concentration of thermal vacancies in the boundary exceeds the geometrically necessary value of the concentration of structural vacancies, the activation energy increases even more. The transition temperature to this value is determined by the degree of imbalance of the boundary structure.
Keywords: nanocrystalline material, grain boundaries, diffusion length, pores, vacancies, internal friction, activation energy.

Malashenko V.V.
Dynamic drag of dislocations in aged aluminum alloys under laser irradiation – page 679
Abstract: The above-barrier glide of dislocations under the action of laser pulses in aged aluminumиalloys containing nanoscale defects (Guinier-Preston zones) is theoretically analyzed. The problem is solved using a theory of dynamic interaction of defects. Analytical expressions for the dependence of the dynamic yield strength on the concentration of copper atoms and the dislocation density in the aged aluminum alloy has been obtained. The conditions for the occurrence of extrema of the functions describing the dependence of the dynamic yield strength of the aluminum alloy on the concentration of copper atoms and the dislocation density are analyzed. The analysis confirms the conclusions of the dynamic interaction of defects theory on the conditions for the occurrence of non-monotonic dependences of the mechanical properties of metals and alloys on the concentration of structural defects. The maximum occurs at the point where the main contribution to the formation of the spectral gap changes. The minimum is at the point where the main contribution to the dynamic drag of dislocations changes. It is shown that the nanoscale defects (Guinier-Preston zones) play an important role in the occurrence of two extrema of these dependences. The existence and position of the extrema are determined by the competition of the interaction of the moving dislocation with other dislocations of the ensemble, copper atoms and Guinier-Preston zones. Numerical estimates of the volume concentration of Guinier-Preston zones, at which the existence of two extrema is possible, areperformed. According to estimates, the concentration of Guinier-Preston zones is of 10²³-10²⁴ m^-3.
Keywords: high strain rate deformation, dislocations, Guinier-Preston zones, point defects, nanomaterials.

Polukhin V.A., Estemirova S.Kh.
Metal membranes for hydrogen purification: problems, trends and prospects of application – page 686
Abstract: The problems associated with the global warming due to greenhouse gas emissions from human activities are driving the search for new technologies to reduce CO₂ emissions from the fossil fuel combustion. Hydrogen is a clean and efficient energy carrier, so the hydrogen energy is considered as one of the strategic directions for the development of the energy security and sustainability. Although hydrogen can be produced by electrolysis of water, most of the hydrogen produced worldwide currently comes from steam reforming of natural gas, which must be purified to ultra-high purity for economic reasons. Traditional methods based on pressure swing absorption-desorption using cryogenic distillation are energy intensive, which motivates the development of new highly selective and energy efficient H₂ purification technologies. Such technologies include rapidly developing membrane technology, which at the moment has not yet reached the level required for its widespread industrial application. In this review article, we analyze the main aspects of current research in the field of hydrogen purification technology using dense metal membranes, with an emphasis on their technological stability due to the selection of their chemical composition (including multicomponent) and optimization of the structural state. We also considered the prospects for further development and use of this technology for economic needs.
Keywords: membrane gas separation, hydrogen purification, BCC structure, FCC structure, high- entropy alloys, amorphous alloys, solubility, hydrogen permeability, diffusion, thermal stability, brittleness.

Ryzhkova D.A., Cherepovskaya A.A.
Modification of perovskite and dye-sensitized solar cells with plasmonic nanoparticles – page 711
Abstract: Dye-sensitized solar cells and perovskite solar cells can operate under conditions of low and diffuse solar radiation. This makes them promising candidates for replacing the silicon-based photoconverters which dominate at the market. The efficiency of such devices is largely determined by the morphology of electron-conducting photoelectrodes. One of the strategies for increasing it is the embedding of Ag and Au nanoparticles into the photoelectrode layer. Due to the phenomenon of the surface plasmon resonance, they enhance the scattering of the supplied light and affect the mechanism of electron transfer to the conduction band of the semiconductor. This leads to an increase in the electric current generated by the solar cell. The present work examines the influence of a number of parameters of embedded nanoparticles on the efficiency of photoconverters, such as size, shape and dielectric environment. It is shown that the use of bimetallic compounds Ag-Au, Ag-Cu and heterogeneous structures of various types allows achieving a higher efficiency of solar cells compared to devices modified with monometallic nanoparticles.
Keywords: dye-sensitized solar cells, perovskite solar cells, nanoparticles, silver, gold, surface plasmon resonance, bimetallic nanoparticles, core-shell structure.

Solnyshkin A.V., Vostrov N.V., Gudkov S.I., Belov A.N.
Temperature evolution of dielectric characteristics of PVDF and P(VDF-TrFE) films produced by 4D printing – page 720
Abstract: In this work, films of polyvinylidene fluoride, copolymer of vinylidene fluoride and trifluoroethylene have been studied. The samples were made by direct ink writing technology. Some of the produced films were polarized in the corona discharge field. The dependences of the relative permittivity on temperature were studied for the films. The study showed that for polyvinylidene fluoride films, no maximum is observed in the dependences of the permittivity on temperature, since the assumed temperature of the ferroelectric phase transition is higher than the melting temperature. The maximum in the temperature dependence of permittivity for polarized copolymer of vinylidene fluoride and trifluoroethylene films is shifted by 10℃ toward higher temperatures compared to the maximum for non-polarized films. In this case, the permittivity of non-polarized films has higher values compared to the corresponding value for polarized samples. This is due to an increase in the proportion of the β-phase after polarization, as well as to the internal electric field caused by the space charge formed during the polarization process at the phase boundaries.
Keywords: ferroelectric polymer, additive technologies, 4D printing, 3D printing, phase transition, permittivity, Curie temperature.

Stolyarov V.V.
Size effects of friction in pure titanium – page 729
Abstract: The article is devoted to an experimental study of the tribological behavior without lubrication of commercial pure titanium under specific conditions close to fretting, which differs from traditional tests by the small amplitude and frequency of indenter movement. Tribological characteristics: wear and the friction coefficient at room and elevated temperatures of Grade 4 titanium are compared in the ultrafine-grained (grain size d_g = 0,45 μm) and coarse-grained state (d_g = 45 μm). It has been shown that at room temperature, reducing the grain size by two orders of magnitude increases wear and the friction coefficient. Reducing the displacement amplitude from 300 to 50 μm brings the friction conditions closer to fretting and reduces both wear and friction coefficient. An increase in temperature from room temperature to 350°C transforms the traditional type of wear into the formation of an oxide film and reduces the friction coefficient. The boundary conditions for the occurrence of fretting and their applicability to nanostructures are discussed.
Keywords: titanium, ultrafine-grained structure, wear, friction, fretting.

Fronya A.A., Sahakyan A.T.
Surface structuring of silicon wafers with low-frequency giant pulses YAG:ND laser – page 738
Abstract: Experimental results on the silicon wafers irradiation by a low-frequency giant nanosecond pulses neodymium-doped yttrium-aluminum garnet laser with a wavelength of 1,064 μm are presented. The pulse duration at the half-height was 170 ns, and the pulse repetition frequency was 2 Hz. The experiments were carried out for the cases of silicon wafers placements in air and in bidistilled water. For the case of irradiation in air, a nanostructured region with a uniform distribution of particles was succeeded to form on the surface of the silicon wafer. The exposure time was 2 minutes, which corresponded to 240 laser pulses. In this case, the particles were formed mainly from silicon dioxide as a result of the thermal oxidation during ablation in air. When the exposure time was doubled, this effect was not achieved, and destruction areas of wafer were formed. For the case of irradiation in bidistilled water within two and four minutes, the mechanical and thermal destructions prevail on the surface of the silicon wafer, which manifest themselves in cracking along the edges of the crystal structure and in the form of the surface solidified melted regions.
Keywords: laser radiation, nanosecond pulses, silicon, surface structuring, destruction, nanoparticles.

5. NANOCHEMISTRY – page 746

Blinov A.V., Pirogov M.A., Yasnaya M.A., Askerova A.S., Shevchenko I.M., Artyushin S.V.
Synthesis and investigation of nanoscale magnesium carbonate stabilized with hyaluronic acid – page 746
Abstract: As part of this work, the synthesis and study of nanoscale magnesium carbonate stabilized with hyaluronic acid was carried out. At the first stage, quantum chemical simulation of the interaction of magnesium carbonate nanoparticles with hyaluronic acid was carried out, as a result of which it was found that the addition of hyaluronic acid forms an energetically advantageous and chemically stable interaction. The most energetically advantageous (∆E = 462,410 kcal/mol) and chemically stable (n = 0,091 eV) is the interaction through a carboxyl group attached to C₆ of the glucuronic acid residue. The synthesis was carried out by mixing solutions of magnesium acetate and hyaluronic acid, adding a solution of ammonium carbonate drop by drop at a rate of 30 ml per minute, stirring for 10 minutes at 700-1000 rpm. Further, the obtained samples were centrifuged for 5 minutes at 3000 rpm in a five-fold repeat and dried at 110°C for 8 hours. The powders were examined by powder diffractometry, scanning electron microscopy and infrared spectroscopy. As a result of X-ray phase analysis, the phase composition of the obtained sample was determined: anhydrous magnesium carbonate, magnesium carbonate crystallohydrate, the mineral «Artinite». Scanning electron microscopy showed that the sample consists of rod-shaped particles with a length of 5 to 10 microns, consisting of nanoparticles with a diameter of 20 to 100 nm. The analysis of the infrared spectra of nanoscale magnesium carbonate stabilized with hyaluronic acid, hyaluronic acid and nanoscale magnesium carbonate without using a stabilizer showed that deformation plane oscillations of the O-H group are observed in the infrared spectrum of nanoscale magnesium carbonate stabilized withhyaluronic acid in the range from 1300 to 1400 cm^-1, which allows us to conclude that the interaction of nanosized magnesium carbonate with hyaluronic acid occurs through the hydroxyl group.
Keywords: nanoscale magnesium carbonate, hyaluronic acid, powder diffractometry, scanning electron microscopy, IR spectroscopy.

Blinova A.A., Gvozdenko A.A., Rehman Z.A., Blinov A.V., Taravanov M.A., Nazaretova E.D.
Development and optimization of the synthesis procedure of selenium nanoparticles stabilized by methylcellulose – page 758
Abstract: As a result of the work performed, a method for synthesizing selenium nanoparticles stabilized with methylcellulose was developed and optimized. Selenious acid was used as a selenium-containing precursor, ascorbic acid as a reducing agent, and methylcellulose as a stabilizer. A multifactorial experiment was conducted to optimize the method for synthesizing selenium nanoparticles stabilized with methylcellulose. It was found that for the synthesis of selenium nanoparticles with the smallest average hydrodynamic radius, the molar concentration of selenious acid in the solution should be in the range from 0,0036 to 0,1033 mol/l, the mass of methylcellulose – from 3,0 to 3,985 g, the molar concentration of ascorbic acid – from 1,52 to 2,12 mol/l. It is shown that pH of the medium, charge and concentration of sodium and barium ions do not affect the average hydrodynamic radius of selenium nanoparticles stabilized with methylcellulose. However, when exposed to iron ions, the radius increases from 150 to 270 nm. It is established that an increase in the concentration and charge of anions has a significant effect on the average hydrodynamic radius of selenium nanoparticles stabilized with methylcellulose. With an increase in the concentration of chlorine ions from 0,1 to 1 mol/l, an increase in the average hydrodynamic radius of particles occurred from 143 to 156 nm, with an increase in the concentration of sulfate ions from 0,1 to 1 mol/l, an increase in the average hydrodynamic radius of particles – from 165 to 6129 nm, with an increase in the concentration of phosphate ions from 0,1 to 1 mol/l, an increase in the average hydrodynamic radius of particles – from 149 to 17000 nm.
Keywords: selenium, nanoparticles, methylcellulose, average hydrodynamic radius, optimization.

Bogdanova E.A., Khonina T.G., Sabirzyanov N.A.
Investigation of transport properties of hydroxyapatite and its silicon-substituted derivatives – page 767
Abstract: The article discusses the possibility of practical application of hydroxyapatite and silicon-substituted hydroxyapatite as components of medicines, pharmaceutical compositions, and biomaterials, the use of which is based on the transdermal delivery route of the active substance. The specific surface area, degree of dispersion and transport properties (transmucose permeability) of hydroxyapatite and silicon-substituted hydroxyapatite were estimated using some modern physicochemical methods of analysis. Particular attention is paid to the joint use of the studied substances and silicon glycerolates as a conductor with pronounced transcutaneous, penetrating properties, contributing to the accumulation of locally applied drugs in biological membranes (skin, mucosa, etc.) without disturbing its structure. It is shown that the transport properties that determine the effectiveness of the action depend on physico-chemical characteristics of these substances being penetrated. Diffusion transfer and the ability to control the processes taking place can be used for optimal design of drugs for targeted delivery through the skin and mucous membranes.
Keywords: hydroxyapatite, siliconsubstituted hydroxyapatite; siliconglycerolatas; transmucosal permeability.

Bogdanova E.A., Skachkov V.M., Nefedova K.V.
Study of the possibility of obtaining composites based on nanoscale hydroxyapatite reinforced with titanium oxide and calcium fluoride – page 779
Abstract: The article discusses the possibility of obtaining a hardened composite material with a porous structure based on nanostructured hydroxyapatite (HAP) synthesized by precipitation from a solution. The new material by the mechanochemical synthesis of hydroxyapatite with aluminum, silicon, nickel, hafnium and titanium was obtained. The synthesized samples are certified using modern physical and chemical methods of analysis. The influence of the qualitative and quantitative composition of the composite on the sintering processes and the strength characteristics of the studied samples is shown. It has been experimentally established that the Ca₁₀(PO₄)₆(OH)₂ – 15%CaF₂-15%TiO_x. system is the most promising for the development of biocomposites based on it. Composite materials of this composition have a dense uniform structure with a high degree of crystallinity, with developed porosity, and are a promising material for further research in order to introduce it into medical practice. The possibility of practical application of the obtained composite material as a component of a bioactive coating is evaluated. A patent application has been filed for the developed composite material.
Keywords: hydroxyapatite, fluorapatite, titanium oxide, calcium fluoride, sintering, composite biomaterials, microhardness, bioactive coating.

Bui C.D., Nalimova S.S., Shomakhov Z.V., Guketlov A.M., Buzovkin S.S., Rybina A.A.
ZnO/Zn2SnO4 nanorod heterostructure coatings for effective detection of acetone – page 794
Abstract: Type II ZnO/Zn₂SnO₄ heterostructure was considered for gas sensor applications. ZnO nanorods surrounded by a Zn₂SnO₄ shell were grown on the surface of BI2 substrate with sputtered electrical contacts (sensor plat-form) by the hydrothermal synthesis method. Gas-sensitive properties were investigated on different gas analytes (isopropanol, ethanol, and acetone) using a combined laboratory setup allowing for resistivity response and electrical impedance spectroscopy measurements. At an operating temperature of 150°C, the sample showed optimum sensitivity to acetone (1000 ppm) and the R_a/R_g ratio reached a value of 11. The variation of the impedance plot based on the results of measurements in the presence of acetone vapors at an operating temperature of 200°C shows consistent changes. This operating temperature showed a clearer optimization compared to other studies where the sensor operating temperature ranged from 300 to 450°C. In addition, the energy band diagram of the ZnO/Zn₂SnO₄ heterostructure was presented and the acetone detection mechanism was discussed. The structure of the ZnO/Zn₂SnO₄ nanorods causes an improved response due to the chemisorption of oxygen on the surface of the Zn₂SnO₄ shells.
Keywords: zinc oxide, zinc stannate, hydrothermal method, gas sensor, acetone detection, ZnO/Zn2SnO4.

Gerk S.A., Golovanova O.A.
Influence of hyaluric acid on the structure of nanohydroxyapatite and morphological characteristics of their compositions – page 805
Abstract: Composites based on hydroxyapatite and natural biopolymers are promising materials for bone grafting. In this work, samples of hydroxyapatite were synthesized by chemical precipitation from aqueous solutions in the presence of high molecular weight hyaluronic acid (0,4-0,8 wt.%). The resulting powders are represented by carbonate-containing nanohydroxyapatite and contain 89-98 wt.% of polysaccharide. A correlation has been established between the content of hyaluronic acid in the mother solution and the crystal chemical, structural and morphological characteristics of the samples. It was revealed that, in comparison with the hydroxyapatite sample, in viscoelastic media of the polysaccharide, powders are formed that have a smaller parameter a of the hydroxyapatite crystal lattice, close in value to the stoichiometric phase. With an increase in the content of hyaluronic acid in the mother solution, the crystallinity, crystallite sizes and specific surface area of the composites decrease; their average value is 16 nm and 47 m²/g. Samples based on nanohydroxyapatite and polysaccharide consist of oval-lamellar agglomerated particles. At the maximum content of hyaluronic acid in the model solution, amorphized round conglomerates, dense in structure, are formed. The synthesized composites can be used in medical practice as osteoconductive implants, as well as to create nanoencapsulated drug delivery systems.
Keywords: nanohydroxyapatite, hyaluronic acid, composites, polymers; crystal chemical parameters, morphology.

Glazov I.E., Krut’ko V.K., Musskaya O.N., Kulak A.I.
Stabilization of amorphous calcium phosphate in the structure of hydroxyapatite during liquid-phase synthesis – page 815
Abstract: Amorphized hydroxyapatite with stabilized inclusions of amorphous calcium phosphate was obtained by a wet synthesis at pH 11. Reliable indicators of the presence of amorphous calcium phosphate in the hydroxyapatite structure includes: 1) peaks of α-tricalcium phosphate in the X-Ray Diffraction patterns after 800°C; 2) a pronounced exoeffect of crystallization of the amorphous phase at 600-850°C in the thermograms. Crystallization of amorphous calcium phosphate into α-tricalcium phosphate is inhibited by the effect of intercluster water (0,5 molecules per cluster). Under wet synthesis conditions, the key factor in stabilizing up to 16% of amorphous inclusions is a high supersaturation of the reaction medium, ensured by the mixing rate of reagent solutions of ~10^-1 mol/s. The high supersaturation of the reaction medium promotes the formation of a hydroxyapatite shell around the core of amorphous calcium phosphate. The hydroxyapatite shell provides stabilization of the amorphous phase toward interaction with the mother solution for 30 days and inhibits the allotropic (α→β)-tricalcium phosphate transition at 800°C.
Keywords: amorphous calcium phosphate, wet synthesis, hydroxyapatite, core-shell, biphasic calcium phosphates.

Golovanova O.A., Kiselev V.M.
Morphology of nanocrystalline structures of hydroxyapatite based on fractal analysis – page 826
Abstract: Currently, the global demand for orthopedic implants exceeds 6 million units per year and continues to increase. It is known that human bone is a composite material, the inorganic part of which is formed by calcium phosphates, mainly in the form of hydroxyapatite of non-stoichiometric composition. This fact determines the interest in studying the possibility of using hydroxyapatite-based materials for biomedical purposes, which are similar to the chemical composition of the bone and dental tissues and have high biocompatibility. Research in this area is necessary from both the fundamental perspective for expanding the scope of the method, and in view of development of new materials and studying biological fluids in health and pathology. The work shows that the presence of organic and inorganic additives in the synthesis of hydroxyapatite affects the composition and morphology of the crystals of the resulting compound. The results of analysis, presented in the form of diagrams, allow us to judge the inversely proportional relationship between the crystallization time and the value of the morphological dimension of the hydroxyapatite structures, regardless of the nature of the additive. The results obtained confirm the possibility of using morphological analysis to establish the patterns of formation of hydroxyapatite-based materials and to perform an express assessment of their properties (composition, morphology, degree of crystallinity, nature and concentration of impurities).
Keywords: crystallization, hydroxyapatite, modification, morphological dimension, structure, calcium phosphates, additives.

Golovanova O.A.
Synthesis of nanohydroxyapatite modified with lanthanum and cerium ions: composition and properties – page 837
Abstract: Lanthanide-doped hydroxyapatite nanoparticles can be used as luminescent labels and become an alternative to organic fluorophores, as they are more stable and have a longer service life. Such materials allow tissue studies in surgery, the bone engineering and tissue regeneration. Lanthanides are known to have a high affinity for hydroxyapatite. This is due to the fact that lanthanides have ionic radii close to that of the calcium ion which is associated with their biological activity. Rare earth elements inhibit the formation of osteoclast-like cells and the process of the bone resorption. At the same time, lanthanides have a biological effect on the body, as a result bacterial growth is suppressed and, at the same time, the structure of the outer cell membrane, responsible for cell permeability, changes. Substituted hydroxyapatites were synthesized with varying content of the lanthanum (III) and cerium (III) ions. The formation of substituted hydroxyapatite was proven by X-ray diffraction and infrared spectroscopy. The parameters of the crystal lattices of the synthesized phases were shown to change, indicating the replacement of calcium ions by rare earth element ions in the hydroxyapatite structure. The presence of rare earth element ions in solid phases was proven by inductively coupled plasma atomic emission spectroscopy. The study of the resorption of thesynthesized samples revealed that cation-substituted hydroxyapatites are less soluble than unmodified hydroxyapatite. Thus, lanthanum (III) and cerium (III) ions can inhibit and suppress the action of osteoclasts and thereby prevent the destruction of the bone tissue maintaining its integrity. Accordingly, the material based on hydroxyapatite dosed with rare earth element ions can have a positive effect when used in bone engineering.
Keywords: synthesis, hydroxyapatite, modification, bioactivity, structure, rare earth elements.

Doroshenko A.E., Krut’ko V.K., Musskaya O.N., Kulak A.I.
Electrochemical and biomimetic deposition of calcium phosphates on titanium alloys – page 848
Abstract: The presence of impurities of other metals in titanium alloys affects the composition of the oxide film after heat treatment: in addition to rutile, the VT 00 alloy contains Ti₆O oxide, which in the VT 1-0 and VT 6 alloys is transformed into Ti₃O oxide, which affects the corrosion resistance and mechanical strength. Calcium phosphate coatings containing brushite, calcite and apatite were obtained by electrochemical deposition on titanium plates at room temperature, pH 5, and a constant current density of 30 mA/cm² from a suspension electrolyte CaCO₃ / Ca(H₂PO₄)₂. A layer of amorphized apatite was applied to the coatings using the biomimetic method in a 3-fold concentrated model solution of Simulated Body Fluid to improve biocompatibility. After heat treatment at 800°C, calcium phosphate coatings obtained on titanium VT 00 have greater biocompatibility, but lower resorbability, due to the presence of a larger amount of crystalline hydroxyapatite in the coating.
Keywords: titanium alloys, calcium phosphate coatings, brushite, calcite, SBF model solution, amorphized apatite, hydroxyapatite.

Dyudyun O.A., Komarova A.A., Elbekyan K.S.
Obtaining fullerene dispersions and investigation of their physical and chemical properties – page 857
Abstract: Prospects for successful use of fullerenes in biology and medicine relate to the possibility of obtaining their non-toxic hydrophilic derivatives, which are able to participate in the metabolism occurring in a living organism. An effective solution to this problem is associated with creation of water-soluble molecular complexes, in which the fullerene molecule is enclosed in a larger water-soluble capsule. A new method for producing colloidal suspensions and aqueous dispersions of fullerenes based on vegetable oil and polyvinyl alcohol by ultrasonic dispersion in an Elmasonic S10H chamber has been proposed. Transmission spectra of the synthesized samples were recorded on a UNICO 2100 spectrophotometer. The hydrodynamic radius of particles was measured on a Photocor Compact-Z particle size analyzer. To create theoretical models, as well as carry out quantum chemical calculations, the 3D modeling program ArgusLab 4.0.1 was used. The structures of hydrogel films of fullerene dispersions were studied by scanning electron microscopy (MIRA-LMH microscope from Tescan).
Keywords: colloidal solutions of fullerenes, fullerene dispersions, ultrasonic dispersion, 3D modeling, physical and chemical analysis.

Zaritovskii A.N., Kotenko E.N., Grishchuk S.V., Glazunova V.A., Volkova G.K.
Studying catalytic synthesis of carbon nanostructures during microwave-assisted pyrolysis of cellulose – page 864
Abstract: One of the ways to develop methods for effective and economical synthesis of carbon nanostructures from the plant raw materials is to use the energy of the microwave electromagnetic field for pyrolytic transformations of biomass. Combining microwave irradiation and pyrolysis process is a new solution with several advantages that increase the efficiency of the biomass processing and determine the prospects of the microwave pyrolysis in obtaining carbon nanoproducts. In this work, the conditions for catalytic synthesis of carbon nanotubes through the microwave pyrolysis of cellulose, a major component of biomass, were studied. The objective of the present investigation is to evaluate the effect of a binary nickel-iron catalyst supported on a carbon substrate on synthesis of carbon nanostructures. This process involves the use of organic additives, such as glucose and thiourea, which are intended to prevent oxidative reactions in the system and maintain the activity of the catalyst. Experiments were carried out by treating the mixture of reagents with the microwave radiation with a frequency of 2450 MHz and a power of 1000 W for 10-12 minutes. The synthesis samples were characterized by X-ray phase analysis and transmission electron microscopy. In all experiments, the formation of multi-walled carbon nanotubes and few-layer graphene particles was observed. It was experimentally found that the used catalyst showed great activity in the microwave synthesis of carbon nanotubes in the presence of glucose.
Keywords: carbon nanotubes, cellulose, microwave pyrolysis, nickel-iron catalyst, glucose, thiourea.

Kartashynska E.S.
Description of complexation thermodynamic parameters for alkanes and polyaromatic hydrocarbons in the framework of semiempirical methods – page 873
Abstract: The paper presents a comparative analysis of quantum chemical semiempirical methods for calculation of the binding thermodynamic parameters for C_nH_2n+2 alkanes (n=6–14) and polyaromatic hydrocarbons of the coronene series as model structures of the graphene surface. Two types of orientation of alkane molecules are considered depending on the relative position of the C–C–C «zigzag» plane of alkanes within the polyaromatic hydrocarbons plane: parallel and perpendicular. The parallel arrangement of alkane molecules on the polyaromatic hydrocarbon surface is revealed to be more energetically advantageous than the perpendicular one. The enthalpy, entropy, and Gibbs energy of alkane formation and binding to polyaromatic hydrocarbons are calculated using the PM3, RM1, PM6-DH2, PM6-D3H4, and PM7 methods. It is shown that the first two methods are improper for describing the intermolecular C–H/π interactions in alkane – polyaromatic hydrocarbon systems, since the Gibbs binding energy estimated in them has positive values, which is inconsistent with the available literature data. The use of the PM6 method with DH2 correction for dispersion interactions and hydrogen bonds is optimal. The values of binding enthalpy in alkane – tricircumcoronene complexes calculated using PM6-DH2 and RM6-D3H4 methods are in good agreement with experimental data on the enthalpy of adsorption of alkanes on the graphite/graphene surface, as well as data from molecular dynamic modeling. However, according to the Gibbs binding energy in the considered alkane complexes with parallel and perpendicular orientation of alkanes on tricircumcoronene, only the PM6-DH2 method gives values that correspond in the best way to the available data on the energy preference of such complexes.
Keywords: alkanes, polyaromatic hydrocarbons, adsorption, enthalpy, absolute entropy, Gibbs binding energy, C–H/π interactions, semiempirical methods.

Klychkov N.A., Simakov V.V., Sinev I.V., Efanova V.V., Zakharevich A.M.
The effect of water vapor on the conductivity and response of gas-sensitive nanostructured ZnO layers to ethanol vapors at room temperature – page 891
Abstract: The paper presents the results of a study on the sensitivity of gas-sensing zinc oxide ZnO film nanostructures at room temperature. The aim of the research was to investigate the effect of ambient humidity on the conductivity of ZnO samples and their response to ethanol vapor in the presence of water vapor. It has been discovered that zinc oxide films are responsive to both water and ethanol vapor at room temperature, across a broad range of concentrations (5% to 50% saturated vapor). The study found that repeated exposure to water vapor can lead to changes in the conductivity of zinc oxide samples when they are exposed to dry air. Additionally, pre-annealing the samples at 400°C can help to replicate the concentration-dependent response of gas-sensitive structures to water vapor. Hysteresis was observed in the relationship between concentration and response to water vapor, in the range of 5% to 90% of the relative humidity. This can be explained by the capillary condensation of water vapor within the mesopores of zinc oxide layers. As the humidity of a gas sample containing ethanol increased, the response values and detection limit for ethanol decreased in the gas-air mixture for ZnO samples. Statistical analysis using the principal component method showed the potential for classifying dry and humid gas samples with ethanol vapor in air. Data processing was used to eliminate the influence of the background humidity on the calibration curve for gas-sensitive ZnO samples, demonstrating the effectiveness of this method.
Keywords: zinc oxide, sol-gel technology, semiconductor gas sensor, ethanol response, gas sensitivity, room temperatures, humidity effect.

Klychkov N.A., Simakov V.V., Sinev I.V.
The effect of deep surface acceptor states on the temperature-dependent conductivity of zinc oxide nanoparticles – page 906
Abstract: An experimental and theoretical study was conducted on the temperature dependence of the conductivity of zinc oxide (ZnO) layers in dry air and ethanol. The study found that the conductivity of ZnO depends non-linearly on temperature, and its type varies depending on experimental conditions. Scanning speed directly affects the type of the temperature dependence, with a local minimum in conductivity between 250±5°C at a scanning rate of 0,4°C/min. However, monotonic dependencies are observed at slower scanning rates, such as 30°C/min, and a mechanism is proposed to explain the effect of the scanning velocity on the type of dependency. This mechanism involves the process of the thermal activation of oxygen molecules to form atomic oxygen at adsorption sites. The key idea behind this mechanism is that atomic oxygen forms deeper acceptor levels on zinc oxide surfaces compared to molecular oxygen. At a high scanning rate, the relaxation time for filling the surface with adsorbed oxygen is significantly longer than the experimental time. Therefore, metastable «frozen» states of atomic forms of adsorbed oxygen appear on the surface of zinc oxide layers. As a result, metastable «frozen» states of adsorbed atoms appear on the surface of zinc oxide layers. Based on calculations using this model, we propose a method for reducing the number of nonequilibrium atomic oxygen states by heating samples in a reducing medium.
Keywords: zinc oxide, semiconductor gas sensor, gas sensitivity at room temperature, temperature dependence of conductivity, oxygen dissociation, surface acceptor, Schottky double barrier model.

Krut’ko V.K., Maslova L.Yu., Suchok V.A., Musskaya O.N., Kulak A.I.
Release of cisplatin from bioinert templates in mixture with hydroxyapatite – page 922
Abstract: The dynamics of cisplatin release and its mixture with hydroxyapatite from bioinert templates based on carbon felt and polyethylene were studied. Changing the polyethylene and carbon felt layer ratio in the templates influenced the volumetric concentration of cisplatin and the duration of its release. The diffusion of cisplatin from the samples was limited by the number of polyethylene layers. After crystallization at 800°C, the phase composition of hydroxyapatite-α is 65% hydroxyapatite and 35% α-tricalcium phosphate, and hydroxyapatite-αβ consists of 50% hydroxyapatite, 35% α- and 15% β-tricalcium phosphate. Long-term (44 days) release was observed in templates with 2-3 layers of carbon felt and 3-4 layers of polyethylene, and it was slowed when using mixtures with hydroxyapatite (58 days). The appending of hydroxyapatite/cisplatin mixtures into the template with varying amounts of hydroxyapatite phases and α-/β-tricalcium phosphates slowed the release of cisplatin by 14 days, totaling 58 days, due to the sorption and/or binding of cisplatin to calcium phosphates.
Keywords: cisplatin, hydroxyapatite, tricalcium phosphate, carbon felt, bioinert template, release.

Menshikov S.Yu., Malyshev A.N., Kurmacheva V.S., Fedorov S.A., Tonkushina M.O., Ostroushko A.A.
The effect of FeSO4, nanoscale silver and { Mo72Fe30} cluster on the oxidation of ethylene glycol by H2O2 – page 933
Abstract: The catalytic properties of FeSO₄, nanocluster iron-molybdenum polyoxometalate {Mo₇₂Fe₃₀} and nanoscale metallic silver in the liquid-phase oxidation of the ethylene glycol aqueous solutions by hydrogen peroxide were studied. O-phenylenediamine was added to the reaction mixtures obtained after oxidation to determine the oxidation products containing the aldehyde group. The polyoxometalate {Mo₇₂Fe₃₀} was synthesized by a well-known and widely used in practice two-step method. The colloidal silver solution was obtained using a technique based on the Turkevich method. According to the analysis carried out on a laser particle size analyzer, the majority of the silver particles have a size of about 2 nm. The analysis of unreacted ethylene glycol was carried out by GC-FID. According to the conversion of ethylene glycol, nanoscale metallic silver was found to have the highest activity at approximately the same percentage of catalysts in the initial reaction mixture. At the same time, with the addition of o-phenylenediamine, the presence of compounds with an aldehyde group, whose exit time from the chromatographic column is longer than that of the initial ethylene glycol, was noted among the oxidation products.
Keywords: polyoxometalate, keplerate, FeSO4, nanosized metallic argentum, catalytic properties, oxidation of ethandiole, H2O2.

Musskaya O.N., Krut’ko V.K., Glazov I.E., Krutsko E.N., Kulak A.I.
Liquid-phase synthesis of magnesium phosphates in the presence of gallic acid – page 942
Abstract: In aqueous solutions of magnesium chloride and sodium dihydrogen phosphate at Mg/P molar ratios of 1,0-1,5 and pH of 5-7 in the presence of gallic acid, crystalline hydrates of magnesium hydrophosphate (newberyte – MgHPO₄ꞏ3H₂O) and orthophosphate (Mg₃(PO₄)₂ꞏ22H₂O) were obtained, which after heating at 800°C transformed into pyrophosphates (Mg₂P₂O₇). X-ray phase and thermal analysis methods, as well as infared spectroscopy, showed that the presence of an organic additive in the liquid-phase synthesis of magnesium phosphates does not lead to a noticeable change in the phase composition of the reaction products. It was revealed that gallic acid affects the formation of the structure of crystalline hydrates depending on the Mg/P molar ratio. It was found that with prolonged maturation of the sediments (over 6 months), the size of the unit cell of magnesium phosphates decreases. The obtained magnesium phosphate powders modified with gallic acid exhibit redox activity and are promising for use in biomaterials as resorbable components with antioxidant properties.
Keywords: magnesium phosphates, newberite, magnesium pyrophosphate, gallic acid, liquid phase synthesis, redox activity, polyphenolic compounds.

Nagdalian A.A., Leontiev P.S., Golik A.B., Askerova A.S., Serov A.M., Tatov A.V.
Investigation of the process of polymer stabilization of mixed iron oxide with amylopectin – page 951
Abstract: In this work, samples of mixed nanoscale iron oxide stabilized with amylopectin were obtained by chemical precipitation in an aqueous medium. This compound has a wide range of applications in biomedical technologies, energy storage and conversion devices due to its supermagnetic properties. The microstructure was studied by scanning electron microscopy and the phase composition by diffractometric method, as well as by computer quantum chemical modeling of the interaction of amylopectin and mixed nanoscale iron oxide. During the study of the phase composition, it was found that the sample is a mixed iron oxide Fe₃O₄ with a cubic face-centered lattice and a spatial group Fd3m. Based on the analysis of the microstructure, it was found that the sample is formed from particles with a diameter of 24 to 54 nm.As a result of computer quantum chemical modeling, it was found that the interaction of iron oxide nanoparticles with amylopectin is energetically advantageous and chemically stable. The most likely interaction is through a hydroxyl group attached to the C₂ first A-bound glucopyranose residue, since optimal values of total energy (E = -3839.330 kcal/mol) and chemical hardness (η = 0.159 eV) are observed during this interaction.
Keywords: nanoparticles, co-deposition method, iron (III) oxide, scanning electron microscopy, stabilizer.

Rekh Yu.V., Bibanaeva S.A., Valova M.S., Skachkov V.M., Fedorova O.V., Sabirzyanov N.A.
Sorption of La3+ cations by zeolites from aqueous solutions – page 960
Abstract: It is shown that the sorption of lanthanum cations by synthetic aluminosilicate zeolite, unlike natural ones, increases both in acidic and neutral conditions by 4 times (from 8 to 26%) and 8 times (from 4 to 33%), and the sorption capacity increases by 3-8 times to 145 and 184 mg/g, respectively. A comparative analysis of the applicability of the adsorption of Langmuir, Freundlich, Temkin, Dubinin-Radushkevich models to describe experimental isotherms of adsorption of lanthanum cations on synthetic zeolite is made. It is shown that the Langmuir model is best suited in aqueous media (R² = 0,9996). This indicates that a homogeneous monolayer surface is formed as a result of sorption. Based on the pseudo-first, pseudo-second order models and the intraparticle diffusion model, an assumption is made about the ion-exchange nature of sorption. It has been shown that zeolites can almost quantitatively extract La³⁺ cations from aqueous solutions and are of interest as sorbents with a high sorption capacity.
Keywords: sorption, purification, sorption activity, synthetic zeolite, aluminosilicate, lanthanum, Langmuir model.

Ryashentsev D.S., Belenkov M.E., Kovalenko L.Y.
Structural varieties of 2D boron nitride – page 971
Abstract: Using the density functional theory method, geometric optimization of layered polymorphic varieties of boron nitride, in which atoms are located in three different structural positions, was carried out and their energy and electronic properties were determined. The structures of the new polymorphs consist of boron and nitrogen atoms in a sp²-hybridized state and were modeled from hexagonal boron nitride by introducing topological defects 4-6-8, 4-6-10, 4-8-10, 4-16 and 4-6-12. As a result of the analysis, the possibility of the existence of nine new structural varieties was established. However, during the geometric optimization process, three structures turned out to be unstable, which were transformed into more stable polymorphic varieties BN-L_4-8 and BN-L_4-6-8. The layer density of the considered polymorphic varieties varies from 0.651 to 0.727 g/cm².The sublimation energy values of the new structures range from 16,93 to 17,69 eV/(BN). The band gap varies from 3,20 to 4,03 eV. The relationships between the energy and structural parameters are determined.
Keywords: boron nitride, two-dimensional materials, polymorphism, ab initio calculations, crystal structure, band structure.

Sabanin K.I., Skachkov V.M., Medyankina I.S., Bogdanova E.A., Sabirzyanov N.A.
Investigation of the effect of titanium and zirconium oxides on the strength characteristics of nanoscale hydroxyapatite – page 981
Abstract: The article discusses the possibility of dispersion strengthening of nanostructured hydroxyapatite synthesized by precipitation from solution introducing reinforcing additives of non-stoichiometric titanium oxide and zirconium dioxide. The reinforced composite material: hydroxyapatite – non-stoichiometric titanium oxide – zirconium dioxide was obtained by mechanochemical synthesis of hydroxyapatite with doping components followed by annealing at 1000°C. The initial components and synthesized samples were certified using modern physicochemical methods of analysis: X-ray phase analysis, differential thermal analysis, scanning electron microscopy, surface area and porosity analysis, dispersion analysis. The influence of the qualitative and quantitative composition of the composite on the sintering processes and strength characteristics of the studied samples in a wide temperature range of 25-1200°C is shown. It has been experimentally established that the most promising system for developing biocomposites based on it ishydroxyapatite – 15% non-stoichiometric titanium oxide – 5% zirconium dioxide. Composite materials of this composition have a dense, uniform, strong structure with a high degree of crystallinity and a developed surface. They seem to be promising materials for further research with the aim of introducing it into medical practice.
Keywords: hydroxyapatite, titanium oxide, zirconium oxide, sintering, composite biomaterials, microhardness.

Sattorov M.Sh., Spivak Y.M., Kotcur Y.M., Kuznetsov A., Flisyuk E.V., Moshnikov V.A.
Spectroscopy of porous silicon nanoparticles impregnated with a drug maloben substance – page 995
Abstract: Using electrochemical anodic etching, porous silicon layers were formed with subsequent production of nanoparticles. The study of the nature of interaction of porous silicon nanoparticles with a new promising 4,4′-(propanediamido) sodium dibenzoate (malobene) substance was performed using infrared and Raman spectroscopy. It was revealed that during the incorporation process, an interaction occurs between the nanoparticle and maloben, during which the degree of influence of porous Si particles during joint scattering of light decreases, and the vibrational modes of the sodium 4,4′-(propanediamido) dibenzoate molecule become more intense. Characteristic absorption bands associated with the formation of chemical bonds by wave and Raman numbers were detected, and an interpretation of the obtained results from the point of view of the formation of the finished substance was proposed.
Keywords: porous silicon, nanostructured layer, nanoparticles, maloben, chemical bonds, infrared Fourier spectroscopy, Raman spectroscopy, scanning electron microscopy.

Skachkov V.M., Bogdanova E.A., Bibanaeva S.A., Shirokova A.G.
Development of a material based on hydroxyapatite and aluminosilicate zeolites with a binding agent for the formation of bioactive coatings – page 1004
Abstract: The hardened composite material with a porous structure was obtained by mechanochemical synthesis of nanostructured hydroxyapatite synthesized by precipitation from an aqueous solution with reinforcing additives of zirconium dioxide and silicic acid. Food gelatin is used as a binder. The influence of the phase composition on physico-chemical properties of coatings (adhesive strength, microhardness, specific surface area, microstructure) is estimated. It has been established that the use of composite material together with gelatin as a part of a bioactive coating makes it possible to increase its hardness and adhesive strength. A patent application has been filed for the developed bioactive coatings based on nanoscale hydroxyapatite and biogenic elements with a binding agent. The composition of the dry mixture based on hydroxyapatite has been developed, which ensures a long shelf life without negative consequences and creates simple transportation conditions. Dilution of the dry mixture with distilled water gives a suspension that is convenient to use for coating implants of any configuration.
Keywords: hydroxyapatite, composite materials, aluminosilicate zeolites, gelatin, collagen, biomaterial, bioactive coatings, adhesion.

Suprunchuk V.E., Kravtsov A.A., Tarala L.V., Medyanik E.V., Malyavin F.F., Lapin V.A., Bedrakov D.P.
Synthesis of yttrium aluminum garnet ceramic powder doped with ruthenium – page 1016
Abstract: In the course of the work, samples of ceramic powders of yttrium-aluminum garnet doped with ruthenium ions were obtained. The introduced amount of ruthenium was 5 and 10 wt.%, respectively. The annealing temperatures were 1150 and 1600°C. In the course of the work, changes in the morphology of ceramic powders of yttrium-aluminum garnet doped with ruthenium ions were considered using scanning electron microscopy. The elemental composition was studied using energy-dispersive spectroscopy. The phase composition was investigated by X-ray phase analysis. The specific surface area of the ceramic powder was estimated using the Brunauer-Emmett-Teller method. For the obtained samples, an increase in the specific surface area of the ceramic powder with a decrease in the quantitative content of ruthenium in the system was revealed. The presence of impurity phases was established for all samples. It was found that increasing the calcination temperature to 1600°C led to a decrease in the quantitative content of impurity phases, but did not lead to their complete elimination. The sample with the closest to a single-phase composition was obtained with a ruthenium content of no more than 5 wt.% in the material. The results obtained using differential thermal analysis showed that the ruthenium content in the amounts used does not affect the kinetics of phase transitions, as well as the kinetics of mass loss of the precursor powders.
Keywords: yttrium aluminum garnet, alloying, ceramic powder, differential thermal analysis, ruthenium.

Tonkushina M.O., Gagarin I.D., Sharadgah B.T.M.A.., Gavrilyuk V.R., Piunov K.A., Ostroushko A.A.
Formation of hybrid carriers based on albumin and polyoxometalate for targeted drug delivery – page 1025
Abstract: The use of proteins to create the targeted drug delivery systems is a promising approach in medicine and has many advantages. The formation of hybrid drug carriers based on proteins and polyoxometalates has a number of additional benefits. Polyoxometalates are able to bind both proteins and molecules of certain drugs to obtain water-soluble products without the use of toxic reagents and organic solvents. The regulation of the experimental conditions allows to control the size of the particles formed in solution. The gradual destruction of polyoxometalate {Mo₇₂Fe₃₀} at blood pH provides a pH-dependent mechanism for drug release from the carrier structure. In our research, we obtained bovine serum albumin associated with coordination complexes {Mo₇₂Fe₃₀}-doxorubicin and {Mo₇₂Fe₃₀}-tetracycline in aqueous solution. A decrease in the rate of the drug release in a phosphate buffer solution at pH 7.4 (blood pH) from the obtained materials compared to systems not containing albumin was observed. The data obtained in this study shed light on the formation patterns of multicomponent supramolecular systems, consisting of polyoxometalates, proteins, and drugs. The results indicate the possibility of creating hybrid carriers for targeted drug delivery based on polyoxometalates and albumin using non-covalent binding.
Keywords: {Mo72Fe30}, doxorubicin, tetracycline, albumin, targeted drug delivery, supramolecular systems.

Chupakhina T.I., Uporova A.M., Gyrdashova O.I., Buldakova L.Yu., Deeva Y.A., Baklanova I.V., Yanchenko M.Yu.
Solid Sr2Ti1-xMnxO4 (x = 0; 0,01; 0,025; 0,05; 0,1) solutions with K2NiF4 structure – page 1035
Abstract: Solid of Sr₂Ti_1-xMn_xO₄ (x = 0; 0.01; 0.025; 0.05; 0.1) solutions with Raddlesden-Popper structure (A_n+1B_nO3_n+1, n = 1, structural type K₂NiF₄) were obtained by a precursor technology. Formate complexes of the corresponding metals synthesized by an original method were used as precursors. The products of thermolysis of the obtained complexes with an organic ligand are isostructural single-phase samples, which crystallize as agglomerates with an average size of 1 μm. Using energy dispersive X-ray analysis, we established a uniform distribution in the agglomerates of Sr²⁺, Ti⁴⁺ and Mn⁴⁺. According to electron spin resonance and optical spectroscopy, manganese in titanium-oxygen polyhedra of Sr₂Ti_1-xMn_xO₄ is predominantly in oxidation degree 4⁺. Increasing the concentration of manganese in the solid solution composition effectively narrows the forbidden band width of strontium titanate from 3.5 eV to 2.5 eV for Sr₂Ti_0,9Mn_0,1O₄. The catalytic properties Sr₂Ti_1-xMn_xO₄ were analyzed in the oxidation reaction of hydroquinone under irradiation of its aqueous solutions in the ultraviolet and visible spectral ranges. Under the described conditions, all photocatalysts showed a high rate of photooxidation. It was found that the photocatalytic activity of Sr₂Ti_1-xMn_xO₄ in 3 consecutive cycles of photooxidation under infrared stimulation exceeds the commercial catalyst Degussa P25 by 4 times.
Keywords: layered wide-gap semiconductors. perovskite, strontium titanate, formate synthesis, photocatalysis, voltammetry. electron microscopy. electron microscopy.

Shirokova A.G., Bibanaeva S.A., Bogdanova E.A., Skachkov V.M., Koryakova O.V.
Study of the physico-chemical properties of composites obtained by mechanochemical synthesis of nanoscale hydroxyapatite and synthetic zeolites – page 1046
Abstract: In this article, the features of synthesis and physicochemical properties of a composite material based on precipitated hydroxyapatite and synthetic aluminosilicate zeolites are investigated. Using modern methods of analysis, both the obtained composite material and individual components included in its composition are certified. The material was synthesized by mixing with simultaneous grinding in a vibration mill of synthetic zeolite and hydroxyapatite, followed by annealing of the resulting mixture. The characteristics of the initial aluminosilicate zeolites and hydroxyapatite were clarified by infared spectroscopy, their interaction during mechanochemical synthesis and subsequent heat treatment of composites obtained on their basis was assessed. X-ray phase analysis of the initial synthetic zeolites indicates the loss of adsorbed and crystallization water and decomposition to complex aluminosilicate oxides of calcium and sodium during heat treatment at 1000 °C. It was also found that although precipitated hydroxyapatite is structurally unstable and its phase composition depends on temperature, the behavior of the composite material obtained on its basis differs significantly during high-temperature treatment. It was proven that thermal annealing of the composite obtained by mechanosynthesis during heat treatment at 1000 °C does not lead to chemical modification of the hydroxyapatite structure and the formation of a new compound due to the introduction of zeolite. Differential thermal analysis showed an increase in the stability of the composite material relative to its individual components. The morphology of the original materials and those subjected to heat treatment was studied using scanning electron microscopy; a change in morphology during sintering was shown. Along with the study of the thermal stability of the materials, an assessment of the linear shrinkage of the samples and their microhardness was carried out. The conducted comprehensive studies made it possible to recommend composites based on precipitated hydroxyapatite, containing 15 wt.% aluminosilicate zeolites in their composition, as promising materials for further study, possessing the best functional characteristics, including strength.
Keywords: synthetic zeolite, hydroxyapatite, infrared spectroscopy, X-ray phase analysis, differential thermal analysis, composite material.

Shomakhov Z.V., Nalimova S.S., Zyryanova O.D., Kondratev V.M., Kalazhokov Z.Kh., Bui C.D., Moshnikov V.A.
Gas sensitivity of WOx/WS2 nanocomposites at room temperature under ultraviolet irradiation – page 1060
Abstract: Currently, semiconductor gas sensors are of interest for various applications, including industry, medicine and environmental monitoring. One of the most important tasks in the sensor technology is to reduce the operating temperature of devices. In this paper, it is proposed to use WO_x/WS₂ nanostructures obtained by a hydrothermal method to solve this problem. The morphology, structure, and composition of the developed nanostructures were studied using scanning electron microscopy, reflected electron diffraction and X-ray photoelectron spectroscopy. It is shown that the nanostructures are formed by 1D and 2D nanoobjects with an average length of 200 nm and are nanocomposites consisting of tungsten oxide WO_x and tungsten disulfide WS₂. The study of sensory properties when exposed to isopropanol, ethanol and acetone vapors at room temperature was carried out. A reversible change in resistance is demonstrated when these gases appear in the atmosphere. Additionally, exposure to ultraviolet radiation during the measurement process leads to an increase in the response value and speed of the sensor layers in the case of interaction with isopropanol and ethanol vapors.
Keywords: gas sensors, room temperature, nanostructures, tungsten oxide, tungsten disulfide, nanocomposites.

Shostak N.A.
Features of determining the parameters of crystal lattice of ice-like associates of water molecules during hydrate formation – page 1071
Abstract: This article describes the features of determining the enthalpy characteristics of the hydrate formation process. Aspects of forming hydrate structures from hydrate-forming agent molecules and water are described. It is shown that the processes of the hydrate formation and dissociation have different natures, which are determined by the interaction of the hydrate former with water in one phase state or another: hydrate former – solid phase of water – ice, hydrate former – liquid phase of water, hydrate former in a critical (pseudocritical) state – liquid phase of water. The dependence of the water crystallization temperature on the pressure and nature of the hydrate former is analyzed. The energy processes occurring during the formation of clusters and unit cells of the crystal lattices of hydrate structures due to the release and absorption of the thermal energy are described. Dependences are proposed for calculating the heat of formation of the crystal lattice from ice-like associates of water molecules. It is shown that the process of restructuring the ice lattice into a hydrate lattice can be both exothermic and endothermic.
Keywords: cluster, crystal lattice, hydrate generator, hydrate formation, hydrate structure, ice-like associates, heat of formation.