Foreword – page 7
1. EXPERIMENTAL STUDIES OF NANOPARTICLES, NANOSYSTEMS, AND NANOMATERIALS – page 8
Anufriev I.E., Muratova E.N., Korolev D.V., Shulmeister G.A., Valeev R.G., Moshnikov V.A.
Development of a manual extruder for liposome homogenization – page 8
Abstract: Medications using liposomes are of great interest in pharmaceuticals. They increase the therapeutic index of the drug by enclosing the medicinal substance inside a biocompatible lipid envelope, which releases the solution only in the required area. Such drugs have already shown their effectiveness in the treatment of diseases related to oncology, dermatology, neurology, surgery, etc. To use liposomes for these purposes, it is necessary that their size be in the range from 50 to 200 nm. There are several ways to create vesicles of this size, but mostly they use either ultrasound exposure to a liposome solution or extrusion. The extrusion method is a method that allows to obtain the most homogeneous solution from liposomal particles. For extrusion, a special device – an extruder is required. It is a system that passes a liposomal solution under pressure through a filter with a certain pore size. In this paper, the process of liposome extrusion, types of liposomal extruders are considered and their pros and cons are evaluated, a model of a manual extruder capable of homogenizing up to 20 ml of solution was also developed. Different materials were considered and used for the construction of this device. The inspection of the extruder showed its operability and showed the advantages of using extrusion compared to the ultrasound exposure method.
Keywords: extrusion, liposomes, homogenization, membrane, porous aluminum oxide, extruder, 3D modeling.
Apekov A.M., Shebzukhova I.G.
Orientational dependence of the interphase energy of low-temperature modification of titanium at the boundary with an organic liquid – page 17
Abstract: Calculations of the interphase energy of low-temperature modification of titanium at the boundary with nonpolar organic liquids are carried out within the framework of the electron-statistical method, corrections to the interphase energy for the dispersion interaction of Wigner-Seitz cells and the electron density oscillation in the transition layer, the polarization of surface metal ions and organic liquid in the field of a semi-infinite metal are obtained. When calculating the interphase energy, changes in all components of the metal bond energy in the transition layer are considered – the eigenenergies of the electron gas, the energies of the interaction of the electron gas with ions. The effect of an organic liquid on the orientational dependence of the interphase energy of alpha-titanium and the corrections to the interphase energy taking into account the permittivity of the organic liquid is established. It is shown that the dispersion and oscillation corrections increase the interphase energy, and the polarization correction reduces the interphase energy. A sharp anisotropy of the interphase energy and corrections is obtained for this titanium structure.
Keywords: interfacial energy, polarization correction, dispersion correction, electron-statistical method, non-polar organic liquid, titanium.
Barbin N.M., Yakupova L.V., Terent’ev D.I., Kuanyshev V.T.
Decomposition of fullerene C28 in a nitrogen atmosphere – page 24
Abstract: A study of the behavior of С28 fullerene when heated in a nitrogen atmosphere was conducted. The calculations were made using the thermodynamic modeling method, which consists in a complete thermodynamic analysis of the system using the TERRA software complex. The range of minimum and maximum heating temperatures was 273-3373 K and pressure was 0,1 MPa. A graph of the carbon balance in the С28 – N2 system was built, chemical reactions were determined, temperature intervals were allocated for each reaction. Temperature intervals of the thermal stability of carbon nanoparticles in the condensed and vapor phases are established. In the gas phase, С28 steam shows increased thermodynamic stability and only reacts with vapors at high temperatures, as evidenced by a sharp decrease in its content. The equilibrium constants of the reactions are calculated, and graphs of the dependence of the equilibrium constants of the reactions on temperature are given. For each reaction, the calculated data were approximated by the linear dependence.
Keywords: fullerenes, carbon nanoparticles, thermodynamic modeling, physical and chemical process.
Bernatskii D.P., Pavlov V.G.
The effect of the interaction of barium atoms on the surface of the rhenium field emitter on the work function – page 31
Abstract: Modification of the emission surface on a nanometer scale during adsorption of barium atoms on the surface of a rhenium field emitter was investigated using field electron and desorption microscopy. Field electronic images of the emitter surface reflecting the localization of barium atoms on the emitter surface, representing the quasi-spherical surface of a rhenium single crystal, were obtained. The influence of the temperature of the emitter with adsorbed barium on the change in the emitter work function is shown. Deposition at room temperature leads to the appearance of a dependence of the work function on the concentration of adsorbate with a minimum in the area of optimal coating. Annealing of the emitter at T = 600 K after deposition of each portion of barium causes the minimum to disappear. After reaching the minimum value (optimal coverage with adsorbed atoms), the work function remains constant with an increase in the number of adsorbed barium atoms on the surface of the emitter. A sharp change in the localization of barium atoms due to a phase transition with the formation of islands in the region of the rhenium face was detected on the field electronic image. The change in the nature of the dependence of the work function is associated with a phase transition in the barium film with the formation of barium islands. The concentration of barium in the islet is constant and corresponds to the optimal coating.
Keywords: field emitters, field electron and desorption microscope, adsorption, rhenium, barium.
Blinov A.V., Shevchenko I.M., Pirogov M.A., Gvozdenko A.A., Golik A.B., Leontev P.S.
Investigation of the effect of the molar ratio of reagents on the dimensional and structural characteristics of cobalt hexacyanoferrate nanoparticles – page 39
Abstract: In this work the influence of the molar ratio on the dimensional and structural characteristics of cobalt hexacyanoferrate nanoparticles was studied. The synthesis was carried out by chemical method in an aqueous medium using potassium hexacyanoferrate and cobalt nitrate. As a result of the study of samples by the method of dynamic light scattering, the values of the hydrodynamic radius of the samples were obtained. It was found that the minimum size (R = 76 nm) has a sample with a molar ratio K3[Fe(CN)6] : Co(NO3)2= 4 : 1. Scanning electron microscopy revealed that cobalt hexacyanoferrate samples are irregularly shaped aggregates consisting of nanoparticles with a diameter of 50 to 150 nm. As a result of X-ray phase analysis, it was found that the samples have a face-centered cubic crystal structure (Fm 3 m). According to the Debye-Scherrer equation, the average size of crystallites in the samples is from 17 to 20 nm.
Keywords: transition metal hexacyanoferrates, cobalt hexacyanoferrate, cobalt nitrate, scanning electron microscopy, dynamic light scattering, powder diffractometry, hydrodynamic radius.
Bolshakova N.N., Druginina N.Yu., Ivanova A.I., Pavlova D.N., Ped`ko B.B., Semenova E.M.
Repolarization properties of copper-containing crystals of triglycine sulfate – page 50
Abstract: The paper presents the results of the analysis of experimental dielectric hysteresis loops and field dependens of polarization switching of initial and annealed crystals of triglycine sulfate, doped copper (the concentration range (4,2–8,7) 10-3 wt.%). It has been experimentally established that their dielectric hysteresis loops do not have distortions. It has been found that the relative and effective permittivities and switchable polarization increase with increasing impurity concentration in crystals of TGS:Cu2+. The field dependences of the effective permittivity have extrema: before annealing the samples, the maxima of the εeff(E) curves correspond to a field value of about (20-40)∙103 V∙m-1, and for annealed samples these fields have a value of ~(15-30)∙103V∙m–1. Annealing of the samples increases the mobility of domain walls, which promotes the transformation of lenticular nuclei of domains into lamellae.
Keywords: triglycine sulfate, repolarization, domain structure, switching processes, hysteresis, permittivity.
Golovanova O.A.
Study of calcium oxalate nanocrystalline structures and kinetics of calcium oxalate deposition – page 61
Abstract: Calcium oxalates, represented by wavellite CaC2O4·H2O and weddellite CaC2O4·2H2O (the most stable forms), are the main components of stones in the genitourinary system, and are also part of dental, gallstones, and other mineral deposits. It is known that modern approaches to the study and modeling of crystallization processes make it possible to analyze the influence of a number of factors (exogenous and endogenous) arising at various levels of organization: from atoms and molecules to macroscopic processes occurring in industrial devices. The process of crystallization, taking into account the variety of acting factors and forms of crystal structures, consists of two main stages: formation of a solid phase nucleus and its growth (formation of a solute crystal). In this work, using modern approaches, the physicochemical and kinetic patterns of crystallization of calcium oxalates under conditions close to physiological are determined. The effect of physiological solution components (organic and inorganic) was studied, the staged mechanism of the solid phase formation was established, and the kinetic parameters of the growth stage were calculated (lgk = 33.1). The inhibitory effect of inorganic additives (Mg2+, Cl–), amino acids (glycine, glutamine, aspartic) and the accelerating effect of hydroxyapatite crystals, seed in the form of calcium oxalate and urea crystals on the crystallization process were revealed.
Keywords: .
Golovanova O.A.
Crystallization of nanocrystalline hydroxylapatite in the presence of albumin – page 71
Abstract: Due to the development of modern biotechnologies and nanomaterials, in the near future it is expected to achieve a new, higher quality level in the design and improvement of the characteristics of intraosseous implants used in orthopedics. Calcium phosphate was synthesized from a model solution of synovia in the presence of albumin. Synthetic solid phases were studied using X-ray phase analysis, IR-Fourier spectroscopy, scanning electron microscopy, and energy dispersive analysis. The supernatant was examined for the presence of ions and to calculate the ratio. It was found that albumin does not affect the phase composition of the samples: the sediments are single-phase and consist of B-type hydroxylapatite carbonate. The study of the structure and morphology of the solid phase showed that the presence of proteins leads to formation of composites with a lower specific surface area compared to hydroxylapatite carbonate. The largest crystallite size is observed for the hydroxylapatite carbonate /albumin sample with the albumin concentration of 12 g/l. With the help of the thermal analysis of the fixation of thermal effects five stages of the thermal transformation were identified in the temperature range of 25-1000 °C; for all samples, the main stages are II–III, associated with the thermal destruction of organic additives. The study of the bioactivity of the samples showed that in the case of active resorption, the most soluble were the samples synthesized in the presence of albumin (>7 g/l), and in the case of passive resorption, the hydroxylapatite carbonate/albumin samples (5 and 7 g/l).
Keywords: crystallization, hydroxylapatite, albumin, adsorption, bioresorbability.
Gudkov S.I., Solnyshkin A.V., Zhukov R.N., Kiselev D.A.
Electrical response of lithium niobate and lithium tantalate thin films to modulated thermal radiation – page 82
Abstract: In this work, we studied the pyroelectric activity of thin polycrystalline lithium niobate films fabricated by radio frequency magnetron sputtering and laser ablation, and thin polycrystalline lithium tantalate films fabricated by radio frequency magnetron sputtering. Using the dynamic method of studying the pyroelectric effect, it was found that all samples have self-polarization that occurs during the post-growth thermal annealing of the structure. An estimate of the pyroelectric coefficient showed that the values of the pyroelectric coefficient of lithium niobate and lithium tantalate thin films are several times lower than the values of the pyroelectric coefficient for bulk crystals of the corresponding materials. This may be due to the fact that the polarization vector of some grains lies in the film plane, as well as to the traps existing in the film volume and at the film/substrate interface, on which charge carriers recombine and do not participate in the generation of the pyroelectric current.
Keywords: lithium niobate, lithium tantalate, thin film, dynamic method, self-polarization, pyroelectric effect, pyroelectric coefficient, LiNbO3, LiTaO3, ferroelectric, laser ablation method, radio frequency magnetron sputtering.
Zernitsa D.A.
Crystallization of lead-free binary tin-zinc alloys produced by the method of rapidly solidification from the melt – page 92
Abstract: The results of studies of the structures of rapidly solidified foils of alloys of the Sn – Zn system with a low content of alloying elements (up to ~1,5 wt.%), alloys of near-eutectic compositions, as well as alloys with an alloying element content of 20 – 95 wt.% are presented. In rapidly solidified alloys containing 1,5 wt. % Sn and 1,2 wt. % Zn, supersaturated solid solutions are formed, which decompose according to the mechanism of formation and growth of nuclei of a new phase at room temperature. Alloys (4,4 – 15 wt.% Zn) after rapidly solidification are supercooled and supersaturated with both components, and experience spinodal decomposition followed by the formation of supersaturated solid solutions based on Sn and Zn, which decompose at room temperature. In all other alloys, a two-phase structure is formed from solid solutions based on Sn and Zn. It was found that as the crystallization front moves from the surface of the contacting foil layer with the surface of the mold, the Sn particles coarsen and the specific surface of the interfacedecreases. It has been established that rapidly solidified foils have a microcrystalline grain structure, with an increase in the concentration of alloying elements, a tendency to a decrease in grain size is observed.
Keywords: rapidly solidified alloys, zinc, tin, grain, spinodal decomposition, supersaturated solution, eutectic, structure.
Zigert A.D., Semenova E.M., Kuz`min N.B., Sdobnyakov N.Yu.
Fractal analysis of magneto-optical images of a magnet surface after exposure to a pulsed field – page 101
Abstract: The results of fractal analysis of images of the surface of a permanent magnet KS37 obtained by the method of the polar Kerr effect using an indicator bismuth-containing ferrite-garnet film after magnetization reversal by a pulsed field of 0,1 – 1,5 T are presented. The obtained dependences of the remanent magnetization on the magnitude of the external pulsed field are compared with the fractal dimension of the magneto-optical images of the magnet surface after exposure to the pulsed field. It is hypothesized that the field dependences of the fractal dimension of the profile of magneto-optical images of the magnet surface coincide in shape with the graphs of the first derivative dMr(H)/dH of the magnetization with respect to the field, i.e. there is a relationship between the nature of the magnetization change in a pulsed field and the type of the magneto-optical image analyzed by using the fractal geometry methods.
Keywords: permanent magnet, effect, ferrite-garnet films, domain structure, fractal dimension, derivative of magnetization with respect to magnetic field.
Ivanov D.V., Antonov A.S., Semenova E.M., Ivanova A.I., Kuz`min N.B., Sdobnyakov N.Yu.
On the formation of fractal iron films – page 108
Abstract: The patterns of formation of the fractal relief of nanosized iron films on the mica surface are considered using the atomic force microscopy. In order to prevent the formation of an oxide layer, iron films were studied immediately after their production employing at a magnetron sputtering unit. It has been established that magnetron sputtering makes it possible to obtain island films of iron, the structural element of which are truncated nanocubes – nanopyramids. The fractal dimension of the resulting agglomerates was determined at various scales: on a scale of 5 µm Dc = 2,462±0,113; on a scale of 3 µm Dc = 2,373±0,122; on a scale of 1 µm Dc = 2,298±0,139. The distribution of the probability of detecting agglomerates on the films under study with a certain fractal dimension of the surface of iron films is estimated. The subsequent elemental analysis of the iron films showed the presence of oxygen and, consequently, the formation of ordered oxide films of the core-shell type.
Keywords: atomic force microscopy, magnetron sputtering, fractal dimension, iron films, nanopyramids.
Ivanova A.I., Svesnikov P.A., Marinicheva K.A., Gugutsidze K.A., Vasilev A.D., Tretiakov S.A., Karpenkov A.Yu.
Comparative studies of the strength properties of germanum and silicon single crystals – page 120
Abstract: In this paper, we present the results of microhardness tests performed by Vickers indentation of germanium and silicon single crystals. It’s shown that in the investigated samples there is a dependence of microhardness on the crystallographic directions and the nature of the alloying impurity. Microhardness anisotropy coefficients are calculated: for germanium KII=1,2 and for silicon KII=1,3. The analysis of high-temperature annealing influence on microhardness value of germanium and silicon crystals is carried out. It has been established, that the microhardness of Ge(111) crystals grows on 12% after annealing at 550°С, the further thermal processing of germanium crystals at T=650°С considerably changes the structure and surface relief which contribute to a decrease in microhardness values. It is shown that the microhardness of silicon crystals increases by 10% after annealing at 750°C, further annealing to T=850°C leads to a decrease in microhardness. The surfaces of single crystals after high-temperature annealing have been studied; it has been established that thermal treatment at T≈0.6 Tm (Tm – the melting temperature of the single crystal) leads to the appearance of defects and a tenfold increase in the maximum height of the surface profile (from 10-12 nm to 100-200 nm).
Keywords: germanium and silicon single crystals, microhardness, Vickers method, microhardness anisotropy coefficient, interatomic bonds, dopants, high-temperature annealing, surface nanorelief, defects.
Ivanova A.I., Musabirov I.I., Semenova E.M., Vasilev A.D., Gugutsidze K.A., Karpenkov A.Yu.
Influence of deformation on the microsructure and magneic properties of Heusler alloys – page 132
Abstract: This paper presents the results of studies of the effects of deformation obtained by the method of multiple isothermal forging on the microstructure and magnetic properties of the NiMnGa alloy system. It is shown that the microstructure of the initial alloy during deformation undergoes changes, grain size decreases and a two-component structure is formed. The magnetic domain structure of the original and deformed alloys was visualized by magnetic force microscopy. It is shown that the distortion of the domain shape is associated with the presence of a martensitic relief and grain boundaries, 180-degree magnetic domains are continuous within the crystallites, while they cross the flat parallel boundaries of the martensite plates. The study of temperature and field magnetization dependences of the initial and isothermal forging samples demonstrates an insignificant magnetization decrease and a shift of the phase transition temperature toward low temperatures. It’s concluded that deformation by the isothermal forging method can be considered as a way to correct the phase transition temperature in NiMnGa alloys with preservation of magnetization.
Keywords: Heusler alloys, martensitic relief, multiple isothermal forging, micro and nanostructure, magnetic domain structure, magnetostructural transition.
Karmokova R.Yu., Karmokov A.M., Molokanov O.A., Khasanov A.I., Kanametov A.A.
Influence of the parameters of acoustic waves on the characteristics of cavitation bubbles in liquid aluminum – page 141
Abstract: Calculation of parameters of a cavitation bubble during irradiation of aluminum melt with acoustic waves is carried out. The dependences of the Mach number on the amplitude at frequencies of 1-20 kHz used in the experiments are obtained. A relationship has been established between the resonant frequency of acoustic waves and the size of cavitation bubbles in liquid aluminum. Allowing the possibility of generalizing the Minnert linear theory to the case of viscous liquids, the dependence of the maximum radius of cavitation bubbles on the frequency of the acoustic field at different temperatures is obtained, taking into account the surface tension, density and viscosity of liquid aluminum. It has been established that with an increase in the frequency of the acoustic field, the radii of the cavitation bubbles decrease. The temperature change inside the cavitation bubble is estimated as a function of the bubble radius at any moment of its compression under adiabatic conditions. It is shown that when the bubble radius decreases to a critical size, the temperature inside it can increase by an order of magnitude.
Keywords: aluminum, acoustic waves, cavitation, cavitation bubble, Mach number.
Karpenkov A.Yu., Rakunov P.A., Musabirov I.I., Dunaeva G.G.
Influence of deformation processing on magnetocaloric effect of Heusler alloys – page 149
Abstract: This paper presents the results of complex studies of the effect of deformation obtained by the multiple isothermal forging method on the magnetocaloric properties of the Ni-Mn-Ga Heusler alloy system. Direct measurements of the adiabatic temperature change show that cycling the sample in a magnetic field μ0ΔH=1,85 T can decrease the maximum of ΔTad(T)0→H by the value corresponding to the latent heat of transition. Neglecting this transformation effect leads to an overestimation of the magnetocaloric effect of materials with the first-order transition. An analysis of the deformation treatment effect on the phase transformation temperatures and the magnitude of the magnetocaloric effect indicates that the application of multiple isothermal forging leads to a small decrease of the magnetization and the magnitude of the magnetocaloric effect. Deformation also causes a shift in the phase transition temperature towards low temperatures and decrease of the temperature hysteresis width.
Keywords: Heusler alloys, multiple isothermal forging, magnetocaloric effect, magnetostructural phase transition.
Kul’kov V.G., Kul’kova V.V.
Internal friction caused by migration of the intercrystalline boundary in the metal – page 159
Abstract: The model of internal friction at the migrating intercrystalline boundary is considered. Under the action of an alternating external stress oriented normally to the boundary, compression and stretching of the mating crystallites occurs. Due to their anisotropy and mutual reversal, Young’s modules in the direction of the stress action are different. The volume density of elastic energy in crystallites is different. This leads to the emergence of an effective driving force for boundary migration. As a model, a square segment of the boundary is selected, fixed along the perimeter by triple grain joints. The Laplace stress from the side of the curved boundary is counteracting. The differential equation of the connection of the boundary displacement with the total voltage is solved by the Fourier method. Based on this solution, the internal friction is calculated. The relaxation time spectrum consists of a series of lines. Each of them corresponds to the peak of Debye. The main peak has a significant value, smaller peaks are superimposed on it. The resulting maximum of internal friction widens in comparison with the Debye peak.
Keywords: driving force, migration of the intercrystalline boundary, peak of internal friction, relaxation time.
Lapin V.A., Kasyanov I.V.
The growth of InAlN/Si heterostructures with a high content of In – page 168
Abstract: InAlN films on Si (111) were obtained by the ion-beam deposition with various technological growth parameters. The results of the study of grown films by the scanning electron microscopy were used to identify the conditions for obtaining InAlN continuous films. Due to the mismatch of the lattice parameters of the film and substrate, the growth has an island character, a solid film was obtained only with the following technological parameters: the energy level of the beam U = 600 eV at the ion current of the beam ji = 32 mA, with the neutralization current of the beam jn = 32 mA, the substrate temperature of 400°C. With an increase of the nitrogen concentration to 80-90% in the gas mixture, a transition from an island to an epitaxial growth mechanism took place. The ratio of the elements In, Al and N in the film showed that the active plasma of the ion beam breaks down weakly bound ions and leaves only normally embedded nitrogen atoms N-3, but excessively strong exposure leads to metallization of the films.
Keywords: heteroepitaxy, InAlN, ion-beam deposition, elemental analysis, scanning electron microscopy, heterostructures.
Malashenko V.V., Malashenko T.I.
Effect of dislocation density on the dynamic yield strength of alloys with nanoscale defects under high energy external actions – page 176
Abstract: A theoretical analysis of inelastic processes in aged alloys under intense external influences is carried out. The analysis was carried out within the framework of the theory of dynamic interaction of defects. An analytical expression for the dependence of the dynamic yield strength on the dislocation density has been obtained. The reason for the different influence of nanostructural defects on the dislocation motion under high strain rate deformation and quasi-static deformation is determined. It is shown that under high strain rate deformation, nanosized defects affect the nature of the dependence of the dynamic yield strength on the dislocation density. This dependence becomes nonmonotonic and has a minimum. At the minimum point, there is a transition from the dominance of the drag of the dislocation by Guinier-Preston zones to the dominance of its drag by other dislocations. Numerical estimates of the contribution of the Guinier-Preston zones to the yield strength are made. It is shown that at a high concentration of Guinier-Preston zones, this contribution is very significant. Numerical estimates are made of the dislocation density at which the Taylor relation is violated.
Keywords: high-speed deformation, dislocations, Guinier-Preston zones, point defects, nanomaterials, Taylor ratio.
Malyshkina O.V., Ivanova A.I., Mamaev D.V.
The effect of tellurium vapor on the structure formation and dielectric properties of a multicomponent system based on sodium-potassium niobate – page 183
Abstract: The paper presents the results of studying the effect of paratellurite vapor during sintering on the dielectric properties of a multicomponent system based on sodium–potassium niobate ceramics (mKNN) with the general formula (Na0,5K0,49Li0,05Sr0,05)(Nb0,9Ta0,05Ti0,05)O3. The inclusion of paratellurite in mKNN ceramics changes the shape and increases the grain size by an order of magnitude. Thus, if grains containing only mKNN material have a cubic shape, then the presence of tellurium leads to the formation of grains in the form of sufficiently long tubes (when the length is several times greater than the diameter) with a porous internal structure. The addition of TeO2 to the mKNN composition leads to the disappearance of the maximum observed for mKNN on the temperature dependence of the permittivity in the region of 220-250°C, which corresponds to a nonferroelectric structural phase transition in KNN ceramics, and to smoothing the resonant- antiresonant peak in the range of 5-15 MHz, which appears in the KNN system with the introduction of modifiers.
Keywords: piezoelectric ceramics of potassium sodium niobate, lead-free materials, grain structure, complex permittivity dispersion.
Malyshkina O.V., Shishkov G.S., Ivanova A.I.
Structure and dielectric properties of a layered composite of barium titanate – barium ferrite – page 194
Abstract: The paper presents the results of a study of the influence of a constant magnetic field on the dispersion of the complex permittivity of a layered composite (connectivity 2-2) based on barium titanate – barium ferrite. It is shown that in the manufacture of a magnetoelectric composite of barium titanate – barium ferrite with a connectivity of 2-2, a strong diffusion of iron appears into the barium titanate ceramic layer at the interface between the two materials. It was found that iron penetrates evenly, with random deviations, and no exponential decline as iron enters into barium titanate is observed. It has been established that a constant magnetic field does not affect the dielectric characteristics in an alternating electric field at frequencies above 1600 Hz. At lower frequencies, annealing in the paraelectric phase increases the resistance of the sample, and subsequent exposure to a constant magnetic field leads to its decrease. It was revealed that changing the type of connectivity of the magnetoelectric composite from 0-3 to 2-2 adds additional, smaller, resonance andantiresonance peaks in the study of piezoelectric properties by the resonance-antiresonance method. At the same time, the samples have sufficient values of the piezoelectric modulus for practical application (d31 > 40·10-12 C/N; d33 > 120·10-12 C/N).
Keywords: multiferroic, barium ferrite, barium titanate, magneto-electric composite, piezoelectric ceramic structure.
Maraeva E.V., Tokmeilova S., Sagitova D.R., Kononova I.E., Moshnikov V.A., Skornikova S.A.
Study on the microporous structure parameters of BEA type zeolites – page 203
Abstract: The paper considers a series of zeolite materials used as catalysts. Since the formation of mesoporosity in a microporous matrix is one of the methods for increasing the efficiency of zeolite materials in catalysis, it is necessary to control their porous structure parameters. The effect of post-synthetic treatment with acid and alkali solutions on the specific surface area of zeolites of the BEA type has been studied. The method of low-temperature (at 77 K) adsorption of nitrogen vapors was used to determine the external specific surface area (excluding micropores) and the volume of micropores in the samples on a Sorbi device. It has been shown that modification of BEA-type zeolite with concentrated mineral acids leads to both a decrease in the volume of micropores and a decrease in the specific surface area. At the same time, it was established by the X-ray phase analysis that the treatment with concentrated acids does not lead to destruction of the crystal structure of zeolites. In the case of treatment with alkali solutions, the specific surface area of the samples increases and the volume of micropores sharply decreases.
Keywords: zeolites, BEA type, hierarchy, mesopores, micropores, adsorption, specific surface area.
Nepsha N.I., Veselov A.D., Savina K.G., Bogdanov S.S., Kolosov A.Yu., Myasnichenko V.S., Sdobnyakov N.Yu.
Variability of structural transformations in bimetallic Cu-Ag nanoalloys – page 211
Abstract: In this work, bimetallic Cu-Ag nanoparticles of five stoichiometric compositions of various sizes were studied by molecular dynamics method using a many body EAM potential. Regularities of the structure formation are established, their characteristic features are described. In particular, in compositions with 10, 70, and 90 at.% Cu content, after the melt cooling, typical fcc structures with intersecting atomic planes of the hcp phase are formed. In compositions of 30 and 50 at.% Cu, the fraction of identified phases does not exceed 20% of the total number of atoms. A tendency to the formation of a core-shell structure was revealed in the case of a high copper content, while in the case of a high silver content, a so-called onion structure is formed. Using the caloric curves of the potential term of the internal energy, the melting and crystallization temperatures were determined. It has been established that the concentration dependences of the melting temperature of bimetallic Cu-Ag nanoparticles have a minimum corresponding to the equiatomic composition for all sizes. For the crystallization temperature, both the concentration dependences and the size dependences are less pronounced, but the minimum value of the crystallization temperature also corresponds to the equiatomic composition for all sizes; with an increase in the size of bimetallic Cu-Ag nanoparticles, a slight increase in the crystallization temperature is observed.
Keywords: molecular dynamics method, LAMMPS, EAM potential, polyhedral template matching method, bimetallic nanoparticles, silver, copper, structure formation, melting and crystallization temperatures.
Sidorov N.V., Smirnov M.V., Titov R.A., Teplyakova N.A., Palatnikov M.N.
Optical properties of LiNbO3:B crystals – page 227
Abstract: The optical properties of nominally pure LiNbO3stoich, near-stoichiometric LiNbO3stoich (6,0 wt% K2O), LiNbO3cong and LiNbO3:B (0,55 and 0,83 mol% B2O3 in the charge) crystals in the visible region of the spectrum (λ = 380-700 nm) were studied by photoluminescence. LiNbO3:B crystals were grown by Czochralski using the technology of a direct solid-phase doping of the congruent charge by boron oxide (B2O3). The photoluminescence intensity increases in the series of crystals: LiNbO3stoich, LiNbO3stoich (6,0 wt% K2O), and LiNbO3cong. The photoluminescence intensity is determined by the concentration of deep electron traps (NbLi – «niobium antisite») and the stoichiometry of these crystals. The photoluminescence intensity of LiNbO3:B (0,55 and 0,83 mol% B2O3 in the charge) crystals is close to the photoluminescence intensity of LiNbO3stoich crystal. This can be explained by the fact that the composition and structure of LiNbO3:B (0,55 and 0,83 mol% B2O3 in the charge) crystals approach the composition and structure of the stoichiometric crystal.
Keywords: lithium niobate, crystal, defects, direct solid-phase doping, photoluminescence.
Sidorov N.V., Kadetova A.V., Titov R.A., Teplyakova N.A., Palatnikov M.N.
Specific features of the defect structure of LiNbO3:B crystals – page 235
Abstract: Specific features of the defect structure of nominally pure LiNbO3:B crystals were studied by the X-ray diffraction analysis. Nominally pure LiNbO3:B crystals were grown by Czochralski using the technology of the direct solid-phase doping of the congruent charge by orthoboric acid (H3BO3). The bonds lengths of Me-O in MeO6 clusters (Me-Li, Nb) determine the ferroelectric and nonlinear optical properties of the lithium niobate crystal. The values of these bonds in LiNbO3:B crystals differ significantly from the bonds lengths of the nominally pure congruent crystal LiNbO3cong. The differences in the bonds lengths are caused by a change in the properties of the boron-containing melt, technological parameters of the growth of LiNbO3:B crystals, and the localization of a trace amounts of boron in tetrahedral voids of the lithium niobate crystal structure. The results of the study of LiNbO3:B crystals were compared with those for nominally pure LiNbO3cong crystals and near-stoichiometric LiNbO3stoich (5,5 wt% K2O) ones.
Keywords: lithium niobate, crystal, defects, direct solid-phase doping, X-ray diffraction analysis.
Strechen A.S., Kurnosov Yu.A., Karpenkov A.Yu., Ivanova A.I., Sinkevich A.I., Semenova E.M., Pastushenkov Yu.G.
Surface study of Tb0,16Ho0,84Fe2,00-xCox intermetallics – page 243
Abstract: The results of the study of the crystal structure, magnetic properties, as well as of micro-and domain structure of the surface of a series of compounds Tb0,16Ho0,84Fe2,00-xCox (x = 0,1; 0,2; 0,3; 0,4) are presented. It is shown that an increase in the relative content of cobalt leads to a decrease in the crystal lattice parameter a from 7,310 Å at x = 0,1 to 7,304Å at x = 0,4. At the same time, the Curie temperature increases accordingly from 581 to 614 K. It has been experimentally established that, as x increases, the specific saturation magnetization decreases linearly with increasing temperature. It has been found that the mechanical impact on the surface of sections during polishing can lead to the appearance of a regular microrelief. The results of studying the domain structure of the surface are presented. It is shown that the configuration and linear dimensions of the domains change as a result of the impact on the surface of the samples.
Keywords: intermetallics, Laves phase, magnetic properties, surface, microstructure, domain structure.
Elcheparova S.A., Kokoevа A.A.
Luminescent method for determination of nanoscale particles of rare earth elements with sulfosalicylic acid derivatives – page 254
Abstract: It was of interest to search for luminescent reactions to terbium in complexes with sulfosalicylic acid derivatives and to enhance them by studying the effect of third components (aminopolycarboxylic acids, organic bases and surfactants). As the results of the conducted studies have shown, surfactants increase the intensity of the glow of terbium ions in complexes with sulfosalicylic acid derivatives. The existence of a bright luminescent reaction of green terbium in complex with the methyl ester of S-(4-bromanilide) sulfosalicylic acid has been established. Optimal conditions for the complexation of terbium have been selected and highly sensitive luminescent methods for the determination of terbium in various objects have been developed. Terbium is converted into a luminescent complex compound with an organic reagent –methyl ether S-(4-bromanilide) sulfosalicylic acid in the presence of a cationic surfactant decylpyridinium chloride in a ratio of 1: 2: 13, pH = 7,9 ± 0,08. The resulting complex compound of terbium, when irradiated with ultraviolet light from a mercury lamp, gives intense green luminescence, stable during standing and irradiation. The proposed method makes it possible to determine terbium in oxides of rare earth elements, which are luminescence quenchers with a sensitivity of 10-6 – 10-8%, bypassing the extraction stage.
Keywords: nanoscale particles, rare earth elements, lanthanides, organic reagent, complex compound, terbium, luminescence, detection limit.
2. THE THEORY OF NANOSYSTEMS – page 264
Anofriev V.A., Nizenko A.V., Ivanov D.V., Antonov A.S., Sdobnyakov N.Yu.
To the problem of automation of the process of determination of the fractal dimension – page 264
Abstract: In this paper, using various software products (Gwyddion, Mountains 9 DigitalSurf, Image Analysis P9) as well as our own program FractalSurface, we analyzed the possibilities of calculating the fractal dimension for various types of data using several numerical methods (cube counting method, triangulation method, variation method, as well as methods of the spectrum power, «scaling» analysis, morphological envelopes) and the possibilities for their working with the obtained values, such as: selecting a linear section of the graph for recalculating the final value of dimension, using matrix convolutional filters with different convolution kernels for image processing and of the batch analysis of the studied images. At the current time, there is no software product that would satisfy all the requirements for image analysis for the presence of self-affine structures, however, the availability of sufficient functionality mainly depends on the type of study. The comparative analysis of the obtained results allows us to evaluate the capabilities of the software product for further use as tools for automating the process of determining the fractal dimension and of the primary image processing.
Keywords: fractal dimension, cube counting method, triangulation method, variance method, power spectrum method, scaling analysis method, morphological envelopes method, image processing software.
Akhmatov Z.A., Akhmatov Z.A.
On the possibility of controlling the band gap in graphene – page 277
Abstract: Using first principles calculations, the possibility of controlling the electronic band structure of the single-layer graphene was investigated. It is shown that when potassium atoms are adsorbed on the graphene surface, an energy gap appears in its electronic spectrum. It was also observed that the band gap strongly depends on the number of adsorbed atoms, namely, with an increase in the number of adsorbed atoms, the band gap in graphene can either increase or disappear. For example, when there is one potassium atom per 32 carbon atoms in the graphene lattice, the band gap is ΔE = 0,1 eV. An increase in the number of potassium atoms to two leads to disappearance of the energy gap, while for three potassium atoms ΔE = 0,22 eV. It should also be noted that the appearance of a band gap during adsorption does not break the symmetry of the graphene sublattices. This observation seems interesting to us, since according to many authors, it is the break of the sublattices symmetry that is the main reason for the appearance of a band gap in graphene.
Keywords: graphene, electronic band structure, ab initio calculations, adsorption, alkali metal atoms.
Belyaeva I.N., Kirichenko I.K., Chekanova N.N.
Solving of some nonlinear ordinary differential equations in the form of power series – page 284
Abstract: In the current scientific literature, a variety of nonlinear ordinary differential equations are widely and successfully used to describe real processes in various fields of natural sciences: optics, elasticity theory, molecular physics, etc. For example, the Ermakov and Riccati equations are used to solve the quantum Schrodinger equation, in electrodynamics. However, unfortunately, there are no well-and reliably developed and generally accepted methods for solving nonlinear differential equations. In addition, most of the Riccati equations are not integrated even in quadratures. In this paper, to construct solutions to the nonlinear Ermakov and Riccati equations, it is proposed to use the corresponding so-called connected linear differential equations, the solutions of the latter are in the form of power series using modern computer systems of analytical calculations.In this paper, solutions for some nonlinear Ermakov and Riccati equations are calculated using this proposed method. It is shown by direct substitution that the obtained solutions in the form of power series satisfy the considered nonlinear equations of Ermakov and Riccati with a known accuracy. Solutions of nonlinear Ermakov and Riccati equations can be used to describe the chemical and physical properties of nanostructures at the quantum level. Besides, solutions of nonlinear Ermakov and Riccati equations can be successfully applied in solving stationary and time-dependent Schrodinger equations.
Keywords: ordinary differential equations, Ermakov equation, Riccati equation, mathematical modeling, power series, Maple computer system.
Zamulin I.S., Gilubnichiy A.A., Chepkasov I.V., Baidyshev V.S.
Methods for describing the reactivity of transition metal nanoparticles – page 292
Abstract: Using modern calculations from first principles, in this work we systematically studied the adsorption of atomic oxygen on the surface of nanoparticles of fcc metals Ag, Cu, Pd consisting of 79 atoms. Two models were considered to describe the reactivity of transition metals based on the d-band center of surface atoms, as well as on the basis of the generalized coordination number. Both methods for predicting the adsorption energy of oxygen atoms at different sites have shown good results, however, the method based on the generalized coordination number is computationally simpler, since this method requires information only about the structure of the particle, while the d-band center model requires electronic structure calculations. The obtained values of the oxygen adsorption energy and d-band center correspond to the known literature data. The most favorable positions for the adsorption of an oxygen atom are on the (100) plane and are hollow consisting of 4 atoms and do not depend on the type of metal under consideration. The highest adsorption energy of the oxygen atom was observed in the case of copper nanoparticles.
Keywords: transition metals, nanoparticles, generalized coordination number, adsorption, electron density functional theory.
Magomedov R.A., Akhmedov E.N.
Water vapor P-ρ-T properties calculation in the temperature range from 773 K to 1673 K – page 298
Abstract: The paper presents the calculation of isotherms of the equation of state of water vapor in the temperature range from T = 773 K to T = 1673 K. The calculation was made using a specially developed software module “Fract EOS”. An approach that improves the accuracy of calculations of the previously described method is proposed. If there are tabular data of the P-V-T (P-ρ-T) ratio for several temperatures and the pressure dependences of the fractional derivative exponent α(ρ) (which is fitting parameter for the proposed model) obtained from them, then it is possible to obtain the dependence α(ρ) for any temperature within the range. After that, the equation of state can be calculated at a given temperature with high accuracy, without fitting α by experimental values. The results obtained are in good agreement with experimental data. It is shown that proposed method is suitable for calculating isotherms in the temperature ranges not presented in tabulated reference data.
Keywords: equation of state, integral-differentiation of fractional order, Maxwell relations, Helmholtz potential, partition function, water vapor, isotherm, thermophysical properties.
Talyzin I.V., Samsonov V.M., Bogdanov S.S., Sdobnyakov N.Yu., Grigoryev R.E., Pervikov A.V., Mishakov I.V.
Identification of complex core-shell nanostructures from the radial distributions of the local density of components – page 307
Abstract: The paper is devoted to the substantiation and further development of the approach to the analysis of the mesoscopic and integral structure of binary metal nanoparticles from the radial distributions of the local density of the components. As an example, the local density distributions of Ni and Al obtained using the results of molecular dynamics modeling of binary Ni-Al nanoparticles with an initial uniform distribution of components and Ni@Al core-shell icosahedral nanostructures are considered. Both patterns demonstrate the surface segregation of Al atoms during relaxation and subsequent quenching of the initial configurations containing 5000 atoms in 1:1 ratio (nanoparticle radius 3 nm). During cooling, the temperature of the nanoparticles decreased from 1000 K to 0,01 K with a low for atomistic simulation cooling rate. Experimentally binary Ni-Al nanoparticles with a radius of about 100 nm (76Ni:24Al at.%) were synthesized by the wire electric explosion. The experimental intensity distributions obtained from the data of energy-dispersive analysis under the action of an electron beam are presented and analyzed. These distributions correspond to a greater extent to the initial configurations in our molecular dynamics experiments, i.e., they are obviously nonequilibrium. At the same time, it was concluded that the final molecular dynamic configurations are also not entirely equilibrium.
Keywords: core-shell nanostructures, Ni-Al nanoparticles, radial density distributions, embedded atom method, tight binding potential, molecular dynamics, wire electric explosion method, energy- dispersive analysis.
Tvardovskiy A.V.
General phenomenological approach for the description of adsorption and absorption equilibria – page 321
Abstract: Up to the present time, the construction of a general theory of the equilibrium adsorption is a very urgent task. In the present paper, a general phenomenological approach is developed to describe both adsorption and absorption equilibria. It was shown that under certain assumptions, the resulting equation transforms into the well-known classical Henry, Langmuir, Brunauer-Emmett-Teller equations with constants having a clear physical meaning. Thus, the constant in the Henry equation is determined by the temperature, 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 the classical version, a clear dependence of the equation constant on the 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 the temperature under consideration, the concentration of adsorbate molecules during the formation of a dense monolayer on the surface of the adsorbent, the energy of interaction of adsorbate molecules with thesurface 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.
Keywords: adsorption, adsorbent, absorption, thermodynamics of phase equilibria, Henry equation, Langmuir equation, Brunauer–Emmett–Teller equation.
Yurov V.M., Portnov V.S., Mausymbayeva A.D.
Thickness of the surface layer of as-class hydrocarbons – page 331
Abstract: The aim of the work is to build a model of the surface layer of objects (crystals) and to elucidate the role of surface energy in physical processes occurring in the nanoscale region. Frame hydrocarbons of the adamantane type, which have a highly symmetrical diamond-like structure, were chosen as objects. On the basis of an empirical model, the thickness of the surface layer and the surface energy of framework hydrocarbons were determined for the first time. In practice, this is very important, since all physical and chemical processes significant in operation occur through the surface layer. For adamantane, the thickness of this layer is 21.6 nm, and for diamond it is 8.2 nm, that is, they represent a nanostructure. Such a difference in the thickness of the surface layer of the two types of structures causes their sharp difference in their properties, in particular, in their surface energy, which determines their mechanical properties. For adamantane, the surface energy is 378.7 mJ/m2, and for diamond it is 9400 mJ/m2. In practice, researchers have found that under shock-wave action, the degree of adamantane→diamond transformation is almost 30%. The work of adhesion for frame hydrocarbons is 400–500 mJ/m2, and internal stresses are 35–45 MPa, which in the surface layer lead to a decrease in adhesive strength and the inverse Hall-Petch effect.
Keywords: surface layer, nanostructure, surface energy, atomic volume, size effect, hydrocarbon, adamantane, diamond, empirical model.
3. FIRST PRINCIPLES AND ATOMISTIC MODELING – page 342
Andre E., Tsirulev A.N.
Modeling of entangled states in qubit clusters – page 342
Abstract: The model of universal quantum computation, which uses quantum circuits consisting of one-qubit and two-qubit logic elements, is implemented in several existing quantum-computing devices. In the last decade, the idea of using multiqubit gates has become very relevant, since this, in the future, will reduce the noise level of quantum circuits. The main resource of quantum computing is the entanglement of individual qubits that form a cluster. Despite the actuality of this issue, so far only a few examples of the simplest logic elements with entanglement are considered in theory for a system of three qubits (Toffoli element and double controlled NOT). This work is devoted to mathematical modeling of the entangled states of quantum systems composed of several qubits. A mathematical method is proposed for the exact or approximate construction of Hamiltonians generating the required unitary transformations. It turns out that the approach based on the representation of Hamiltonians and unitary transformations in the Pauli basis is the most suitable in this context for two reasons: firstly, the Pauli basis forms the Lie algebra of the corresponding unitary group; secondly, there are only real coefficients in the decompositions of Hamiltonians and state density operators in this basis. The method is considered in detail on the example of a three-qubit cluster driven by a ternary Hamiltonian to obtain the Greenberger-Horn-Zeilinger entangled state. For this system, the thermal state is also studied and the corresponding density operator is obtained.
Keywords: quantum gate, quantum entangled state, unitary transformation, decomposition of Hamiltonian, Pauli basis, Greenberger-Horn-Zeilinger state.
Blinova A.A., Blinov A.V., Pirogov M.A., Ogurkov K.A., Maglakelidze D.G., Yakovenko A.A.
Computer quantum chemical modeling of the interaction of calcium phosphate with amino acids – page 352
Abstract: In this work, a quantum-chemical modeling of the process of interaction of calcium phosphate with amino acids was carried out. Within the framework of the quantum chemical modeling, the total energy of the molecular complex E, the energy difference between the amino acid molecule, and the «calcium phosphate – amino acid» system ∆E, the energy of the highest occupied molecular orbital EHOMO, the energy of the lowest free molecular orbital ELUMO, and the chemical rigidity of the system η were calculated. In this work, 8 essential proteinogenic amino acids were considered as stabilizers. As a result of the data analysis, it is found that all the presented interactions are energetically favorable: ∆E > 3370 kcal/mol, and the chemical rigidity of these interactions is in the range from 0,049 to 0,090 eV. Based on the obtained data, the most stable and energetically favorable interaction is the «calcium phosphate – Lys» system (∆E = 3395,848 ± 0,151 kcal/mol, η = 0,085 ± 0,006 eV). To confirm the data obtained, the samples were examined by IR spectroscopy. It has been established that the interaction of the amino acid lysine with the surface of a calcium phosphate particle occurs when oxygen is bound to amino groups in the lysine molecule.
Keywords: quantum chemical modeling, calcium phosphate, valine, leucine, isoleucine, methionine, threonine, lysine, phenylalanine, tryptophan, chemical rigidity, IR spectroscopy method, total energy of the molecular complex.
Vasilyev S.A., Puitov V.V., Talyzin I.V., Samsonov V.M.
Comparative molecular dynamics simulation of synthesis of silver nanoparticles from the gas phase – page 362
Abstract: A comparative molecular dynamics simulation of the gas-phase synthesis of Ag nanoparticles is carried out employing two different types of many-particle potentials of the interatomic interaction: a potential corresponding to the embedded atom method and the tight-binding potential. The initial temperature was varied from 1000 to 3000 K, and then it gradually decreased to 77 K, which corresponded to the temperature of liquid nitrogen. The results obtained using alternative force fields are consistent with each other, but, at the same time, they significantly differ both in the dynamics of evolution of the system and in theobtained final configurations of nanoparticles. Increasing the cutoff radius of the tight binding potential significantly changes the rate of the nanoparticle formation. However, an increase in the cutoff radius when using the embedded atom method does not affect the evolution of the system. The configurations obtained as a result of simulation using the embedded atom method are characterized by a smaller size and a shape close to spherical, while when using the tight binding potential, larger nanocrystals with an elongated shape are formed.
Keywords: silver nanoparticles, gas-phase synthesis, embedded atom method, tight binding potential, molecular dynamics.
Veresov S.A., Savina K.G., Veselov A.D., Serov S.V., Kolosov A.Yu., Myasnichenko V.S., Sdobnyakov N.Yu., Sokolov D.N.
To the problem of investigating the processes of structure formation in four-component nanoparticles – page 371
Abstract: Various types of configurations of the Au-Cu-Pd-Pt four-component nanosystem, including complex core-shell structures, have been studied. The Monte Carlo method was used as a simulation method, the interatomic interaction was described by the tight-binding potential, i.e. the Gupta potential. According to the results of a series of computer experiments, it was found that four-component nanoparticles of this system do not tend to form a core-shell structure, even though gold atoms have an increased surface segregation. The melting temperatures for the nanosystems under study have been determined. The obtained values are in the range from 1100 K to 1250 K and weakly depend on the composition of nanoparticles (the ratio of the number of atoms). A stoichiometric composition based on these metals was found, for which, during cooling, an FCC crystal structure with inclusions of the HCP phase is formed. However, no distinctive features in the nature of segregation for this stoichiometric composition have been established. All considered stoichiometric compositions in the studied temperature range were stable with respect to decomposition.
Keywords: Monte Carlo method, tight-binding potential, four-component nanoparticles, structure formation, melting temperature, stability.
Gafner Yu.Ya., Ryzhkova D.A.
Simulation of the synthesis process Cu-Au nanoparticles from a gas medium: general analysis – page 383
Abstract: The process of synthesis of CuAu nanoclusters from a high-temperature gas phase was simulated. The molecular dynamics method was used. 91124 Cu and Au atoms were used as the initial configuration. The atoms were arranged randomly in space, the average distance between them was 30 Bohr radii. The set of parameters was chosen in such a way as to simulate the conditions of the inert gas condensation. This system was cooled with a thermal energy removal rate of 108 K/s. Based on the data obtained, conclusions were drawn about the main stages of the evolution of the model system. It is shown that the initial stage of synthesis consists of five different stages, which gradually lead to the formation of primary spherical nanoparticles of the CuAu binary alloy. At the final stage, the eventual transformation of the formed primary nanoparticles takes place. The initial atomic atmosphere almost completely disappears and spherical binary nanoparticles are formed, a characteristic feature of which is the displacement of gold atoms to the surface.
Keywords: nanotechnology, nanopowders, computer simulation, tight-binding model, nanoparticles, copper, gold.
Gafner Yu.Ya., Ryzhkova D.A.
Analysis of the chemical composition of Cu-Au nanoparticles during simulation of the process of gas-phase synthesis – page 391
Abstract: The process of synthesis of CuAu nanoclusters from a high-temperature gas phase was simulated. The molecular dynamics method was employed, 1124 Cu and Au atoms were used as the initial configuration. The computer model of synthesis from the gas phase was based on an experimental setup located at the Budker Institute of Nuclear Physics SB RAS. On the basis of the data obtained, conclusions were made concerning the real chemical composition of clusters at the final stage of formation. It is shown that clusters larger than 400–500 atoms adhere to the given target ratio. The maximum deviations from the target ratio were recorded only for atomic vapor of stoichiometric composition. In other cases, with a reduction in the percentage of gold atoms in the initial pair, the deviations of clusters from the required composition decreased. It was determined that the reason for this was a different crystal structure of the nanoparticles obtained by modeling.
Keywords: nanotechnology, nanopowders, computer simulation, tight-binding potential, nanoparticles, copper, gold.
Gafner Yu.Ya., Ryzhkova D.A.
Influence of gold atoms on the structure of Cu-Au nanoparticles at simulation of the process of gas-phase synthesis – page 399
Abstract: The article considers the process of formation of binary Cu-Au nanoclusters with different target composition from a high-temperature gaseous medium. The molecular dynamics method was used. The main attention was paid to studying formation of the crystal structure in such clusters and determination its type. It is shown that an increase in the percentage of gold atoms in the primary gaseous medium significantly affects the formation of the internal structure of simulated nanoparticles. With a relatively small increase in the proportion of gold atoms, there is a complete disappearance of clusters with the fcc structure. The formation of nanoparticles with, as a rule, five-particle symmetry is observed. In this case, the Dh configuration prevails. If both precursors are evaporated at the same rate, then an increase in the percentage of gold atoms in the gas mixture leads to the fact that CuAu clusters are often unable to form any clearly distinguishable crystalline form, due to which approximately every fourth cluster was fixed in the amorphous state. We concluded that the cause of this phenomenon may be the separation of atoms of different types, which is typical for binary nanoparticles of the studied chemical composition.
Keywords: nanotechnologies, nanopowders, computer simulation, tight-binding model, nanoparticles, copper, gold.
Kartashynska E.S.
Temperature dependences of the molecular area of surfactant 2D monolayers at the air/water interface – page 408
Abstract: The dependences of the molecular area (Ac) at the onset of the transition from the liquid-expanded to liquid-condensed (LE-LC) phase for 2D surfactant monolayer on the temperature and chain length are considered for seven surfactant classes at the air/water interface. A thermodynamic model of the amphiphilic monolayer behavior (taking into account the nonideality of mixing entropy) is used to evaluate Ac, as well as a quantum chemical approach that allows an assessment of the thermodynamic and structural parameters of surfactant associates. The calculated Ac values adequately reflect the experimental temperature dependence for the considered phase transition: the temperature increase leads to a decrease of the area per surfactant molecule with the fixed chain length and vice versa lengthening of the surfactant carbon chain at a fixed temperature results to the Ac value increase. The average values of the slope in the Ac = f(T) dependences for the regarded surfactant classes are in the range of 0,57-1,32 Å2/°C. The estimation of the (dAc/dn)T value shows that the best agreement of the calculated and available experimental data is achieved for saturated carboxylic acids and dialkyl-substituted melamine. The obtained results demonstrate applicability of the proposed approach for predictive purposes.
Keywords: 2D monolayer, clusterization Gibbs energy, unit cell, phase transition, thermodynamic model.
Kolosov A.Yu., Mitinev E.S., Taktarov A.A., Myasnichenko V.S., Bazulev A.N., Sdobnyakov N.Yu.
Regularities of structural transformations in bimetallic Pd-Pt nanoparticles – page 419
Abstract: The processes of melting and crystallization of bimetallic Pt- and Pd-based nanoparticles have been studied by the method of molecular dynamics. The possibility of obtaining stable nanoparticles containing 3000 and 4000 atoms in the temperature range from 500 K to 1600 K is established. The concept about the possibility of fixing the temperatures of starting and ending of the phase transition for melting and crystallization is confirmed which was put forward earlier for monometallic platinum and palladium nanoparticles. The analysis shows that during the cooling of Pd-Pt nanoparticles with an initially uniform distribution of components, formation of a mixed structure with a surface monolayer of Pd atoms is observed. The possibility of structural segregation in bimetallic Pd-Pt nanoparticles containing 3000 and 4000 atoms is shown. At the same time, these two sizes correspond to different scenarios. For bimetallic nanoparticles with 3000 atoms, local zones are mainly polyhedral, and for bimetallic nanoparticles containing 4000 atoms, formation of extended band structures is observed.
Keywords: molecular dynamics method, bimetallic nanoparticles, platinum, palladium, segregation, structural transformations, stability.
Komarov P.V., Malyshev M.D.
Investigation of welding process of vitrimer-based material: meso-scale simulation – page 435
Abstract: A self-healing epoxy material is considered, based on bisphenol A diglycidyl ether and atricarboxylic fatty acid hardener, belonging to a new class of polymers called vitrimers. The res toration of the integrity of such systems in the case of a damage occurs due to the exchange reaction of covalent bonds between the comonomers forming a polymer network. In our previous work, we have developed a model of this material based on the method of reactive dissipative particle dynamics. In this work, we apply our model to study the welding process of vitrimer samples cut into two parts. The control of the integrity of the structure of the systems was carried out using a topological analysis by calculating the distributions over the lengths of simple cycles and the density of the number of load-bearing circuits. It has been shown that the rate of restoration of the integrity of the systems is determined by the concentration of the catalyst and the degree of crosslinking of the polymer. The results obtained also indicate that in the case of a high degree of crosslinking of the polymer, as well as a low catalyst concentration, the structure of the system is highly inhomogeneous.
Keywords: vitrimers, network polymers, mesoscopic modeling, dissipative particle dynamics, bond exchange reaction.
Kuznetsov Yu.A., Lapushkin M.N.
Electron-stimulated desorption of rubidium atoms adsorbed on the surface of gold-rubidium intermetallide – page 450
Abstract: The calculation of the density of states of various thicknesses of the 2D-layers of the intermetallic compound RbAu has been carried out. 2D-layers of intermetallic compound RbAu are simulated by supercells RbAu (111) 2×2×2. For a monolayer 2D-layer of an intermetallic compound RbAu the presence of a bandgap with a width of 2,70 eV has been established. An increase in the thickness of the 2D-layers of the intermetallic compound RbAu to three monolayers showed a decrease in the bandgap to 0,80 eV. A further increase in the thickness of the 2D-layers of the intermetallic compound RbAu leads to the disappearance of the band gap, which indicates a semiconductor-metal transition for the 2D-layer of the intermetallic compound RbAu with a thickness of four monolayers. The valence band of the 2D-layer of the intermetallic compound RbAu is formed mainly by Au 5delectrons, with an insignificant contribution from Au 6s and Au 6p electrons. The conduction band of RbAu is formed mainly by Au 6p electrons with an insignificant contribution of electrons Rb 5s.
Keywords: electronic structure, ab initio calculation, intermetallic compounds, rubidium auride, 2D-layer.
Kurbanova E.D., Polukhin V.A.
Strength and functional characteristics of hexa and pentagonal 2D materials. Hydrogen – page 458
Abstract: An analysis of synthesized unique two-dimensional 2D materials with nanolayer hexagonal and pentagonal structures (based on carbon, silicon, tin, binary compounds CN2, BN2, PdSe2 and ternary compounds – BCN, CNP, PdSSe, Zn2C2P2) was carried out. The synthesis of these materials was performed by the chemical vapor deposition or metal epitaxy on pre-prepared substrates. The strength and functional characteristics (electronic, optical) of the created models were also analyzed using the DFT theory in the form of triple monolayers with double-sided deposition of hydrogen on the surface of the p-Si2C4 monolayer: hydrogen/p-Si2C4/hydrogen. It was found that the p-Si2C4-4H layer with its two-sided hydrogen adsorption and good properties was the most dynamically stable. This article also presents relatively recently obtained hexa- and pentagonal two-dimensional materials not only for the elements C, Si, Ge, B, but also for Cu1–xNix, Ti1–xNix alloys and Bi1–xSbx, CN2, BN2, PdSe2, etc. compounds. So, with the new unique materials created – the synthesis of superstrong, thermostable nanocomposites, superconducting layered composites (based on Bi, Hg and Sb), prospects are opening up for the development of nanoelectronics, spintronics, computer technology, as well as the creation of portable strain gauges, pressure sensors, gas sensors and dialysis catalysts for water dialysis with the release of hydrogen and oxygen.
Keywords: hexagonal and pentagonal structures of 2D materials, material modeling, mechanical properties, catalytic properties.
Myasnichenko V.S., Sokolov D.N., Bazulev A.N., Nepsha N.I., Ershov P.M., Sdobnyakov N.Yu.
Construction of a lattice Monte Carlo model of layer-by-layer growth of bimetallic nanoparticles – page 468
Abstract: Based on the Metropolis software, a lattice statistical model of the layer-by-layer growth of bimetallic nanoparticles has been implemented. As an example, this paper analyzes two types of lattices: fcc and decahedral. On their basis, the growth of free Au-Ag nanoparticles is modeled in three modes that differ in growth stages: 3, 4, or 7 bimetallic layers are added. The interatomic interaction is set by the tight-binding potential, however, the constructed model does not exclude the possibility of using other modifications of the proven many-particle potentials. The change in the specific potential energy of entire nanoparticles and gold atoms during layer-by-layer growth is analyzed. The dependence of the number of mixed bonds on the layer number is studied for the entire nanoparticle and for the gold subsystem.
Keywords: computer experiment, Monte Carlo method, Metropolis scheme, layer-by-layer growth, bimetallic nanoparticles, mixed bonds.
Pan’kin N.A.
Molecular dynamic simulation of heating of titanium nanoclusters – page 479
Abstract: The melting of titanium nanoclusters Tin (n = 3599, 28725, 97045) with different heating rates (from 0,1 to and 10,0 TK/s) was studied by the molecular dynamics method. Molecular dynamics simulation was carried out using the LAMMPS program on a multiprocessor computer. A many-particle potential of interatomic interaction was used. The crystal structure of a titanium nanocluster upon heating passes into the liquid phase through the formation of a system of atoms (islands) with an ordered local environment near the melting point. The appearance of the latter is due to the non-equilibrium of the simulated heating process – the system does not have time to relax to an equilibrium state for a chosen temperature. The melting temperature was taken as the average value between the temperatures of the beginning and finishing of the phase transition process. The temperature of the beginning of melting corresponded to the state of completion of formation of individual islands. At the end of melting, the nanostructure is characterized by a completely disordered structure. It is noted that the melting temperature increases with the size of the nanoparticle and the rate of its heating. The limiting temperatures of the considered phase transition (at N → ∞) are significantly lower than the melting temperature of the bulk titanium.
Keywords: titanium, nanocluster, melting point, heating rate, structure, islands, molecular dynamics method.
Ryzhkova D.A., Gafner S.L., Gafner Yu.Ya., Cherepovskaya A.A.
Molecular dynamics study of the size limit of the transition of silver nanoclusters with an initial amorphous substructure into FCC phase – page 490
Abstract: Silver nanoclusters with diameter of 3,0 to 7,0 nm were studied by the molecular dynamics method using the tight binding potential TB-SMA (second moment approximation of tight-binding potential). A search was made for the stability limits of structural modifications of these nanoclusters for determination of the size limit of the thermally induced structural transition from the initial amorphous morphology to the fcc phase. The new data were compared with the results of previous studies for Ag nanoparticles up to 2,0 nm in size with initial fcc and amorphous structures. It is shown that the studied nanoclusters can be conditionally divided into three categories. The first one (N < 100 atoms) is characterized by partial preservation of the original morphology. For the second one (d < 4,0 nm), there is competition between the icosahedral and decahedral structures. And for the thirds (d > 4,0 nm), the mixed fcc/hcp phase predominates. In this case, the size limit of the transition from the initial amorphous morphology to the structure characteristic for the bulk matter is a diameter of about 7,0 nm.
Keywords: nanoclusters, silver, computer simulation, structure, tight binding, phase transitions, structural stability.
Savina K.G., Galuzin I.R., Kolosov A.Yu., Bogdanov S.S., Veselov A.D., Sdobnyakov N.Yu.
On the processes of segregation and stability of bimetallic nanoparticles Ni@Ag and Ag@Ni – page 499
Abstract: This work studied bimetallic nanoparticles Ni@Ag and Ag@Ni with the total number of atoms 4000 by the molecular dynamics method using the tight-binding potential. The pattern of segregation and structural formation is established and its characteristics are described. Based on the analysis of the behavior of the calorie curves of the potential part of the internal energy, the melting and crystallization temperature was determined. The data obtained suggest that the processes of segregation in Ni@Ag and Ag@Ni nanoparticles are associated with the nanoparticle stability. The silver shell loses its stability above 900 K, while the nickel core remains solid and retains its structure. At the same time, in Ni675@Ag3325 nanoparticles the processes of the surface segregation of the nucleus atoms were less pronounced, whereas in Ag675@Ni3325 nanoparticles silver atoms actively segregated onto the surface of the nanoparticle. The features and fundamental differences in the processes of melting and crystallization of these nanosystems, as well as the temperature ranges of their stability, are analyzed. The relationship between the degree of intensity of segregation processes of nanoalloys during modeling and the stability of these systems is shown.
Keywords: molecular dynamics method, bimetallic nanoparticles, nickel, silver, segregation, structure formation, stability, core-shell.
4. PHYSICAL AND CHEMICAL BASES OF NANOTECHNOLOGIES – page 512
Belyakova R.M., Kurbanova E.D., Polukhin V.A.
Alloying and strain hardening of high-entropy membrane storage nano and crystalline alloys – page 512
Abstract: The article presents both molecular dynamics calculations of binary Fe–Ni alloys and experimental studies of Ti and Co alloyed nanocrystalline alloys with a B2–Ti(Fe, Co) matrix structure as well as bcc-(Nb, Ti) and B2– eutectic phases Ti(Fe, Co). The structures of membrane alloys based on Fe–Ni (arrangement of atoms in coordination polyhedra and interatomic distances between atoms), as well as the kinetics of hydrogen – diffusion and permeability have been studied. It is shown that in the membranes of alloyed alloys with the substitution of Ni for cobalt Fe35-XCoXTi35Nb30, with an excess of Fe than for cobalt, mechanical brittleness is manifested in the B2–TiFe phase, and the plasticity of the B2 phase also decreases. At the same time, the resistance to an increase in hydrogen absorption is also weakened, up to mechanical destruction of membranes, so that in high-entropy alloys Fe0,2Ni0,2Cr0,2Co0,2Mn0,2, Fe0,2Co0,2Cr0,2 Ti0,2Al0,2 Fe and Co in equal parts. Other intermetallic alloys are also promising, having more complex compositions with high or moderate entropy, for example, Zr0,2Ti0,2Nb0,2V0,2Co0,2 and Zr0,2Ti0,2Ta0,2V0,2Co0,2, in addition to hydrogen evolution, also have storage properties. Within the framework of molecular dynamics, the effect of strain hardening of membrane HEA alloys is experimentally presented – the mechanism of synergy with multiple deformation. As a result of such hardening, a partial transformation of the austenitic phase into amartensite phase occurs with the formation of twinning in their fcc/hcp grains and the formation of a two-phase matrix structure.
Keywords: nanocrystalline alloys, modeling, alloying, work hardening, matrix structure, eutectic phases, high-entropy alloys, austenite, martensite, membranes, hydrogen, hydrides.
Bogdanova E.A., Skachkov V.M., Nefedova K.V.
Preparation of biocomposites based on nanoscale hydroxyapatite with titanium compounds – page 521
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 HAP with reinforcing additives of titanium compounds was obtained. The synthesized samples are certified using some modern physico-chemical methods of analysis. The influence of the qualitative and quantitative composition of the composite on the sintering processes, porosity, strength characteristics, the degree of dispersion and morphology of the studied samples is shown. It has been experimentally established that a sample based on hydroxyapatite, reinforced with non-stoichiometric titanium dioxide of the composition Ca10(PO4)6(OH)2 – 15%TiOx has the maximum strength characteristics and constant composition. The composite material, having a dense uniform structure with a high degree of crystallinity and a developed porosity, is a promising material for further research in order to introduce it into medical practice. A patent application has been filed on the developed composite material.
Keywords: hydroxyapatite, titanium oxide, titanium compounds, composite biomaterials, crystallinity, microhardness.
Bolotov A.N., Novikova O.O., Meshkov V.V.
Viscometric studies in the process of synthesis of magnetic lubricant nano-oils – page 531
Abstract: In the field of tribology, magnetic lubricating oils are promising, in which polymers are used to increase their colloidal stability, but their use is limited by the low magnetization of the colloid. It is possible to increase the magnetization of nanooils by synthesizing polymer shells directly on the surface of magnetic particles in the process of obtaining nanooils. The features of the technology for the synthesis of magnetic lubricating nanooils with polymeric solvation shells on particles, which protect them from coagulation, are described. Polymerization of hydroxy acid molecules proceeds by the mechanism of polycondensation on the solid surface of magnetite. The viscosity of the magnetic colloid increases due to the increase in the thickness of the solvate shell. Proceeding from this, a differential equation is proposed, which shows the dependence of the growth rate of the colloid viscosity on the rate of the polycondensation reaction. An experimental verification of the equation showed that it is fulfilled with an accuracy up to 8%. The resulting equation makes it possible to determine an important thermodynamic characteristic – the activation energy of the process of synthesis of polymer shells on the surface of dispersed particles. For calculations, it is necessary toknow the rate of change in the viscosity of a colloid with a dispersion medium without a monomer (hydroacid). Therefore, in the process of the polymer synthesis, samples of the intermediate magnetic colloid of a small volume are taken, which are used to determine the viscosity of the colloid and dispersion medium containing monomers. Then the viscosity of the colloid with a pure dispersion medium is found, which is necessary for calculating the activation energy of the polycondensation reaction. According to estimates, the error in determining the activation energy does not exceed 11%. In practice, using the values of the activation energy of polymerization, it is possible to carry out a purposeful choice of the optimal temperature-time regime for stabilizing the magnetic colloid in order to obtain a magnetic nanooil with the required viscosity and aggregative stability characteristics. Experimental studies were carried out on specially designed instruments for assessing the colloidal stability and dynamic viscosity of magnetic colloids.
Keywords: colloidal systems, magnetic lubricating nanooils, viscosity, colloidal stability, activation energy of polymerization.
Bolotov A.N., Novikova O.O.
The effect of the nanodisperse phase of magnetic oils on their lubricating properties – page 545
Abstract: The work is devoted to the study of processes occurring in the boundary lubricant layer, in which nanodisperse magnetic particles play a decisive or significant role. The friction between metal surfaces with lubricated oils of different concentrations of the magnetic nanodisperse phase was studied. The dispersion medium of magnetic oils consisted of liquids with various physico-chemical properties: dioctylsebacinate, triethanolamine, polyethylsiloxane. It has been shown that the wear intensity of surfaces with a hardness higher than that of nanoparticles monotonically increases with increasing the particle concentration, and wear is abrasive in nature. The wear rate of softer materials passes through a minimum at a particle concentration of about 2 vol.%. Magnetic separation of large agglomerates in oil allows for some time to reduce the abrasive wear until they are formed again under friction conditions. It was not possible to identify the regularities of the influence of nanodispersed particles on the friction force, it is probably insignificant. Several examples of the indirect effect of nanodispersed particles on the boundary friction are considered. In all the examples, the determining role plays huge area of the active surface of particles per unit volume of oil. For example, under conditions of friction, atomic hydrogen can be actively formed during the chemical interaction of fatty acids with the surface. Atomic hydrogen accumulates in the subsurface pores and is crystallized there. The increased pressure in the pores created by hydrogen molecules leads to an increase in wear by the peeling mechanism. The established regularities of the influence of nanodispersed particles on the rate of formation of the boundary lubricant layer and the corrosion wear of surfaces caused by surface-active additives in magnetic oil are of scientific interest.
Keywords: nanodisperse particles, magnetic oil, grease, friction, wear.
Vostrov N.V., Solnyshkin A.V., Morsakov I.M., Belov A.N., Krylov P.N.
Investigation of the physical properties of PVDF thin films obtained by 4D printing – page 561
Abstract: In this work, we searched for the optimal way to create ferroelectric nanostructured composite materials based on 4D-printed polyvinylidene fluoride polymer films. Method fused deposition modeling allow using polyvinylidene fluoride and its copolymers not only in microelectronics as pyroelectric and piezoelectric sensors, as well as creating dynamic memory elements, organic solar cells and used in robotics. At the first stage of the work, the authors were selected optimal extrusion parameters for the manufacture of a thread from powder and granules. The next stage of the work included the analysis and determination of printing parameters by the method of layer-by-layer filament deposition to obtain the best quality of polymer films. Using scanning electron microscopy, the existence of two phases, a polar β-phase and a nonpolar α-phase, is shown, where the crystalline phase is observed in the form of lamellar crystals chaotically oriented in the α-phase matrix. Pyroelectric measurements performed by the dynamic method showed the presence of a noticeable pyroelectric response in polyvinylidene fluoride films obtained using additive technologies, bypassing the orientation extraction stage. The calculation of the pyroelectric coefficient gives values corresponding to the values of the pyroelectric coefficient for polyvinylidene fluoride samples obtained by traditional methods.
Keywords: composite, polymer ferroelectric, additive technologies, 4D printing, 3D printing, spontaneous polarization, piezoelectric effect, pyroelectric effect, scanning electron microscope.
Guseva O.S., Malyshkina O.V., Mitchenko A.S.
Effect of modifiers on the barium niobate-calcium ceramics structure – page 572
Abstract: In this work, the ceramic samples Са0,3Ba0,7Nb2O6 pure and with modifying additives (5%) SrTiO3, KTaO3 or LiTaO3 were obtained by solid-phase synthesis. All studied compositions of ceramics revealed the presence of large and small grains. It is shown that the addition of LiTaO3 to the composition of Са0,3Ba0,7Nb2O6 ceramics reduces the grain size by an order of magnitude, while the addition of SrTiO3 leads to an elongation of the grain shape. Based on the analysis of the elemental composition, it was found that the introduction of modifiers into the composition of Са0,3Ba0,7Nb2O6 reduces the excess of oxygen in the structure of tetragonal tungsten bronze, compared to unmodified Са0,3Ba0,7Nb2O6 ceramics. The maximum on the temperature dependence of the permittivity is practically independent of the type of modifier and is located in the range of 279-285°C. This is 60 degrees higher than the Curie temperature of the Са0,3Ba0,7Nb2O6 single crystal. Regardless of the measurement temperature, Са0,3Ba0,7Nb2O6 + 5%SrTiO3 material has the maximum value of the permittivity. Whereas the minimum value of the permittivity at room temperature has the Са0,3Ba0,7Nb2O6 + 5%LiTaO3 sample, and at the Curie point, the Са0,3Ba0,7Nb2O6 sample.
Keywords: piezoelectric ceramics, barium-calcium niobate, lead-free materials, modifiers, grain structure, permittivity.
Gyrdashova O.I., Stepanov A.E., Naumov S.V., Shkerin S.N.
Effect of synthesis conditions on the formation of Y3-xLaxFe5-yO12+δ/La1-xYxFe1-yO3 composite – page 583
Abstract: Glass-like composite materials with high oxygen conductivity values were obtained by growing from a homogeneous melt by the method of non-melting zone melting. A complex architecture of the composite is observed: the main phase is highly defective in cationic and anionic sublattices Y3-xLaxFe5-yO12+δ with a garnet structure, inside which the germination of filamentous crystals La1-xYxFe1-yO3 with a perovskite structure is observed. The effect of the method of synthesis of polycrystalline precursors used as raw materials for the production of the melt on the formation of the structure of composites La1-xYxFe1-yO3/Y3-xLaxFe5-yO12+δ is investigated. The composite obtained from the precursor formed by the formate method contains ~87 mol.% of the main phase.The composite obtained from the precursor formed by the self-propagating high-temperature synthesis is ~76 mol.% of the garnet phase. The obtained composites have a certain growth direction of the main phase Y3-xLaxFe5-yO12+δ <100>.
Keywords: yttrium ferrite, garnet structures, synthesis, precursors, morphology, composites, oxygen conductivity.
Devitsky O.V.
Structure and composition of thin GaAs1-x-yNxBiy films produced by pulsed laser deposition – page 593
Abstract: Uniaxial cold pressing was used to fabricate GaAs0,9Bi0,1 targets with 10% Bi content. Thinfilms of GaAs1-x-yNxBiy onto a GaAs (100) substrate were obtained from the formed GaAs0,9Bi0,1 targetby pulsed laser deposition in an argon-nitrogen gas atmosphere, and their structure and compositionwere studied. It is shown that on the surface of the film there are predominantly small microdropletswith a diameter of less than 0,5 μm, formed by Bi atoms. Large microdroplets with a diameter of 2 to 6μm consist partly of Bi and Ga. No microdroplets formed only from Ga were found. It is noted thatsmall Ga microdroplets are adsorbed on the surface of large Bi microdroplets without forming a GaBialloy. It was also found that the formation of Bi microdroplets also occurs due to the segregation of Biatoms on the film surface. The energy-dispersive spectroscopy data make it possible to characterizethe resulting thin films as GaAs0,995N0,015Bi0,03. The mean square roughness of the film surface was 12,2nm. The resulting GaAs0,995N0,015Bi0,03 film has a polycrystalline structure. An analysis of the X-raydiffraction data showed that the film grew according to the Volmer-Weber law, when islands arenucleated and their sizes subsequently increase. The nuclei are most likely formed by GaAs, GaN,GaAsN, GaAsBi, and GaAsNBi. The calculated full width at half height for GaAs0,995N0,015Bi0,03 was –0,8656ʺ, and the average crystallite size was 1,6 nm.
Keywords: thin films, III-V-N-Bi, GaAs1-x-yNxBiy, pulsed laser deposition, diluted nitrides, diluted bismuthides.
Zajogin A.P., Trinh N.H., Malets M.A., Patapovich M.P.
Peculiar properties of methods for obtaining amorphous nanofilms for creating gas-sensitive sensors under the action of laser double pulses on the surface of a target containing tin – page 602
Abstract: A layer-by-layer analysis of metals and alloys has been carried out, and the possibility of deposition of nanofilms containing tin in their composition on various types of surfaces (metal, glass) under the action of dual laser pulses on a target in an air atmosphere has been studied. The experiments were carried out using the laser two-pulse multichannel atomic emission spectrometer LSS-1. The advantages of the pulsed laser deposition as a method for producing clusters and fractals are: versatility in relation to the material, the ability to exclude impurities, the flexibility of the method, and the ability of controlling the formation of film structures. The performed spectroscopic studies of the laser plasma formed by the action of two successive pulses on a target illustrate the development of methods for obtaining nanoclusters of various chemical elements. This method can be used to obtain nanofilms of not only pure metals, but also composite alloys. The possibility of obtaining nanofilms for creating gas-sensitive sensors is shown.
Keywords: double laser pulses, laser plasma, layer-by-layer analysis, deposition of thin films, nanopowder technologies, multichannel atomic emission spectrometry.
Ivanov Yu.F., Klopotov A.A., Lopatin I.V., Ivanova O.V., Petrikova T.L., Petukevich M.S., Nikonenko E.L.
Phase formation in high-chromium steel under electron-ion-plasma treatment – page 609
Abstract: The surface alloying was carried out by single-cycle and multi-cycle (5 cycles «sputtering-irradiation», in each cycle the thickness of the titanium film 0,5 µm), i.e. high-speed melting of the system «film (Ti)/(steel AISI 310S) substrate» by pulsed electron beam. Nitriding (793 K; for 1, 3 and 5 hours) was carried out under conditions of realization of the elion (electron and ion) treatment mode. The isothermal cross sections of the ternary systems of the state diagram of the Cr – Fe – Ni – Ti – N alloy formed at different stages of the complex treatment of steel are considered. It is shown that (1) irradiation of steel by a pulsed electron beam is accompanied by the formation of a structure of high-speed cellular crystallization of solid solution based on γ–Fe; (2) nitriding of steel in the initial state is accompanied by formation of nitrides of iron Fe4N and chrome CrN with a total content of 79,8 wt.%; (3) pulsed electron-beam pre-irradiation of steel leads to a decrease in the rate of nitride formation during subsequent nitriding; the total nitride content of 53 wt.%; (4) regardless of the number of alloying cycles (titanium concentration in the surface layer) after five hours of nitriding in the samples formed a surface layer of nitrides of chromium and iron (1 cycle of doping) or nitrides of chromium and titanium (5 cycles of doping).
Keywords: complex electron-ion-plasma treatment, electron plasma component heating of samples, high-chromium steel, surface alloying, phase composition.
Kapustinа G.G., Leonenko N.A.
Mechanisms of laser impact on ultra-fine mineral medium – page 621
Abstract: The development of modern technologies for the complex extraction of valuable components from refractory ores and technogenic deposits is possible on the basis of the latest achievements of fundamental sciences, a combination of physicochemical, enrichment and metallurgical processes. The paper describes the results on the impact of laser radiation on mineral samples with ultrafine «non-recoverable» gold from silt ponds-settlers of alluvial deposits in the Far East. The object of research is the impact of a source of continuous laser radiation on samples of minerals, objects of alluvial deposits containing submetric and nanosized forms of gold that are not recoverable by traditional gravity methods. The purpose of this work was to study the processes of interaction of laser radiation with dispersed mineral media containing ultrafine gold and to determine the conditions for agglomeration of ultrafine gold. Electron microscopic images of the samples were obtained using a LEO EVO 40HV microscope (Carl Zeiss, Germany) equipped with an INCA-ENERGY energy-dispersive analyzer. A model is proposed that describes the processes at the boundary of heterogeneous phases. An analysis of the discovered effect of gold agglomeration made it possible to formulate technical solutions that were reflected in patents for inventions. The discovered effect of gold agglomeration made it possible to find technical solutions in the form of patents for inventions.
Keywords: laser-induced, ultrafine, colloid-ion, gold, gold-bearing mineral products, structural ordering, scanning electron microscopy.
Klychkov N.A., Simakov V.V., Sinev I.V., Shikunov D.A.
The effect of copper and zinc oxide additives on the electrical and gas-sensitive properties of tin dioxide composite layers – page 632
Abstract: Composite thin films based CuO:SnO2 and ZnO:SnO2 with different impurity concentrations was synthesized by sol-gel method by mixing sols. The films were annealed in oxygen-containing atmosphere at 550°C. A contact system was formed on top of the films by thermal evaporation of chromium, followed by deposition through a mask onto the sample. Based on the temperature dependence of conductivity for layers based on pure tin dioxide, a local maximum of conductivity is observed in the range of 250°C, which is probably due to the thermal activation process of oxygen desorption. Conductivity of SnO2 layers was decreased as the concentration of Cu dopant. 2% Cu additive reduces the long-term conductivity drift by an order of magnitude. Arguably it’s the consequence of occurrence the low mobility complexes created by copper atoms and oxygen vacancies. The best sensitivity to ethanol vapors in all concentration range was shown by 6%Zn doped samples. Accordingly, supplementations of Cu and Zn boost sensitivity of SnO2 layers to ethanol and decrease response time by its impact at 150-300°C range.
Keywords: sol-gel method, composite gas-sensitive layers, tin dioxide, conduction drift, gas sensor’s response time.
Korolkov O.E., Pakhomov M.A., Polyakov A.V., Valiev R.Z., Stolyarov V.V.
Effect of grain size and duty ratio on the mechanical behavior of titanium under tension with pulsed current – page 639
Abstract: The influence of a high-density pulsed current on the deformation behavior of titanium with different structure refinement is studied. A comparison of the features of the deformation curves has been carried out of coarse-grained and nanostructured commercial pure Ti Grade 4 under tension with the introduction of a pulsed current. A current of various duty ratio and densities was supplied from a pulse generator to a sample in the grips of a tensile testing machine. The microstructure of a coarse-grained titanium in the sample head and near the fracture region in the longitudinal section was studied by optical microscopy. To study the microstructure of nanostructured titanium foils, the transmission electron microscopy was used. The electroplastic effect in the studied materials manifested itself in the tensile curve in the form of separate downward stress jumps. Under the same regimes of high-duty ratio pulsed current, the amplitude of stress jumps in the coarse-grained titanium is higher than in the nanostructured titanium. For a low duty ratio current the stress jumps are the same in the plastic region. A high duty ratio pulsed current in nanostructured titanium led to an anomalous hardening effect, the physical nature of which needs a further investigation. The used modes of the pulsed current did not lead to structural changes noticeable under optical magnification of the tensile samples, except for the disappearance of twins and the separation of impurity particles in the coarse-grained titanium. The fractographic fracture patterns of nanostructured titanium tested with and without current indicate ductile fracture without significant changes, which testified a minimal thermal contribution during the experiments.
Keywords: tension, titanium, nanostructure, electroplastic effect, pulsed current, fractography.
Kravchenko D.A., Medvedeva O.N.
Studies of the structure and properties of dental crowns made by selective laser melting and according to the technology of casting – page 652
Abstract: In recent times, 3D printing technologies are a young and actively developing production sector for many areas of economy, from aerospace and mechanical engineering to medicine. The obvious advantage of introduction of the additive technologies in medicine and in particular in dentistry is high accuracy in producing complex details, individually designed implants and prostheses for their maximum match with a place of injury or a substituted object, considerable reduction both the product materials and auxiliary materials usage. However, questions arise about the limits of applicability and reliability of the additive technologies with their active introduction. The properties of dental crowns made of nickel-chromium alloy NH-Dent NS vac and cobalt-chromium powder PR-KH28M6 were studied in this research. For the production of samples was used selective laser melting technology, which belongs to a number of additive technologies, and the casting technology in the mold. A comparative analysis of the microstructure of the samples, the surface profile and the Vickers hardness was carried out.
Keywords: additive technologies, medicine, dentistry, selective laser melting technology, selective laser melting, microstructure, surface profile, hardness of samples.
Masloboeva S.M.
Analysis of investigations of the lithium niobate charge LiNbO3:Mg synthesized on the basis of Nb2O5:Mg precursors of different genesis – page 662
Abstract: An analysis was made of studies on the preparation of a charge of lithium niobate used for growing crystals LiNbO3:Mg by the Czochralski method. The charge was synthesized on the basis of precursors Nb2O5:Mg of different genesis. The results of studies of the mixture by X-ray phase analysis, atomic emission spectrographic analysis, gas chromatography-mass spectrometry, mass spectrometry with inductively coupled plasma and laser ablation are presented. It has been established that in the studied systems, a uniform distribution of magnesium impurities in the charge is observed, which leads to the production of crystals of high optical quality with impurity distribution coefficients above unity. It has been shown that the presence of organic inclusions makes it possible to introduce more magnesium into the growing crystal. The results are of great importance in the technology of growing single crystals of lithium niobate when choosing a method for the synthesis of a charge in order to use the crystals obtained from it in specific areas of technology.
Keywords: niobium pentoxide, genesis, doping with magnesium, synthesis of lithium niobate charge, impurity distribution, single crystal, optical quality.
Nagaplezheva R.R., Orakova M.M., Kushkhova M.Yu., Tseeva F.M., Mishaev H.A.
Influence of vacuum-plasma treatment modes on the surface photo-EMF of single-crystal silicon – page 671
Abstract: Plasma technologies in the last quarter of the twentieth century made a real scientific and technological revolution in microelectronics. Having come to the world of microelectronics technology as a necessary alternative to liquid etching, which had exhausted its resource by that time, plasma or «dry» technologies became the main tool for creating elements of electronic products. The 21st century, undoubtedly, began and proceeds under the sign of the improvement of such technologies in solid-state electronics. Plasma technologies include a set of methods for depositing thin and ultrathin layers on a semiconductor substrate, as well as a set of methods for dimensional etching of such layers with specified etching parameters. If we consider the methods of size etching using dry technologies, it should always be taken into account that the whole range of such methods is wide. Some methods, such as radical and plasma-chemical etching, imply a mild, purely chemical interaction of the plasma medium with the substrate material, resulting in the formation of a volatile etch product and its removal (pumping) from the plasma volume. Another group of «dry» methods includes methods of purely physical impact of high-energy plasma particles on the surface of the material and the removal of atoms from the surface only as a result of sputtering of the material. The surface photo-EMF method was used to study the real surface of single-crystal p-type silicon in the temperature range T = 289-473 K before and after plasma treatment. A significant difference was found in the surface electronic states spectra obtained by heating and cooling the samples. Heating leads to desorption of gases and dissociation of water molecules in the surface layer, which reduces the surface potential by an order of magnitude.
Keywords: plasma, photo-EMF, plasma surface treatment, silicon, surface electronic states.
Nalimova S.S., Shomakhov Z.V., Gerasimova K.V., Punegova K.N., Guketlov A.M., Kalmykov R.M.
Gas-sensitive composite nanostructures based on zinc oxide for detecting organic solvent vapors – page 678
Abstract: The paper shows the possibilities of using ZnO-Fe composite structures as gas-sensitive layers for detecting organic solvent vapors exemplifying on isopropyl alcohol. Composite structures were formed based on zinc oxide nanorods synthesized by the hydrothermal method, due to changes in their composition in a ferrous sulfate solution. The chemical composition of the surface was studied using X-ray photoelectron spectroscopy. It is shown that when using a ferrous sulfate solution with a concentration of 0,025 mol/l, iron and zinc atoms are observed on the surface. An increase in the concentration of the solution to 0,05 mol/l leads to the deposition of iron oxide particles on the surface of the nanorods. The study of some gas-sensitive characteristics was carried out at 250°C when exposed to isopropyl alcohol vapors in the concentration range from 200 to 1000 ppm. It was found that the response value of composite structures ZnO-Fe (0,025) exceeds the corresponding value for the zinc oxide nanorods, that may be due to the high content of oxygen vacancies in the composite sample.
Keywords: zinc oxide, gas sensors, composite nanostructures, X-ray photoelectron spectroscopy, organic solvent.
Nikolaychuk P.A.
Electrodeposition of silver nanoparticles for the development of electrochemical sensors: a short review – page 688
Abstract: In the present review the studies performed in the last two decades devoted to the electrodeposition of silver nanoparticles on the surface of carbon electrodes and their implementation in analytical chemistry are described. Usually graphite or glassy carbon electrodes (including screen-printed electrodes) are used, and the electrodeposition is performed from the solutions of potassium nitrate and silver nitrate during a few minutes. Silver nanoparticles or modified nanocomposites including silver nanoparticles are then immobilized on the surface of the electrodes, and obtained electrochemical sensors are capable to determine various compounds using different voltammetric methods with excellent selectivity and very good linearity range and precision. The described methods of analysis allow the determination of microgram quantities of hydrogen peroxide, glucose, cholesterol, methyl parathion, Pb2+ ions, chloramphenicol and metronidazole, doxorubicin, entacapone, tyrosine and tryptophan, lamotrigine, chromium (VI), antimony (III), trinitrotoluene, oligonucleotides and the bacterium Pseudomonas aeruginosa.
Keywords: silver nanoparticles, glassy carbon electrode, graphite electrode, electrodeposition, electroanalysis, voltammetry.
Skachkov V.M.
Features of dynamics change of properties of diffusion-hardening solder at various conditions – page 699
Abstract: A study was conducted of the change in the hardness of diffusion-hardening solder based on a low-melting gallium alloy: gallium-tin-zinc when interacting with the Spherical copper-tin alloy powder (SCTAP5) under normal conditions (temperature 25°C) and subjected to low-temperature (125°C) heat treatment. Mechanical properties are estimated by measuring microhardness at various time intervals. A differential thermal analysis was carried out, with calculations of thermal effects. The phases formed as a result of diffusion hardening were determined by X-ray phase analysis, and the parameters of the crystal lattices of the phases were compared under different conditions of diffusion hardening. It is shown that at different processing temperatures, different phases are formed – nanoscale intermetallic compounds, and with the help of a scanning electron microscope, the phase of tin released as a result of physicochemical transformations is found. It has been experimentally proved that diffusion-hardening solder without heat treatment gains hardness slowly, and after 60 days the hardness approaches to that of the sample subjected to heating, which also continues to gain hardness very slowly. Thus, it is shown that diffusion-hardening solders after six hours of low-temperature treatment have not yet reached physico-chemical equilibrium.
Keywords: composite diffusion-hardening solders, exothermic effects, properties, microhardness, differential thermal analysis, X-ray phase analysis.
Skachkov V.M., Pasechnik L.A., Medyankina I.S., Sabirzyanov N.A.
Properties of diffusion-hardening composite solder modified with tungsten powders – page 707
Abstract: The article considers the regulation of the properties of diffusion-hardening solder based on a low-melting gallium-tin-zinc alloy and copper-tin alloy powder by introducing inert tungsten metal powders. After heat treatment at low temperatures (125°C), the microhardness of composite diffusion-hardening solders with a tungsten content of 5, 10, 15 and 20% is estimated. It is shown that the heat treatment at low temperatures for 6 hours does not lead the solder to reach an equilibrium state, physico-chemical transformations are still ongoing, which shows an increase in the hardness of the samples after two months. The X–ray phase analysis has been used to determine the phases formed as a result of the diffusion hardening: micro- and nanoscale intermetallic compounds and metallic tin in the form of nanoscale inclusions in the space between the grains of copper alloy powder. Due to small additions of tungsten as a filler, inert to the effects of gallium, but well wetted by it, the characteristics of diffusion-hardening solder are improved. Judging by the microhardness, the introduction of 15% tungsten is optimal.
Keywords: composite diffusion-hardening solders, metal powder, properties, tungsten, microhardness, differential thermal analysis.
Sokolova E.M., Boiko A.S., Fokina M.I., Ponomareva A.A.
Development of tetraethoxysilane-based polymer absorbing coating with an adding of the cobalt oxide for a laser surgery – page 717
Abstract: The use of generated jets as «micro incisors» finds its application in laser surgery. Such methods of laser exposure are used to remove neoplasms, such as intervertebral hernias and cysts. An optical fiber is attached to the laser, which is inserted into the hernia or cyst through a puncture needle. To increase the efficiency of laser exposure, it is necessary to accumulate energy at the end of the waveguide by forming an absorbing coating, which should have high adhesion to quartz. In this work, a study was carried out on the development of a technique for polymer films by the sol-gel method for use in laser surgery as an absorbing coating. Tetraethoxysilane was chosen as a precursor for the formation of a polysilicate mesh holding small cobalt oxide particles. Optical, morphological, and absorbing properties of coatings obtained onto quartz glasses were studied in this work. Additionally, the solutions and the obtained coatings were studied using IR spectroscopy, the results of which showed the absence of a qualitative change in the sols during long-term storage (up to 3 weeks) and the formation of a three-dimensional silicate network and cobalt oxide in the films. The study of the surface morphology of the obtained coatings showed that high concentrations of cobalt salts are not required for the uniform distribution of the synthesized cobalt oxide. The absorbing properties of the samples were tested using an IR laser and a thermal imager. Owing to the research the optimal composition of the coating for the deposition on quartz waveguides was chosen.
Keywords: tetraethoxysilane, cobalt oxide, quartz, sol-gel technology, IR spectroscopy, laser radiation, absorbing coating.
Shomakhov Z.V., Nalimova S.S., Shurdumov B.Z., Maximov A.I., Moshnikov V.A.
Zinc stannate nanostructures for fast response gas sensors – page 726
Abstract: The possibilities of using zinc stannate nanostructures as sensitive elements of fast response gas sensors are considered, which are of great interest for use in a variety of applications from the detection of toxic substances to air quality monitoring or medical diagnostics. The synthesis of zinc stannate nanostructures was carried out by hydrothermal treatment of zinc stannate nanorods in a solution of potassium stannate and urea at different concentrations of precursors. The chemical composition of the sample surface was analyzed by X-ray photoelectron spectroscopy. It is shown that as a result of hydrothermal treatment, Sn4+ ions appear on the surface of zinc oxide nanorods. The study of gas-sensitive characteristics was carried out under the influence of isopropyl alcohol vapors at temperatures of 156°C and 310°C. It is shown that the maximum response at 310°C to 1000 ppm of isopropyl alcohol is 8,24. At the same time, the zinc stannate samples have a fast response of 23 s.
Keywords: .
Yurov V.M., Ibragimova D.A., Portnov V.S., Mausymbayeva A.D.
Nanostructures of rare-earth metals in the coals of the shubarkol deposit – page 736
Abstract: The rare metals of the Shubarkol coal deposit have a surface layer thickness of about 3 nm, i.e. are nanostructures. The thickness of the surface layer of the coal itself is of about 0,2 µm, i.e. it is a mesostructure. The pore radius in the coal substance is 30,6 nm, which corresponds to mesopores, and the specific surface area of coal is 857 m2/g. Rare metals, either in the form of pure impurities (~ 3 nm), or in the form of oxides (~ 7 nm), or in the form of organic impurities (~ 1-3 nm), freely enter into mesopores of the coal. The forms of occurrence of uranium and rare metals in the coals of the Shubarkol deposit indicate that their concentration in the coal is due to the leading role of the hydrogenous mechanism. In the d(I) layer, all rare metals are nanoluminophores, which can be considered as sensitive molecular probes for studying the structure of coal. It is emphasized that the influence of size effects on kinetics of the luminescence decay and anomalous thermalization of rare earths can be easily obtained experimentally. The fractal dimension of Shubarkol coal is 2,60, which is lower than that of anthracite – 2,74. In the mesoporous structure of Shubarkol coal, the adsorption of rare metal impurities is highly developed due to the formation of adsorption layers on the surface of these mesopores, which lead to volumetric filling of these pores by mechanism of the capillary condensation.
Keywords: surface layer, rare metal, nanostructure, mesostructure, atomic volume, size effect, carbon matter, fractal.
5. NANOCHEMISTRY – page 747
Bibanaeva S.A.
Synthesis of aluminosilicate zeolites in the conditions of alumina production – page 747
Abstract: The work is devoted to study of the possibility of obtaining synthetic sodium and calcium aluminosilicates from recycled solutions of alumina production by the hydro-alkaline method. The chemical qualitative and quantitative composition and morphology of zeolites obtained under conditions of high-temperature autoclave leaching have been studied. X-ray phase studies aimed at determining the composition and structure of the obtained aluminosilicate zeolites were carried out. The prospects of the method of the autoclave synthesis of synthetic zeolites with a high yield of the final product with the particle size up to 5 microns are shown. It has been established that the method allows the production of zeolites in parallel with the technological scheme of bauxite processing at an alumina plant, while minimally weighing down the production process. The resulting aluminosilicate zeolite has a wide range of applications in various industries. According to the results of the research, 2 applications for invention patents were filed.
Keywords: circulating solution, zeolite, calcium aluminosilicate, processing, calcium oxide, alumina production.
Blinov A.V., Slyadneva K.S., Gvozdenko A.A., Golik A.B., Taravanov M.A., Nazaretova E.D.
The effect of the mixing rate of the reaction mixture on the dispersed characteristics of the nanoemulsion of fat-soluble vitamin E (alpha-tocopherol acetate) – page 754
Abstract: The article presents the results of a study of the effect of the mixing rate on the dispersed characteristics of nanoemulsions of the fat-soluble vitamin E (alpha-tocopherol acetate). The mixing speed was varied in the range of 3000-22500 rpm. The average hydrodynamic radius of the micelles of fat-soluble vitamin E was considered as an output parameter, which was determined by the method of the dynamic light scattering. It was found that as a result of synthesis, micelles of the fat-soluble vitamin E emulsions are formed, having a monomodal size distribution. The smallest average hydrodynamic radius of the particles was 22 nm. It was found that an increase in the mixing speed from 3000 to 22500 rpm causes a decrease in the average hydrodynamic radius of micelles. The greatest changes are observed at τ = 30 s: a decrease in the average hydrodynamic radius of micelles Rm occurs by 3,3 times (from 210 to 63 nm). It is important to note that an increase in other synthesis parameters also leads to a decrease in the value of the average hydrodynamic radius of micelles of the vitamin E nanoemulsions. By v = 22500 rpm an increase in the mixing time τ from 30 s to 270 s leads to a decrease in Rm by 19 nm (from 63 to 44 nm).
Keywords: fat-soluble vitamin E, nanoemulsion, hydrodynamic radius, mixing speed.
Blinova A.A., Yasnaya M.A., Maglakelidze D.G., Taravanov M.A., Lapin V.A., Leontiev P.S.
Study of the structure and properties of zinc silicate stabilized with L-histidine – page 763
Abstract: This paper presents the results of a study of the process of stabilization of zinc silicate nanoparticles using the amino acid L-histidine. Zinc acetate was used as a precursor, sodium silicate was used as a precipitant, and the amino acid L -histidine acted as a stabilizer. Synthesis was carried out by chemical precipitation in an aqueous medium. A simultaneous thermal analysis was carried out, as a result of which it was found that the addition of an amino acid to nanosized zinc silicate has a great influence on the crystal structure and thermal transitions for this material. Next, the X-ray phase analysis was carried out, which showed that of zinc silicate particles have an amorphous structure and are in a nanoscale state. At the next stage of the work, the process of interaction of an amino acid with a zinc silicate particle was studied by IR spectroscopy. The results of the study showed that stabilization of particles is accompanied by the formation of a chemical bond between silicon in the zinc silicate molecule and the amino group in the L -histidine molecule.
Keywords: nanosized zinc silicate, amino acids, L-histidine, zinc acetate, sodium silicate, phase composition, simultaneous thermal analysis, derivatogram, IR spectroscopy, powder diffractometry.
Bogdanova E.A., Skachkov V.M., Nefedova K.V.
Development of composite mixtures based on hydroxyapatite and biogenic elements for the formation of bioactive coatings – page 771
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 the 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, biogenic elements, gelatin, collagen, bioactive coatings, adhesion.
Krut’ko V.K., Doroshenko A.E., Musskaya O.N., Kulak A.I.
Obtaining octacalium phosphate in aqueous medium during the interaction of calcite with monocalcium phosphate monohydrate – page 782
Abstract: Calcium phosphate composite powders consisting of brushite and calcite were obtained in an aqueous medium from a CaCO3/Ca(H2PO4)2 suspension at Ca/P ratios of 1,33, 1,50, 1,67, pH 5–7, and maturation time of 21-50 days. Prolonged maturation (up to 68 days) of composite calcium phosphate powders led to a hydrolytic transition of brushite to octacalcium phosphate, the amount of which increased with increasing duration of the maturation stage. Drying calcium phosphate powders at 37°C for 24 h contributed to the partially transition of the metastable phase of octacalcium phosphate to apatite represented by amorphous calcium phosphate. The presence of vibrations of О–Н at 633 cm-1 as the shoulder on the IR spectra indicates the presence of apatite in calcium phosphate powders. The use of an electric current (20 mA/cm2, 3–20 min) for a local increase of the pH value made it possible to increase the amount of octacalcium phosphate in the composition of the composite powder, which has a characteristic rosette morphology of thin lamellar crystallites.
Keywords: octacalcium phosphate, calcite, monocalcium phosphate monohydrate, brushite, apatite, hydrolytic maturation.
Krut’ko V.K., Maslova L.Yu., Musskaya O.N., Kulak A.I.
Composites based on calcium phosphate foam ceramic and hydroxyapatite gel – page 791
Abstract: Bioactive calcium phosphate composites were obtained, consisting of open-pore multiphase calcium phosphate foam ceramic based on α / β-tricalcium phosphate, β-calcium pyrophosphate, biomimetic apatite and 5% hydroxyapatite gel at a mass ratio (ceramic foam / hydroxyapatite gel) of 1:3 and 1:10. Preliminary modification of the calcium phosphate foam ceramic with biomimetic apatite in a concentrated SBF×5 solution allows increasing the static strength to 0,05 MPa with a slight decrease in porosity and maintaining the open-pore structure of polyurethane foam. Calcium phosphate composites have increased resorbability in SBF×5 and are resorbed 3–5 times faster compared to calcium phosphate foam ceramic. The presence of a significant amount of hydroxyapatite gel increases the rate of resorption of calcium phosphate foam ceramic and the ongoing processes of apatite formation with the participation of SBF×5 ions due to its high reactivity. The obtained calcium phosphate composites are used in regenerative treatments to fill bone defects in unloaded areas.
Keywords: calcium phosphate foam ceramic, tricalcium phosphate, hydroxyapatite gel, simulated body fluid, biomimetic apatite, resorbability.
Medyankina I.S., Svetlakova K.I., Pasechnik L.A.
Formation of cobalt hydroxosilicate in amorphous silica matrix – page 800
Abstract: The synthesis of cobalt hydroxysilicate Co3(Si2O5)2(OH)2 in a matrix of high dispersity amorphous silica has been proposed. It is shown the formation of a hydroxosilicate, which combines coordinated silica and cobalt-oxygen polyhedrons in the overall structure, as well as the availability of surface hydroxyl groups, contribute to the preservation of a high specific surface area as is in amorphous SiO2. The hydroxosilicate also contributes to the effective manifestation of photocatalytic properties due to the presence of cobalt (2+), which has a high reactivity. As methods of synthesis of SiO2/Сo composites hydrochemical methods are used by impregnation and autoclave treatment with solution of cobalt formate of silica. The influence of the amount of introduced cobalt on the composition, structure, and properties of a composite material containing Co3(Si2O5)2(OH)2 in a SiO2 matrix has been traced. SiO2/Co composites have been tested in the hydroquinone photooxidation reaction when exposed to ultraviolet radiation. The highest degree of hydroquinone decomposition amounting to 84% in 18 hours was achieved for SiO2/Co at a molar ratio of components Co:Si = 0.01:1.
Keywords: amorphous silica, cobalt silicate, hydrothermal synthesis, mechanosynthesis, microstructure, photocatalysis, hydroquinone.
Musskaya O.N., Krut’ko V.K., Kulak A.I., Krutsko E.N.
Modification of fiber cellulose materials with amorphized calcium phosphates and copper nanoparticles – page 811
Abstract: Etherification of the surface of cellulose carriers with phosphoric acid in the presence of urea yielded fiber materials characterized by an increased degree of swelling in aqueous media (by a factor of 1,1-1,5). The copper nanoparticles and their composites with amorphized calcium phosphates were synthesized by the borohydride method using the sodium salt of carboxymethyl cellulose as a stabilizer polymer. The obtained colloidal solutions of copper and their composites with hydroxyapatite are characterized by stability from several days to 2 months. It was found that the modification of cellulose materials (initial and phosphorylated) by the immersion method using aqueous compositions containing amorphized calcium phosphates, copper nanoparticles or composites based on them in the presence of sodium carboxymethylcellulose and ascorbic acid at pH 6 and 11 leads to a decrease in the crystallinity of the polymer carrier. It has been shown by IR spectroscopy that the amorphization of modified fiber cellulose materials is due to a change in the static homogeneity of the system of hydrogen bonds in the polymer structure.
Keywords: cellulose, phosphorylated cellulose, sodium carboxymethylcellulose, amorphized calcium phosphates, hydroxyapatite, copper nanoparticles.
Ostroushko A.A., Zhulanova (Maksimchuk) T.Yu., Kudyukov E.V., Gagarin I.D., Russkikh O.V.
Lanthanum manganite nanopowders synthesis via combustion reactions under the influence of electromagnetic field – page 820
Abstract: Lanthanum manganite doped with strontium samples were synthesized by the combustion method of nitrate-organic precursors of different composition. The combustion process was realized under the influence of an external alternating electromagnetic field and in its absence. It was found that thermochemical generation of charges occurs during precursor’s combustion, recorded as a potential difference of precursor-earth. It is shown that the composition of the initial precursor (organic component and its quantity), as well as the presence of an external alternating electromagnetic field, affect the magnitude of the potential difference that occurs, varying from -7 to 125 V. The relationship between the studied electromagnetic properties (saturation magnetization, coercive force, Curie temperature) of the obtained samples and the precursor–earth potential difference arising during synthesis is shown. The Curie temperature values varied in the range of 38-79°C for samples obtained under the influence of an alternating electro-magnetic field, and 49-104°C in its absence.
Keywords: Complex oxides, lanthanum manganite, synthesis, combustion reactions, charges, electromagnetic field, magnetic properties.
Ostroushko A.A., Menshikov S.Yu., Rozhentsev D.A., Tkachev N.K., Golub A.Ya., Tonkushina M.O.
Nanostructured catalysts of the turpentine emulsion polymerization under the influence of potassium persulphate – page 829
Abstract: We have revealed the catalytic activity for initiating the water-emulsion turpentine polymerization of some nanostructured materials such as Keplerate type Mo72Fe30 nanocluster polyoxometalate, nanoporous iron and nanoporous composite of intermetallic compounds Pd2In@Pd3In obtained by dealloying of equiatomic alloys Fe – Mn and Pd – In. For polyoxometalate solutions and nanoporous metal samples, respectively, the yield of sufficiently pure polyterpene resins when using the potassium persulphate initiation depends on the nature of the contact between the catalysts and substrates: solid-liquid-liquid or liquid-liquid. A system that did not contain catalysts was taken as the reaction medium for comparison. Based on the obtained data on the softening point, the molecular weight of the resin samples was determined. Infrared spectroscopy was used to identify the obtained products. In the reaction medium (mainly aqueous) after the isolation of polyterpene resins, chromatographic analysis revealed so valuable products as alpha-terpineol, which is used as an intermediate for obtaining flavors and flotation agents.
Keywords: Nanostructured initiation catalysts, polyoxometalates, metals, emulsion polymerization, turpentine, polyterpene resins, potassium persulfate.
Permiakov N.V., Lebedeva A.I., Maraeva E.V.
Obtainanig and study of the material based on hydroxyapatite and polycaprolactone for extrusion three- dimensional printing – page 838
Abstract: The work is devoted to the search for a scientific and technical solution for the creation of filaments based on hydroxyapatite and polycaprolactone for extrusion three-dimensional printing. Hydroxyapatite powders were obtained by chemical precipitation using microwave radiation, and the average particle size in the powder was determined. Options for creating a filament by extrusion based on a composition of hydroxyapatite and polycaproloctone for subsequent printing of scaffolds (temporary scaffolds necessary for the formation of new functional tissues) are proposed. Images of the surface of calcium hydroxyapatite were obtained using a scanning probe microscope to assess the parameters of surface roughness, which is one of the most important factors for successful cell adhesion to the scaffold surface during osseointegration processes.
Keywords: hydroxyapatite, polycaprolactone, 3D printing, nanocomposite, scaffold, scanning probe microscopy.