Editor’s column

M.Sh. Sattorov¹, Y.M. Spivak¹, Y.M. Kotcur², A. Kuznetsov³, E.V. Flisyuk², V.A. Moshnikov^1
1 St. Petersburg Electrotechnical University «LETI»
² St. Petersburg State Chemical and Pharmaceutical University
³ Moscow Institute of Physics and Technology (National Research University)

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

K.I. Sabanin¹, V.M. Skachkov², I.S. Medyankina², E.A. Bogdanova^2,3, N.A. Sabirzyanov^2
1 Ural Federal University named after the first President of Russia B.N. Yeltsin
² Institute of Solid State Chemistry of the Ural Branch of RAS
³ JSC Giredme

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

D.S. Ryashentsev, M.E. Belenkov, L.Y. Kovalenko
Chelyabinsk State University

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

Yu.V. Rekh¹, S.A. Bibanaeva², M.S. Valova¹, V.M. Skachkov², O.V. Fedorova¹, N.A. Sabirzyanov^2
1 I.Ya. Postovsky Institute of Organic Synthesis of the Ural Branch of RAS
² Institute of Solid State Chemistry of the Ural Branch of RAS

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

A.A. Nagdalian, P.S. Leontiev, A.B. Golik, A.S. Askerova, A.M. Serov, A.V. Tatov
North Caucasus Federal University

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

O.N. Musskaya, V.K. Krut’ko, I.E. Glazov, E.N. Krutsko, A.I. Kulak
Institute of General and Inorganic Chemistry of the NAS of Belarus

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

S.Yu. Menshikov¹, A.N. Malyshev^1,2, V.S. Kurmacheva¹, S.A. Fedorov^3,1, M.O. Tonkushina², A.A. Ostroushko^2
1 Ural State Mining University
² Ural Federal University
³ Institute of Metallurgy of Ural Branch of RAS

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

N.A. Shostak
Kuban State Technological University

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

Z.V. Shomakhov¹, S.S. Nalimova², O.D. Zyryanova², V.M. Kondratev^3,4, Z.Kh. Kalazhokov¹, C.D. Bui², V.A. Moshnikov^2
1 Kabardino-Balkarian State University named after H.M. Berbekov
² Saint Petersburg Electrotechnical University «LETI»
³ Moscow Institute of Physics and Technology
⁴ Alferov University

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