Physical and chemical aspects of the study of clusters, nanostructures and nanomaterials. Founded at 2009

Editor’s column

Influence of the structural factor on the tribological characteristics of titanium alloy obtained by selective electron beam melting

L.E. Afanasieva, V.V. Izmailov, M.V. Novoselova
Tver State Technical University

Abstract: The article is devoted to an experimental study of the influence of microstructure features of the Ti – 6Al – 4V alloy obtained by electron beam melting technology on the tribological properties: hardness; friction coefficient; abrasive wear resistance. The microstructure of the alloy consists of colonies α′-plates 1.5…2 μm thick and interlayers of the β-phase 0.2 μm in size. Hardness was measured at low loads N = 1-2 N (microhardness) and at loads N = 90–180 N (indentation hardness). The friction coefficient was determined on a microtribometer according to the ball-plane scheme in a pair with a steel indenter at loads of 2-5 mN. Wear resistance was studied by friction against a fixed abrasive according to the ball-plane scheme. The microstructure and properties of the samples were studied in two mutually perpendicular planes: in the layer and in the direction of synthesis. Anisotropy of microhardness and friction coefficient under low loads was revealed. In the layer plane, the microhardness under loads of several newtons is 900…1000 MPa lower than on the lateral surface of the sample. Under low contact loads, the friction coefficient in the contact of a spherical steel sample with a flat layer surface is approximately 20% lower than in the contact of the same steel sample with the lateral surface of a titanium alloy sample. With increasing contact load, the difference in properties disappears. Abrasive wear resistance in the direction of sample synthesis is 30% higher than in the layer plane, which is explained by the role of the structural factor. It is shown that the orientation of the colonies of α′-plates has a decisive effect on the tribological properties.
Keywords: titanium alloy, selective electron beam melting, microstructure, hardness, friction coefficient, wear resistance

Adsorption deformation of Na-montmorillonite during interaction with methanol vapours

A.V. Tvardovskiy
Tver State Technical University

Abstract: Classical ideas about the adsorption process have always been based on the fact that the adsorbent remains inert and does not change its size when interacting with gases or vapors. Its role is limited to creating an adsorption field where the adsorbate molecules fall. It is on the basis of this principle that the well-known adsorption equations of Henry, Langmuir, Fowler-Guggenheim, Brunauer-Emmett-Teller and others were derived. However, modern experimental studies show that adsorbents are deformed in the adsorption process. This fact significantly changes the entire picture of the consideration of this phenomenon. For example, when the geometric dimensions of the pores of the adsorbent change during deformation of the latter, the adsorption field into which the adsorbate molecules fall changes significantly. And this affects the value of the calorimetric heat of adsorption removed during the studies. Thus, the adsorbent is an equal participant in the adsorption process along with the adsorptive, and the adsorption system should be considered as a two-component one. In this regard, when conducting adsorption studies, a comprehensive approach is needed, including taking isotherms, measuring calorimetric heats of adsorption, and conducting dilatometric experiments to study the adsorption deformation of adsorbents. Such a comprehensive approach was used for the Na-montmorillonite – methanol vapor system. The differential heat and adsorption isotherm at T = 293 K were obtained using a Calvet-type microcalorimeter and a McBain-Bakr microbalance. The adsorbent deformations were measured using a highly sensitive dilatometer. The main part of this dilatometer was a linear differential transformer, the core of which was connected to the adsorbent by means of a rod. Any changes in the geometric dimensions of the adsorbent changed the position of the core in the transformer, which affected the signal taken from the secondary winding of the transformer. Having calibrated the dilatometer, the adsorption deformation of the adsorbent was determined. Such a comprehensive approach allowed us to significantly detail the description of the adsorption process for this studied system.
Keywords: adsorption, adsorbent, adsorption isotherm, calorimetric heat of adsorption, adsorption deformation of the adsorbent, dilatometric method

Issue no. 16 (2024) is available on website

Sixteen issue of journal “Physical and chemical aspects of the study of clusters, nanostructures and nanomaterials” is available on our website! Open list of articles of issue.

Spectroscopy of porous silicon nanoparticles impregnated with a drug maloben substance

M.Sh. Sattorov1, Y.M. Spivak1, Y.M. Kotcur2, A. Kuznetsov3, E.V. Flisyuk2, V.A. Moshnikov1
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

Investigation of the effect of titanium and zirconium oxides on the strength characteristics of nanoscale hydroxyapatite

K.I. Sabanin1, V.M. Skachkov2, I.S. Medyankina2, E.A. Bogdanova2,3, N.A. Sabirzyanov2
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

Structural varieties of 2D boron nitride

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-L4-8 and BN-L4-6-8. 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

Sorption of La3+ cations by zeolites from aqueous solutions

Yu.V. Rekh1, S.A. Bibanaeva2, M.S. Valova1, V.M. Skachkov2, O.V. Fedorova1, N.A. Sabirzyanov2
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

Investigation of the process of polymer stabilization of mixed iron oxide with amylopectin

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

Liquid-phase synthesis of magnesium phosphates in the presence of gallic acid

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

The effect of FeSO4, nanoscale silver and { Mo72Fe30} cluster on the oxidation of ethylene glycol by H2O2

S.Yu. Menshikov1, A.N. Malyshev1,2, V.S. Kurmacheva1, S.A. Fedorov3,1, M.O. Tonkushina2, A.A. Ostroushko2
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