Editor’s column

A.M. Pshukov, A.A. Kokoevа, Yu..F. Yakuba, A.Z. Kashezhev
Kabardino-Balkarian State University named after H.M. Berbekov

Abstract: The work presents a synthesis method, structural and optical characteristics as well as a comparative analysis of properties of colloidal quantum dots based on halide perovskites doped with Nd³⁺ ions with 20% substitution of lead ions. Nanocrystals with a controlled content of a rare-earth element were synthesized by a hot injection method, which ensured the production of stable colloidal structures with a specified level of doping. The structural analysis using an auto-emission scanning electron microscope confirmed the polycrystalline nature of the nanoparticles with the grain size of ~30 to 200 nm. The elemental composition corresponds to the initial materials, which indicates the controllability of the doping process. The quantum yield of photoluminescence was 40%, which is a high value for Nd-doped perovskite systems. The emission spectrum with a maximum at 458 nm shows a pronounced blue shift due to the effect of Nd³⁺ on the band gap. Diluted dispersions are recommended to obtain reliable spectral data. The obtained results confirm the effectiveness of the proposed approach and open up prospects for the application of doped perovskite nanocrystals in optoelectronics, photonics, and scintillation technologies.
Keywords: perovskite quantum dots, neodymium, neodymium doping, synthesis, light output, elemental composition, nanocrystal morphology, optical properties, quantum yield, liquid organic scintillator

A.P. Prudchenko¹, Y.A. Moroz¹, N.S. Lozinsky¹, O.Yu. Poliakova¹, J.S. Protasevich¹, V.A. Glazunova^2,1, G.K. Volkova^2,1, V.V. Burkhovetsky^2,1
1 L.M. Litvinenko Institute of Physical Organic and Coal Chemistry
² Galkin Donetsk Institute for Physics and Engineering

Abstract: This paper presents the results of an assessment of the possibility of obtaining hybrid carbon-mineral nanomaterials by the method of catalytic chemical deposition of carbon from the gas phase using complexes of polyoxotungstometalates with 3d-metals of the general formula (NH₄)_X[PW₁₁O₃₉Me(L)]×nH₂O, where Ме – Fe, Co, Ni, Cu; L – H₂O, C₆H₁₂N₄ (hexamethylenetetramine), as components of metal oxide catalysts for the growth of carbon nanotubes, which are a source of reduced metal particles active in the catalytic process. The synthesis products were studied by transmission electron microscopy and X-ray phase analysis. It has been established that even at a very low molar metal-carrier ratio (0,03÷1), a catalytic process is realized with the formation of carbon nanotubes. It is shown that, regardless of the qualitative composition of the catalyst, there is also an accumulation of the product of the non–catalytic flow, nanocarbon, which forms a hybrid supramolecular carbon-carbon complex in the form of lateral deposits of graphene-like carbon on the outer surface of carbon nanotubes. According to X-ray phase analysis of isolated and purified synthesis products using structurally different polyoxotungstometalates, X-ray diffractograms show reflexes at the same angular positions, which makes it possible to assume the formation of two types of hybrid carbon-mineral nanomaterials: carbon nanotubes-nanocarbon-tungsten oxides and nanocarbon-tungsten oxides.
Keywords: carbon nanotubes, metal oxide catalysts, polyoxotungstometalates, hybrid carbon-mineral nanomaterials

V.A. Polukhin, S.Kh. Estemirova
Vatolin Institute of metallurgy of the Ural Branch of the RAS

Abstract: Current studies of metal-graphene (G) nanocomposites (such as Al/G, Ni/G, Ti/G) demonstrate their outstanding mechanical properties when combining an amorphous metal matrix with dispersed graphene. Analysis of the literature data allows us to identify two key factors responsible for the increased strength and thermal stability of such materials: (i) the formation of hybridized metal-carbon bonds at the phase interface and (ii) special deformation mechanisms, including the activity of shear transformation zones and dislocation locking at the interfaces. For amorphous alloys, the free volume plays a decisive role, promoting local restructuring and the formation of strengthening nano phases. Comparative analysis of molecular dynamics modeling data and experimental results shows their good consistency, which confirms the effectiveness of graphene as a reinforcing phase. The obtained results allow us to consider metal-graphene nanocomposites as a promising direction in the development of new materials with improved mechanical and thermal characteristics, including providing exploitation in extreme conditions.
Keywords: graphene, metal composites, amorphous alloys, molecular dynamics modeling, deformation mechanisms, reinforcement, bond hybridization, interface interactions, mechanical properties

A.A. Ostroushko, A.E. Permyakova
Ural Federal University named after the first President of Russia B.N. Yeltsin

Abstract: It is evident from the extant results of experimental studies that the possibility of the manifestation of the template effect in the formation of anisometric micro- and nanoscale formations in oxide and composite systems has been analysed. In the synthesis of micro- and nanoscale oxide (complex-oxide) materials, compositions based on them, such as metal-oxide, in the combustion reactions of glycine-nitrate precursors, the template effect is observed, which promotes the formation of anisometric (extended) particles and their ensembles. In addition to the established facts documented in the extant literature, the occurrence of the aforementioned morphology (i.e. the synthesis of hydroxides and oxides of lanthanum, neodymium, praseodymium, holmium, samarium, yttrium, gadolinium, erbium and europium) has been observed in systems involving the synthesis of magnetic particles (e.g. strontium hexaferrite) and in other non-magnetic materials. In the process of synthesising magnetic complex oxides, this effect is instrumental in the production of high coercivity materials. The aforementioned effect is also applicable to samples of bactericidal composition of aluminium oxide with silver nanoparticles obtained in combustion reactions. The formation of anisotropic formations may be attributed to the presence of glycine, whose amphoteric molecules, in their zwitterion form, possess the capacity to establish ordered spatial structures that function as templates for the synthesis of target phases in combustion reactions.
Keywords: oxide materials, compositions, synthesis with salt forms, morphology, organic components, glycine

S.S. Nalimova¹, Z.V. Shomakhov^2
1 Saint Petersburg Electrotechnical University «LETI»
² Kabardino-Balkarian State University named after H.M. Berbekov

Abstract: The increased absorption of light by metal oxide materials modified with plasmonic nanoparticles in the visible range makes them excellent candidates for use in photocatalysts and light activated gas sensors. The photocatalytic properties of these nanocomposite materials are studied. The main results of research on the decomposition of various organic dyes using these catalysts are analyzed. The effect of metallic nanoparticles on photocatalytic properties is explained by the formation of a Schottky barrier, as well as the effect of localized surface plasmon resonance (LPPR). The Schottky barrier at the metal-oxide interface efficiently separates and transfers charge carriers through an internal electric field, leading to an increase in photodegradation efficiency. This is achieved by separating electron-hole pairs and reducing the rate of charge carrier recombination. Due to the LPPR, the absorption of light increases, which leads to an increase in the generation of active charge carriers. Various authors have studied the response of composite structures composed of metal oxides and plasmonic nanoparticles to oxidizing and reducing gases under different experimental conditions, and their results have been summarized. The main reason for this increased response is an increase in the concentration of adsorbed oxygen ions due to transfer of photogenerated in plasmonic nanoparticles electrons. Mechanisms of the influence of the surface plasmon resonance effect on the properties of chemical gas sensors and photocatalysts involves the formation of a Schottky barrier when a noble metal contacts a semiconductor, the direct transfer of electrons, a local amplification of the electric field, and the transfer of the plasmon resonance energy.
Keywords: nanoparticles, metal oxide, photocatalysts, gas sensors, localized surface plasmon resonance

E.G. Korzh, V.E. Burlakova
Don State Technical University

Abstract: In the work, nanodiamonds were obtained by the method of hydrodynamic cavitation by LLC ICC «Sintez». The synthesized nanodiamonds were studied using atomic force microscopy and it was found that their particles have a shape close to spherical, and the particle size along the Z axis does not exceed 10 nm. The particles agglomerate and form larger structures up to 100 nm in size. The synthesized nanodiamonds in the form of colloidal solutions with a concentration of 0,5%, 1%, 3%, 5% and 7% were used in a galvanizing electrolyte to obtain composite zinc-nanodiamond coatings. The resulting coatings were studied using X-ray phase analysis and scanning electron microscopy. The presence of a carbon phase in the composition of the composite zinc coating corresponding to a diamond-like structure was proven. It was found that the morphological features of the zinc-nanodiamond coating surface differ significantly from the morphology of the zinc coating surface, which is expressed in the absence of a large number of depressions and irregularities. The corrosion activity of zinc-nanodiamond coatings was tested in a 3% sodium chloride (NaCl) solution. It was determined that composite zinc-nanodiamond coatings have increased corrosion resistance compared to zinc coatings, while the corrosion rate is reduced by 42%.
Keywords: nanodiamonds, zinc coating, composite coating, zinc-nanodiamond coating, corrosion

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

Abstract: Ionic forms of V⁺⁵ are promising modifying agents for hydroxyapatite, endowing the biomaterial with increased solubility and antibacterial activity. Formation of vanadate-substituted hydroxyapatites was studied under conditions of precipitation from VO₃^–, HPO₄^2–-containing solution with pH 10 and maturation for 4 days. It was shown that V⁺⁵ in apatitic structure represents V₂O₇^4– and VO₄^3– ions, for which the characteristic bands in the Raman spectra are located at 920-917 cm^–1, 897-882, 873-862 and 390-367 cm^–1, respectively. Incorporation of VO₄^3–-ions in the apatitic structure occurred in the entire studied range of [V]/[P] ratios from 1/8 to 1/1 due to its isomorphism with apatitic PO₄^3--ions. Under precipitation conditions at [V]/[P]≥1/4, the apatitic structure accommodates V₂O₇^4–-ions, which prevail in the reaction medium with pH 10. Presence of V₂O₇^4–-ions provides deviation of the apatitic Ca/(V+P) ratio from stoichiometric value of 1,67 to 1,50 and contributes to a lowering of the size of apatitic crystallites formed from 14 nm to 6 nm. Heating at 800°C of vanadate-substituted hydroxyapatites with Ca/(V+P)<1,67 is accompanied by the removal of V₂O₇^4–-ions from the apatitic structure with formation of hydroxyapatite and tricalcium phosphate vanadate.
Keywords: vanadate-substituted hydroxyapatite, vanadate ions, divanadate ions, amorphized apatite, Raman spectroscopy

A.A. Gaidash¹, A.I. Kulak¹, V.K. Krut’ko¹, O.N. Musskaya¹, K.V. Skrotskaya², E.N. Krutsko^1
1 Institute of General and Inorganic Chemistry of the NAS of Belarus
² Research Institute for Physical Chemical Problems of the Belarusian State University

Abstract: In hydrolysates of tendon sheaths obtained by acetate extraction of paravertebral tendons of laboratory rats, the stages of disintegration and reparative regeneration of fibrillar collagen were established. It was shown that collagen material is destroyed by a mechanism of the spinodal disintegration. In this case, the main anatomical fractions (tendon, sesamoid islets) exhibit different sensitivity to the action of an acidic agent – sesamoid islets are the most resistant, which may be due to the presence of proteoglycans resistant to acetate stress in the extrafibrillar matrix. The mechanisms of fibrillar collagen assembly correspond to the principle of its hierarchical organization. At the mesodimensional level, the predominant mechanisms of the self-assembly are «side-to-side» and «tip-to-tip» fusion, and the final forms are uni- and bipolar microfibrils. At the nanoscale level, the structural mechanism of fibrillar collagen growth is the twisting of microfibril spirals predominantly to the left as they mature. At the nanoscale level, fibril development occurs via the mechanism of intercalary growth with the formation of branched supramolecular formations.
Keywords: fibrillar collagen, acetate hydrolysis, assembly by side-to-side and tip-to-tip mechanisms, «tip-to-tip», intercalation