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Introduction. Nanomaterials based on binary and multicomponent oxides are of interest for the development of catalysts, photocatalysts, gas sensors, solar cells, as well as in other fields. The most effective methods to produce oxide systems of various compositions are those of chemical co-deposition, as well as two-stage approaches.Aim. To develop sensor nanomaterials based on ZnO, Zn–Fe–O, and Zn–Sn–O ternary oxide nanosystems, as well as to develop methods for assessing their properties.Materials and methods. ZnO and ZnFe2O4 nanopowders were synthesized by chemical coprecipitation, and ZnFe2O4 and Zn2SnO4 nanostructures were produced by modifying ZnO nanowires. The surface chemical composition and microstructure were studied using scanning electron microscopy, backscattered electron diffraction, and Xray photoelectron spectroscopy. The sensor responses of the samples to vapors of organic solvents were analyzed.Results. The response value of zinc oxide and zinc ferrite samples synthesized by chemical coprecipitation was found to be 2–4 orders of magnitude higher than that of modified zinc oxide nanowires. The formation of ternary oxide nanostructures led to an increase in the sensor response of zinc oxide nanowires. This effect can be explained by the formation of adsorption sites of various types during formation of such systems. The samples produced by chemical coprecipitation showed an extremely high sensor response. This may be due to the formation of fractal structures at the percolation threshold.Conclusion. ZnO and ZnFe2O4 oxide nanostructures produced by chemical coprecipitation exhibit a high sensor response to acetone and ethanol vapors. Methods for the formation of multicomponent oxide systems with improved sensor properties compared to the original zinc oxide nanowires were developed. The resultant sensor nanomaterials are promising for use as sensitive layers of gas sensors for detecting organic solvent vapors.

Currently, the search for new types of carriers for low-molecular weight substances, as well as the development of optimal methods for the eff ective encapsulation of these substances are important tasks of modern chemistry and pharmacology. However, there are still limitations in this area, among which one of the most signifi cant is the lack of the optimal carrier capable of stably retaining a low-molecular weight substance. The work presents hybrid polymer structures obtained by in situ hydrothermal synthesis as an eff ective candidate for these purposes. The fl uorescent dye rhodamine B has been used as a model low-molecular weight substance for encapsulation into the structures. The resulting hybrid polymer structures demonstrated good stability when stored in an aqueous environment for 336 h with the release of the low-molecular weight dye rhodamine B no more than 2%. In addition, the infl uence of the conditions for obtaining hybrid carriers (including the composition of the carriers (thickness of the polymer shell and the presence of a calcium carbonate core) and synthesis temperature) on their physical-chemical characteristics has been studied. Thus, the optimal approach for obtaining fl uorescent hybrid polymer carriers with a set of desired properties has been revealed. In particular, it has been shown that the optimal production conditions are hydrothermal synthesis temperature of 180 °C and the absence of CaCO3 core inside the polyelectrolyte shell which allow us to obtain a stable hybrid polymer carrier with bright fl uorescence. The results presented in this study can be used to create functional platforms and systems with tunable fl uorescent properties and the ability to deliver low-molecular weight substances.

Objectives. To examine the general principles and recent advances in the synthesis of high-purity and high-homogeneity barium titanate powders in the manufacture of electronic components.Results. The main publications regarding the synthesis of barium titanate powder, including the works of recent years, were analyzed. The technological advantages and disadvantages of various synthesis methods were identified. Groups of methods based on solid-state interaction of reagents and methods of “wet chemistry” were also considered. The possibilities of producing barium titanate particles of non-isometric shapes for creating textured ceramics were discussed separately.Conclusions. Barium titanate is a well-known ferroelectric with a high dielectric constant and low dielectric loss. It is used as a component in ceramic electronic products, for example, capacitors, memory devices, optoelectronic devices, and piezoelectric transducers. The possibilities of producing functional ceramics based on barium titanate powder largely depend on its state and morphological characteristics, determined during the synthesis stage. The most important factors affecting the functional characteristics of ceramics are the purity and morphology of the powder raw materials used.

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.

Background. To decompose water, electrocatalysts based on expensive Pt, Ir are used. However, there is an alternative - catalysts from compounds of d-elements: Fe, Co, Ni, Cu. Purpose. Study of structural morphology features of Ni-Co-P bimetallic phosphide.. Methodology. The synthesis of Ni-Co-P was carried out by a one-stage hydrothermal method, in air. The structure of the sample was studied by electron microscopy (SEM), energy-dispersive spectroscopy, and X-ray diffractometry. Originality. It was revealed that the synthesized Ni-Co-P has a pronounced crystal structure of the compounds Ni2P4O12 (59%), NiP2O7 (37%) and NiCoP (4%). Findings. The synthesis of Ni-Co-P was carried out. The phase composition, morphology of the surface and crystal structure, the nature of the distribution of elements over the volume of Ni-Co-P bimetallic phosphide were studied by physicochemical methods of analysis. [ABSTRACT FROM AUTHOR]

This paper presents the results of facile fabrication of a non-enzymatic glucose sensor by forming a sensing element based on TiO2 nanofilaments using direct ink writing (DIW). The glucose concentration in the solution was determined by changing the resistance of the TiO2 layer. Nanowires (NW) were obtained by hydrothermal synthesis in 10 M sodium alkali solution followed by heat treatment. The surface morphology of obtained samples was studied using scanning electron microscopy. The formation of a sensitive layer was carried out on a 3D printer with a specially designed print head from a suspension based on an aqueous solution of polyvinyl alcohol (PVA) followed by heat treatment in air. The suspension was analyzed for viscosity and contact angle. The sensitive layers were formed on a silicon substrate with a SiO2 surface oxide layer and gold contacts. Layers of TiO2 NW were formed between the contacts. The sensitivity of the sensor to glucose solutions of various concentrations was studied. As a result of the studies, the studied structures showed sensitivity to a glucose solution in the range from 1 to 100 mmol.

The fluorescent properties of products obtained by the hydrothermal treatment of organic raw materials are of great interest. Such products are usually colloidal stability in water, have low cytotoxicity, and high photostability. One of their advantages is a wide choice of starting materials and the relative simplicity of synthesis. The use of folic acid as a precursor for fluorescent nanostructures opens up the possibility of targeted imaging. This article shows a one-step synthesis of fluorescent nanostructures from folic acid and citrates. The effect of citrate concentration in the range from 0.05 to 2 mol/l on the optical properties of the synthesized structures is also studied.

Zinc stannate nanostructures were synthesized by hydrothermal method, and zinc oxide nanorods were used as starting materials. Formation of multicomponent oxides was studied by using the X-ray photoelectron spectroscopy. It was found that tin ions are gradually embedded in the crystal lattice of zinc oxide nanorods and replaced zinc ions during hydrothermal synthesis with the formation of zinc stannate nanostructures. The study of the synthesis time effect on the surface chemical composition of the prepared samples has shown formation of zinc stannate after hour, that is confirmed by changes in the binding energies of zinc and oxygen. With a longer synthesis, zinc stannate nanostructures collapsed, thus zinc and tin oxides are practically not observed on the sample surface.

A composite material based on zinc oxide nanoparticles synthesized by the chemical hydrothermal method and a polymer insulated matrix of sodium silicate was obtained. Free zinc oxide nanoparticles were formed by heating an equimolar solution of zinc nitrate and hexamethylenetetramine with different pH values (3–5). Nanoparticles were introduced into an aqueous sodium silicate solution and applied on a silicon substrate by centrifugation. Using scanning electron microscopy, we studied the structure and morphology of zinc oxide nanoparticles on a silicon substrate in unbound state and after their introduction into the sodium silicate matrix. It was found that the obtained particles have a hexagonal crystal lattice and a bimodal size distribution. After introduction in the matrix of sodium silicate, only smaller zinc oxide nanoparticles with an average diameter of 45 nm remain in it. Studying of the photoluminesclence spectra of a composite material, including zinc oxide nanoparticles obtained at different pH values of the initial solution, showed the presence of exciton and defectrelated photoluminescence bands with intensity’s maximums located at 383 and 590 nm, respectively. Zinc oxide nanoparticles in the stabilizing matrix of sodium silicate exhibit a higher relative intensity of exciton photoluminescence than unbound particles. The highest value of the relative intensity of exciton photoluminescence was achieved for a composite material including zinc oxide nanoparticles synthesized at pH=3,35 of the initial solution. The resulting composite materials can be used in optoelectronic and photovoltaic devices, and as an optical medium of non-cavity lasers.

The main aim of the study: The actuality of the discussed issue is caused by the lack of systematic studies of structural phase transformations of zirconium tungstate at temperature increase. The methods used in the study:High temperature in situ X-ray analysis, refinement of the structure by the Rietveld method using TOPAS v.4.2 (Bruker) software, thermogravimetric differential scanning calorimetry. The results: The morphology of the material was represented as rod-shaped particles having a block structure. The ZrW2O8 synthesized was kinetically stable from 25 to 540 °C. Temperature increase has initiated structural change which resulted decomposition of ZrW2O8 into ZrO2 and WO3. The ZrW2O8 synthesized demonstrated a negative thermal expansion behavior from 25 to 750 °C.

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Copyright of Metallophysics & Advanced Technologies / Metallofizika i Novejsie Tehnologii is the property of G.V. Kurdyumov Institute for Metal Physics, N.A.S.U and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ti-MCM-41 silicate with vanadium introduced in mesoporous structure has been obtained by hydrothermal template synthesis with participation of VOSO4 and pyrogenic titanoaerosil with 1.4 wt. % tetrahedrally coordinated titanium. By the X-ray diffraction, X-ray fluorescent spectroscopy, DR UV-vis analysis and adsorption of nitrogen it has been shown that even 0.3 wt. % V causes raising spatial order and hydrolytic stability of Ti-MCM-41. It has been found that additional supporting of VOx groups on a surface of the synthesized bimetallic silicate allowed to obtain the catalyst 5 %VOx/V, Ti-MCM-41 which due to dehydrogenation of propane generated propylene with bigger selectivity and yield than those when VOx was supported on MCM-41 and Ti-MCM-41. [ABSTRACT FROM AUTHOR]