Žurnal neorganičeskoj himii

The results of the 15th Young Scientists' Conference on General and Inorganic Chemistry, dedicated to the 165th anniversary of the birth of Nikolay Semenovich Kurnakov, are summarized. The main stages of the 15-year development of this conference are outlined. The presentations by young scientists, recognized by leading academic journals and the Scientific Council on Inorganic Chemistry of the Russian Academy of Sciences, are discussed. These presentations were delivered within the conference's scientific sections in the field of inorganic materials science, inorganic and coordination chemistry, chemical technology.

The effect of differences in the surface roughness (160 and 45 nm) of polycrystalline α-Al₂O₃ wafers on the composition, structure, and properties of titanium oxide coatings formed on it during chemical assembly by atomic layer deposition by alternating treatment of the substrate with titanium tetrachloride and water vapor a set number of times (up to 600) has been studied. Based on the results of X-ray fluorescence analysis and scanning electron microscopy, it was found that the titanium concentration is higher in samples with a higher initial surface roughness. According to diffuse reflection electron spectroscopy data, the coordination state of titanium in oxide coatings corresponds to aluminotitanate, tetrahedral, and anatase-like structures, the ratio between which depends on both the thickness of the coating and the surface roughness of the substrate. Using atomic force microscopy, it has been shown that an increase in the roughness of the substrate leads to the formation of layers consisting of larger particles. At the same time, as the thickness of the coating increases, its roughness increases and the gas sensitivity to oxygen in the sensors based on it increases.

A comparative analysis of the surface processes of atomic layer deposition (ALD) of AlMo_xO_y using H₂O, molybdenum (VI) oxydichloride (MoO₂Cl₂), trimethylaluminium (Al(CH₃)₃, TMA) or aluminum chloride (AlCl₃) was carried out. The difference between AlMo_xO_y's ALD processes was the use of TMA or AlCl₃ as an aluminum precursor. XPS analysis of the deposited films revealed that the molybdenum content was lower than the aluminum content. Molybdenum in the oxidation state of Mo⁺⁶ and reduced forms of molybdenum (Mo⁺⁵ and Mo⁺⁴) were also found in the films; the ratio of the atomic concentration of Mo+6 to Mo⁺⁵ and Mo+4 in the case of the TMA process was 0.76 : 1, and in the case of AlCl₃ — 6.3 : 1. The replacement of TMA with AlCl₃ in the AlMo_xO_y ALD process has significantly reduced the amount of reduced Mo in films. To evaluate the thermodynamic parameters of film growth reactions, molybdenum reduction, and MoO_x to AlO_x conversion for ALD using AlCl₃ and TMA, quantum chemical calculations using the DFT method were performed. According to the calculated data, AlMo_xO_y ALD using TMA is more thermodynamically advantageous in comparison with AlCl3 due to the greater reactivity of TMA.

Powders Mg₃(PO₄)₂·22H₂O, MgHPO₄·3H₂O, NaMg₄(PO₄)₃·xH₂O, NH₄MgPO₄·6H₂O from different salts, magnesium oxide and phosphoric acid were synthesized by precipitation from solutions at 25°C. Depending on the precursors, products of different compositions were obtained at a specified pH = 9, they were characterized using X-ray diffraction, electron microscopy, and static light scattering. The selection of the sintering mode for the printed sample was carried out using TG and DTA to determine the temperature intervals at which the organic component of the printing suspension was removed. The fundamental possibility of obtaining porous ceramics by 3D printing from magnesium orthophosphate obtained by the solution method with an average size of agglomerates of 28.3 μm and Kelvin structure has been shown. This opens up prospects for the use of magnesium phosphate-based ceramics, in particular magnesium orthophosphate, in regenerative medicine.

New hybrid materials based on Ag, Cu, AgCu nanoparticles and their conjugates with quercetin were obtained using an environmentally friendly method of metal-vapor synthesis (MVS). The composition and electronic state of the nanocomposites were studied by XPS, PXRD and SEM/EDX. It was found that modification of metals with flavonoid leads to stabilization of smaller particles in the conjugate compared to metal powders. PXRD analysis showed that the average crystallite size of metals upon introduction of quercetin decreases from 4.1 to 3.6 nm for Ag and from 8.7 to 4.8 nm for Cu. According to XPS data for bimetals and their conjugates, silver is in the ground state Ag⁰, and the states of Ag⁺ and acetate silver are present in small amounts. Copper is in the states of Cu⁰, Cu⁺, Cu²⁺. Bimetallic nanoparticles are a solid solution with a disordered structure and Ag–Cu, Ag–O–Cu and Ag–O–Cu–O– bonds.

The reaction of bis(dioxane) and bis(tetrahydropyran) derivatives of iron(II) bis(dicarbollide) [8,8'-{О(СН₂СН₂)₂X}₂-3,3'-Fe(1,2-C₂B₉H₁₀)₂] (X = О, СН₂) with pyridine in an inert atmosphere has been studied. It was found that the ring-opening of oxonium cycles proceeds stepwise, with the formation of the corresponding mono- and dipyridinium iron(II) complexes. Using the bis(dioxane) dipyridinium derivative as an example, it was found that, when in solution, oxidation of the resulting products to the corresponding paramagnetic complexes of iron(III) is possible. This approach opens the way to obtain bifunctional iron bis(dicarbolide) derivatives with different substituents. The obtained compounds were characterized by multinuclear NMR and IR spectroscopy, as well as high-resolution mass spectrometry. The structure of the symmetrical dipyridinium iron(II) complex [8,8'-{С₅H₅NCH₂CH₂OCH₂CH₂O}2-3,3'-Fe(1,2-C₂B₉H₁₀)₂] was determined by single crystal X-ray diffraction.

A combined quantum chemical and molecular dynamics study of atomic layer etching of amorphous zinc oxide by β-diketones: acetylacetone, 1,1,1-trifluoroacetylacetone, and 1,1,1,5,5,5-hexafluoroacetylacetone was carried out using the ORCA 6.0.1 and LAMMPS software packages. Within the framework of density functional theory at the PBE-D3BJ/def2-SVP level, the energetic parameters of adsorption and desorption were investigated, and the induced surface stress was quantitatively evaluated. It was found that acetylacetone induces the highest surface stress (1.62 eV) and enables spontaneous etching due to its low desorption energy (2.10 eV). The fluorinated derivatives exhibit a self-limiting interaction behavior: 1,1,1-trifluoroacetylacetone, with a desorption energy of 3.27 eV, induces a surface stress of 1.05 eV, while 1,1,1,5,5,5-hexafluoroacetylacetone causes the weakest effect on the surface structure (1.01 eV) with a desorption energy of 2.53 eV. The obtained results suggest that 1,1,1-trifluoroacetylacetone can be considered the most suitable precursor for controlled atomic layer etching of zinc oxide.

New collagen-chitosan materials modified by (containing) Ag nanoparticles promising for creating wound coatings are based on a porous hybrid material obtained from collagen and chitosan in powder and gel forms. The paper presents an original process concept of the hybrid biomaterials formation. Powders of collagen and chitosan polymers previously modified with Ag nanoparticles obtained by metal-vapor synthesis were used for synthesis of the materials. Metal containing powder systems with Ag particles were used as precursors for gels preparation after lyophilization of which porous hybrid materials were obtained. Nanocomposites were studied using XPS, PXRD and SEM/EDX methods. A homogeneous distribution of Ag nanoparticles over the collagen-chitosan composite volume was recorded and the composition and electronic states of the metal in the material were studied.

Liquid-phase hydrogenation of styrene at atmospheric pressure in an aqueous medium was studied on a series of supported nickel catalysts Ni/SiO₂ with different nickel content (from 6 to 28 wt. %). The effect of textural characteristics of the catalysts and controlled deactivation with sulfide ions on the catalytic activity was studied. It was shown that with decreasing nickel content, dispersion increases, but the area of the active surface of the reduced metal decreases. Partial deactivation was simulated by introducing a controlled amount of Na₂S, which made it possible to quantitatively estimate the density and activity of different types of catalytic centers. It was found that for complete deactivation of one Ni atom on the surface, an average of 0.6 to 1.2 S^2– anions are required, depending on the morphology of the catalyst. An analysis of the catalyst stability to the catalytic poison was performed based on the TOF and TON_дезакт parameters. The obtained results expand the understanding of deactivation mechanisms and can be used in the development of new generation catalysts resistant to the action of sulfur-containing impurities in hydrogenation reactions.

The research on the development of heat storage materials based on Zn(NO₃)₂ · 6H₂O with a phase transition in 25–40°C. It was established that the most stable composition is the one containing Zn(NO₃)₂ · 6H₂O/Co(NO₃)₂ · 6H₂O/expanded graphite/CMC. Its crystallization heat is determined taking into account the contribution of heat capacity in the supercooled region before and after 500 cycles of thermal cycling. Its value is 146.0 ± 7.3 and 140.6 ± 7.01/g and is comparable with the corresponding heats of fusion of 147.4 ± 4.4 and 130.6 ± 3.91/g. The composition of Zn(NO₃)₂ · 6H₂O/Co(NO₃)₂ · 6H₂O/expanded graphite/CMC was investigated in a pilot sample of an electric underfloor heating system. It was found that the energy consumption for heating the heating film with material was reduced by 67% compared to the heating film without material.

Thin films of zinc oxide were obtained by the AACVD method. The variable parameter was the synthesis temperature, which was from 350 to 500°C with a step of 25 degrees. The analysis revealed that ZnO particles have a wurtzite structure with an average crystallite size of 26 ± 4 nm. As a result of the analysis of the morphology of the obtained films, it was shown that in the temperature range from 400–450°C, continuous films with an average particle size of 52 ± 14 nm are formed, and at synthesis temperatures of 350–375°C; 475–500°C, films with a discontinuous island-like morphology with an average size of 51 ± 13 nm are formed. The optical properties of the obtained films were studied, and the estimated values of the band gap were 3.31–3.34 eV. A temperature-dependent mechanism of film formation was proposed. The chemosensory properties were studied at an operating temperature of 150–350°C using a wide range of analyte gases: CO, NH₃, H₂, CH₄, C₆H₆, ethanol, acetone and NO₂. The thin films showed high sensitivity (4–100 ppm) to volatile oxygen-containing organic compounds (acetone and ethanol) at an operating temperature of 350°C. The effect of humidity on the magnitude and shape of the signal obtained during acetone detection was studied.

Ultra-high-temperature ceramics based on zirconium and hafnium diborides are of great scientific and technical interest, as they can be very promising, including as components of descent vehicles for space exploration. To study the behavior of these ceramics under the influence of high-speed flows of dissociated gases of complex composition and to determine the effect of modifying the ZrB₂-HfB₂-SiC system with carbon nanotubes, the process of surface degradation under the influence of a subsonic flow of dissociated nitrogen containing 5 mol. % CO₂ was examined. Despite the relatively low CO₂ content in the nitrogen plasma, the surface oxidation process dominated the conversion of the initial ZrB₂/HfB₂ into solid solutions based on monocarbonitrides of these metals. In this case, it was noted that a protective layer of silicate glass does not form on the surface, unlike similar materials under the influence of subsonic flows of dissociated air at temperatures <1750–1800°C.