Institute of Solid State Chemistry and Mechanochemistry

Ternary transition metal borides exhibit a wide variety of crystal structures and, as a consequence, a wide range of functional properties. This work investigates ternary phases formed via the interaction of zirconium diboride with iridium. The analysis of powder XRD, SEM, and WDS indicates the formation of three known ternary boride phases (Zr2Ir6B, ZrIr3B4, and Zr2Ir5B2) and two novel phases (ZrIr7B2 and ZrIr2B). In the wide range of reagents' mixture compositions, the main products are Zr2Ir5B2 and ZrIr2B; in the 4-fold excess of iridium, the composition of products changes to a mixture of Zr2Ir6B and ZrIr7B2. The structure of the novel phase, ZrIr7B2, was studied with single-crystal X-ray diffraction and powder time-of-flight neutron diffraction, which showed that it crystallizes in a new structure type with a layered hexagonal structure P6̅2m: a = 5.5683(7) Å, c = 5.6058(7) Å. The structure consists of Kagomé net layers formed by [BIr6] trigonal prisms, with Zr atoms in the free space of each layer and Ir atoms in the interlayer space. Additionally, the Vickers microhardness of the ternary borides was measured; all ternary compounds display microhardness in the range of 15-19 GPa.

This study explores the development of new room-temperature NO2 sensors utilizing carbon nanofibers (CNFs), single-walled carbon nanotubes (SWCNTs), and their hybrids with reduced graphite oxide (rGO), fabricated via a facile drop casting method with varying concentrations of carbon/ethanol mixtures. The concentration-dependent relation of sensor response to NO2 has been found. Comprehensive characterization techniques, including electron microscopy, Raman spectroscopy, optical microscopy, and X-ray diffraction were employed to analyze the sensing materials. Our results reveal that CNFs exhibit superior sensitivity, reaching −1.32%/ppm at an optimal suspension concentration of 1.5 mg/mL, outperforming SWCNTs. The creation of hybrid composites, specifically CNFs/rGO and SWCNTs/rGO, further enhances sensing performance due to synergistic effects. Molecular dynamics simulations revealed increased adsorption behavior of the CNFs/rGO hybrid sensing material. The fabricated devices, based on all-carbon composites, are effective and energy-efficient platforms for NO2 detection, offering promising solutions for environmental monitoring, the chemical industry, and industrial safety applications.

The authors study the effect ionizing and UV radiation have on the physico-mechanical characteristics of polymer materials based on Tarkosil® SiO2 nanoparticles and injection molded polyurethane with different storage times of the initial components. It is shown that because of exposure to ionizing radiation (1000 Gy), the tensile strength and elongation of polyurethane based on components manufactured 1 month before the synthesis of samples rise to 30% (from 23 to 30 MPa) and 65% (from 382 to 627%), respectively. The effect such external factors as UV and ionizing radiation have on the performance of products and parts based on injection molded polyurethane is studied to improve their physical and mechanical properties.

CrystalShift is an open-source computational tool tailored for the analysis, transformation, and conversion of crystallographic data, with a particular emphasis on organic crystal structures. It offers a comprehensive suite of features valuable for the computational study of solids: format conversion, crystallographic basis transformation, atomic coordinate editing, and molecular layer analysis. These options are especially valuable for studying the mechanical properties of molecular crystals with potential applications in organic materials science. Written in the C programming language, CrystalShift offers computational efficiency and compatibility with widely used crystallographic formats such as CIF, POSCAR, and XYZ. It provides a command-line interface, enabling seamless integration into research workflows while addressing specific challenges in crystallography, such as handling non-standard file formats and robust error correction. CrystalShift may be applied for both in-depth study of particular crystal structure origins and the high-throughput conversion of crystallographic datasets prior to DFT calculations with periodic boundary conditions using VASP code.

The precipitation process of bismuth(III) from perchloric acid solutions upon the addition of malonic acid has been studied as a function of the molar ratio of malonate ions to bismuth in the system. A basic bismuth malonate with the composition BiOH(C3H2O4) (compound I) was synthesized, along with two structurally distinct but compositionally identical bismuth malonates containing a water molecule: Bi(C3H2O4)(C3H3O4)H2O (II) and [Bi(C3H2O4)(C3H3O4)]⋅H2O (III). Compound I was obtained in an X‑ray amorphous form, whereas the crystal structures of compounds II and III were determined by X-ray diffraction. In compound II, the water molecule coordinates directly to the bismuth atom as a ligand, whereas in compound III this is not observed. Both compounds form one-dimensional (1D) coordination polymers. Upon calcination of compounds II and III at 120°C, anhydrous bismuth malonate with the composition Bi(C3H2O4)(C3H3O4) (IV) is produced via dehydration. All new compounds (I–IV) were characterized by IR spectroscopy, thermal analysis, and powder X-ray diffraction, and their compositions were confirmed by elemental analysis. The structural features of polymers II and III are discussed, including a topological analysis of the electron density in Bi–O contacts, allowing for the identification of primary and secondary bonds within the coordination polyhedra.

Using the method of dynamic diffractometry with the use of synchrotron radiation beams, experimental studies of phase formation processes occurring during the high-temperature synthesis of mechanically activated powder mixture Ti + Al + C were conducted. High-temperature synthesis has been carried out in situ in thermal explosion mode using a microwave induction heater on an experimental complex adapted to the method of dynamic diffractometry. The experiments were conducted at the “Diffraction Cinema” station of VEPP-3, channel 5B, at the Budker Institute of Nuclear Physics, Siberian Branch, Russian Academy of Sciences. It has been experimentally shown that the synthesis of a composite material occurs in multiple stages. The onset of phase changes begins at a temperature of approximately 870°C. Initially, the formation of intermetallic compound TiAl3 is observed. Then a Ti–Al melt is formed with the release of TiC grains, which provides the main heat release and initiates a thermal explosion reaction. Further, the Ti–Al melt due to the dissolution of TiC grains in it is saturated with carbon, and when the temperature reaches 1800°C, MAX phase Ti2AlC crystallizes from it. The maximum amount of this phase is fixed at the exposure stage. With a decrease in temperature, along with Ti2AlC, MAX phase Ti3AlC2 is formed. At this stage, by controlling the temperature, it is possible to control the content of MAX phases in the reaction product. The composition of the final product includes Ti3AlC2, Ti2AlC, and TiC.

The Raman scattering intensity of oriented polyvinyl alcohol (PVA) films doped with cadmium sulfide and iodine is found to depend on the position of the sample with respect to the direction of the exciting radiation polarization. This dependence agrees with the supposed polymer structure of the inorganic component of the complex and the Raman scattering mechanism with its participating similar to the surface-enhanced Raman spectroscopy (SERS). The spectra are found to contain bands similar to the G- and D‑bands of carbon materials in the Raman shift range 1000–2000 cm–1. The origin of these bands is discussed.

This study investigates the ignition, combustion, and thermal decomposition processes of composite fuels produced from pine sawdust and anthracite coal through mechanochemical activation. The research aims to optimize the co-combustion of low-reactivity coal and biomass by analyzing the nonadditive effects of composite formation on fuel reactivity and combustion efficiency. Experimental methods include synchronous thermal analysis (STA) to evaluate thermal decomposition stages, ignition delay measurements in a vertical tube furnace, and flare combustion tests in a 50 kW semi-industrial burner to assess practical performance. The results show that composite fuels outperform physical mixtures in combustion characteristics. Thermogravimetric analysis reveals a threestage decomposition process for composites, with overlapping stages of volatile release, coke residue oxidation, and anthracite carbon combustion. The composite achieves stable torch combustion, while the equivalent mixture fails to stabilize. Ignition delay times for composites are significantly lower than for mixtures or pure components, with the optimal ratio reducing ignition time by 20-30%. Mechanochemical activation generates paramagnetic centers on particle surfaces, accelerating ignition through radical-initiated reactions. The findings highlight the superiority of composite fuels in improving combustion efficiency, particularly for low-reactivity coals like anthracite. This study lays the groundwork for developing advanced solid biofuels applicable to co-firing systems, advancing sustainable energy solutions and biomass waste utilization.