The formation of a class of alkaline coordination nitrates of lanthanides was established by complex systems studies of the interaction of structural components in nitrate systems of rare earth elements and elements of groups IA and IIA of the Periodic Table - precursors of modern multicomponent oxide polyfunctional materials. All of them are synthesized in single crystal form. Their composition, atomic-crystalline structure, forms of coordination of polynuclear Ln, types of the ligand coordination and a number of their properties were studied using a set of physico-chemical methods: chemical, X-ray diffraction, IR spectroscopy, crystallo-optical, thermographic, the generation of the second harmonic of laser irradiation. Obtained new crystallochemical regularities of the structure of Ln compounds deepen the understanding of the chemical and physical properties, their composing ability. The obtained data can serve as the basis for detection, identifying, controlling the formed phases in innovative technologies using nitrate precursors of elements of different electronic structures.

The work is dedicated to the study of phase and structural evolution in titanium matrix composites reinforced with a pre-synthesized master alloy of the TiH2 – FeSiMn – B4C system. The composite was fabricated using powder metallurgy techniques, employing PTM-1 grade titanium powder and a pre-synthesized TiH2 - FeSiMn - B4C master alloy in varying weight percentages (10, 20, and 30 wt. %) followed by vacuum sintering at 1100 – 1200 °C. The influence of sintering temperature and master alloying element concentration on porosity, microstructure, phase composition, and microhardness was analyzed. The composites sintered at 1200 °C exhibited lower porosity and higher microhardness due to intensified diffusion processes. SEM, XRD, and microprobe analysis confirmed the availability of reinforcing phases such as TiB, TiC0.5, and Ti5Si3B, and revealed a clear dependence of phase morphology and grain structure on the master alloy content. Microhardness increased with increasing reinforcement content and sintering temperature, reaching peak values of up to 12 GPa in regions enriched with high-modulus compounds in the composite with 30 wt.% master alloy.

Using the crystal energy theory of isomorphous miscibility, the mixing energies, critical decomposition temperatures, and substitution limits were calculated, and the thermodynamic stability ranges of solid solutions Sr1-x(Na0.5Ln0.5)xMoO4 (where Ln represents rare-earth elements, REEs) were determined. It was shown that both the mixing energies and the critical decomposition temperatures increase systematically with the REE atomic number. A thermodynamic stability diagram and dependencies of solubility limits of the solid solutions were built for concentrations ranging from x = 0 to x = 1.0 with a step of Δx = 0.05. These diagrams allow one to determine the limits of equilibrium substitution at a given decomposition temperature, decomposition temperatures for a specified substitution limit, or the thermodynamically stable composition regions. The results may be helpful for immobilizing radioactive isotopes of REEs, actinides, and strontium-90 in nuclear waste disposal and developing new inorganic materials for phosphors and lasers.

A new method of creating a multilayer scintillation element for the registration of thermal neutrons using 3D printing technology on an FDM printer has been developed. The influence of thermophysical parameters of printing materials on the geometric shape and functional properties of the printed product was investigated. Optimal settings of the printing technology were selected. Samples of the scintillation element, which consists of layers of light guides alternating with scintillator layers, have been produced. Polystyrene was used as the light guide. A composite material based on polystyrene with a filler of zinc sulfide powder activated by silver, with the addition of a boron oxide (B2O3) neutron converter – ZnS:Ag/B2O3 – was used as a scintillator. The use of 3D printing with two materials in a single technological cycle made it possible to significantly simplify the process of creating a scintillation element compared to traditional technologies. The thermal neutron registration efficiency of the scintillation element sample created using 3D printing technology is 68%, which is comparable to the modern analogs of solid-state detectors created using traditional technology.

The energetics of oxygen self-diffusion in NpO2 over a range of temperatures is important for nuclear fuel applications. This can be realized using the cBΩ thermodynamic model where the defect Gibbs energy is proportional to the isothermal bulk modulus (B) and the mean volume per atom (Ω). In the present study we employ elastic and expansivity data in the framework of the cBΩ model to derive the oxygen self-diffusion coefficient in NpO2 in the temperature range 2000 K to 2900 K. The predicted results are in agreement with the available experimental and theoretical data.

Liquid crystal (LC) systems based on 4-n-pentyl-4′-cyanobiphenyl (5CB) doped with non-mesogenic salicylaldoxime (SA) and resorcinol (RES), where one could expect non-trivial behavior due to specific intermolecular interactions, were studied using differential scanning calorimetry (DSC), UV-Vis and FTIR spectroscopy. It was shown that eventual formation of supramolecular complexes led to additional temperature stabilization of the nematic phase. This effect, which we noted earlier for SA, is much more pronounced for RES. In the latter case, an increase in the nematic-to-isotropic phase transition temperature by ~15 °С was observed at RES concentration of 12 % w/w (3 : 1 molar ratio). Basing on the UV absorption data in LC state and dilute solutions, the values of optical band gap (Eg) were determined for 5CB+SA and 5CB+RES as functions of temperature and the dopant content. The concentration dependence of Eg for the 5СВ+RES system shows an extremum at 3 : 1 molar ratio, which is consistent with DSC data. Possible structures of supramolecular aggregates were proposed, taking into account dipole-dipole interactions, hydrogen bonding between cyano- and OH-groups of the component molecules as well as steric factors facilitating their tightest packing.

The setup for growing single-crystal high-melting-point oxides using top-seeded solution growth method was modified to provide controlled regulation of the crucible bottom temperature. The modified setup was used for growing bulk KTaO3 single crystals, a material with a unique combination of high dielectric constant and other properties in demand in various fields including electronic and optical industries as well as the development of highly sensitive and compact radio-spectroscopic instruments. The quality of KTaO3 single crystals grown in the modified setup was analyzed by several methods, and high crystallinity and purity of the samples were demonstrated.

The article is devoted to the development of a method for the synthesis of polymers based on alginic acid modified with flavonol fragments and the study of the spectral properties of the obtained compounds. The conditions for the direct esterification reaction of alginic acid with 7-hydroxyflavonol and 4′-hydroxyflavonol are described. The reaction demonstrates the regioselectivity: it leads to the formation of ester bridges between the polymer chain and flavonols involving the 7-hydroxy- and 4′-hydroxy groups, while esterification of the 3-hydroxy group of flavonols does not occur. This allows keeping the spectral properties of flavonol fragments, the ability to complex, and intramolecular proton transfer in the excited state. It was shown that the absorption and fluorescence spectra of the modified polymers are similar to the neutral forms of free flavonols. The results obtained will enable the use of flavonol-containing alginate polymers in the gel phase for the detection and accumulation of metal ions, for examination of solvent′s polarity, and for medical practice as a depot for the slow release of biologically active flavonoids.

Lithium titanates are known as promising materials for anodes of lithium-ion batteries. Intensive research is being conducted on the synthesis of various lithium titanate composites to improve the electrophysical characteristics of batteries. Micropowders of the composites (lithium titanate – TiO2) were obtained by heat treatment of the batch (Li2CO3 + Ti) in the temperature range of 900-1000 °C for 4 minutes using the one-step rapid synthesis method developed by the authors. The phase composition and structure of the composites were studied using a DRON-3M diffractometer and a JSM-6700F SEM. Based on the composites synthesized at a temperature of 975 °C, prototypes of experimental cells with a lithium electrode were manufactured. Cycling in the range of 0-3 V relative to the lithium electrode at a current density of 15 mA/g showed a reversible capacity of 101 mA·h/g. The obtained test results confirm the possibility of using composites for lithium-titanium batteries.

The effect of the selenium concentration in the composition of the Cd1-xZnxTe1-ySey semiconductor crystals on their etching with a bromine-methanol solution was studied. A thermodynamic model is proposed to describe the degree of etching of Cd1-xZnxTe1-y and Cd1-xZnxTe1-ySey crystals. A thermodynamic law is obtained for the first time to describe the change in the etching rate of Cd1-xZnxTe1-ySey crystals with different selenium concentrations. Experimental curves of the etching trajectories and rates of Cd1-xZnxTe1-ySey crystal samples with nominal x ≈ 0.1 and selenium concentrations of y=0, y=0.02, y=0.06, and y=0.1 using 5% bromine-methanol solutions were constructed. The average etching rates were 24 μm/min, 18 μm/min, 15 μm/min, and 13 μm/min. The threshold effect of a strong decrease in the etching rate upon transition from ternary Cd1-xZnxTe1-y to quaternary Cd1-xZnxTe1-ySey crystals, associated with hardening of the crystal structure, was identified and theoretically explained. The obtained experimental data are in good agreement with the theoretical estimates and will be useful for choosing the optimal regimes of crystal treatment.