Frantsevich Institute for Problems in Materials Science

Biopolymers, particularly polysaccharides such as pectin, chіtosan and alginate, offer significant potential in addressing numerous current environmental and health issues. In contrast to synthetic polymers, natural polysaccharides possess valuable properties such as biodegradability, biocompatibility, and non-toxicity. Due to that, they have proven their efficiency in biomedical applications for drug encapsulation and delivery, wound healing and tissue engineering. Moreover, their natural origin and environmental compatibility make them highly suitable for applications in agriculture, particularly in soil conditioning and remediation. These well-known, commercially available biopolymers have unique functional properties which, when combined, can improve their physicochemical properties synergistically. Methods of Calcium Alginate and mixed polysaccharides based on Alginate and Pectins A and LM synthesis in the form of spherical beads with adjustable diameter were developed, and the influence of the nature and concentration of the components on their properties was analysed. The morphology of the synthesized polysaccharide gels (based on Alginate, Alginate-Pectin A and Alginate-Pectin LM) was examined by means of electron microscopy (SEM), while their chemical structure was confirmed by FTIR. The elemental composition of the synthesised polysaccharides was studied using energy-dispersive X-ray spectroscopy (EDX), while their thermostability and thermolysis processes were analysed using thermogravimetric analysis. It was demonstrated that the synthesised polysaccharide beads could withstand steam sterilisation at 121 °C without undergoing significant changes. This opens up the possibility of using them in various biomedical technologies. Studying the swelling kinetics of polysaccharide gels in different solvents (water, saline and phosphate-buffered saline (PBS)) enabled us to determine their inherent Fick diffusion type. The developed mixed polysaccharides show promise as a synthetic soil conditioner for agricultural use and for targeted delivery and controlled release of medicine.

Abstract Microstructural and microprobe analyses of as-cast and annealed alloys (1,000 °C for 61 h) revealed a new congruently melting Hf 0.45 Ti 0.55 Ni 2 compound in the Hf–Ti–Ni system. The compound forms two-phase equilibria with Hf 7 Ni 10 , Hf 3 Ni 7 , αHfNi 3 and TiNi 3 and exhibits a homogeneity range of 18–24 at.% Ti at 65 ± 0.5 at.% Ni. Its crystal structure was determined by single-crystal and powder X-ray diffraction. Hf 0.45 Ti 0.55 Ni 2 crystallizes in a derivative of the Co 1.75 Ge prototype exhibiting statistical mixture of hafnium and titanium atoms on 2 d site and two 2 a , 2 c sites occupied by nickel atoms: PS hP 6, SG P 6 3 / mmc , a = 4.225(2), c = 5.044(4) Å. The Rietveld-refined composition, Hf 0.482(2) Ti 0.518(2) Ni 2 , is in close agreement with both the single-crystal X-ray diffraction data and the energy-dispersive X-ray analysis results. The homogeneity range of the compound Hf x Ti 1- x Ni 2 has been refined from powder X-ray diffraction and energy-dispersive X-ray data: (0.55 ≤ x ≤ 0.72), variation of the lattice parameters is the following: a = 4.2045(3) – 4.185(1), c = 5.0055(4) – 5.000(1) Å. The microstructure shows a characteristic twin morphology. The microhardness of the compound was measured as 1,160 ± 20 and 1,140 ± 60 H μ for single-phase as cast alloys containing 18 and 24 at.% Ti, respectively. Electronic structure calculations based on the LMTO method for the ordered model HfTiNi 4 ( P 6/ mmm ) indicate a metallic behavior with significant Ti–Ni, Hf–Ni, and Ti–Hf bonding interactions. The analysis of DOS and COHP indicates strong covalent contributions alongside Ni–Ni antibonding states, suggesting a complex hybrid metallic–covalent bonding nature that stabilizes the Hf–Ti–Ni three-dimensional network.

First-principles calculations were performed to investigate the structural, electronic, mechanical, and spintronic properties of InTeX (X = Cl, Br, and I) monolayers formed via full halogenation of pristine InTe. Halogenation induces a structural transformation from the four-sublayer Te-In-In-Te configuration to a three-sublayer Te-In-X geometry, accompanied by the formation of polar covalent In-X bonds and the suppression of metallic In-In interactions. The resulting monolayers preserve a buckled hexagonal lattice and exhibit enhanced thermodynamic, thermal, and dynamical stability. InTeX monolayers display moderate Young's moduli (22.18-25.26 N m-1), isotropic in-plane elastic behavior, and Poisson's ratios from 0.31 to 0.32, rendering them promising candidates for flexible and wearable nanoelectronic applications. The electronic band structures reveal tunable direct band gaps and strong, anisotropic Rashba spin-orbit coupling, with Rashba parameters α R ranging from 0.81 to 1.04 eV Å, indicating potential for spintronic and optospintronic devices. Importantly, charge-carrier mobilities were evaluated by explicitly accounting for phonon and impurity scattering, yielding realistic values consistent with experimental expectations and underscoring the importance of accurate mobility modeling for device performance. Overall, the combination of structural stability, tunable electronic properties, robust spin-orbit effects, and reliable carrier transport makes InTeX monolayers highly promising materials for future research in flexible electronics, spintronics, and multifunctional two-dimensional nanomaterials.

Preliminary mechanical loading at a temperature close to the ductile-brittle transition temperature leads to stress relaxation near cracks in brittle materials due to local plastic deformation at microcrack tips. As a result, such preloading increases the physical and mechanical properties of ceramic materials when tested at room temperature. In the present work, this phenomenon is investigated for silicon and silicon-based ceramics. A thermomechanical treatment (TMT) method of the mentioned materials has been developed to increase their strength and fracture toughness.

We report on theoretical and experimental studies of the electronic structure of triclinic copper tungstate, CuWO 4 . The present data carried out within a Density Functional theory (DFT) framework reveal the importance of spin-resolved calculations for this tungstate. The spin-resolved DFT calculations indicate that that Cu 3d electronic states dominate the top of the valence band, whereas the main input of W 5d states occur at its bottom and lower part. However, the principal contributions to the valence band of CuWO 4 come from O 2p electronic states giving the main input to the whole valence-band region except of its top. The chemical bonding in CuWO 4 is characterized by essential contribution of the covalent component in addition to the ionic component. The present theoretical data are found to be in excellent agreement with the experimental XPS and XES measurements of polycrystalline copper tungstate.

Multicomponent solid solutions of (Ti,V)(C,N) were synthesized using VN nitride, graphite, and industrial titanium powder grade PT-4, containing a TiH 2 and α-Ti mixture (2:1 ratio). The synthesis was performed via high-pressure high-temperature (HPHT) sintering (7.7 GPa, 2150 °C) of (PT-4)-VN-C and (PT-4)-VN mixtures that had been pre-treated by high-energy mechanochemical milling. The initial and sintered products were characterized by XRD, SEM, EDS, and Raman spectroscopy. The mechanochemical treatment resulted in the formation of fine-crystalline, strained solid solutions, including V 0.67 Ti 0.33 N, TiV 0.33 H 0.66 C x , and α-(Ti,V), characterized by a high density of structural defects. These defects function as active sites, facilitating subsequent transformations. The HPHT sintering has been shown to promote diffusion and phase consolidation, resulting in the formation of dense, nearly single-phase (Ti,V)(C,N) solid solutions with approximate compositions of ∼V 0.5 Ti 0.5 N 1- x C x . The synthesized compacts exhibited microhardness values ranging from 11 to 15 GPa.

The phase interaction in the Fe2O3–Gd2O3 system at 1300 and 1400 °C were studied across the full concentration range using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Samples, prepared in 1–5 mol% composition increments, were obtained by dissolving the oxides in HNO₃ (1 : 1), evaporating the solutions, and decomposing the nitrates at 800 °C for 2 h. The resulting powders were pressed at 10 MPa into 5 mm × 4 mm pellets and heat-treated in air at 1300 °C (300 h) and 1400 °C (100 h). The phase composition was determined using X-ray diffraction (XRD, DRON-3) and microstructural analysis (Superprobe-733, JEOL, Japan; Palo Alto, California, USA). At 1300 and 1400 °C, the isothermal sections of the Fe₂O₃–Gd₂O₃ phase diagram comprise four single-phase regions (B–Gd₂O₃, GdFeO₃(R), Gd₃Fe₅O₁₂, Fe₂O₃) and three two-phase regions (B–Gd₂O₃ + GdFeO₃, GdFeO₃ + Gd₃Fe₅O₁₂, Gd₃Fe₅O₁₂ + Fe₂O₃). The concentration dependence of the unit cell parameters for phases in the studied system was established. In the Fe₂O₃–Gd₂O₃ system at 1300 and 1400 °C, an ordered perovskite-type phase with orthorhombic distortion (GdFeO₃) is formed. Its homogeneity range at both temperatures extends from 48 to 52 mol.% Gd₂O₃.