New Publications

https://doi.org/10.1007/s10854-024-13521-4

The magnetic, transport and acoustic properties of materials Tm_XMn_1−XSe (0.025 ≤ X ≤ 0.2) have been studied in magnetic fields of up to 12 kOe at temperatures of 80‒600 K. The magnetic phase transition temperatures (T_N) and change in the sign of resistance at DC current in vicinity of the T_N were established. The temperature and concentration ranges corresponding to the maximum magnetoresistance (− 50% for X = 0.025) and magnetoimpedance (12% for X = 0.2) have been determined. The mechanism of relaxation has been established from the impedance spectrum and the activation energy change upon temperature and concentration has been found. The difference between the dc and ac magnetoresistances has been disclosed. The concentration range with hole and electron type carriers is determined. The mobility anomalies in the vicinity of the valence transition have been established. It is shown that the current and electrical resistance in the Tm_XMn_1−XSe compound can be manipulated by ultrasound and a magnetic field. A qualitative difference between the interaction of current and ultrasound in the magnetically ordered and paramagnetic regions is found.

https://doi.org/10.1007/s00339-024-07921-w

ZnO films grown on a glass substrate through the magnetron sputtering were subjected to ion implantation of Ni⁺ and Ag⁺with different irradiation doses. The resulting ZnO: Ag and ZnO: Ni films were studied using optical and magneto-optical spectroscopy. Magnetic circular dichroism (MCD) spectra for the samples were analyzed along with MCD spectra for nickel and silver nanoparticles (NPs). The MCD data for Co-doped ZnO films was also considered. It has been found that MCD spectrum shape reflects different polarization states of charge carriers in the samples, as well as their magnetic behavior. In addition, it has been established that MCD spectroscopy can serve as a tool for the detection of Ni and Ag nanoparticles in matrices of ZnO: Ni and ZnO: Ag solid solutions. The general pattern of the MCD spectra observed for doped ZnO films in various magnetic and polarized states is expected to apply to other dilute oxides.

https://doi.org/10.1016/j.jallcom.2024.176577

There is an urgent need to develop stable and high-energy storage dielectric ceramics; therefore, in this study, the energy storage performance of Na_0.5-xBi_0.46-xSr_2xLa_0.04(Ti_0.96Nb_0.04)O_3.02 (x = 0.025–0.150) ceramics prepared via the viscous polymer process was investigated for energy storage. It was found that with increasing Sr²⁺ content, the material transforms from a mixture of rhombohedral and tetragonal phases (x = 0.025) to a mixture of orthorhombic and pseudo-cubic phases (x = 0.15). The emergence of a dielectric plateau for the sample with x = 0.15 widens the applicability of the host compound. Finite element simulations show that a smaller grain size has a beneficial effect on the critical breakdown electric field and that the relaxor transformation benefits from the reduction of residual polarization (P_r). The obtained ceramics achieve a value of 6.69 J/cm³ for the energy storage density (W_rec) and 89.48 % for the energy storage efficiency (η) under an applied electric field of 400 kV/cm, with a discharge time (t_0.9) of 0.168 μs at 90 % of the energy under an electric field of 280 kV/cm, and a power density (P_d) of 148 MW/cm³. This study shows a novel strategy for the modification of the dielectric and ferroelectric properties of NBT-based ceramics, providing an effective way to expand the operational temperature range and improve energy storage performance.

https://doi.org/10.1557/s43578-024-01442-1

Magnetic properties of mixed spinel ferrites are determined, in great extent, by the magnetic cation distribution among tetrahedral and octahedral positions in a crystal. In the case of CoZn-ferrites, most researchers reported a predominant localization of the divalent cobalt ions in octahedral positions. Using the citrate precursor auto-combustion method, we successfully synthesized Co_xZn_1-xFe₂O₄ nanoparticles (x changed from 0.0 to 0.5) with an approximately evenly distribution of Co²⁺ ions between these interstitial positions. Fe³⁺ ions are localized preferably in octahedral positions. This type of 3d-ion distribution predetermined the combination of the large saturation magnetization and very low coercive field of the nanoparticles, which may be of importance for applications. MCD spectra of Co_xZn_1-xFe₂O₄ nanoparticles are studied here for the first time. Revealed intense MCD peak at 1.75 eV corresponds to the emission wavelength (710 nm) of some lasers, e.g., ALP-710 nm (NKT Photonics, Denmark) which may be of interest for photonic devices.

DOIhttps://doi.org/10.1039/D4CP00778F

Plasmonics serves as a most outstanding feature of nanoparticle technology and is nowadays used in numerous applications within imaging, sensing and energy harvesting, like plasmonically enhanced solar cells, nanoparticle bioimaging, plasmon-controlled fluorescence for molecular tracking in living cells, plasmon-controlled electronic molecular devices and surface enhanced Raman spectroscopy for single molecular detection. Although plasmonics has been utilized since ancient times, the understanding of its basic interactions has not been fully achieved even under the emergence of modern nanoscience. In particular, it has been difficult to address the “ultra-fine” 1–10 nm regime, important for applications especially in bioimaging and biomedical areas, where neither classical nor quantum based theoretical methods apply. Recently, new approaches have been put forward to bridge this size gap based on semi-empirical discrete interaction models where each atom makes a difference. A primary aim of this perspective article is to review some of the most salient features of these models, and in particular focus on a recent extension – the extended discrete interaction model (Ex-DIM), where the geometric and environmental features are extended – and highlight a set of benchmark studies using this model concerning size, shape, material, temperature dependence and other characteristics of ultra-fine plasmonic nanoparticles. We also analyze new possibilities offered by the model for designing ultra-fine plasmonic particles for applications in the areas of bioimaging, biosensing, photothermal therapy, infrared light harvesting and photodetection. We foresee that future modelling activities will be closely connected to collaborative experimental work including synthesis, device fabrication and measurements with feedback and validation in a systematic fashion. With this strategy we can expect that modelling of ultra-fine plasmonics particles can be integrated in the development of novel plasmonic systems with unprecedented performance and applicability.

https://doi.org/10.1080/1536383X.2024.2400270

It was shown that the method of mechanical separation with filtration could be used to separate metal nanoparticles in a carbon shell. The method was used for separation of FeNi nanoparticles with a carbon shell, previously isolated from carbon condensate by boiling in acids. The particles had a crystalline structure and magnetic characteristics (Mr/Ms = 0.30, Hc = 270 Oe). Method of mechanical separation with filtration made it possible to separate the sample into particles coated with a carbon shell (particles size 40–50 nm, size of the metal core 10–15 nm), and into metal particles with a diameter of 6–15 nm, dispersed in a carbon matrix. The work shows that the samples have similar magnetic properties (Mr/Ms = 0.27, Hc = 236 Oe) and chemical composition (Ni ∼ 10 wt.%, Fe ∼ 12 wt.%, C ∼ 57 wt.%). However, the samples differ in structure, one contains FeNi(220), FeNi(200), FeNi(111) and C(002) phases, while the other contains only FeNi(200) and C(002) phases.

https://doi.org/10.33383/2024-011

Experimental photo-biological studies have been carried out to find effective stable spectral PAR fluxes for cultivating tomato seedlings and to estimate the effect of the change in the spectral irradiation mode during the growing season under electrical light.
The purpose of the study was to test the capabilities of the newly developed LED irradiators with an adjustable PAR radiation spectrum to estimate the effectiveness of spectral irradiation modes to treat tomatoes for the formation of high-quality seedlings and to increase tomato yields by changing the PAR radiation spectrum during the plant flowering stage under electrical light.
The study showed that for the formation of high-quality seedlings with a well-developed photosynthetic apparatus and a well-formed habitus, the most favourable was the PAR spectrum with proportions of blue (400–500) nm and red (600–700) nm rays of about 30 % and green (500–600) nm – about 40 % in a three-component PAR flux.
The change of the spectral irradiation mode during the stage of mass fruiting of tomato plants grown for fruit production, namely, an increase in the proportion of radiation in the red (600–700) nm spectral region by 15 % at the expense of the green (500–700) nm spectral region, caused tomato fruits to ripen 20 days earlier. Parameters of the biochemical composition of the fruits (carbohydrate and vitamin C contents) were also higher in the treatment with the change of spectrum. The experiments demonstrated that by changing the spectrum of the prototypes of the phosphor LED irradiators with the adjustable spectrum in certain stages of plant growth, these irradiators could be effectively used to cultivate long-season crops (for example, tomatoes).
The results obtained can be used to select spectral irradiation modes for producing greenhouse tomato seedlings and growing fruit-bearing tomato plants under electrical light in northern regions and in isolated spaces in various climatic zones using “City-farm” technologies.

https://doi.org/10.1016/j.solidstatesciences.2024.107703

Calorimetric, dilatometric and pressure studies of (NH₄)₃WO₂F₅ were performed over a wide temperature range, including the Pm-3m ↔ Pa-3 phase transition. Comparison of the obtained results with data for related fluorides (NH₄)₃SnF₇ and (NH₄)₃TiF₇ undergoing the same structural changes showed a significant role of chemical pressure in the formation of thermal and barocaloric properties. A decrease in anomalous entropy in oxyfluoride, ΔS₀ = 12.2 J/mol·K, is accompanied by a significant increase in sensitivity to hydrostatic pressure, dT₀/dp = 93 K/GPa, the preservation of a large change in anomalous deformation δ(ΔV/V)₀ = 0.45 % and a small temperature hysteresis, δT₀ < 1 K. This combination of thermal characteristics has led to both a significant increase in extensive and intensive barocaloric parameters in the low pressures area, and to their high reversibility in the modes of increasing and decreasing pressure.

https://doi.org/10.1016/j.cjph.2024.08.018

The all-dielectric germanium nanohole (GNH) metasurface with a sub-wavelength thickness supports simultaneous excitation of quasi bound state in the continuum (BIC) and super radiant mode. By selecting the different hole depths in a germanium slab, we present a trade-off metasurface between high Q-factor and high absorption in the photonic system. The presented device demonstrated absorption of super-radiant mode ∼98.5% and quasi-BIC ∼93% without back-metal reflector at the telecommunication wavelength. The numerical results, obtained by the finite difference time domain (FDTD) method are explained in the framework of temporal coupled mode theory (TCMT).

https://doi.org/10.1007/s10948-024-06829-z

We studied the dynamical spin susceptibility within the Hubbard model for hole-doped cuprates using cluster perturbation-based methods. Together with the one-electron spectral function, the two-particle response for 3 × 3 and 4 × 4 clusters are calculated and compared to each other. The results obtained are in qualitative agreement with the resonant inelastic neutron scattering and quantum Monte Carlo data.

https://doi.org/10.1134/S2635167624600834

The need to develop a surgical instrument that can most effectively and minimally invasively remove a malignant tumor, and distinguish and destroy only tumor cells without damaging the normal cells of healthy tissue surrounding the tumor is being considered. To achieve this goal, it is proposed to use nanodiscs with special magnetic, electronic and optical properties. Nanodiscs modified with recognition ligands (aptamers) are able to bind to tumor cells and destroy them under the influence of a weak, nonheating alternating magnetic field. This allows for effective tumor destruction while minimizing the impact on surrounding healthy tissue.

https://doi.org/10.1134/S2635167624600731

Aptamers, short oligonucleotides, are capable of high-affinity binding to targets due to their unique structure. Shortening the aptamer while maintaining the active site will increase the affinity and reduce the cost of synthesis. Using the example of the aptamer LC-224, a method for rational optimization of its length and verification of the validity of the developed approach is tested. The use of computer modeling and small-angle X‑ray scattering shows the possibility of optimizing the aptamer structure by removing nucleotides that do not participate in binding to the target. It is shown that truncation of the aptamer does not reduce the affinity and specificity of the DNA aptamer. Thus, theoretical and experimental studies demonstrate successful experience in optimizing the structure of a DNA aptamer by shortening it without compromising its affinity and specificity for its target.

10.23919/INC-USNC-URSI61303.2024.10632342

Accelerated technological progress responds to the dynamic evolution of wireless communication systems, fueled by the advent of 5G, the emergence of 6G, and the pervasive integration of the IoT paradigm. Smart antennas play a pivotal role in this advancement, facilitating electronic beam steering to meet escalating demands for enhanced bandwidth and elevated operating frequencies. The spotlight shifts to reconfigurable reflectarray antennas, gaining prominence over conventional phased arrays. Notably, liquid crystals (LCs) emerge as a promising avenue for creating electronically reconfigurable/switchable reflectarrays, specifically tailored for short millimeter and terahertz waves. LCs, as a unique aggregate state combining solid and liquid features, address current technology limitations. Their uniaxial nature and the ability to manipulate molecule orientation enable effective fine-tuning of dielectric permittivity without drawbacks present in existing technologies.

DOI: 10.21883/TPL.2022.02.53582.19042 

A plasma-chemical method for the modification of silicon carbide particles is presented, which makes it possible to obtain particles with a controlled surface morphology. The variable parameter of particle processing was the ratio of the fraction of plasma-forming (Ar) and additional (H) gases. It was shown that at Ar/H = 100/0, the formation of a carbon shell is observed; at Ar/H ratios of 91/9 and 84/16, the particles are characterized by a carbon shell decorated with silicon nanoparticles or nanowires, respectively. The modified particles were analyzed using scanning electron microscopy and Raman spectroscopy. Keywords: silicon carbide, plasma chemistry, surface morphology, nanoparticles, nanowires, carbon shell, core-shell

https://doi.org/10.1116/6.0003772

Using the methods of atomic force and electron microscopy and the magneto-optical Kerr effect, the role of the interface, roughness, and thickness of the magnetic layer in the temperature-dependent magnetic properties of thin Al₂O₃–Co films with a naturally oxidized cobalt surface was studied. The layers were deposited by magnetron sputtering. The thickness of the cobalt layer varied from 2 to 100 nm. For the first time, the dependences of coercive forces and exchange displacements on the thickness of the cobalt film in the temperature range from 80 to 300 K were obtained and analyzed. The contribution to the coercive force and exchange displacement from the oxidized cobalt surface increases as the temperature decreases below 160 K. The magnitude of the contribution depends on the base material on which the cobalt film is deposited and is maximum for a cobalt film with a thickness of ∼20 nm in the Al₂O₃/Co structure. A weakly magnetic layer was found at the Al₂O₃/Co interface. The behavior of the exchange bias in this layer is similar to the behavior of a ferromagnetic Co core with a naturally oxidized CoO shell. The thickness of this layer depends on the speed and order of deposition of the layers. When the order of deposition of layers (Co/Al₂O₃) changes, the behavior of the exchange displacement of the interface becomes similar to that observed in the ferromagnet/antiferromagnet system. That is, when the deposition order changes, the value of the exchange shift changes sign when the cobalt layer thickness is below 10 nm.

DOI 10.1088/1361-648X/ad6e48

Magnetic circular dichroism (MCD) spectroscopy for manganite films of various compositions and morphologies has been studied in the range of 1.2–3.7 eV. The primary focus was on the temperature behavior of the MCD spectra, as well as the magnetization and resistivity of the films. The data obtained were analyzed in comparison with magneto-optical spectroscopy of the Kerr rotation (KR) on both single crystal and thin film of manganites. It has been established that the MCD response at 2.3 eV is typical for manganites transitioning into a conducting state. Consequently, it reflects a change in the band structure of the material. This response is also observed in the KR spectrum of manganites in the range 2.3–2.6 eV below the metal-insulator transition temperature. These findings complement the understanding of the electronic structure of manganites in general. Moreover, they also provide a basis for the search for new functional materials.

 https://elib.sfu-kras.ru/handle/2311/152994

In this work, a study of iron and silver nanoparticles was carried out by Raman spectroscopy. The spectra were obtained by changing the temperature. The positions of individual spectral lines were found to determine the presence or absence of second-order phase transitions. Based on the data on the shift of spectral lines, one can also draw a conclusion about the stability of the objects of study under changing external conditions and how this affects changes in the suspensions in which they are included. Absorption coefficients were measured, and the sizes of the studied nanoparticles in aqueous suspensions were determined

https://doi.org/10.1016/j.jallcom.2024.176188

Na_0.5Bi_0.5TiO₃ (NBT)-based ceramics exhibit significant potential as energy storage dielectric materials due to their high maximum polarization (P_max). However, their limited energy storage density significantly restricts their practical applications. To address this, this study optimizes the dielectric energy storage characteristics of lead-free relaxor ferroelectric ceramics based on 0.91Na_0.5Bi_0.5TiO₃-0.09 K_0.7La_0.1NbO₃ (NBT-KLN) by incorporating Sr_0.7Bi_0.2TiO₃ (SBT) relaxor additives. The introduction of SBT helps maintain large polarization and induces local disorderly fields, promoting the formation of polar nanoregions. Subsequently, a viscous polymer processing (VPP) technique was employed to reduce defects and enhance density, markedly improving the breakdown strength (BDS). The findings indicate that the BDS of the optimized 0.30SBT (VPP) ceramics increased to 440 kV/cm, while achieving a high energy storage efficiency (η) of 78 % and an elevated energy storage density (W_rec) of 6.29 J/cm³. Additionally, the 0.30SBT (VPP) ceramics demonstrate excellent temperature stability across a broad temperature range from 30 to 120 °C, making them ideal for long-term operation in variable environments. This study demonstrates superior results compared to previous research, thereby opening up new avenues for developing novel lead-free relaxor ferroelectric ceramics with superior energy storage characteristics.

https://pubs.acs.org/doi/abs/10.1021/acs.cgd.4c00582

Single crystals of Co₂AlBO₅ were synthesized using flux. The structural, magnetic, and electrical properties have been studied, with emphasis on cationic disorder effects. The Al³⁺ and Co²⁺ ions share four symmetry inequivalent sites. Large amplitudes of the displacement parameters for the M2 and M4 metal sites and the O4 oxygen site were found. The compound exhibits two magnetic transitions at T₁ = 41 K and T₂ = 20 K and shows a high crystallographic anisotropy. The random cationic distribution induces magnetic softness and an increase in electrical resistivity. The sources of the cationic disorder and the approach for controlling it are discussed.

https://pubs.acs.org/doi/full/10.1021/jacs.4c06716

Gliomas remain challenging brain tumors to treat due to their infiltrative nature. Accurately identifying tumor boundaries during surgery is crucial for successful resection. This study introduces an innovative intraoperative visualization method utilizing surgical fluorescence microscopy to precisely locate tumor cell dissemination. Here, the focus is on the development of a novel contrasting agent (IR-Glint) for intraoperative visualization of human glial tumors comprising infrared-labeled Glint aptamers. The specificity of IR-Glint is assessed using flow cytometry and microscopy on primary cell cultures. In vivo effectiveness is studied on mouse and rabbit models, employing orthotopic xenotransplantation of human brain gliomas with various imaging techniques, including PET/CT, in vivo fluorescence visualization, confocal laser scanning, and surgical microscopy. The experiments validate the potential of IR-Glint for the intraoperative visualization of gliomas using infrared imaging. IR-Glint penetrates the blood–brain barrier and can be used for both intravenous and surface applications, allowing clear visualization of the tumor. The surface application directly to the brain reduces the dosage required and mitigates potential toxic effects on the patient. The research shows the potential of infrared dye-labeled aptamers for accurately visualizing glial tumors during brain surgery. This novel aptamer-assisted fluorescence-guided surgery (AptaFGS) may pave the way for future advancements in the field of neurosurgery.

https://doi.org/10.1134/S0021364024601192

Interest in hybrid quasi-one-dimensional systems with an inner semiconducting part coated with a superconductor (the so-called core/shell structure) has been grown in the last decade. Materials with a strong spin‒orbit coupling and a large g-factor (InAs, InSb) are chosen as semiconductors. Due to the proximity effect, such objects can be considered as superconducting wires, where the existence of Majorana states has been predicted. This review briefly summarizes the current experimental studies aimed at the detection of Majorana quasiparticle excitations in superconducting wires. Furthermore, prospects of using the interference geometry of devices including such wires are discussed. In particular, the coherent transport in a spatially inhomogeneous one-dimensional normal metal/superconductor/normal metal system, where normal metal wires serve as arms of an interference device, which interact with a normal metal contact, has been analyzed theoretically. It has been found that responses of Majorana and Andreev low-energy excitations of the device can be distinguished.

https://doi.org/10.1134/S0021364024601945

We calculate electronic structure and spin susceptibility dependencies on doping within the framework of a cluster perturbation theory for strongly correlated electronic systems. The change in the susceptibility with increasing doping is qualitatively consistent with the experimental data on resonant inelastic X-ray scattering and inelastic neutron scattering, as well as with the results of the calculations within the quantum Monte Carlo method.

https://doi.org/10.1016/j.commatsci.2024.113329

The unique properties of two-dimensional (2D) materials make them highly versatile for a wide range of applications. Recently, low-dimensional structures obtained from bulk non-van der Waals materials have received particular interest. Yttrium carbonate is an example of such materials which hold the potential for creating 2D structures, however, its fundamental properties have been investigated only rarely. In this work, we demonstrate the possibility of obtaining 2D yttrium carbonate with the tengerite-(Y) structure. The electronic and optical properties of both bulk and two-dimensional Y₂(CO₃)₃·2H₂O are investigated using the PBE and HSE06 functionals. While the bulk material is predicted with a bandgap of 7.06 eV at the HSE06 level, the 2D Y₂(CO₃)₃·2H₂O material possesses a bandgap of, untypically, 0.4 eV narrower than the bulk material due to surface effects and different stoichiometry. The optical properties reveal that both the bulk and 2D forms are transparent in the visible and near-UV regions positioning them as promising candidates for various optical applications including doping-induced luminescent devices.

ttps://doi.org/10.1103/PhysRevB.110.075305

We consider double perforated slabs (membranes) that support a symmetry-protected bound state in the continuum (BIC). These slabs are immersed into a liquid at room temperature. Laser excitation of the BIC generates giant optical forces that strongly affect the Brownian motion of nanoparticles in a colloidal solution. By solving of the Fokker-Planck equation we show that a single membrane can localize only larger nanoparticles. However, system of two parallel membranes can trap extremely small nanometer-sized nanoparticles by a resonant excitation of quasi-BICs, with varying intensities in each membrane

DOI: 10.1039/d4cp02289k

Successful recognition of a dynamically stable carbonitride structure revealed that unlike other planar layered structures in the case of g-C₃N₄ the stable configurations are distorted [J. Wang et al., Chem. Mater., 2017, 29(7), 2694-2707, DOI: https://doi.org/10.1021/acs.chemmater.6b02969.]. This generates interest in a detailed study of the possibilities of controlling the structure and its properties both in its pristine and heterostructure forms. Here, we present the results of the investigation of dynamically stable bulk and monolayer g-C₃N₄, and a g-C₃N₄/MoS₂ heterostructure. The bulk g-C₃N₄ was found to be an indirect band gap semiconductor exhibiting an indirect-to-direct band gap transition upon dimensionality reduction. In the case of the heterostructure, the analysis of partial density of states shows a charge transfer from nitrogen ions in g-C₃N₄ to the MoS₂ layer. The Raman spectra of bulk g-C₃N₄ are discussed in detail, and the changes occurring in the spectra upon the transition to the monolayer form and in the g-C₃N₄/MoS₂ heterostructure are demonstrated. It was found that the characteristic features of such an atomic transition can be seen in the region below 300 cm^-1 and between 700 and 800 cm^-1.

https://doi.org/10.1134/S1062873824707220

The authors study the formation of crystals of Fe-Ga oxides and Fe–Ga–Cu borates in a multicomponent flux system based on Bi₂Mo₃O₁₂–Na₂B₄O₇. The Curie–Weiss temperature (θ_CW = 289 K) and the temperature of the ferrimagnet–paramagnet phase transition (T_C = 288 K) are determined from the electron spin resonance (ESR) spectrum and the magnetization of an Fe_1.1Ga_0.9O₃ single crystal, depending on temperature. Lines of spin-wave resonance are observed in the spectrum of magnetic resonance in the ordered phase.

https://doi.org/10.1002/pssa.202400244

Thermal stability of the multilayer (Mg/NbO_x)₈₂ nanostructure and the effect of heat treatment on its electrical properties and phase composition depending on the bilayer thickness are studied. The studied (Mg/NbO_x)₈₂ samples contain 82 bilayers whose thickness varies in the range from 2.2 to 6.2 nm. The NbO_x layer thickness in the multilayers is the same (0.96 nm) in all samples, while the magnesium layers thickness is varied. It is established that the magnesium layers are either discrete (a set of nanosized particles) or continuous depending on their thickness. A metallothermic reaction occurs in (Mg/NbO_x)₈₂ multilayer nanostructures at a temperature of 430 °C: niobium oxide decomposes and the released oxygen partly oxidizes the magnesium layers. That leads to the conductive magnesium metal layers breaking and to the sharp increase of the nanostructures’ resistance by more than two orders. Despite the metallothermic reaction, the layering of the (Mg/NbO_x)₈₂ nanostructures as a whole and the presence of unoxidized magnesium inclusions remain even after heating up to 450 °C.

 https://doi.org/10.1002/chem.202402084

Complex oxides Eu₂MeO₆ (Me–Mo, W), Eu₂W₂O₉ were obtained by a solid-phase reaction between binary oxides. The thermodynamic and kinetic mechanisms of the reaction processes were established using a variety of physical-chemical methods. All compounds obtained in this work crystallize in the low-symmetry monoclinic system, forming complex framework structures, which determine a set of very valuable physical-chemical properties. Comparison of experimental Kubelka-Munk functions and DFT- calculated absorption spectra shows adequate agreement and reveals the origin of the fundamental absorption. In addition, the deficiency in DFT calculations in the part of mutual contribution of CTBs of Mo−O and W−O, from one side, and Eu−O contributions, from the other side, is reported. Calculations of absorption spectra are shown to be superior to band structure analysis in the determination of optical band gaps. Additionally, luminescent properties of Eu₂MeO₆ and Eu₂W₂O₉ compounds were investigated. These studies provide a better understanding of the electronic and optical properties of the compounds Eu₂MeO₆ and Eu₂W₂O₉, along with their potential applications in various areas.

https://doi.org/10.1134/S1070363224060094

Using the methods of X-ray diffraction, Mössbauer spectroscopy, and temperature-programmed reduction with hydrogen, the relationship between the phase composition, structural characteristics of the phases, and the reactivity with respect to hydrogen was investigated for calcium ferrites-based catalysts. The catalyst samples were prepared via solid-state synthesis from CaO and Fe₂O₃ at 900 and 1000°C by varying the Fe₂O₃ content in the CaO–Fe₂O₃ system. The phase composition of the resultant samples corresponds to the CaO‒Ca₂Fe₂O₅, Ca₂Fe₂O₅‒CaFe₂O₄, and CaFe₂O₄‒α-Fe₂O₃ regions. In the CaO–Ca₂Fe₂O₅ samples the lattice parameters of Ca₂Fe₂O₅ and its activity with respect to hydrogen depend on the phase ratio. The activity of CaFe₂O₄ is higher in Ca₂Fe₂O₅‒CaFe₂O₄ compared to CaFe₂O₄‒α-Fe₂O₃ catalysts.https://doi.org/10.1134/S1070363224060094

https://doi.org/10.1134/S1062873824707190

Results are presented from investigating the structure of Mn_2.25Co_0.75BO₅ via powder neutron diffraction. Crystals of ludwigite Mn_2.25Co_0.75BO₅ are grown by flux method using a Bi₂Mo₃O₁₂-based solvent diluted with Na₂CO₃ carbonate. Boric acid H311BO3 is used as the boron-containing reagent. Powder neutron diffraction measurements are made at a temperature of 100 K on powder prepared by grinding grown single crystals. Rietveld studies show that the grown Mn_2.25Co_0.75BO₅ crystals belong to Pbam space group. Crystallographic sites occupied by cobalt and manganese ions are identified by analyzing powder neutron diffractograms. A bottleneck regime is observed in the temperature dependence of the EPR spectra.