Новые публикации

https://doi.org/10.1107/S2052520624011569

The crystal structures and hyperfine magnetic parameters of EuFe₃(BO₃)₄ and mixed Eu_0.82La_0.18Fe₃(BO₃)₄ were studied over a wide tem­per­a­ture range in order to analyze correlations of the structural and magnetic features and the phase transitions in multiferroic com­pounds of the rare-earth iron borate family. The chemical com­positions of the crystals are reported from X-ray fluorescence analysis. The crystal structures of EuFe₃(BO₃)₄ and Eu_0.82La_0.18Fe₃(BO₃)₄ were determined using single-crystal X-ray diffraction in the temperature range 25–500 K. A structural phase transition is observed in EuFe₃(BO₃)₄ below 89 K which is related to distortions in the inter­atomic distances and angles. The most significant of which are for R—O, R—B, R—Fe, Fe—O and Fe—Fe distances, and the angles between the BO₃ triangles and the ab plane. There is no structural phase transition in lanthanum-doped EuFe₃(BO₃)₄ based on specific heat measurements (2.2–101.3 K) and structure analysis (25–500 K), and the tem­per­a­ture dependences of the inter­atomic distances and angles are smooth. The lengths of the superexchange paths needed for the appearance of a structural phase transition in RFe₃(BO₃)₄ have been proposed. Negative thermal expansion is observed for both com­pounds below 90 K, resulting from a growth of the inter­atomic Fe—Fe distances in the iron chains during cooling. The largest atomic displacement parameters are observed for O atoms (O2), indicating that they have the highest mobility. The magnetic properties of EuFe₃(BO₃)₄ and Eu_0.82La_0.18Fe₃(BO₃)₄ were analyzed using Mössbauer spectroscopy in the tem­per­a­ture range 4.5–298 K. Néel tem­per­a­tures (T_N) of 34.57 (1) and 32.22 (1) K are obtained based on Mössbauer spectroscopy for the pure and doped crystals, respectively. The maximum specific heat capacity tem­per­a­ture dependence related to the magnetic phase transition for the doped crystal is observed at 31.2 K. A violation of the strict arrangement of anti­ferromagnetic ordering in the ab plane in the La-doped crystals at low tem­per­a­tures is suggested. The magnetic contributions of the two structural positions of the iron ions to the Mössbauer spectra could not be distinguished in either pure and doped com­pounds, regardless of whether they are in the paramagnetic and anti­ferro­magnetic regions.

https://doi.org/10.1016/j.jssc.2025.125284

In nonstoichiometric (MnSe)_1‒х(Tm_0.76Se)_х manganese selenide, the temperature and concentration regions with the same sign of carriers determined from the Hall constant and thermoelectric power have been found. The correlation of the temperature dependences of the thermopower and electrosound has been explained within the polaron model. A change in the sign of the longitudinal and transverse Nernst‒Ettingshausen coefficients upon variation in temperature and concentration has been detected. The agree of the temperature dependences of the Nernst‒Ettingshausen coefficients with a change in the electrosound in a magnetic field has been established. The maxima of the thermopower and Nernst‒Ettingshausen coefficients versus temperature have been explained within the model of coupled electron‒hole pairs with dissociation of the pairs and pinning of coupled polarons.

https://doi.org/10.1007/s10948-025-06928-5

In this work, the change in the energy and structure of local many-particle states of HTSC cuprate La2−�Sr�CuO4 under the uniaxial compression along the c-axis is studied. Local copper-oxygen states are obtained using exact diagonalization of the CuO6 octahedron as a part of the GTB method for the five-band p-d model. The dependence of interatomic distances on the c-axis compression is calculated according to Hooke’s law using elastic constants; the influence of interatomic distances on the on-site energies and hopping integrals is obtained using linear extrapolation of the results of ab initio calculations and the theory of MT-orbitals, respectively. The c-axis compression leads to a decrease in the energy of hole states with the nature of the �1� symmetry orbitals. At a pressure value of ��1(�)=11.8 GPa, a spin crossover between the Zhang-Rice singlet and the triplet state �1 occurs. At higher pressures, a second spin crossover between two-hole states and a crossover of single-hole states with different orbital compositions were also detected. Taking into account the competition of various local states with changing the value of uniaxial compression, the effective five-band Hubbard model is formulated to describe the electronic structure of quasiparticle excitations.

DOIhttps://doi.org/10.1039/D4DT03135K

It is known that in a weak magnetic field (H < 1 kOe) at T < T_C ≈ 87 K, rare-earth cobalt oxide LaCoO₃ has ferromagnetic properties. The physical mechanism of the emergence of ferromagnetism in LaCoO₃ still remains unclear. We provided experimental evidence of the ferromagnetism and crystal lattice interconnection – the cause of ferromagnetic ordering is near-surface (defects) structural stresses. A theoretical model is proposed, within the framework of which the mechanism of the emergence of the magnetically ordered state in LaCoO₃ is discussed.

https://doi.org/10.1134/S1062873824708766

We described the synthesis method and presents the results of a study of the magnetic and magnetotransport properties of vertical hybrid structures Fe₃Si/Ge/Mn₅Ge₃/Si. The mechanisms responsible for the detected magnetoresistive effect and the possible contribution of the spin-valve effect, realized through spin injection/extraction into/from germanium, are discussed.

https://doi.org/10.1134/S1062873824708778

We studied the magnetic properties of Ni_{3 – x}Co_xB₂O₆ solid solutions with the kotoite structure, where x = 0; 0.19; 0.6; 0.93; 2. The compounds Ni₃B₂O₆ and Co₃B₂O₆ are antiferromagnets, with their easy axis of magnetization coinciding with the crystallographic directions c and b, respectively. In the Ni_2.81Co_0.19B₂O₆ solid solution, two features are found on magnetization curves, while in other solid solutions there is only one feature. With the cobalt ion concentration x > 0.9, the magnetic moments are predominantly oriented along the b axis.

https://doi.org/10.1134/S1062873824708729

The structure, magnetic properties and ferromagnetic resonance curves of cobalt ferrite particles synthesized by chemical coprecipitation technique have been studied. The possibility of resonant heating of powder in a magnetic anisotropy field of particles is shown, which can find application in medicine for magnetic hyperthermia

https://doi.org/10.1007/s10909-025-03265-8

In the framework of an ensemble of spin-polaron quasiparticles formed owing to the strong coupling between the spins of copper ions and holes on oxygen ions in cuprate superconductors, the temperature dependences of the Hall coefficient �� for undoped, lightly doped, underdoped, optimally doped and overdoped regimes are calculated. The anomalous behavior of kinetic coefficients is considered beyond the relaxation-time approximation within the multi-moment method for solving kinetic equation. Dependences ��(�) calculated in the four-moment approach for noted doping regimes demonstrate the main qualitative peculiarities of the dependences found in the experiments on the Hall effect in cuprates. It is shown that change of the hopping integral of oxygen holes influences on the modification of anomalous sharp drop and change of �� sign observed experimentally at low temperatures in underdoped regime.

https://doi.org/10.1021/acs.cgd.4c01598

Three polymorphs were found to exist for Cs₃ScF₆ in the room temperature range of up to 280 °C. Two phase transitions were identified by differential scanning calorimetry (DSC) analyses at 92 and 196 °C upon heating. In situ high-temperature solid-state NMR, synchrotron and laboratory X-ray diffraction, and neutron powder diffraction were used for structural characterization. The crystal structure of the high-temperature (γ) phase adopts the cubic Fm3̅m (Z = 4) space group with a = 9.6048(7) Å at 250 °C. The other two polymorphs, α and β, have tetragonal symmetry with space groups I4₁/a (Z= 80) and I4/m (Z= 10), and lattice parameters are a = 21.15222(6) Å, c = 38.21648(8) Å and a = 15.0401(2) Å, c = 9.6341(2) Å at RT and 150 °C, respectively.

https://doi.org/10.1016/j.mseb.2025.118074

Nitric oxide is an important molecule that plays a crucial role in regulating physiological processes in mammals. To develop a sensitive method for detecting NO, new heterostructures based on cobalt phthalocyanine (CoPc) films decorated with Ir-IrO₂ nanoparticles were considered as active layers of chemiresistive sensors for the direct NO detection. Within deposition conditions, Ir-IrO₂ nanoparticles with an Ir concentration of 0.48–1.5 µg/cm², a fraction of IrO₂ phase of 10–20 %, and particles sizes from 1 to 3 to 14 nm were obtained on the surface of CoPc films. The influence of these parameters of Ir-IrO₂ particles on the sensor response of Ir-IrO₂/CoPc heterostructures to NO was investigated using theoretical and practical approaches. Based on DFT calculations, an electronic sensitization mechanism of NO detection by Ir-IrO₂/CoPc heterostructures was proposed. These heterostructures are able to detect of NO gas at the ppb level and show the selectively to NO_x in the presense of other gases.

 https://doi.org/10.1002/adom.202402889

Incorporation of phase-change materials (PCM) into nanophotonic structures is a straightforward method for making them tunable. The binary semiconducting chalcogenide antimony trisulfide (Sb₂S₃) is a suitable PCM for nanophotonic applications in the near-infrared (NIR) owing to its high refractive index, low optical losses, and wide bandgap. Therefore, in this study, Sb₂S₃ Tamm plasmon polaritons (TPPs) are fabricated with a focus on their widespread use in nanophotonic applications. For this, a gold film and Sb₂S₃ are deposited on the distributed Bragg reflector through e-beam evaporation. TPPs are excited at the interface between the distributed Bragg reflector (DBR) and the metal layer. The refractive index, extinction coefficient, and high-Q reflectance spectra of the developed Sb₂S₃ are measured and analyzed. The Sb₂S₃ TPPs exhibit a resonance shift of 45 nm caused by the phase change of Sb₂S₃ from amorphous to crystalline. In addition, the angle-dependent resonance shifts of 85, 76, and 63 nm are achieved by unpolarized, transverse magnetic (TM), and transverse electric (TE) modes near NIR light, respectively. The developed Sb₂S₃ TPP can be applied in various nanophotonics applications, including optical memory, optical data storage, and LiDAR receiver systems.

https://doi.org/10.1021/acs.chemmater.4c03162

Machine learning models were applied to predict the scintillation performances of organic–inorganic hybrid metal halides (OIMHs), focusing on their photoluminescent quantum yield (PLQY). Random Forest and Decision Tree algorithms identified the most critical structural parameter of organic molecules influencing the M···M distance between metal ions and correlated PLQY value, with an optimal distance of approximately 8 Å correlating with enhanced luminescence efficiency. This prediction was experimentally validated through the synthesis of several OIMH compounds, demonstrating strong agreement between predicted and measured PLQY values. The machine learning approach not only enabled the screening of efficient compounds but also deepened the understanding of how structural factors, such as the structure of organic molecules, govern scintillation properties. These findings underscore the potential of machine learning in accelerating the development of next-generation luminescent materials with improved performance, offering a powerful tool for future material design and optimization.

https://doi.org/10.1016/j.ptlrs.2025.01.004

The effectiveness of surfactant solutions, polymers and nanosuspensions in capillary imbibition was studied comparatively. Two series of experiments on capillary imbibition with displacing liquids from cores saturated with low-viscosity (4.2 mPa s) and high-viscosity (28.9 mPa s) oil were performed. Water, a polymer solution of polyacrylamide, surfactant solutions (AES and SDS), as well as suspensions of spherical nanoparticles were considered as displacing fluids. The mass concentration of the substances varied from 0.05 to 0.25%. The rate of change in the volume of the displaced oil for 0.1% AES solution and suspension 1030 over time was greater than for other displacing liquids. The smallest increase in the volume of displaced oil was observed for the polymer solution. The coefficient of low-viscosity oil displacement from sandstone by water as a result of capillary imbibition was found to be 58%. When using surfactant solutions and suspensions, an increase in the oil displacement coefficient was observed: the SDS solution increased the capillary imbibition rate by 4%, and the suspension of SiO₂ nanoparticles (10 nm) gave a 3% increase. The polyacrylamide solution reduced the capillary imbibition rate by 12%. In the series with higher oil viscosity, the effect of additives was more significant. The rate of capillary imbibition increased by 22% in the case of 0.1% SDS solution and by 24% for 0.1% SiO₂ suspension (10 nm). The analysis of the factors influencing the displacement coefficient during capillary imbibition with solutions of surfactants, polymers and nanosuspensions was carried out. It has been shown that nanosuspensions are not inferior to surfactant solutions and leave polymer solutions far behind in terms of their positive effect on the oil displacement coefficient.

https://doi.org/10.1016/j.optlastec.2025.112465

Light-field microscopy techniques inherently suffer from image degradation outside the imaging system’s depth-of-field (DOF). Deviation from the correct imaging system’s focal plane resulted in a loss of resolution and distortion of image details. Here, we present a ghost imaging microscopy which is based on spatial intensity correlations of the light field. Ghost imaging microscopy allows us to overcome the limitations connected with the objective focusing tolerance leading to unprecedented high DOF. The obtained results promote the route to imaging volumetric microscopic structures up to several millimeters long.

DOI https://doi.org/10.1039/D4NJ05015K

Magnetic nanoparticles, consisting of a metallic iron core with a shell of gold and iron oxides, were synthesized by ultra-high vacuum surface nucleation on a water-soluble NaCl substrate followed by oxidation in water. Using the methods of electron microscopy, electron diffraction, photoelectron spectroscopy and calculation of the specific density of iron in the oxidized shell, the oxides γ-Fe₂O₃, Fe₃O₄ and oxyhydroxide α-FeO(OH) were discovered. A non-uniform distribution of the Fe³⁺/Fe²⁺ ion ratio over the particle depth and a predominance of α-FeO(OH) in the contrast shell of nanoparticles, directly observed in transmission electron microscopy, were discovered. Comparison of the magnetic properties of partially gold-coated particles with similar Fe particles without gold showed a larger residual volume of unoxidized metal core with partial gold coating. This points to the anisotropy of the surface chemical properties associated with the Janus-like structure. For the first time, the magnetodynamic properties of partially gold-coated Fe nanoparticles were assessed by ellipsometric measurements of the surface of a colloidal solution in a gradient magnetic field.

https://doi.org/10.3390/s25010149

This paper presents the results of quantum-chemical modeling performed by the Density Functional-Based Tight Binding (DFTB) method to investigate the change in the band structure of hybrid materials based on carbon nanotubes and unsubstituted, tetra-, or octa-halogen-substituted zinc phthalocyanines upon the adsorption of ammonia molecules. The study showed that the electrical conductivity of these materials and its changes in the case of interaction with ammonia molecules depend on the position of the impurity band formed by the orbitals of macrocycle atoms relative to the forbidden energy gap of the hybrids. The sensor response of the hybrids containing halogenated phthalocyanines was lower by one or two orders of magnitude, depending on the number of substituents, compared to the hybrid with unsubstituted zinc phthalocyanine. This result was obtained by calculations performed using the nonequilibrium Green’s functions (NEGF) method, which demonstrated a change in the electrical conductivity of the hybrids upon the adsorption of ammonia molecules. The analysis showed that in order to improve the sensor characteristics of CNT-based hybrid materials, preference should be given to those phthalocyanines in which substituents contribute to an increase in HOMO energy relative to the unsubstituted macrocycles

https://doi.org/10.1016/j.photonics.2024.101350

A resonant microcavity with photonic crystal mirrors and a chiral liquid crystal resonant layer is fabricated. In our experimental set-up the microcavity is illuminated at Brewster’s angle, for which the TM-polarized scattering channels are open, while the TE-polarized channels are closed. Thus, the problem is reduced to two-channel scattering. By applying an external voltage to the resonant layer it is possible to control the position, linewidth and amplitude of multiple resonant lines via changing the radiation decay rate into the scattering channels due to polarization mixing within the chiral layer. It is found, that under a certain value of the applied voltage, the microcavity becomes transparent over a wide spectral range, i.e. none of the resonant modes can be excited.

https://doi.org/10.1016/j.jssc.2025.125183

A series of single crystals of solid solutions KTi_1-xZr_xOAsO₄ (x = 0.025, 0.05, 0.075, 0.1) have been grown by the Czochralski method. The structural analysis of this series of samples showed that at titanium partial substitution (0.025 ≤ x ≤ 0.1) Zr⁴⁺ occupies the T1 position of the Ti1O₆ octahedron, as well as the T2 position of the Ti2O₆ octahedron, at the same time the volume of octahedra increases. But at 0.05 ≤ x ≤ 0.1 the volume of the Ti1O₆ octahedron stops growing, and only the volume of Ti2O₆ increases, consequently, at x = 0.05 Zr saturation is observed at position Ti1. The Raman spectrum of a pure KTA crystal is very different from the spectra of the entire range of solid solutions. In the transmission spectrum of samples with partial substitution of titanium atoms by zirconium atoms, there is practically no wide absorption band at 3.5–4 μm typical for pure KTA, the maximum crystal transparency in this region is achieved for x = 0.075. It was found that the introduction of large Zr ions into the KTiOAsO₄ structure leads to a distortion of the lattice and an increase of the band gap.

https://doi.org/10.1016/j.jallcom.2024.178297

For the first time, single crystals of Ni_3−xMn_xBO₅:Cu, measuring up to 0.4×0.4×4 mm³, have been grown using the flux technique. The flux used was based on Bi₂Mo₃O₁₂-B₂O₃; the addition of CuO served as a solvent component and promoted the growth of Ni_3−xMn_xBO₅:Cu. Energy-dispersive X-ray spectroscopy (EDX) showed that the concentration of copper in the crystal, relative to the flux content was low-approximately 1:8. Subsequently, neutron diffraction, alternating current (AC) magnetization, and electron spin resonance (ESR) were performed on the Ni_3−xMn_xBO₅:Cu compound, which is classified as ludwigite-type compound. Neutron diffraction results confirmed that the Ni_3−xMn_xBO₅:Cu structure belongs to the Pbam space group. Furthermore, AC magnetization and ESR measurements identified three ferrimagnetic phase transitions occurring at 90 K, 95 K, and 150 K, as well as a canonical spin-glass transition near 50 K.

https://doi.org/10.1016/j.jallcom.2024.178421

Fe-doped cobalt oxide nanoparticles, Fe_xCo_3-xO₄, attract considerable attention due to their unique properties, high application potential, and the ability to vary the properties over a wide range by changing the technological conditions. The annealing temperature is one of the decisive parameters critically affecting the properties of nanoparticles. In this work, we studied the Fe_0.5Co_2.5O₄ (Co₃O₄ type) nanoparticles synthesized by the combustion method: the impact of annealing temperature (400, 500, 600, 700 and 800 °C) on their structural, morphological, magnetic characteristics and on their ability to absorb organic dyes. X-ray diffraction analysis revealed that the nanoparticles under study consisted of a crystalline phase of Fe_0.5Co_2.5O_4, with an admixture of the iron oxide phase in trace concentrations. A giant increase in the crystallite size due to annealing was observed. Overall, the average crystallite size increased from ⁓5 nm in the as-prepared sample to ⁓110 nm in the sample annealed at 800 °C. These changes in size are explained by the efficiency of the Ostwald ripening process. They are accompanied by an increase in the magnetization of nanoparticles and an appearance of magnetic hysteresis. The study of the adsorption properties of the nanoparticles with respect to the most important water pollutants – organic dyes, i.e. cationic methylene blue (MB) and anionic Congo red (CR) revealed their high selective adsorption capacity to CR. The as-prepared nanoparticles had the highest capacity: the CR dye concentration in water decreased by 90 percent within 5 minutes of exposure to the nanoparticles in concentration of 1 g/L. When the annealing temperature increased from 400 to 800 °C, the adsorption capacity decreased by approximately half, but remained high enough to consider these nanoparticles as a promising material for CR selective removal from water.

https://doi.org/10.1016/j.solidstatesciences.2024.107821

New structure of Na₃Yb(BO₃)₂ has been synthesized for the first time using a solid-state reaction method. The crystal structure of the title compound was elucidated using a simulated annealing method. Samples used in powder diffraction analysis for structure determination were prepared via solid-state synthesis. To refine obtained crystal structure, the Rietveld method was applied, yielding the following parameters: triclinic symmetry (sp. gr. P 1¯.), a = 5.1661(1) Å, b = 6.6249(2) Å, c = 8.5991(2) Å, α = 92.089(1)°, β = 93.281(2)°, γ = 88.010(1)°, Z = 2, V = 293.47(1) ų, R_wp = 4.83, GOF = 4.85. The double borate Na₃Yb(BO₃)₂ congruently melted at 1119 °C exhibited a complex thermal profile, as evidenced by DSC, with four polymorphic transitions observed at 277 °C, 497 °C, 653 °C, and 694 °C. Ab initio calculated IR spectrum of Na₃Yb(BO₃)₂, exhibited a high degree of agreement with the experimentally obtained IR spectrum. The band gap of the title compound was calculated to be 4.7(2) eV using the combination of the Tauc method and DASF method. The calculated energy barrier for sodium ion migration, equal to 0.5 eV, was in a reasonable agreement with the experimentally determined activation energy of 0.75 eV. The title compound exhibited an ionic conductivity of 0.4 × 10⁻³ S/cm at 1023 K.

https://doi.org/10.1080/01431161.2024.2440670

In this theoretical paper, a method for temperature profile retrieval in frozen tundra soil is proposed based on the thermoevolutionary relationship between polarimetric multi-angular brightness temperature (TB) at 1.4 GHz, observed in sliding time window with a fixed duration, and the time series of soil temperature profiles, predicted by the heat equation. For TB modelling, the profiles of volumetric moisture, dry bulk density, and organic matter content in the active layer, measured at the Franklin Bluffs test site (North slope of Alaska, U.S.) from 12 December 2022 to 5 May 2023, were used. When solving the inverse problem, the retrieving temperature profiles were specified as a linear interpolation function between four known depths 0 cm, 25 cm, 50 cm, and 95 cm. The thermodynamic properties of the frozen active layer were considered independent of soil temperature, time, and vertical coordinates, which made it possible, based on weather station data, to determine the apparent value of the thermal diffusivity coefficient in the heat equation. The practically significant accuracy of retrieving soil temperature up to a depth of 70 cm with a root-mean-square error of 0.5–1.8°C and a coefficient of determination of 0.877–0.988 was demonstrated by the proposed method. The pursued research shows the advantage of the synergy of the heat equation and polarimetric multi-time compared to only single-moment TB observations for temperature profile retrieval in frozen tundra soil.

https://doi.org/10.1016/j.jallcom.2024.178230

The magnetic properties of rare-earth borates evoke keen interest, since the coexistence of two interconnected magnetic subsystems, 3d and 4 f ions, in the crystals of this family causes a diversity of magnetic structures and phase transitions between them. A comparative study of the effect of synthesis conditions on the structure and magnetic properties of the terbium chromoborate TbCr₃(BO₃)₄ single crystals grown from bismuth molybdate and lithium tungstate solvents has been carried out. In the single crystals with the monoclinic symmetry synthesized from the bismuth molybdate solvent, partial substitution of Bi³⁺ions for Tb³⁺ ions occurs, which entails a change in the magnetic anisotropy of the crystal and the formation of an angular magnetic structure, in which, unlike the crystals grown from another solvent, the Ising axis of Tb³⁺ ions deviates from the С₃ pseudo-axis direction by an angle of ∼40°. In the case of the lithium tungstate solvent, single crystals with the trigonal and monoclinic symmetry are formed and their temperature and field dependences of the magnetization coincide. At a Néel temperature of T_N1 = 9.2 K, the antiferromagnetic ordering with the magnetic moments lying in the basal plane is established in the Cr³⁺ ion subsystem. Due to the weakness of the exchange interaction between Cr³⁺ and Tb³⁺ ions, the antiferromagnetic order in the terbium subsystem of all the investigated TbCr₃(BO₃)₄ crystals is formed at a lower temperature: T_N2 = 5.5 K. The existence of two temperatures of the successive ordering of the magnetic subsystems of 3d and rare-earth ions has been found for the first time in the crystals of the huntite family and confirmed by the results of the magnetization and specific heat investigations. The lower ordering temperature of the terbium subsystem, which has a strong easy-axis magnetic anisotropy, also explains the nature of the easy plane→easy axis orientational transition in the chromium subsystem discovered previously at a temperature of ∼5 K.

https://doi.org/10.1007/s10948-024-06894-4

The Boltzmann sigmoid function effectively describes parameter changes during transitions between different states. A method using the Boltzmann function is proposed to analyze the temperature dependencies of superconductors near their critical temperature. Data for various superconductors (MgB₂, YBCO, Bi2212, a high-entropy alloy, CeH₉) are described, and parameters characterizing their resistive transition are estimated.

https://doi.org/10.1016/j.mssp.2024.109237

Light-induced transport phenomena in semiconductor-based structures with magnetic layers, have been the subject of significant scientific research. One notable mechanism for inducing magnetotransport effects in semiconductor-based devices is the lateral photovoltaic effect (LPE), which arises from the separation of photogenerated carriers under illumination. We present a study on the simulation of spectral dependence of diffusion-induced photovoltage in Mn/SiO₂/n-Si hybrid structure. By analyzing both lateral and transverse photovoltaic effects in terms of light absorption depth, we gain a deeper insight of the mechanisms governing light-induced transport. The magnetic field's effect on photovoltage is attributed to the Lorentz force and sample's geometry. Additionally, the photovoltage's dependence on the magnetic field exhibits ferromagnetic hysteresis, suggesting the presence of a ferromagnetic MnSi phase near the Mn/SiO₂ interface.

https://doi.org/10.1021/acsomega.4c07152

The magnetization and anisotropy of magnetic susceptibility of a 5CB nematic liquid crystal doped three extracts containing chlorophylls a and b and carotenoids in different weight percentage has been studied. The extracts have been dissolved in the liquid crystal matrix at a concentration of 2%. The magnetic susceptibility of the substances has been measured by the Faraday–Curie balance method. The field σ(H) and temperature Δχ(T) dependences of molar magnetizations σ and anisotropy of magnetic susceptibility Δχ for the investigated objects have been obtained. The divergence of the σ(H) dependences for the extracts dissolved in the liquid crystal matrix and in acetone has been found. The growth of the Δχ values in the Δχ(T) dependence with an increase in the weight percentage of chlorophylls in the extracts has been established. The influence of molecules of the dopants on the anisotropy of magnetic susceptibility has been evaluated with allowance for the π-electron currents in the conjugated systems of the benzene rings and in the porphyrin nuclei of chlorophylls, as well as in chemical bonds of the aliphatic fragments.

http://journal.sfu-kras.ru/en/article/154329

Study of the molecular transport of benzene and cyclohexane in mesoporous mesostructured powders of SBA‑15 was carried out using the diffusion NMR method. An isotropic character of the translational motion of hydrocarbon molecules was observed on a length scale of 35–80 μm. It was found that at low content of hydrocarbons (φ<0.3, where φ is a mass content), the mobility of their molecules is 2–3 times higher than those typical for a liquid media. It was also shown that for benzene molecules, unlike to cyclohexane, in the range of 0.4<φ<0.6 the hindering of translational motion is observed as compared to those in liquid state, which can potentially lead to a shift of the equilibrium in the benzene/ cyclohexane mixture at the outlet of the porous material sample.

Методом ЯМР‑диффузометрии проведено исследование процессов молекулярного транспорта бензола и циклогексана в мезопористых мезоструктурированных порошках SBA‑15 в зависимости от массового содержания углеводородов. Обнаружен изотропный характер трансляционного движения молекул углеводородов в масштабах 35–80 мкм. Найдено, что при малых значениях содержания углеводородов (φ<0,3, где φ – массовая доля) мобильность их молекул в 2–3 раза превышает значения, характерные для жидкой среды. Для молекул бензола, в отличие от циклогексана, в концентрационном диапазоне 0,4<φ<0,6 наблюдается торможение скорости трансляционного перемещения по сравнению с жидкой средой, что может приводить к изменению равновесного содержания одного из компонентов в смеси на выходе из объема материала.

https://doi.org/10.3390/cryst14121025

The effect of the Mn³⁺ ion on the local distortions of FeO₆ octahedra in orthoferrite samples was investigated. Mössbauer spectroscopy measurements for a series of HoFe1−𝑥Mn𝑥O3HoFe1−�Mn�O3 (x = 0–0.7) orthoferrite samples with the space group Pnma were carried out at temperatures above the Néel point (700 K). The electric field gradient (EFG) tensor on Fe ions for these compounds was found using first-principle calculations. The concentration dependence of quadrupole splitting was obtained using experimental and theoretical data. Mn³⁺ cations were found to affect the Mössbauer spectra mainly due to distortions of the crystal lattice. Theoretical calculations show that the values of all electric field gradient components increase significantly with the manganese concentration in the system, and the eigenvectors 𝐞𝐱𝐱�xx and 𝐞𝐲𝐲�yy of the electric field gradient tensor sharply change their direction at concentrations of x > 0.1.

https://doi.org/10.1007/s10854-024-14121-y

Developing new environmentally friendly methods of producing materials for electronics is critical important task for material science. Manufacturing process of semiconductor materials, transparent electrodes, electrical and thermal conductive pastes, fillers for conductive inks and some other materials should be improved from environmental point of view. Here we present a waste-free closed cycle fabrication of two important materials for electronics based on the concept of a self-organized cracked template. Optically transparent silver meshes and silver microflakes were obtained in waste-free manufacturing cycle. The morphological, structural, optoelectric, and shielding properties of transparent silver meshes and silver microflakes films were studied in detail. Also, we made transparent heater in close manufacturing cycle. The first type of materials are transparent silver meshes with irregular structure that have a transparency of more than 80% in visible range and with a shielding efficiency of more than 40 dB in the S and L bands and about 30 dB in the K and K_a bands. The second type of material is silver microflakes. We produced solid films using vacuum filtration with our silver microflakes. These films have a shielding efficiency of 90.1 dB with a thickness of 6.2 ± 1.2 μm in the K and K_a bands. A detailed analysis of the shielding properties showed that both types of the obtained shielding materials are comparable to the best literature results in shielding efficiency and are significantly lower in cost than analogs. We show silver mesh transparent heater with contact pads based on self-made conductive pastes filled with silver microflakes. Self-made conductive paste has a low resistivity of 5.26 ± 1.13 µΩ∙m. Optically transparent heaters obtained in a waste-free closed cycle demonstrate uniform temperature field distribution and high heating efficiency. Our results show a new approach for creating materials for electronics and this is significant addition for this emerging industry.

 https://doi.org/10.1002/pssr.202400279

The epitaxial alignment of Mn₂GaC MAX phase on 12 common single-crystalline substrates is analyzed through a crystallographical approach utilizing near-coincidence site lattices. This method effectively predicts epitaxial relationships in MAX phase thin films grown on MgO(111) and Al2⁢O3(001), as well as prospective rutile, muscovite, MgAl2⁢O4 and SrTiO3 substrates, highlighting the chemical affinities and atomic configurations at their interfaces. Novel epitaxial relationships for Mn₂GaC MAX phase are identified, offering alternatives to the traditional (001) out-of-plane orientation and exploring variations in epitaxial lattice stress. Additionally, this study examines the temperature dependence of interface strain for the most promising orientation relationship candidates, offering insights into the effect of substrate temperature on the growth of the MAX phase thin films.