Новые публикации

https://doi.org/10.1107/S2052520625007413

Cover illustration: Crystal structure of Cu2FeO2(BO3) represented in terms of cation- and oxo-centered polyhedra in comparison with figures of eigenvalues of thermal expansion tensor at 300 K (green color) and 1000 K (red color). The anisotropy of thermal expansion is explained by (i) the preferable orientation of the [BO3]3− units, (ii) the theory of shear deformations of the monoclinic ac plane and (iii) an arrangement of the oxo-centered double chains.

https://doi.org/10.1134/S199079312570085X

The processes of water freezing and ice thawing were studied in hydrogels based on sodium polyacrylate, sodium alginate, carboxymethylcellulose of different degrees of crosslinking, and para-aramid hydrogels filled with water. Using magnetic resonance imaging (MRI) method the hydrogels swelling, water distribution within the para-aramid hydrogel, freeze/thaw front propagation and resulting changes in ice composites structure were visualized. It was observed that the presence of a polymer macromolecular network in ice composites based on cross-linked hydrogels hinders the size of ice crystallites formed during freezing, leaving the qualitative picture of the freezing processes unaffected. At the same time, the water-filled porous structure of the para-aramid hydrogels undergoes irreversible changes during the freezing process, which leads to the destruction of the ice composite. It was found out that the rate of freeze/thaw front propagation in ice composites based on cross-linked hydrogels depends on both the mass content of the polymer material and its crosslinking degree. The results obtained demonstrate the capabilities of MRI in studying the heat and mass transfer processes in ice composite materials, which have potential for practical application.

https://doi.org/10.1007/s11051-025-06467-z

The possibility of using magnetite nanoparticles as a sorbent in the isolation of nucleic acids from cells was investigated in this study. Nanoparticles were synthesized by polyol method in ethylene glycol with addition of polyethylene glycol. Then, the nanoparticles were coated with silicon oxide by Stöber method. Particles characterization was performed by transmission electron microscopy, infrared spectroscopy, vibrational magnetometry, and ferromagnetic resonance. The study of the IR spectra showed the presence of bands characteristic of polyethylene glycol related to hydroxide and ether groups. The magnetization curves in the region of approaching magnetization to saturation were investigated and the saturation magnetization, magnetic anisotropy constant, and average size of nanoparticles were determined. The fitting of the temperature dependences of the linewidth and resonance field of the ferromagnetic resonance also allowed us to determine the magnetic characteristics of the nanoparticles. Three different methods used to determine the anisotropy constant (from the line width and resonance field of the ferromagnetic resonance and from the field dependence of the magnetization) showed good agreement with each other. The determined anisotropy constant was approximately 1–2·10⁵ erg/cm³, which is close to the anisotropy constant of bulk magnetite. It is shown that 0.5 mg of the developed particles allows obtaining 2.88 (2.67–3.08) μg μg of nucleic acids. Gel electrophoresis has demonstrated a high degree of purity and integrity of the isolated molecules. The results of evaluating the expression of the ACTB and GAPDH housekeeping genes using particle-isolated RNAs were similar to those using a commercial nucleic acid isolation kit.

https://doi.org/10.1016/j.jallcom.2025.184336

The development of a multibit three-dimensional magnetic memory utilizing segmented nanowires necessitates the establishment of sufficiently strong perpendicular magnetic anisotropy for each memory element to counteract the shape anisotropy inherent in a thin disk. Materials exhibiting significant uniaxial magnetocrystalline anisotropy are suitable for this purpose. Cobalt, characterized by a hexagonal close-packed lattice, emerges as a prime candidate due to the controllability of its magnetocrystalline anisotropy's spatial orientation through the manipulation of crystalline texture via various electrodeposition conditions. Here, we broaden the spectrum of methodologies to manipulate the direction of effective anisotropy, uncovering a robust correlation between the orientation of cobalt's effective magnetic anisotropy and the substrate materials upon which it is deposited. Our results demonstrate that alterations in the composition of the conducting layer and spacer within segmented nanowires enable the modulation of the magnetic properties of individual cobalt segments, thereby allowing for the precise customization of their magnetic characteristics. These findings expand the range of potential applications of nanowires in nanoelectronics.

https://doi.org/10.1002/lpor.202501813

Flexible thermal sensors are crucial for monitoring the important thermodynamic parameter of temperature in daily life, industrial production, and scientific research. However, significant challenges remain in simultaneously achieving reproducible, sensitive, real-time, and in situ temperature sensing capabilities. Herein, a Mn⁴⁺ mono-doped CsNaNbOF₅:Mn⁴⁺ (CNNOFM) phosphor is designed and synthesized as a dual-mode optical thermometric material, showing high luminescence efficiencies and excellent temperature-dependent behaviors. Combined density functional theory calculations and experimental characterization reveal the isovalent group substitution mechanism between [MnF₆]²⁻ and [NbOF₅]²⁻ octahedrons, eliminating charge compensation defects in the CNNOFM system and thereby leading to enhanced luminescence efficiencies. Furthermore, CNNOFM exhibits remarkable water resistance, retaining 88.12% of its luminescent efficiency after 4 h of water immersion. The CNNOFM demonstrates high relative sensitivity in both fluorescence intensity ratio and lifetime modes, with S_r values of 0.37% K⁻¹ and 5.8% K⁻¹ at 440 K, respectively. Finally, a flexible composite fluorescent fiber temperature sensor is fabricated based on the CNNOFM phosphor to monitor the temperature of an ice-water mixture, exhibiting satisfactory performance. This work not only provides a promising thermally sensitive material for optical thermometry but also offers a new pathway for the development of flexible optical temperature sensors.

https://elib.sfu-kras.ru/handle/2311/156665

The paper presents the results of obtaining an Al-B alloy by treating aluminum ingots with boron in an arc discharge plasma (66 kHz). It was established that the proposed method of plasma alloying allows, on one hand, to move impurities from the inner part of the monolith to the peripheral area, and on the other hand, to uniformly introduce boron into the aluminum monolith

https://www.researchgate.net/publication/395776605_Evaluation_of_the_influence_of_different_methods_of_processing_three_types_of_dental_implant_surfaces_on_their_morphology_and_elemental_composition_in_the_treatment_of_peri-implantitis

Objective. To investigate changes in the morphological structure and elemental composition of dental implants with three types of surface (TiO2, SLA, RBM) after treatment with various methods — Er, Cr: YSGG laser with a wavelength of 2780 nm, Air Flow with erythritol and Vector Paro ultrasound device. Material and methods. A total of 36 dental implants were included: 9 new implants (3 of each surface type) were used as the control group, and 27 implants, explanted from patients with peri-implantitis, were evenly divided into three subgroups according to the cleaning method used. Surface morphology was evaluated using scanning electron microscopy (SEM), and elemental composition was analyzed using energy-dispersive X-ray spectroscopy (EDS). Results. Laser treatment demonstrated versatility and cleaning efficiency without damaging the microrelief for all types of surfaces. The Air Flow air-abrasive method was most effective for the RBM surface, but showed residual surface contamination when treated with TiO2 and SLA. The ultrasonic method using the Vector Paro device was especially effective for the TiO2 surface, probably due to its hydrophilic properties. Conclusion. The choice of decontamination method for the treatment of peri-implantitis should take into account the surface type and characteristics of the dental implant. The Er, Cr:YSGG laser proved to be a universal and effective method, while Air Flow and Vector Paro were more efficient when used for specific surface types.

https://doi.org/10.1016/j.commatsci.2025.114306

The improved criterion of agreement between ab initio simulation and experiment is tested forthe case of bandgaps in strontium and lead tetraborate. Instead of extracting the bandgap from the band structure diagram, we have compared calculated transmission/absorption spectra with experimental ones, obtaining excellent agreement in case of PBO and fair agreement in case of SBO. Certain disagreement in case of SBO can be ascribed to the contribution of indirect interband transitions. More probably, this disagreement indicates the presence of impurities and stresses the necessity of further improvement of crystal growth technology. The nonlinear optical coefficients of SBO are shown to originate from boron‑oxygen network while those of PBO and and β-SnB₄O₇ originate from metal ions with their lone pair electrons.

DOI: 10.21046/2070-7401-2025-22-4-187-204

The article compares incoherent and coherent models of brightness temperature (BT) for layered, non-isothermal bare soils with smooth boundary. BT models include incoherent models obtained on the basis of phenomenological radiative transfer theory (with and without considering a single reflection of the wave from the lower boundary of partial layers of the layered medium), and exact coherent models: Wilheit, Njoku, Klepikov–Sharkov. As non-isothermal layered-inhomogeneous dielectric half-spaces, thawed and frozen soils are considered with modeled and synchronously measured moisture and temperature profiles in the active layer. The complex permittivity of soils is modeled using proven dielectric models. The statistical analysis is based on synchronous calculation of the BT (using all the models under consideration) at frequencies of 409 MHz and 1.4 GHz in the range of viewing angles from 0 to 60° at vertical and horizontal polarizations. As a result, it is shown that coherent BT models (Wilheit, Njoku, Klepikov–Sharkov) have the same accuracy within the limits of computation error or digitization of graphic data from third-party origins. The average absolute difference between the BT calculated by incoherent and coherent models for all considered sets of moisture and temperature profiles can reach 20 and 8 K at frequencies of 409 MHz and 1.4 GHz, respectively, if the condition of smoothness of the refractive index profile at the soil surface is not met (large scale of vertical dielectric inhomogeneities in relation to the wavelength). If this condition is met, then the error does not exceed several degrees Kelvin. It is shown that the modification of the incoherent model by introduction into the reflectivity of a coefficient of coherent reflection from the air-soil interface allows achieving accuracy close to coherent models, even for freezing soils with a sharp jump in the complex permittivity between the freezing and thawed parts of the active layer. This study corroborates the applicability of a partially coherent emission model for calculating, in a wide frequency range, the angular dependencies of BT at horizontal and vertical polarizations of bare soils with smooth boundary and virtually any moisture and temperature profiles observed in the active layer.

https://doi.org/10.3390/ijms26188952

The seed drying process is one of the most important aspects of post-harvest treatment, which determines the quality of the final product, cost accounting, and storage capacity. Sorption drying is of great scientific and practical importance due to its ability to gently remove moisture, which improves seed quality and ensures energy efficiency. In this study, wheat grains with an initial moisture content of 22% were dried to a moisture content of 13% using sorption, thermal, and natural air drying. The seed germination capacity after drying was 97%, 93%, and 95%, respectively. The effect of different drying methods on the morphological characteristics, microstructure, and moisture content of wheat grains was studied using a combination of experimental techniques. ATR-MIR and MAS NMR analysis revealed the biochemical stability of sorption-dried grains and the complete preservation of characteristic protein amide bands, indicating the absence of molecular degradation. Statistically significant differences in wheat grains after thermal and sorption drying were observed in luminescence peak intensities and standard deviation of the main spectral band’s half width. The MRI method demonstrated that sorption drying preserves optimal grain tissue microstructure while maintaining proper moisture levels and distribution prior to germination, as well as supporting natural mass transfer processes and moisture distribution evolution during dehydration.

DOI https://doi.org/10.1039/D5CE00638D

The response of the diiodobutenyl-bis-thioquinolinium triiodide crystal structure to hydrostatic compression from 1 atm to 4 GPa and mechanical stress was studied using experimental techniques (Raman and Brillouin spectroscopy, single-crystal X-ray diffraction) and periodic DFT modeling. A phase transformation above 2.5(1) GPa manifested itself by abrupt changes in the unit cell parameters and non-merohedral twinning. The changes in the band positions in the low-wavenumber region of Raman spectra were attributed to a change in the bridging hydrogen position in the N⋯H⋯N fragment and to the changes in the anion. The DFT modeling of the crystal structure on compression revealed the changes in the structural fragments that can explain why a high-pressure phase transition takes place.

 https://doi.org/10.3390/magnetochemistry11090072

High-calcium fly ash (HCFA), produced from the lignite combustion, has emerged as a global concern due to its fine particle size and adverse environmental impacts. This study presents the characteristics of dispersed microspheres from HCFA obtained using modern techniques, such as XRD, SEM-EDS, ⁵⁷Fe Mössbauer spectroscopy, DSC-TG, particle size analysis, and magnetic measurements. It is found that an increase in microsphere size is likely due to the growth of the silicate glass-like phase, while the magnetic crystalline phase content remains stable. According to the ⁵⁷Fe Mössbauer spectroscopy, there are two substituted Ca-based ferrites—CaFe₂O₄ and Ca₂Fe₂O₅ with a quite different magnetic behavior. Besides, the magnetic ordering temperature of the brownmillerite (Ca₂Fe₂O₅) phase increases with the average diameter of the microspheres. FORC analysis reveals enhanced magnetic interactions as microsphere size increases, indicating an elevation in the concentration of magnetic microparticles, primarily on the microsphere surface, as supported by electron microscopy data. The discovered the magnetic crystallographic phases distribution on the microsphere’s surface claims the accessibility for further enrichment of the magnetically active particles and the possible application of fly ashes as a cheap source for magnetic materials synthesis.

https://doi.org/10.1063/5.0235000

Rare earth substitution in cuprate superconductors has sparked intense interest, driving progress in both fundamental research and advanced technology. In this investigation, we focus on SmBa 2Cu 3O 7−� (SmBCO), synthesized via the top-seeded melt growth method, with an aim to understand the corresponding vortex phases. Despite the minimal impact on transition temperature (⁠ ��⁠) when yttrium in YBa 2Cu 3O 7−� is replaced by Sm, the critical current density (⁠ ��⁠) remains exceptionally high under intense magnetic fields. Introducing Sm 2Ba 1Cu 1O 5 (Sm-211) phase as point defects significantly boosts the pinning potential (⁠ �⁠) and pinning force (⁠ ��⁠) and enhances their stability against external magnetic fields. Contrary to other superconductors, the SmBCO sample displays a notable peak effect in the magnetic field-dependent ��⁠, driven by point defects introduced by the Sm-211 phase, which prompts vortex lattice softening and initiates a transition from an ordered to a disordered vortex glass phase, leading to the emergence of a second magnetization peak. Analysis suggests that the primary pinning mechanism in SmBCO involves a combination of normal point and Δ� pinning. Additionally, investigations of the vortex glass phase beneath the thermally activated flux flow regime indicate that vortices in SmBCO may freeze into a state akin to a 2D vortex glass state. This study leads to a detailed phase diagram that clarifies the evolution of vortex phases in SmBCO.

https://doi.org/10.1021/acs.chemmater.5c01429

Introducing large-radius cations usually causes structural relaxation, leading to a spectral redshift and low optical performance in Cr³⁺-activated phosphors. Here, MNAl₁₀O₁₇:Cr³⁺ phosphors are synthesized, and the substitution of large-radius cations induces the abnormal lattice shrinkage of the N site and atomic site splitting of the M site due to the unique hexaaluminate structure, further distinctly improving luminescent properties. To investigate the university of atomic site splitting, a series of phosphors, Na_2(1–m)K_2mAl_10.8O₁₇:0.2Cr³⁺ and Gd_1–nLa_nMgAl_10.8O₁₉:0.2Cr³⁺, are synthesized, and the variation of their luminescent properties conforms to the expected rule. Finally, Ga³⁺ ions are introduced to improve the luminescence efficiency. Internal/external quantum efficiencies of the optimal sample are 98.1 and 65.8%, respectively. Meanwhile, an anomalous spectral blueshift indicates the existence of Cr³⁺–Cr³⁺ exchange coupling pairs, and a comparative analysis of similar cases is conducted to provide some insights into the luminescence of coupling pairs.

https://doi.org/10.1016/j.jallcom.2025.183960

Cr³⁺-doped phosphors still suffer from limitations, such as low quantum efficiency, poor thermal stability, and spectral peak mismatch, restricting their application in pc-LEDs for indoor agriculture. In this study, cation Sc substitution strategy was applied in Y₃Ga₅O₁₂. Given that the emission location, an efficient far-red (FR) phosphor Y₃ScGa₄O₁₂:Cr³⁺ (YSGO:Cr³⁺) with high matching to phytochrome was constructed, under 442 nm excitation, realizing FR emission (728 nm) with FWHM 99 nm. The optimized phosphor demonstrates exceptionally high internal quantum efficiency of 95.4 % and excellent thermal quenching property (91.6 %@423 K). Furthermore, a fabricated phosphor-converted light-emitting diode (pc-LED), combining YSGO:0.07 Cr³⁺ with a 450 nm chip, delivers FR output power of 36.74 mW with a photoelectric conversion efficiency (PCE) of 12.8 % at 100 mA, demonstrating ultra-low quenching rate (<5 % intensity loss after 3 months operation). A supplemental lighting model for lettuce growth was constructed, which significantly improves in physiological parameters, confirming the great potential of this phosphor for plant lighting applications.

DOI: https://doi.org/10.1103/gymx-jk1g

Magnon-phonon hybridization in ordered materials is a crucial phenomenon with significant implications for spintronics, magnonics, and quantum materials research. We present direct experimental evidence and theoretical insights into magnon-phonon coupling in Mn3⁢Ge, a kagome antiferromagnet with noncollinear spin order. Using inelastic x-ray scattering and ab initio modeling, we uncover strong hybridization between planar spin fluctuations and transverse optical phonons, resulting in a large hybridization gap of  ∼2  meV. This coupling is driven by interlayer Heisenberg exchange interactions and is enhanced by the material’s symmetry and magnetic frustration. The simplicity of the Mn3⁢Ge structure enables clear identification of the hybridized modes, bridging theoretical predictions and experimental observations. Our findings establish Mn3⁢Ge as a model system for exploring magnon-phonon interactions and offer a pathway for designing materials with tunable magnetoelastic properties.

https://doi.org/10.3390/ma18174102

Highly efficient shielding materials, transparent in the visible and IR ranges are becoming important in practice. This stimulates the development of cheap methods for creating transparent conductors with low sheet resistance and high optical transparency. This work presents a complex approach based on preliminary modeling of the shielding characteristics of two-layer sandwich structures based on irregular aluminum mesh (IAM) formed by the cracked template method. Experimentally measured spectral dependences of the transmission coefficient of single-layer IAM are used as a reference point for modeling. According to the simulation results, two types of sandwich structures were designed using IAM, with varying filling factors and a fixed PMMA layer thickness of 4 mm. The experimentally measured shielding characteristics of the sandwich structures in the range of 0.01–7 GHz are in good agreement with the calculated data. The obtained structures demonstrate a shielding efficiency of 55.96 dB and 65.55 dB at a frequency of 3.5 GHz (the average range of 5G communications). At the same time, their optical transparency at a wavelength of 550 nm are 84.07% and 75.78%, respectively. Our sandwich structures show electromagnetic shielding performance and uniform diffraction pattern. It gives them an advantage over structures based on regular meshes. The obtained results highlight the prospect of the proposed comprehensive approach for obtaining highly efficient, low-cost optically transparent shielding structures. Such materials are needed for modern wireless communication systems and metrology applications.

https://doi.org/10.3390/molecules30173604

Rapeseed is a valuable oilseed crop, and efficient drying plays a crucial role in preserving its quality. Because of the high moisture content in rapeseed, drying using the conventional methods may cause it to overheat. The benefit of energy-efficient sorption drying is that it allows one to carefully remove moisture from seeds without using heat, thus ensuring better quality. This study focuses on the characteristics of rapeseed drying using fine crystalline magnesium sulfate MgSO₄·nH₂O as a desiccant. The properties of the desiccant were analyzed using the SEM–EDS, XRD, ATR–MIR, and DSC-TG techniques before and after contacting rapeseed. The findings demonstrate that the desired moisture content of 7–8% can be achieved within 60–240 min, depending on the initial moisture content of rapeseed (ranging from 12% to 16%) and the desiccant-to-rapeseed ratio (1:2, 1:4, or 1:6). An analysis of crystalline hydrates after sorption drying indicates that the desiccant can be reused without intermediate regeneration during multi-stage drying of two to three rapeseed batches. The germination capacity of the seeds after sorption drying was as high as 90%, meeting the standards for elite rapeseed categories. This research demonstrates that sorption drying using magnesium sulfate is an efficient method for reducing moisture content in oilseeds, while maintaining their quality.

DOI: 10.1039/d5dt01230a

A novel oxyborate, NiCr(BO₃)O, is synthesized using a flux method. The material crystallizes in an orthorhombic warwickite structure, space group Pbnm(62), with lattice parameters a = 9.3438(13) Å, b = 9.0908(13) Å, and c = 3.0507(4) Å. Although Ni and Cr atoms are highly disordered over two inequivalent metal sites, the compound undergoes a magnetic phase transition at T_N = 45 K, as characterized by maximum dc magnetization and ac susceptibility and a λ-peak in heat capacity. Upon further cooling, another magnetic anomaly occurs at about 10 K. At high temperatures, magnetic susceptibility follows the Curie-Weiss law, with a highly negative Weiss temperature (θ ≈ -130 K), indicating strong predominance of antiferromagnetic coupling. The effective magnetic moment (μ_eff) is ≈4.9μ_B per f.u. Field-induced spin-orientation transition is observed below T_N for an external field applied perpendicular to the c-axis. Magnetic heat capacity was determined by subtracting the lattice heat capacity of the nonmagnetic analog. Debye temperature is evaluated to be 365 K. NiCr(BO₃)O is the first example demonstrating magnetic ordering in the highly disordered oxyborate family.

https://doi.org/10.1016/j.cej.2025.168055

Development of multifunctional nanomaterials for visible-light-driven environmental remediation remains a major challenge in green chemical engineering. In this study, we report on solution combustion synthesis of biocompatible Sc_xLu_1-xFeO₃ (x = 0, 0.5, 1) nanocrystals with unique photocatalytic and magnetic properties. Structural characterization confirmed phase-pure formation of orthorhombic (o-LuFeO₃), hexagonal (h-Sc_0.5Lu_0.5FeO₃), and cubic (c-ScFeO₃) perovskite-type phases with crystallite sizes of 89.3, 36.7, and 54.3 nm, respectively. Morphologically, the materials exhibited a porous foam-like architecture with BET surface areas of 10.06–14.36 m²/g and dominant mesopores (3.9–11.2 nm). Diffuse reflectance spectroscopy revealed a strong visible-light absorption and narrow band gaps ranging from 1.97 to 2.30 eV. Under visible-light irradiation (λ = 410 nm), h-Sc_0.5Lu_0.5FeO₃ showed superior photocatalytic degradation of methylene blue, achieving 100 % removal within 30 min with a rate constant of 0.1448 min⁻¹, outperforming both o-LuFeO₃ (45 %, 0.0206 min⁻¹) and c-ScFeO₃ (60 %, 0.0321 min⁻¹). Magnetic studies revealed strong coercivity in o-LuFeO₃ (2.5 T), spin-glass-like features in h-Sc_0.5Lu_0.5FeO₃ (T_N = 151 K), and weak antiferromagnetism in c-ScFeO₃. Biocompatibility testing using THP-1 and K562 cell lines showed more than 80 % of cell survival at concentrations up to 0.25 mg/mL, with no significant morphological damage among THP-1 and K562 cells. Owing to their combined photocatalytic efficiency, magnetic separability, and biological safety, these materials are promising for integration into hybrid wastewater treatment systems as biocompatible visible-light-responsive photocatalysts.

https://doi.org/10.1016/j.jssc.2025.125637

Y₂OSe₂, a novel phosphor matrix, was first synthesized via sintering/melt crystallization of Y₂Se₃ and Y₂O₂Se precursors. Guided by LLM predictions (accurately forecasting synthesis at 800–1000 °C and incongruent melting ∼1450 °C), it crystallizes orthorhombically (Pnma, Gd₂OSe₂-type; a = 15.9748 (2), b = 3.89420 (5), c = 6.96804 (9) Å, V = 433.476 (10) ų, Z = 4), contrasting the LLM's initial monoclinic (P2₁/c) prediction. Particles are oval with layered granular morphology (microhardness 290 ± 8 HV). The phase is stable under standard conditions and melts incongruently at 1470 ± 8 °C (forming melt + Y₂O₂Se), validating LLM thermal forecasts. Polycrystalline Y₂OSe₂ coexists in equilibrium with Y₂Se₃ or Y₂O₂Se. Raman spectra analysis, combining experimental data and DFT calculations, was performed. It has been shown that in the crystal structure of Y₂OSe₂, ion vibrations exhibit collective behavior in the low-frequency region, while the intense peaks above 110 cm^–1 are mainly due to vibrations of specific types of ions. The simulation of the band structure and of the absorption spectrum reveals the origin of the onset of fundamental absorption, namely, the onset of direct transition at 1.76 eV into highly dispersive part of conduction band that contributes to the indirect bandgap, then the onset of more pronounced absorption above 3 eV at transitions to less dispersive part of conduction band. Four of five experimentally observed bands in the absorption spectrum are present in the simulated spectrum. Observed features are common to a variety of chalcogenides that were investigated in last two years.

https://doi.org/10.1016/j.jssc.2025.125610

Detailed studies of heat capacity, thermal expansion, sensitivity to hydrostatic pressure, as well as mechanocaloric effects were carried out for single-crystal and ceramic (NH₄)₃H(SO₄)₂ undergoing a number of structural transformations at atmospheric pressure: R-3m ↔ (C2/c) ↔ (P2/n)₁ ↔ (P2/n)₂ ↔ P-1. A significant smearing of the anomalous contribution to the deformation of the ceramic sample was observed, especially near first order transformations, while the behavior and values of the anomalous entropy are in satisfactory agreement for both samples. For the first time, the region of the T – p phase diagram, including low temperature phase transitions, was experimentally investigated. A good correspondence was found between the measured and calculated volumetric baric coefficients. A comparative analysis of the baro(BCE)- and piezo(PCE)-caloric effects was carried out using entropy–temperature phase diagrams at various hydrostatic/uniaxial pressures. Inverse BCE is characteristic of all studied phase transitions, which is caused by a decrease in their temperatures under hydrostatic pressure. Due to rather low symmetry of the crystalline phases, (NH₄)₃H(SO₄)₂ demonstrates a strong anisotropy in the thermal expansion which leads in turn to the difference in the values and sign of the linear baric coefficients and, as a result, to conventional and inverse PCE associated with the various crystallographic axes. The caloric parameters of single-crystal and ceramic (NH₄)₃H(SO₄)₂ are analyzed in comparison with some other derivatives of ammonium sulphate.

https://doi.org/10.1016/j.photonics.2025.101436

Bound states in the continuum (BICs) are specific resonant modes with infinite radiative quality factors that arise from a mismatch with free-space radiation through mechanisms of symmetry protection, parameter tuning, or accidental degeneracy. To harness the significant potential of BICs for light-emission applications such as LEDs and lasers, it is essential to efficiently integrate light-emitting nanomaterials with BIC-based architectures. Here, we numerically model the effect of a light-emitting capping layer on the plasmon-photonic hybrid system consisting of an aluminum substrate with a two-dimensional periodic wave-like interface to an anodic alumina photonic crystal slab. We consider CdSe/CdS nanoplatelets (NPLs) as the gain material because of their high potential for industrial applications. The proposed practical guide for compliance with the conditions for bound states formation, spectrally aligned with the photoluminescence band of the NPLs, can be further used for experimental realization in high-performance solution-processable lasers.

https://doi.org/10.1016/j.jallcom.2025.183213

Complex ludwigite Cu2MnBO5 was doped by Cr ions in amount of 0.08 per unit cell. It demonstrates two close phase transition temperatures of 52 and 59 K into a canonical spin-glass state. It is shown that with an increase of the external magnetic field up to the magnetic field 3 T, the effective magnetic moment drops from 5.33 up to 4.38 �B and Curie–Weiss temperature elevates from −70 up to −15 K. This is probably due to the transition from a high-spin state to a low-spin state for manganese ions. The magnetization, XPS and EPR spectra were measured. The temperature dependence of the specific heat in a zero magnetic field and 9T has been measured. It is shown that Einstein temperatures change in a 9T magnetic field.

https://doi.org/10.1038/s41598-025-16192-1

We consider resonances induced by symmetry protected bound states in the continuum in dielectric gratings with in-plane mirror symmetry. It is shown that the shape of the resonance in transmittance is controlled by two parameters in a generic formula which can be derived in the framework of the coupled mode theory. It is numerically demonstrated that the formula encompasses various line-shapes including asymmetric Fano, Lorentzian, and anti-Lorentzian resonances. It is confirmed that the transmittance zeros are always present even in the absence up-down symmetry. At the same time reflectance zeros are not generally present in the single mode approximation. It is found that the line-shapes of Fano resonances can be predicted to a good accuracy by the random forest machine learning method which outperforms the standard least square methods approximation in error by an order of magnitude in error with the training dataset size �≈104.

https://orcid.org/0000-0002-6000-4930

Near-infrared (NIR) light has a high application value in various fields due to its spectral characteristics. Typically, the broadband NIR emission of Cr³⁺ is based on the transition of ⁴T₂→⁴A₂, while the ²E level emits narrowband emission. This work discovered broadband NIR emission from the [⁴A₂, ⁴T₂] coupling excited state energy level in the spinel structure. The dense and adjacent Al1O₆ as the occupied sites of Cr³⁺ provides a structural basis for the exchange coupling effect under high Cr³⁺ concentration, as confirmed by the analysis of site occupancy, formation energy, bond valence sum, and effective coordination number. Spectral information and EPR signals indicate that the [⁴A₂, ⁴T₂] coupling excited state in the emission spectrum corresponds to the downward shift of the T₂ energy level caused by the Cr³⁺–Cr³⁺ exchange coupling interaction in the strong crystal field of LAO:Cr³⁺. The internal and external quantum efficiencies of LAO:0.15Cr³⁺ are 80.6% and 30.3%, respectively. The luminescence intensity at 370 and 423 K is approximately 92% and 85% respectively of that at room temperature. The excellent luminescence thermal stability is attributed to the activation energy of 0.21 eV and the Huang–Rhys factor S = 3.95. Finally, the material was fabricated into pc-LEDs and its applications in night vision and plant lighting were explored.

https://doi.org/10.1016/j.jmmm.2025.173467

This work explores the magnetic phase transition and magnetocaloric properties of epitaxial Mn₅Ge₃ (001) films on Si(111) synthesized via molecular beam epitaxy. Critical exponents (β = 0.34 ± 0.01, γ = 1.05 ± 0.01, δ = 3.82 ± 0.16) exhibit behavior between 3D Ising and Heisenberg models, attributed to anisotropic exchange interactions. Magnetocaloric entropy change (ΔS) and relative cooling power (RCP) were calculated from isothermal magnetization data, yielding ΔS_max = 3.2 ± 0.21 J·kg⁻¹·K⁻¹ and RCP = 91 ± 6 J·kg⁻¹ at 15 kOe, comparable to bulk Mn₅Ge₃. At low field (H < 6 kOe) positive ΔS is observed due to magnetocrystalline anisotropy. At high filed (H = 15 kOe) estimated adiabatic temperature changes (ΔT_ad) is 1.5 ± 0.1 K. The films’ critical indices and magnetocaloric performance align closely with bulk material, demonstrating minimal decrease from interfacial and strain effects. These results highlight Mn₅Ge₃ thin films as possible candidates for rare-earth-free solid-state cooling micro and nanodevices, combining relatively high efficiency and scalable integration into microsystems. The study advances the understanding of thin film magnetocaloric materials for future application in energy-efficient technologies.

https://doi.org/10.1134/S0021364025607353

Magnetic hysteresis loops of two representative samples of synthetic ferrihydrite nanoparticles with the same sizes (the average size of ≈2.7 nm) and various interparticle distances have been studied under cooling conditions in the presence and absence of an external field. One initial sample is characterized by the aggregation of nanoparticles, and a shift in the magnetic hysteresis loop along the abscissa axis is observed after cooling from a temperature exceeding the superparamagnetic blocking temperature in the external field. The particles in another sample are spatially separated by coating their surface with an arabinogalactan layer, and the shift of the hysteresis loop after cooling in the external field is not observed in this sample. This experimental fact indicates that one of the important factors determining the shift of the hysteresis loop of nanoparticle systems is a pronounced subsystem of surface spins formed during the close contact of particles, which can be considered as a kind of the surface effect. Because of the exchange coupling between the subsystem of surface spins (common for a conglomerate of particles) and uncompensated moments of particles, an additional source of the unidirectional magnetic anisotropy arises during cooling in the external field, which is the origin of the observed exchange bias of the magnetic hysteresis loop.

https://doi.org/10.1016/j.jallcom.2025.182636

Recently, Cr³⁺-doped fluoride materials for phosphor-converted near-infrared light-emitting diodes (NIR pc-LEDs) have been extensively studied, however, their external quantum efficiency (EQE) must be improved. In addition, designing broadband NIR-emitting fluoride phosphors that are sufficiently excited by blue light to match with commercial 460 nm InGaN LED chips is still challenging. In this work, broadband NIR-emitting Cs₂KGaF₆:Cr³⁺, Mn⁴⁺ (CKGF:Cr, Mn) phosphors are synthesized through ion exchange route. Tunable excitation of CKGF:Cr NIR phosphor shifts from 430 nm to 460 nm by co-doping with Mn⁴⁺, which could serve as an additional strategy to improve the photoluminescence of Cr³⁺-doped broadband NIR-emitting phosphors. The NIR emission of CKGF:Cr, Mn is significantly improved, with internal quantum efficiency (IQE) and EQE of 85.9% and 29.0%, respectively. The Mn-free CKGF:Cr phosphor, in comparison, has an EQE of only 15.8% (�ex �ex = 467 nm) and 20.0% (�ex = 433 nm). Furthermore, with excellent thermal stability, CKGF:Cr, Mn phosphor are well suitable for LED applications and the fabricated NIR pc-LED device has high photoelectric efficiency (19.4%@20 mA) and it well performs in night vision, quick inspection and strengthening for deep colors. The described ion exchange method of Cr³⁺-doped fluoride NIR phosphors by co-doping with Mn⁴⁺ is an attractive strategy for optimizing the luminescent properties of blue-excited NIR phosphors.

https://doi.org/10.1111/jace.70177

Lead-free dielectric ceramics are gaining prominence in energy storage due to their superior power density and rapid charge/discharge capabilities. However, Na_0.5Bi_0.5TiO₃ (NBT)-based ceramics stand out as particularly promising dielectric materials, but face two critical challenges: excessive remnant polarization and inadequate dielectric strength, which substantially limit their energy storage performance. To enhance energy storage performance in lead-free ferroelectric ceramics, a stepwise optimization method was adopted in this study. The strategy combines compositional engineering through precise elemental ratio adjustment to tailor microstructural characteristics, and processing optimization to significantly enhance breakdown strength (E_b). This dual-approach methodology has been experimentally demonstrated to effectively boost the energy storage capabilities of the ceramic system. The incorporation of SrTiO₃ as a modifier successfully induced nanoscale domain structures in the 0.91Na_0.5Bi_0.5TiO₃-0.09K_0.7La_0.1NbO₃ (NBT-KLN-based) system, yielding desirable slim P-E loops. Subsequently, the viscous polymer processing (VPP) technique was utilized to minimize defects and boost density, thereby significantly enhancing the E_b. The optimized NBT-KLN-0.20ST-vpp composite ceramics demonstrated remarkable energy storage properties, achieving a high W_rec of 5.34 J/cm³ and efficiency of 82% under 460 kV/cm. This study not only offers a viable strategy for improving NBT-based ceramics but also lays the groundwork for designing advanced energy storage materials, demonstrating promising applications in compact power electronics.