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On 21 January 2024, asteroid 2024BX1, discovered the three hours before, fell to Earth south of Ribbeck in the Havelland region of Germany. In this study, fragments of the Ribbeck meteorite, characterized by white and gray colors lithology, were examined for their chemical and phase compositions. The white lithology fragment exhibited a homogeneous chemical and phase structure typical of orthopyroxene, which crystallizes in the orthorhombic system. The gray lithology fragment showed a greater diversity in chemical and phase compositions. Raman spectra analysis revealed that, in addition to the pyroxenes found in the white lithology fragment, minerals from the olivine group (fayalite and forsterite) were also present, along with plagioclase and sulfur in pure crystalline form. [ABSTRACT FROM AUTHOR]

Exploring the intrinsic mechanisms of rare-earth ions entering the crystal phase has great significance for finely tuning the luminescent properties of glass–ceramics. Using Er3+ ions as a probe, X-ray diffraction was employed to precisely measure the crystallinity of SiO2-PbF2-Er2O3 glass–ceramics synthesized under various heat treatment conditions, confirming the occurrence of a rapid crystallization process. Additionally, by combining Judd–Ofelt theory with comprehensive analyses of absorption and fluorescence spectra, we calculated the relative proportions of Er3+ ions present in the crystal phase. We found that the crystallization process in the glass–ceramics and the incorporation of Er3+ ions into the crystal phase did not occur synchronously. This discovery provides new theoretical foundations and practical guidance for understanding the mechanism of rare-earth ion incorporation into crystal phases, which is significant for the development of functional materials with specific luminescent properties. [ABSTRACT FROM AUTHOR]

High-performance catalysts for the oxygen reduction and hydrogen evolution reactions (ORR and HER, respectively) are highly sought-after, particularly with the commitment of numerous agencies to the removal of conventional gas vehicles in the next few decades. Surprisingly little focus has been placed on the development of magnetic models to describe these systems. The current work will review the current understanding of surface heterogeneous catalysis across select magnetic surfaces, with attention focused on studies involving extended surfaces, which inherently are more accessible to fundamental analysis than the more applied nanoparticle systems. However, even the most up-to-date magnetic variants of this theory have focused on the tight binding limit of the d-band model. In this limit, the reactivity of the surface is governed by the position of the center of the d-band, and the model does not account for the higher moments of the d-band, such as the width, asymmetry, and modality. A summary of the theory supporting this analysis will be presented, along with a summary of the current literature on this level of analysis. The review will then conclude with a discussion of suggested directions for future investigations. [ABSTRACT FROM AUTHOR]

Thermal fluctuations in two-dimensional (2D) isotropy systems at non-zero finite temperatures can destroy the long-range (LR) magnetic order due to the mechanisms addressed in the Mermin-Wanger theory. However, the magnetic anisotropy related to spin–orbit coupling (SOC) may stabilize magnetic order in 2D systems. Very recently, 2D FexGeTe2 (3 ≤ x ≤ 7) with a high Curie temperature (TC) has not only undergone significant developments in terms of synthetic methods and the control of ferromagnetism (FM), but is also being actively explored for applications in various devices. In this review, we introduce six experimental methods, ten ferromagnetic modulation strategies, and four spintronic devices for 2D FexGeTe2 materials. In summary, we outline the challenges and potential research directions in this field. [ABSTRACT FROM AUTHOR]

Samples of nanocrystalline PbF2 glass ceramics were obtained by heat-treating SiO2–GeO2–PbO–PbF2–CdF2 glasses. The Ho2O3 and Tm2O3 doping effects on the structural features of PbF2 nanoparticles were studied using small-angle X-ray scattering and X-ray diffraction methods. The enlargements of the average sizes of nanoparticles and the sizes of local areas of density fluctuations have been found to be correlated with an increase in concentrations of Ho2O3 and Tm2O3 in initial glasses. A variation in the concentrations of Ho2O3 and Tm2O3 does not affect the morphology and fractal dimension of the formed PbF2 nanoparticles. [ABSTRACT FROM AUTHOR]

Herein, we carefully investigated the Fe3+ doping effects on the structure and electron distribution of Cr2O3 nanoparticles using X-ray diffraction analysis (XRD), maximum entropy method (MEM), and density functional theory (DFT) calculations. We showed that increasing the Fe doping induces an enlargement in the axial ratio of c/a, which is associated with an anisotropic expansion of the unit cell. We found that as Fe3+ replaces Cr in the Cr2O3 lattice, it caused a higher interaction between the metal 3d states and the oxygen 2p states, which led to a slight increase in the Cr/Fe–O1 bond length followed by an opposite effect for the Cr/Fe–O2 bonds. Our results also suggest that the excitations characterize a well-localized bandgap region from occupied Cr d to unoccupied Fe d states. The Cr2O3 and Fe-doped Cr2O3 nanoparticles behave as Mott–Hubbard insulators due to their band gap being in the d−d gap, and Cr 3d orbitals dominate the conduction band. These findings suggest that the magnitude and the character of the electronic density near the O atom bonds in Cr2O3 nanoparticles are modulated by the Cr–Cr distances until its stabilization at the induced quasi-equilibrium of the Cr2O3 lattice when the Fe3+ doping values reaches the saturation level range. [ABSTRACT FROM AUTHOR]

Modeling the meso-scale behavior of a material allows one to answer many problems in an inductive reasoning approach. By simulating the behavior of the sample, researchers can correct the overall behavior of the material. The purpose of this article was to gather the main information linking the issue of tomographic imaging to the modeling of damage mechanisms. This paper addresses the topic of meso-scale modeling of cementitious materials. The authors have mapped the interconnectedness of the issues of cementitious materials and X-ray computed tomography (µCT) according to the Web of Science database. The main interconnecting threads are indicated. The authors focused on the use of µCT. The theoretical basis for conducting tomographic measurements is presented. Reference was made to the basics of physics and mathematics in X-ray projection and data reconstruction. Tools and analyses for data processing are indicated. The benefits of in situ µCT are indicated with reference to the practical application of the method. In addition, the main developments of recent years in the most widely used computational methods for meso-scale models are presented. [ABSTRACT FROM AUTHOR]

The crystal and magnetic structures of van der Waals layered ferromagnet Cr Br 3 were studied using X-ray powder diffraction and neutron powder diffraction at pressures up to 23 GPa at ambient temperature and up to 2.8 GPa in the temperature range 6–300 K, respectively. The vibration spectra of Cr Br 3 were studied using Raman spectroscopy at pressures up to 23 GPa at ambient temperature. The anomalous pressure behavior of structural parameters and vibrational modes was observed, associated with a gradual isostructural phase transition in the pressure range 2.5–7 GPa. The Curie temperature TC reduced rapidly with a pressure coefficient d T C / d P = − 4.1 (4) K/GPa. A full suppression of the ferromagnetic state was expected at PC~8.4 GPa, where onset of the antiferromagnetic spin arrangement or magnetically disordered state may take place. Anomalies in Raman spectra at P~15 GPa point to another possible phase transformation in Cr Br 3 , which may be related to the proximity of metallization of this van der Waals ferromagnet. [ABSTRACT FROM AUTHOR]

The CoFe2O4/La0.7Sr0.3MnO3 composites with the La0.7Sr0.3MnO3 mass ratio of 18% was prepared by solid state reaction method, and the magnetic properties under pressure (P) were studied. As P < 0.21 GPa, the grain spacing was reduced by the pressure, resulting in the simultaneous enhancement of the exchange coupling interaction and the dipole interaction between the grains. The results are as follows: (1) the temperature region (ΔT) in which the exchange coupling dominates in the field-colding magnetization (MFC) curve broadens with the pressure. (2) The MFC value at 10 K, i.e., MFC(10 K) increases with pressure. (3) The difference between the zero-field-colding magnetization (MZFC) as P > 0 and as P = 0 was denoted as ΔMZFC(T); it shows the result of ΔMZFC(T) > 0, i.e., the pressure increases the magnetization. Moreover, the values of ΔMZFC(T) increases with the increase in pressure. As P > 0.21 GPa, ΔT and MFC(10 K) hardly change with the pressure; the ΔMZFC(T) curve approximately coincides; the strength of inter-grain exchange-coupling hardly changes with the pressure. These results show that the 0.21 GPa pressure compresses the grain spacing to the greatest degree, and the magnetic moments between grains or within the grain boundaries were arranged in parallel to the greatest extent. In addition, the paramagnetic-ferromagnetic transition temperature Tc of La0.7Sr0.3MnO3 in the composite changes faster with pressure than the Tc of the single-phase La0.7Sr0.3MnO3 sample does. Finally, the pressure can improve the magnetic performance; specifically, the 0.21 GPa pressure increases the saturation magnetization Ms and the remanence ratio Mr/Ms by 3.5% and 17.9%, due to the contribution of grain boundary magnetization. [ABSTRACT FROM AUTHOR]

In this work the magnetocaloric effect in the TbCo2-H system in the region of the Curie temperature was studied both by direct and indirect methods in external magnetic fields up to ~1.4 and 14 T, respectively. We have paid special attention to the magnetic and magnetothermal properties of the TbCo2–H with high hydrogen content. The mechanisms responsible for the change in the Curie temperature were established, and the field and temperature dependences of the magnetocaloric effect were analyzed in detail. In addition, the magnetocaloric properties (including critical parameters) for various systems based on the TbCo2 compound were compared. The main regularities of the change in the MCE value and the Curie temperature depending on the composition are discovered and discussed. [ABSTRACT FROM AUTHOR]

Many non-molecular elemental solids exhibit common features in their structures over the range of 0 to 0.5 TPa that have been correlated with equivalent valence electron configurations. Here, it is shown that the pressures and volumes at polymorphic transitions obey corresponding states given by a single, empirical universal step-function Vtr/L = −0.0208(3) · Ptr + Ni, where Vtr is the atomic volume in Å3 at a given transformation pressure Ptr in GPa, and L is the principal quantum number. Ni assumes discrete values of approximately 20, 30, 40, etc. times the cube of the Bohr radius, thus separating all 113 examined polymorphic elements into five discrete sets. The separation into these sets is not along L. Instead, strongly contractive polymorphic transformations of a given elemental solid involve changes to different sets. The rule of corresponding states allows for predicting atomic volumes of elemental polymorphs of hitherto unknown structures and the transitions from molecular into non-molecular phases such as for hydrogen. Though not an equation of state, this relation establishes a basic principle ruling over a vast range of simple and complex solid structures that confirms that effective single-electron-based calculations are good approximations for these materials and pressures The relation between transformation pressures and volumes paves the way to a quantitative assessment of the state of very dense matter intermediate between the terrestrial pressure regime and stellar matter. [ABSTRACT FROM AUTHOR]

The development of neutron imaging facilities provides a growing range of applications in different research fields. The significance of the obtained structural information, among others, depends on the reliability of phase segmentation. We focused on the problem of pore segmentation in low-resolution images and tomography data, taking into consideration possible image corruption in the neutron tomography experiment. Two pore segmentation techniques are proposed. They are the binarization of the enhanced contrast data using the global threshold, and the segmentation using the modified watershed technique—local threshold by watershed. The proposed techniques were compared with a conventional marker-based watershed on the test images simulating low-quality tomography data and on the neutron tomography data of the samples of magnesium potassium phosphate cement (MKP). The obtained results demonstrate the advantages of the proposed techniques over the conventional watershed-based approach. [ABSTRACT FROM AUTHOR]

An approach is formulated for calculating bulk and surface size characteristics of multidomain KDP-type crystals using the lattice gas model (LGM). Energy states of various proton configurations responsible for the development of spontaneous polarization of the crystal as the temperature is lowered are calculated nonempirically. With the use of statistical equivalence between orientations of pseudospins in KDP crystals and states of LGM site occupancy by the components of an A + B binary mixture, we derive equations describing size dependences of the critical ordering temperature, interfacial tension, and surface tension. Calculations are performed in the quasi-chemical approximation with allowance for direct correlations between neighboring A and B components. The critical ordering temperature, interfacial tension (IT), and surface tension (ST) are considered as functions of the linear size L of a cubic domain, when the contribution of the surface to thermodynamic functions of the substance becomes important. The size dependence of IT is calculated for a 180° orientation of neighboring phases. All three size dependences of the critical ordering temperature, IT, and ST in dimensionless form, normalized to the corresponding value for a macroscopic system, are shown to decrease with decreasing liner domain size L. [ABSTRACT FROM AUTHOR]

Core-shell nanostructures are widely used in many fields, including medicine and the related areas. An example of such structures are nanogold-shelled Fe3O4 magnetic nanoparticles. Systems consisting of a magnetic core and a shell made from nanogold show unique optical and magnetic properties. Thus, it is essential to develop the methodology of their preparation. Here, we report the synthesis methodology of Fe3O4@Au developed so as to limit their agglomeration and increase their stability. For this purpose, the impact of the reaction environment was verified. The properties of the particles were characterized via UV-Vis spectrophotometry, dynamic light scattering (DLS), X-ray diffraction (XRD), and Scanning Electron Microscopy-Energy Dispersive X-ray analysis (SEM-EDS technique). Moreover, biological investigations, including determining the cytotoxicity of the particles towards murine fibroblasts and the pro-inflammatory activity were also performed. It was demonstrated that the application of an oil and water reaction environment leads to the preparation of the particles with lower polydispersity, whose agglomerates' disintegration is 24 times faster than the disintegration of nanoparticle agglomerates formed as a result of the reaction performed in a water environment. Importantly, developed Fe3O4@Au nanoparticles showed no pro-inflammatory activity regardless of their concentration and the reaction environment applied during their synthesis and the viability of cell lines incubated for 24 h with the particle suspensions was at least 92.88%. Thus, the developed synthesis methodology of the particles as well as performed investigations confirmed a great application potential of developed materials for biomedical purposes. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) magnetic materials exhibiting unique 2D-limit magnetism have attracted great attention due to their potential applications in ultrathin spintronic devices. These 2D magnetic materials and their heterostructures provide a unique platform for exploring physical effect and exotic phenomena. However, the degradation of most 2D magnetic materials at ambient conditions has so far hindered their characterization and integration into ultrathin devices. Furthermore, the effect of degradation on magnetoelectric transport properties, which is measured for the demonstration of exotic phenomena and device performance, has remained unexplored. Here, the first experimental investigation of the degradation of CrBr3 flakes and its effect on magnetoelectric transport behavior in devices is reported. The extra magnetic compounds derived from oxidation-related degradation play a significant role in the magnetoelectric transport in CrBr3 devices, greatly affecting the magnetoresistance and conductivity. This work has important implications for studies concerning 2D magnetic materials measured, stored, and integrated into devices at ambient conditions. [ABSTRACT FROM AUTHOR]

The rock fabric of two lamprophyre dike samples from the Koy-Tash granitoid intrusion (Koy-Tash, Jizzakh region, Uzbekistan) has been studied, using the neutron tomography method. We have performed virtual segmentation of the reconstructed 3D model of the tabular igneous intrusion and the corresponding determination of dike margins orientation. Spatial distributions of inclusions in the dike volume, as well as further analysis of size distributions and shape orientations of inclusions, have been obtained. The observed shape preferred orientations of inclusions as evidence of the magma flow-related fabric. The obtained structural data have been discussed in the frame of the models of rigid particle motion and the straining of vesicles in a moving viscous fluid. [ABSTRACT FROM AUTHOR]

The effect of the mutual doping of C, Si, and Al atoms on the electronic structure and magnetic properties of FeXO3 (X = C, Al, Si) compounds, which are constituent compounds of the Earth's lower mantle, was studied. In our first principles calculations, it was found that doping with carbon for both FeSiO3 and FeAlO3 leads to the transition of the compound from a half-metallic state to a metallic one. The values of the magnetic moments of Fe were obtained for pure and doped compounds. For the doped compounds, there is a tendency of the Fe magnetic moment to increase with the growth in the number of substituted ions in the case of replacing Si with C and Si for Al; on the contrary, in the case of replacing Al with C and Si, a decrease in the magnetic moment was revealed. For FeXO3 (X = C, Al, Si), the obtained magnetic moment values were found to be in a good agreement with the known experimental data. [ABSTRACT FROM AUTHOR]