Russian Physics Journal最新文献

Geant4 integral nucleus-nucleus cross-sections based on the Glauber–Gribov approach are compared with the AMS-02 experimental data for a carbon target in the energy range of 1–100 GeV/n. A better agreement with the experimental data is observed for the integral inelastic nucleus-nucleus cross-sections in the case where a correction on the elastic scattering of nucleons is introduced in the framework of the Geant4 model.

The effects of Cd_Zn substitution and oxygen vacancy (V_O) on the structural, electronic, and optical properties of ZnO have been investigated using density functional theory (DFT) with a 3 × 3 × 3 supercell model. V_O generates donor levels near the conduction band minimum, thereby enhancing n‑type conductivity, while Cd_Zn modifies the valence band through Cd-4d/O-2p hybridization. The combined system is characterized by intensified intermediate levels near the band gap, increased spin asymmetry, and a red shift of the absorption edge. The results obtained demonstrate that the optoelectronic properties of ZnO can be systematically tuned through defective engineering.

In this paper, the performance of a plasmonic filter based on a metal-air waveguide containing a washer-shaped resonator is analyzed. Influence of geometric design parameters, such as the washer width d, gap width g, outer washer radius, and material composition on the transmission, reflectivity, and absorbance have been investigated. The results show that increasing d results in a red shift in the transmission spectrum and enhances resonant coupling, while decreasing g reduces the optical coupling and shifts the spectrum toward shorter wavelengths. The full width at half-maximum (FWHM) and the quality factor are also highly dependent on the washer radius and structural length, highlighting the trade-off between the transmission efficiency and resonance resolution. The proposed filter achieves a transmittance exceeding 70%, a transmittance bandwidth of 10 nm, and a quality factor of up to 70. Furthermore, the comparison of silver and gold using the Drude model showed that silver offers higher transmission efficiency and better quality factor compared to gold, making it an ideal choice in high-performance optical filtering applications. These results provide a solid basis for the design and optimization of tunable plasmonic devices in the fields of sensing, filtering, and energy absorption.

This study reports the synthesis of a binary sodium phosphate glass system with the composition (50−x)Na₂O–50P₂O₅–xCrCl₃ (x = 0–9 mol%) produced via the melt quenching technique. The resulting glasses were characterized using various analytical techniques. X‑ray diffraction (XRD) confirmed the amorphous nature of samples containing up to 6 mol% CrCl₃, as evidenced by a broad diffraction halo between 20 and 30°. At higher CrCl₃ concentrations, partial crystallinity was observed. Fourier-transform infrared (FTIR) spectroscopy indicated a gradual increase in bridging oxygen content, suggesting enhanced polymerization within the phosphate network. Substituting Na₂O with CrCl₃ led to an increase in the density, molar volume, and packing density, accompanied by a reduction in the free volume. UV-visible spectroscopy revealed two prominent absorption bands near 470 and 650 nm, attributed to Cr³⁺ ions in distorted octahedral coordination. A weak band near 300 nm, associated with Cr⁶⁺ ions, was detected only in samples with lower CrCl₃ concentrations. The optical band gap decreased from 3.5 to 2.8 eV (indirect transition) and from 4.04 to 3.0 eV (direct transition), while the refractive index increased from 2.214 to 2.371 with CrCl₃ addition up to 9 mol%. These results demonstrate that incorporating CrCl₃ enhances the structural, physical, and optical properties of the glasses, underscoring their potential for optoelectronic and photonic applications.

The paper investigates mechanical properties of TiNi thin wires of a diameter ~950 µm after the synthesis of the surface alloy based on the Ti-Ni-Ta system with the amorphous structure and a thickness of ≤ 2 µm. The surface alloy is synthesized during 30 cycles of deposition and melting of the alloying film Ti₆₀Ta₄₀ (at.%) ~50 nm thick consisting of a film/substrate liquid-phase mixture using a wide-aperture (up to ~10 cm²), low-energy (≤ 30 keV), high-current (up to ~25 kA) pulsed electron beam with ~2.5 J/cm² energy density and ~2–3 μs pulse duration in one vacuum cycle. The deformation behavior of thin wires is studied in torsion tests at ~6% cyclic loading (20 cycles) and loading to failure. During cyclic loading, the synthesized surface alloy shows no critical effect on the inelastic behavior of TiNi thin wires. According to tests to failure, the shear strength and failure strain decrease by ~350 MPa and ~11%, respectively, as compared to those of the initial TiNi alloy. After torsion tests, the amorphous surface alloy does not delaminate from the surface. With regard to the low adhesive resistance of the Ti-Ta coating leading to its delamination from TiNi alloy surface, the synthesized surface alloy being an alternative coating, demonstrates positive results of mechanical torsion tests.

The microstructural evolution and corrosion behavior of AA2024 aluminum matrix composites reinforced with varying weight percentages (2, 4, 6, and 8 wt.%) of brass particles, processed by Friction Stir Processing (FSP) are investigated. The microstructural characterization by optical microscopy, scanning electron microscopy (SEM), and XRD reveals that 4 wt.% brass provides the most uniform particle dispersion, optimal grain refinement, and favorable precipitation of intermetallic phases, including Al₂Cu, Al₂CuMg, and Al-Cu-Zn. An excess reinforcement (6–8 wt.%) leads to particle agglomeration, grain coarsening, and phase heterogeneity. The corrosion resistance is assessed using Tafel polarization tests in a 3.5 wt.% NaCl solution. The 4 wt.% brass composites demonstrate the best corrosion resistance, with the most noble Ecorr (+72 mV), the minimal pitting, and the lowest corrosion rate (1.1⋅10⁻³ mpy), attributed to its uniform microstructure and stable intermetallic phases. Higher brass contents increase the galvanic activity, cause negative Ecorr values, and severe localized corrosion due to clustering and microgalvanic coupling.

The changes in the supramolecular structure of ultrafine polypropylene fibers exposed to microwave radiation are studied. It is found out that heating of materials based on ultrafine fibers with a water content of approximately 10 wt.% causes phase transformations within the polymer, leading to the transition of the unstable mesomorphic phase to a stable monoclinic phase and the formation of a more homogeneous crystalline polymer structure. This change in the supramolecular organization of polypropylene leads to an increase in the melting point and a decrease in the moisture absorption, but does not cause any degradation or affect the morphological or sorption properties of the fibrous material.

In this work a new set of cross sections based on the Itikawa cross sections is regrouped to give a better agreement of the electron swarm parameters in nitrogen calculated by the Monte Carlo model with the experimental measurements. A comparison is made between the electron swarm parameters calculated using the new cross sections using Itikawa cross sections, Phelps-Pitchford cross sections in the Monte Carlo code, and Phelps-Pitchford cross sections in the Boltzmann equation code. The new set provides the best agreement with the experimental measurement in a wide range of the reduced electric fields from 0.5 to 1000 Td.

Photophysics of 9,9-dioctylfluorene copolymers has been studied for the first time using quantum-chemical calculations. The study revealed that structural modifications of fluorene copolymers directly influence the excited-state energies and non-radiative rate constants. These tailored copolymers consequently exhibit photoluminescence tunable across the visible spectrum, from the blue-to-red spectral region. Calculations confirmed fluorescence as the dominant decay pathway and identified internal conversion as the primary cause of efficiency loss in red-emitting copolymers. Corresponding OLEDs based on fluorene copolymers have been fabricated, achieving a maximum luminance of 7683 cd/m² and a current efficiency of 1.82 cd/A for a green-emitting device.

This review systematizes modern methods of silver nanoparticle (AgNP) synthesis for their subsequent sorption on surfaces of materials and coatings. Physical, chemical, and biological synthesis methods and their hybrids are considered. It is shown that the controlled synthesis parameters (the reducing agent and ligand, ionic strength, temperature, radiation dose, etc.) determine the balance of nucleation and growth, morphology, particle size distribution, and synthesis purity. The prospects for hybrid and continuous processes and the need for further research for reproducible optimization of morphology for a target sorption function are noted.