Russian Physics Journal最新文献

This study examines how the substrate temperature affects the electrical characteristics of the Zr-doped HfO₂/Al/Zr-doped HfO₂ (HZO/Al/HZO) tri-layer stack. Tri-layer stack is deposited by a simultaneous use of RF magnetron sputtering for HfO₂ and DC magnetron sputtering for Zr and Al targets. During deposition, the substrate temperature is varied from 25 to 300°C. The observed hysteresis loop is prominent for the stack deposited at room temperature, while it becomes minute at higher temperatures. Interface trap density and oxide charge density of the tri-layer stack are minimum at 300°C and maximum at room temperatures. Frequency dispersion is detected in the stack deposited at room temperature, but it disappears in stacks deposited at 300°C. In addition, compared to other tri-layer stacks, the stack deposited at 300°C shows good conductivity. Therefore, compared to other samples, the tri-layer stack deposited at 300°C has improved electrical characteristics. It is shown that the substrate temperature has a significant impact on the electrical properties of the stack.

Using the method of computer thermodynamic modeling, the stability of higher fullerene C₉₀ heated in a nitrogen atmosphere at a pressure of 0.1 MPa is studied. The simulation is performed using the TERRA software package in the temperature range from 273 K to 3373 K. The equilibrium composition of compounds in the C₉₀–N₂ system is obtained and the physico-chemical processes causing the formation of these compounds are described. The equilibrium constants of the processes forming the equilibrium composition of compounds are calculated for different temperature ranges using the least squares method.

Using the methods of advanced material physics, the structural-phase state of a layer of high-entropy high-speed non-equiatomic molybdenum tool steel formed by electric arc surfacing in a nitrogen atmosphere is studied. The thermodynamical and mechanical (elastic moduli) properties of the surfaced layer are examined in a temperature interval of 300–1400°C, and a phase-composition diagram is presented. It is observed that a temperature increase is accompanied by an α→γ polymorphic transformation, followed by a decrease in the content of carbide phases and elastic moduli.

Porous-monolithic TiNi-based materials are fabricated by sintering TiNi powder on monolithic TiNi plates, followed by their surface modification with a low-energy high-current electron beam. Their corrosion resistance is examined in a biological medium by the method of voltamperometry using linear scanning, and their structural features are studied by the methods of optical profilometry, scanning electron microscopy and X-ray microanalysis. A comparison of the corrosion rates of the porous-monolithic samples is performed, and it is found out that the new composites possess better corrosion resistance compared to that of TiNi plates due to a homogeneous phase composition of the surface. A treatment of the TiNi-based powder alloy with LEHCEB is thought to be effective in optimizing the properties of materials used in implantology.

Synthesis and characterization of Eu³⁺-doped Er₂SiO₅ phosphor are reported. The samples are prepared using the modified conventional solid-state synthesis technique with variable concentrations of doping ions and their structural studies are carried out by X–ray diffraction (XRD). The information on the morphology of the samples prepared with optimized doping ion concentrations is obtained by scanning electron microscopy (SEM). A photoluminescence (PL) analysis of the phosphor samples is also done for the fixed doping ion concentrations. The identified PL emission bands are attributed to the intra 4f transitions of a Eu³⁺ ion, such as ⁵D₀→⁷F₁ at 590 nm, ⁵D₀→⁷F₀ at 602 and ⁵D₀→⁷F₂ at 613 nm. The corresponding transitions of the doping ions and the concentration quenching effect are studied in detail. The 1931 Commission Internationale de l’éclairage (CIE) (x, y) chromaticity coordinates show the spectral distribution calculated from the PL emission spectrum. A thermoluminescence (TL) glow curve analysis is performed for variable doping ion concentrations, and the corresponding trap parameters are calculated using the Computerized Glow Curve Deconvolution (CGCD) technique. Our study shows that as-prepared phosphor may be useful for display devices.

A EuZnSb₂ antiferromagnetic (AFM) semi metal with a P4/nmm space group (No. 129) is synthesized using the Sb-flux method. The magnetic properties, specific heat, and resistivity of the EuZnSb₂ single crystals are analyzed. The magnetic and specific heat properties indicate an antiferromagnetic order of Eu²⁺ with T_N ~ 20 K. The magnetic field is observed to suppress the AFM transition of Eu²⁺ and the magnetic susceptibility vs. temperature curves exhibit differences when the magnetic field is applied along the ab-plane and c-axis of EuZnSb₂ single crystal, reflecting a weak in-plane anisotropy of Eu²⁺. When the temperature is below 20 K, a spin‒flop transition of the AFM order appears at approximately 1.6 T. The electronic transport measurements indicate that a EuZnSb₂ single crystal exhibits metallic properties and an extremely unsaturated positive MR effect. A twofold period of anisotropic magnetoresistance is observed, indicating that the resistivity characteristics correlate with the magnetic field intensity and the angle between the magnetic field direction and the crystallographic axis direction. These studies contribute to enriching the magnetic, specific thermal, and electrical transport properties of EuZnSb₂. These results also provide valuable information for further research on other AFM materials.

This study investigates the thermal conductivity and moisture absorption characteristics of bamboo, coir, and date palm fiber composites, specifically examining their suitability for use in solar distillation applications. Four composite samples comprising alkali-treated bamboo and coir fiber (sample 1), untreated bamboo and coir fiber (sample 2), treated coir and date palm fiber (sample 3), and untreated coir and date palm fiber (sample 4) have been experimentally analyzed. Samples 1 and 3 showed 17.6 and 16.6% lower thermal conductivities and 45.8 and 44.2% lower moisture absorptions than untreated samples 2 and 4. Alkali-treated fibers had decreased lignin and hemicellulose and more cellulose, supporting the observed benefits after chemical analysis. Post-alkali scanning electron microscopy showed improved fiber surface morphology, highlighting cellulose energy-saving significance. The results indicate that these composites, due to their improved thermal insulation characteristics, provide a sustainable choice for integration into solar distillation systems.

The paper presents calculations of the two-stage separation of silicon isotopes in Q-cascade models. Feed flow profiles are obtained for Q-cascades, and the concentration distribution by stages is determined for silicon isotopes. It is shown that three highly-enriched (>99%) products can be obtained at a 35 g/s feed flow, namely: 32.31 g/s ²⁸Si, 1.61 g/s ²⁹Si, and 1.08 g/s ³⁰Si.

The paper deals with the high-speed formation of nanocomposite structures on a polycarbonate matrix with a metal film affected by pulsed laser radiation at a wavelength of 1064 nm. Studied is the micro- and nanosized ordering depending on the laser power. Based on confocal laser scanning microscopy and using the area similarity method, structural groups and fractal dimensions are determined, and 2D-to-3D structure transition is studied herein.

The paper deals with the optical radiation interaction with solids. It is shown that none of the existing ideas about the light reflection gives explanations to the known phenomena arising from the interaction between optical radiation and a solid. It is suggested that the optical radiation reflection is a collective process associated with the self-organization of electrons with a photon. This suggestion explains a number of physical phenomena that have not been explained before, for example, the Goos–Hänchen and Imbert–Fedorov beam shifts, which are natural processes in such representation of reflection.