The effects of CdZn substitution and oxygen vacancy (VO) on the structural, electronic, and optical properties of ZnO have been investigated using density functional theory (DFT) with a 3 × 3 × 3 supercell model. VO generates donor levels near the conduction band minimum, thereby enhancing n‑type conductivity, while CdZn 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
This study reports the synthesis of a binary sodium phosphate glass system with the composition (50−x)Na2O–50P2O5–xCrCl3 (x = 0–9 mol
The plasma emission generated by a low-pressure, pulsed-periodic discharge in different gases containing a small amount of water vapor is studied. Broadband radiation is detected in argon, nitrogen, and air, as well as in their mixtures with water vapor. It is shown that this radiation has a maximum intensity at low water vapor concentrations, increases with the increasing specific energy input, and is attributed to the H2(a3Σg+) → H2(b3Σu+) transition of the hydrogen molecule. The emission spectra of water and hydrogen vapor, as well as mixtures of argon, nitrogen, and air with water vapor are presented.
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.
The effect of multi-cycle combined processing (ЕCAP combined with ultrasonic exposure) on the structure, mechanical, and corrosion properties of the bioresorbable Mg‑8.6Zn‑1.2Zr alloy is examined. It is shown that this deformation processing scheme allows achieving a tensile strength of 305 MPa. There is a tendency for the corrosion rate to decrease with an increase in the number of deformation cycles, and a value of 3.0±0.2 mm/y is achieved. This is attributed to an increase in the proportion of recrystallized grains in the Mg‑8.6Zn‑1.2Zr alloy structure.
The paper presents a hybrid physico-mathematical model for the quantitative analysis and prediction of optical losses in standard fiber-optic cables subjected to mechanical loading. The stress-strain state is calculated by the finite element modeling in ANSYS Mechanical, which is combined with numerical solutions of the Helmholtz equation in COMSOL Multiphysics to describe the light propagation. It is shown that tension and microbending cause the stress redistribution in the fiber core and a change in the refractive index according to ∆n = −0.5n3pε, leading to an increase in the attenuation coefficient following the exponential law α = α0exp(kσ). Numerical results are in good agreement with the experimental data (R = 0.95, deviation < 7
Dry sliding of C235 steel against quench-hardened C45 steel is performed at a high-density alternating electric current. The contact layer is subjected to plastic deformation. The formation of a tribolayer consisting mainly of FeO and α‑Fe phases is demonstrated. The contact surface is found to contain two sectors with different morphological features. One of the sectors shows the signs of melt formation. Using an EDX analysis, higher oxygen content is demonstrated in the melt zone, compared with that in the other sector. Oxygen serves as an indicator of FeO formation. A decrease in the oxygen concentration is found with the increasing distance from the sliding surface. It is noted that this is not indicative of a gradient structure. These data are used to calculate the melt layer thickness, which decreases with the decreasing electrical power at the contact spot. The maximum power at the contact spots causes the formation of a melt layer thinner than 7 μm under mild wear conditions. The calculation serves as the evidence for melt formation due to Joule heat, but not due to electric arc formation. A tribolayer scheme consisting of three sublayers is proposed.
This study investigates how changes in vibrational frequencies upon electronic transition (the squeezing effect) affect internal conversion rate constant (kIC) calculations in an indocyanine molecule. Results obtained demonstrate that the squeezing effect alters kIC by only 0.38
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.
A possibility of designing an adaptive plasma antenna for satellite communications is discussed. The feasibility of dynamically tuning the plasma antenna parameters is evaluated. The laser radiation intensity required to create a long plasma channel in an aerosol with an electron density of 1010–1017 cm–3 is estimated. It is shown that the high-frequency electric current through the ionized channel or dielectric rod is localized in the peripheral region. Therefore, it is proposed to use the plasma formation rather than the dielectric in the rod antenna to excite the HE11 surface wave. The simulations in CST Studio Suite 2022 show that as the plasma channel length increases from 0.1 to 8 m, the antenna beamwidth narrows from 70 to 20°, remaining unchanged with a further increase in the plasma channel length.
This study fabricated SnO2 thin films doped with CdTe using pulsed laser deposition under vacuum. The influence of CdTe doping on structural, morphological, optical, and electrical properties was evaluated. X‑ray diffraction confirmed polycrystalline tetragonal SnO2 with preferred (110) orientation, while the higher (20–40
In this research, Pseudomonas aeruginosa bacteria were used as a reducing agent in the green approach of producing copper oxide nanoparticles. The characteristics of the prepared particles were confirmed using various techniques, including UV-Vis analysis, where the highest absorption peak was found at 288 nm and a 1.9 eV energy gap was determined. X‑ray diffraction analysis calculated the size of crystals using the Scherer equation, showing an average crystalline size of 28.5867 nm. Atomic force microscopy revealed a grain size of 43.42 nm. The sample quality was verified using energy dispersive X‑ray spectroscopy, which revealed a high-purity substance devoid of contaminants. Using Fourier transform infrared spectroscopy, the presence of a Cu–O bond was established at 603 cm–1.
Thermal and productivity analysis of a stepped single-slope solar still (SSSSS) employing MWCNT nanofluid (0.05 wt.
In recent years, rare-earth-doped up-conversion luminescent materials have been widely applied across various fields. In practical applications, we have observed that different dopant ions exert various effects on numerous host materials. Based on this, we successfully synthesized a dual-excited Sr3La2Ge3O12 (SLGO) material. By introducing Yb3+/Er3+ in designed phosphor, it exhibits green and red emissions under 980 nm and 1550 nm excitation, respectively, making it suitable for a variety of scientific and technological applications. Systematic investigation of up-conversion mechanisms driven by different excitation sources, show that adjusting the molar ratio of Er3+ to Yb3+ can significantly enhance the material performance, making it highly suitable as a high-performance optical thermometer based on FIR technology. These results demonstrate that SLGO:Er3+/Yb3+ phosphors exhibit unique temperature sensing characteristics, highlighting their potential as temperature sensors.
Silver nanoparticles (AgNPs) were successfully synthesized using an atmospheric pressure plasma jet operated under different argon flow rates (0.5, 1.5 and 2.5 L/min). The gas flow effect on structural, morphological, optical, and chemical characteristics of AgNPs was systematically investigated. UV–Vis spectroscopy revealed a progressive blue shift of the surface plasmon resonance peak from 450 nm at a low flow to 420 nm at a high flow, accompanied by a narrowing of the FWHM, indicating to the particle size reduction and improved dispersion. X‑ray diffraction patterns confirmed the formation of face-centered cubic Ag with the decreasing crystallite size with the increasing flow, as calculated from the Scherrer equation. SEM images demonstrated that higher flow rates produced smaller and more uniform spherical nanoparticles, whereas the lower flow resulted in agglomerated clusters. The FTIR analysis identified hydroxyl, nitrate, and organic groups associated with the nanoparticle surface with diminished intensities at higher flows, reflecting an improved reduction and stabilization of metallic Ag. Collectively, these findings establish argon flow rate as a decisive parameter for tailoring the nanoparticle size, crystallinity, and surface chemistry, highlighting plasma jet synthesis as a green and efficient route for producing high-quality AgNPs.
Polyetherimide (PEI) and polyethersulfone (PES) films are used as technological layers for the fabrication of laminates from PEI-based prepregs reinforced with carbon fiber (CF) fabric and veil by ultrasonic (US) consolidation. It is known that the use of these dissimilar polymers enables the formation of the samples with high interlaminar shear strengths. Despite the difference in their elastic moduli and glass transition temperatures, similar melting points (266 °C for PEI and 262 °C for PES) ensure the formation of uniform structures at the interfaces with negligible discontinuities when using the prepregs reinforced with the CF fabric. In the laminates with the CF veil and the PES technological layer, some discontinuities at the interfaces are caused by the differences in the physical, mechanical, and thermal properties of the joined components. PES has a lower elastic modulus than PEI, so its frictional heat generation is decreased. On the other hand, PEI is the first to melt during US–consolidation due to its lower glass transition temperature (194 °C versus 227 °C for PES). At the same time, the irregular reinforcement of the laminates with the CF veil does not prevent the polymers from their intensive mixing, contributing to the formation of pores and reducing their mechanical properties.
Single crystals of L‑Lysinium L‑Mandelate dihydrate (LLYSMD) are grown by a slow evaporation solution growth technique. It is shown that LLYSMD crystallizes in a triclinic system with the space group P1. Its unit cell parameters are a = 5.7257 (3) Å, b = 7.4898 (4) Å, c = 10.7754 (6) Å, α = 99.560 (2)°, β = 99.504 (2)°, γ = 107.922 (2)° and volume 421.90 (4) Å3. The crystalline nature of the grown crystal is confirmed using the powder X‑ray diffraction technique. The optical absorbance of the grown crystal is verified by the UV-VIS-NIR studies and the bandgap is determined by the Tauc’s plot for photonic uses. The antimicrobial activity is tested against the gram positive and gram negative bacteria by the disc diffusion method. A 0.2 mbar pressure-based sensor of red LED based 8
Using the methods of materials science of physical systems, the structural-phase states and properties of a layer of the T11909 (SAE/AISI) high-speed steel faced on the 4130 (SAE/AISI) medium-carbon steel are studied after its tempering and electron-beam processing. The metal structure in the as-faced and high-tempered states consists of the eutectics and iron-based solid solution grains. It is shown that the e‑beam processing results in a cardinal change of the surface layer morphology and mechanical and tribological properties.
