Applied Physics A最新文献

PVA/PVP (80/20 wt%) films containing various concentrations of V₂O₅ NPs (0, 1, 2, and 3 wt%) were prepared. This study explores the effect of varying concentrations of V₂O₅ NPs on the structural, optical, and optoelectrical properties of biodegradable PVA/PVP blends. The V₂O₅ NPs have a crystallite size value of 37.5 nm, and the crystallite size of PVA/PVP/V₂O₅ films increases with the increase in V₂O₅ NPs concentrations. FTIR spectra investigated the functional groups of PVA/PVP/V₂O₅ films. The direct band gap for the PVA/PVP blend (80/20 wt%) was 3.4 eV and decreased to 2.48 eV for the PVA/PVP blend doped with 3 wt% of V₂O₅ NPs. At the same time, the indirect band gap value for pure PVA/PVP blend was 3.06 eV and decreased to 2.16 eV for PVA/PVP blend doped with 3 wt% of V₂O₅ NPs. The PVP/PVA film has an E_u value of 0.85 eV, and the Eu values rise gradually from 0.85 to 3.65 eV as the V₂O₅ NPs content in the PVP/PVA matrix boosts from 0 to 3 wt%. Furthermore, the refractive index and extinction coefficient variation for the PVA/PVP/V₂O₅ nanocomposites as a function of V₂O₅ NPs content was addressed. Additionally, the impact of V₂O₅ NPs contents on the dispersive and oscillator energies was displayed. The results revealed that doping with V₂O₅ NPs increases the number of free carriers from 2.38 × 10¹⁹ cm⁻³ to 7.48 × 10²⁰ cm⁻³. Meanwhile, the optoelectrical parameters such as plasma frequency (ω_p), relaxation time (τ), and optical mobility were computed. The optical and opto-electrical characteristics suggest that the PVA/PVP/V₂O₅ films suit optoelectronic devices and optical switching applications.

Two significant factors that improve dye-sensitized solar cells’ (DSSCs’) performance are increased electron concentration and effective charge transport. In the present work, pristine and Cr-doped biphasic TiO₂ in various phase ratios were prepared and utilized as the photoanode of the DSSC. Doping created oxygen vacancies, leading to phase transformation at lower calcination temperatures. The doped biphasic TiO₂ photoanode’s photovoltaic performances were superior to its pristine counterparts. The sample with 70% anatase and 30% rutile (CrTi-400) showed the highest photoconversion efficiency (PCE) compared to the rest. The low crystallite size of CrTi-400 facilitated a higher dye adsorption, leading to a better photo-excited electron injection. The photoelectrochemical study revealed an efficient charge transport in CrTi-400, and this, coupled with the improved electron concentration due to the oxygen vacancies created via Cr doping, enhanced the photocurrent (J_SC). The synergy between doping and biphasic junction improved the structural, optical, and electrical properties, improving its J_SC and overall photovoltaic performance. This study showcases a novel strategy for enhancing the photoanode performance of the TiO₂-based DSSC by utilising the synergy of doping and heterojunction.

Laser melting deposition (LMD) of Ti-6Al-4 V with engineered performance for aerospace applications requires a comprehensive and detailed understanding of the microstructure evolution. The complex thermal cycles during LMD and heat treatment (HT) process of Ti-6A1-4 V affect the phase transformation, leading to heterogeneous microstructure and property variations within builds. The current study aims to investigate the effect of heat treatment temperature on the heterogeneities through the utilisation of multiscale characterisation techniques. Influenced by the spheroidisation and thermal grooving effect, the microstructure of LMDed Ti-6Al-4 V changed after heat treatment, especially the spine-like semi-continuous structure was identified inside the 1020℃ STA specimen. The thermal profile of HT process increased the size of α-phase and volume fraction of β-phase with increasing HT temperature. The solution-aging treatment has also been demonstrated to enhance the elimination of anisotropy of UTS, YS and strain-hardening coefficients, which is influenced by the boundary break-up and migration theories. A post-LMD heat treatment at a temperature just below the transus temperature lead to an improvement of strength and ductility, accompanied by the losses in strain-hardening coefficients.

0.39Bi(Ni_0.5Ti_0.5)O₃–0.20PbZrO₃–0.41PbTiO₃:x(Bi₂O₃ + PbO) (BNPZT:xBiPb, x = 0, 1, and 2) piezoceramics were prepared via conventional solid-state route. The impact of excess Bi₂O₃ and PbO on the structural, dielectric, ferroelectric, bipolar strain, and piezoelectric properties of BNPZT ceramics was investigated. The Rietveld refinement results indicated that all sintered ceramics were well crystallized into a pure perovskite structure with major rhombohedral and minor tetragonal phases. The temperature and frequency dependence of dielectric measurements revealed relaxor behavior and a high Curie temperature (Tc ~ 290 °C) for BNPZT:1BiPb ceramics. High remnant polarization (Pr ~ 25.43 μC/cm²), low coercive field (Ec ~ 16.73 kV/cm), and bipolar strain (0.12%) were achieved in BNPZT:1BiPb ceramics. This study outlines a route for exploring new piezoelectric materials with enhanced electrical properties.

This paper presents a sensor based on commercial semi-conductor laboratory 180 nm complementary metal–oxide–semiconductor technology. Sensor can detect total ionizing dose on metal–oxide–semiconductor devices. Simulation and mathematical study determined the sensor optimized oxide thickness at 20 nm. Sensor radiation doses range from 100 rad to 1 Mrad, including low and high levels. Considering threshold voltage shift of capacitive sensor as a sensitivity parameter, the sensor’s sensitivity is 20, 3.9 and 0.6 mV/krad for 0–10 krad, 10 krad—100 krad and 100 krad—1 Mrad radiation doses respectively. The capacitive radiation sensor was designed, analysed, and evaluated using Visual TCAD simulation. Proton and Cobalt, Iron, and Nickel ions produce radiation damage, as simulated by stopping and range of ions in matter simulator. This simulation was conducted to calculated energy loss, vacancy fluctuation, nuclear stopping power, and electronic stopping power. Displacement per atom was calculated at various proton/ion energies and irradiation fluences. The observation demonstrates a direct relationship between the energy of protons/ions and the concentration of their trajectory. The vacancies concentration is higher with low-energy proton/ion irradiation than with high-energy. This is due to material interaction with lower cross section and lattice atom energy transmission. The decrease in displacement damage is observed as the projected range increases, suggesting that the proton/ion irradiation is the cause of this damage and that it decreases as the proton energy increases.

In the current work, Mn_xZn_1−xLa_0.1Fe_1.9O₄ ferrite nanoparticles were prepared using a solid-state reaction, with x values of 0, 0.1, 0.3, 0.5, 0.7, and 1. The structure, morphology, optical, magnetic, and dielectric characteristics of the prepared samples were characterized using X-ray Diffraction (XRD), Fourier Transformed Infrared Spectrometer (FTIR), Scanning Electron Microscopy (SEM), UV-Vis spectrophotometer, Vibrating Sample Magnetometer (VSM) and impedance analyzer. XRD and FTIR spectra assured the formation of the cubic spinel phase structure as well as tetrahedral and octahedral bonding in the synthesized samples. SEM analysis of the surface morphology revealed irregular and semi-spherical shapes. The prepared samples’ elements were confirmed to be present based on their chemical composition by the EDX analysis. The Kubelka-Munk function was used to calculate the optical band-gap energy E_g based on the near-infrared (NIR) and visible (VIS) reflectance spectra, which are dependent on Mn dopant ion concentration. The VSM findings demonstrate that the characteristics of the samples transformed gradually from antiferromagnetic to ferromagnetic behavior with increasing Mn content. The dielectric results exhibit that the doping of Mn ions decreases the dielectric constant and dielectric loss and increases the resistivity. The physical properties of Mn_xZn_1−xLa_0.1Fe_1.9O₄ nanoparticles, such as their low power losses, coercivity, high resistivity, permittivity, and saturation magnetization, make them suitable for many applications, from biomedical to electronic devices.

Graphene nanoribbons (GNRs) with precise structural properties have become attractive options for next-generation nanoelectronics because of their adaptable electrical topologies and their uses in quantum electronics, photovoltaics, and transistors. These interesting properties have recently collected significant attention in the field. Cove-edged graphene nanoribbons (CGNRs) are especially interesting because of their distinctive electromagnetic properties. This type of nanoribbon features asymmetric edges composed of sequential hexagons, exhibiting remarkable mechanical and electrical properties. In this paper, we find the new Zagreb-type topological indices and the corresponding entropy measures of graphene nanoribbons with curved edges. We establish correlation analysis between the Zagreb-type indices and entropy measures through the curve-fitting model and the Pearson correlation coefficient. The results of this study may reduce the amount of work needed to investigate the physicochemical characteristics of graphene nanoribbons with curved edges.

Arsenic antimony alumina boro lead oxide (AAABPbO) glasses doped with Europium (Eu³⁺) ions were synthesised utilising the melt quenching method. The titled glasses were characterised using X-Ray Diffraction (XRD), Fourier-Transform Infrared spectroscopy (FT-IR), thermal, absorption, excitation, photoluminescence (PL) emission, and PL decay techniques to examine their physical, structural, and optical features. The XRD and FT-IR recorded for an un-doped as well as Eu-doped AAABPbO glass confirms the glassy nature and bonding characteristics respectively. The Differential Scanning Calorimetry (DSC) recorded for an un-doped AAABPbO glass confirms the glass transition temperature. The Judd-Oflet (J-O) parameters were calculated based on the PL emission spectral data rather than the absorption spectral data. The J–O values estimated for AAABPbO glasses doped with Eu³⁺ ions exhibit a consistent trend of Ω₂ > Ω₄ > Ω₆. The J–O values evaluated were further used to estimate the radiative parameters, such as transition probabilities, branching ratios, quantum efficiency, and emission cross-sections for the titled glasses. Among all the glasses studied in the present work, the one with 2.0 mol% of Eu-ions demonstrates the most notable quantum efficiency (88%) and stimulated emission cross Sect. (7.71 × 10^–22 cm²). The CIE coordinates (0.4502, 0.4187) evaluated from PL emission spectral data revealed reddish-orange emission from the titled glasses. Radiation shielding parameters of the as prepared glasses are estimated in 0.015-15 MeV range using Phy-x/PSD software. Comparison of all results obtained for the titled glasses with the literature values confirms potential of the titled glasses for optical as well as radiative shielding applications.

Photon-assisted charge transport through a double-barrier laser structure, separated by a region assisted by a magnetic field, is studied. Employing Floquet theory and matrix formalism, the transmission probabilities for the central band and sidebands are calculated. The temporal periodicity of the laser fields creates an infinite number of transmission modes due to the degeneracy of the energy spectrum. The challenge of numerically addressing all modes necessitates the limitation to the first sideband corresponding to energies (varepsilon pm varpi). A critical phase difference between the two laser fields is found to cancel the transmission through the sidebands due to quantum interference. Varying the width of the region where the magnetic field is applied allows for the suppression of lateral transmission and control over the transmission mode. The intensity of the laser fields also allows for the suppression of Klein tunneling and blocking transmission processes with zero photon exchange, as well as activating transmission processes with photon exchange. The conductance is also affected by changes in the system parameters. Increasing the intensity of the laser field reduces the conductance due to the confinement of the fermions by the laser fields. In addition, increasing the size of the region where the magnetic field is applied reduces the conductance because the increased distance gives the fermions a greater chance of diffusion and increases their interaction with the magnetic field.

The aircraft engine plays an important role in the aviation field, and the gear is the key part of the aircraft engine. During the service, the contact fatigue of the gears surface aggravates the gears surface wear and leads to the initiation of micro-cracks. Laser quenching surface heat treatment technology is one of the effective ways to strengthen the surface of aircraft gear. Due to the solid-state phase transition effect of laser quenching, the residual stress can be effectively controlled, the formation of micro-cracks on the gears surface can be reduced, and the uniform distribution of the quenching layer on the gears surface is realized. To enhance laser quenching efficiency and ensure precise process control, a rectangular laser heat source model was established. This model was based on the characteristics of actual laser processing heat sources. A numerical model coupling temperature, stress, and phase transition was developed for 12Cr2Ni4A aircraft gear double lap laser quenching, revealing the process’s instantaneous evolution. The numerical simulation results show the temperature characteristics of laser quenching rapid heating and cooling, and residual stress concentration distribution phenomenon appears in the secondary tempering zone. The phase transformation results after quenching reveal the presence of a large amount of martensite in the quenching layer. Finally, the effectiveness of the numerical simulation was verified by the laser quenching experiment of the aircraft gear. The research on laser quenching of aircraft gears is crucial for improving their surface hardness, wear resistance, and extending their service life.