Applied Physics A最新文献

The selection of precursor materials is of foremost importance in enhancing the electrochemical performance of electrode materials utilized in supercapacitors. This investigation carefully assesses the influence of various salts derived from cadmium, namely cadmium nitrate (Cd (NO₃) ₂), cadmium acetate (Cd (CH₃COO) ₂), and cadmium sulfate (CdSO₄), on the structural, morphological, and electrochemical characteristics of cadmium electrodes. The results highlight how differences in precursor materials can lead to significant variations in surface area and overall energy storage capability, thereby impacting the efficiency of the supercapacitor. A comprehensive understanding of the correlation between precursor selection and material performance is vital for propelling the advancement of supercapacitor technology, as it facilitates the design of electrodes with customized properties to meet specific application requirements. The salts function as initial agents for producing cadmium-centric nanostructures via a one-step hydrothermal method, following which they find application in supercapacitor electrode fabrication. The materials produced are analyzed through techniques such as X-ray diffraction, Field Emission Scanning Electron Microscopy, Cyclic Voltammetry, Chronopotentiometry, and Electrochemical Impedance Spectroscopy to evaluate their crystallinity, surface structure, and capacitive behavior. Electrochemical studies reveal that the choice of precursor significantly influences ion diffusion, charge storage capacity, and overall energy density. Among the tested precursors, Cadmium Nitrate salt demonstrates superior electrochemical properties, exhibiting a high specific capacitance, i.e.,.275.69 F/g, excellent rate capability. This work provides valuable insights into the optimization of precursor selection for enhanced energy storage performance in Cadmium-based Supercapacitors.

Among different additive manufacturing (AM) technologies, laser-induced forward transfer (LIFT) has been widely investigated, owing to the eco-friendly rapid processing and the compatibility with a broad range of materials. In this work, the combination of the LIFT of solder materials (Gold-tin (AuSn) thin film and solder paste) and of a laser-based bonding station comprising a vacuum-assisted pick-and-place tool, and a laser soldering setup is reported for the bonding of small dimension optoelectronic components onto test silicon substrates. The findings of this study determined the optimal laser soldering parameters for integrating resistors and LEDs onto test substrates comprising LIFT printed solder patterns of solder paste with particles’ size of 2–11 μm and AuSn thin film materials. Optimal conditions for solder paste and AuSn thin film bonding were determined, ensuring reliable attachment of components and consistent process performance. The proposed methodology enables thermally localized, non-contact bonding with high positional accuracy and reproducibility. Initial experimental results validate the robustness and repeatability of the process, demonstrating its potential as a scalable solution for heterogeneous integration in advanced photonic and microelectronic packaging architectures.

To improve the high-quality drilling capability of 2.5D-Cf/SiC ceramic matrix composites (CMCs) for high-temperature structural applications, this study systematically investigates the drilling quality and efficiency characteristics of millisecond pulse laser under varying hole diameters (0.6 mm to 1.7 mm). Key metrics such as hole geometry accuracy, sidewall roughness, taper angle, and machining time were evaluated using optical microscopy, scanning electron microscopy (SEM), and laser confocal microscopy. Results reveal a consistent entrance-export diameter mismatch during laser drilling, resulting in positive tapers ranging from 3.2° to 4.2°. Smaller holes (< 1 mm) exhibited more pronounced export deformation, while larger holes significantly increased machining time. The constituent materials showed distinct responses to laser ablation: carbon fibers exhibited anisotropic ablation with transverse scratches on the hole walls, whereas the SiC matrix developed regular vertical striations, leading to notable roughness variations. The 1.2 mm hole diameter demonstrated the poorest surface quality across roughness parameters, indicating a nonlinear mismatch between laser energy and hole size. This study confirms the potential of millisecond pulse laser for efficient drilling in Cf/SiC CMCs and elucidates the critical coupling relationship between hole diameter and process parameters. These findings provide theoretical insight and experimental evidence supporting the application of laser precision machining in high-performance ceramic structures.

The interaction of energetic ions with semiconductor heterojunctions can significantly influence interfacial states and charge transport, thereby impacting device performance and long-term reliability. In this study, ZnO/p-Si heterojunctions were irradiated with 120 MeV Ag⁸⁺ ions at fluences ranging from 1 × 10¹¹ to 5 × 10¹² ions·cm⁻², and their current-voltage characteristics were systematically examined. Swift heavy-ion irradiation generated lattice disorder, point defects, and interface traps, which reduced the barrier height from 0.82 eV for the pristine diode to 0.68 eV at 5 × 10¹² ions·cm⁻² and increased the reverse leakage current. At low fluence, transient thermal-spike effects slightly improved junction quality, whereas higher fluences produced defect-dominated transport. Under UV illumination, the irradiated heterostructure showed enhanced photocurrent, but its sensitivity decreased due to the irradiation-induced increase in dark current. These results provide important insights into radiation-driven modifications in oxide/semiconductor heterojunctions and emphasize the need to account for such effects while developing devices for radiation environments.

In this study, we explore the hysteresis behavior of a bilayer graphene system consisting of mixed spins ((S = 7/2, sigma = 1/2)) in ferrimagnetic interaction. The model considered is based on a modified Blume-Capel Hamiltonian, incorporating intra- and inter-layer exchange interactions, a uniaxial crystal field, and an external magnetic field. The analysis is performed using Monte Carlo simulations based on the Metropolis algorithm. We examined the influence of physical parameters, in particular the exchange interactions (J_1), (J_2), (J_3), the crystal field D and the temperature T, on the hysteretic behavior of the system. The results obtained reveal a strong dependence of the topology of the hysteresis loops on these parameters. For example, increasing the temperature causes a gradual decrease in the surface area of the loops, until they disappear above a critical temperature. These observations are consistent with the results reported in other multilayer magnetic systems and open up prospects for the development of multistate magnetic memory devices.

For the first time, Eu³⁺-doped Zn2V2O7 nanoparticles (NPs) were successfully synthesized via an eco-friendly solution combustion route using Menthaspicata leaf extract. X-ray diffraction con- firmed the monoclinic crystal structure (C2/c(2/m) space group), with crystallite sizes of 25–35 nm, consistent with TEM analysis. A morphological transition from irregular to hexagonal-shaped NPs was observed upon Eu³⁺ doping. Optical studies revealed a systematic reduction in the band gap from 3.03 to 2.94 eV with increasing dopant concentration. Photoluminescence analysis showed strong red emission under 300 nm excitation, with the electric dipole transition dominating and optimal intensity achieved at 5 mol% Eu³⁺. The CIE chromaticity coordinates (x = 0.64, y = 0.35) were well-positioned in the red region, and the correlated color temperature (CCT) of 3110 K confirmed a warm light emission. Electrochemical studies further demonstrated promising energy storage behavior, with specific capacitance values ranging from 73.76 to 123.74 F/g at 10 mV/s. The Bode plot analysis revealed a short relaxation time constant (τo = 0.011 s), indicating fast charge–discharge capability. These findings suggest that Eu³⁺-doped Zn2V2O7 NPs are multifunc- tional materials with significant potential for both photonic and supercapacitor applications.

This work studies the interplay between nanostructural anisotropy, dielectric confinement, and polarization memory in porous silicon films with embedded carbon dots (CDs). Using polarization-resolved photoluminescence spectroscopy and theoretical modeling based on the Lavallard-Suris dielectric confinement model, which is extended to spatially ordered ellipsoidal nanostructures, we demonstrate that the polarization degree of the photoluminescence emission of CDs is determined by the geometric morphology and dielectric contrast of the host matrix. Elongated nanostructures within porous silicon enhance the polarization memory, while the porous matrix spatially confines the CDs, aligning their emission dipoles and reducing depolarization by restricting rotational freedom. Controlled oxidation of the porous silicon films is found to eliminate structural anisotropy, diminishing the polarization memory despite improved CDs integration. Experimental results confirm that both in-plane anisotropic porous silicon films and oxidized ones with incorporated CDs retain matrix anisotropy and align well with the ordered model. Angular shifts in the photoluminescence polarization correlate with preferential crystalline axis orientation in the porous silicon matrix. These findings enable the rational design of polarization-sensitive optoelectronic devices, such as optical sensors and switches, by leveraging the tunable nanostructure and dielectric properties of hybrid porous silicon-CDs systems.

Nonlinear optical materials are of great interest for applications in photonics, optoelectronics, and advanced nonlinear optical devices. In this work, we synthesized Borophene/TiO₂ nanoparticle nanocomposites with varying Borophene concentrations and systematically investigated their nonlinear optical response. TEM, EDX, XRD, FTIR, and UV-Vis absorption spectroscopy confirmed the successful synthesis of the nanocomposites. The optical bandgap progressively decreases from 3.50 eV to 2.90 eV with increasing Borophene loading, indicating enhanced light absorption ability of nanocomposites. Nonlinear optical properties were studied through the Z-scan technique using a femtosecond laser centered at 800 nm wavelength in two modes: Open and close aperture configurations. The open-aperture measurements reveal reverse saturation absorption behavior of the nanocomposites, which is further supported by TRFS analysis. The nonlinear absorption coefficient (β) increases from 0.188 × 10⁻¹² cm/W for pristine TiO₂ nanoparticles to 0.546 × 10^− 12 cm/W at 10 wt% Borophene concentration. Closed-aperture Z-scan results show a negative nonlinear refractive index (n₂), confirming self-defocusing behavior of nanocomposites, with the magnitude rising from 0.691 × 10⁻¹⁷ cm²/W for TiO₂ nanoparticles to 1.569 × 10^− 17 cm²/W for the highest Borophene loading. Correspondingly, the third-order nonlinear optical susceptibility (χ⁽³⁾) and figure of merit of the nanocomposites also increase with Borophene concentration, with χ⁽³⁾ improving from 8.07 × 10^− 16 esu for pristine TiO₂ nanoparticles to 23.87 × 10^− 16 esu for 10 wt% Borophene. The findings show that the Borophene/TiO₂ nanoparticles nanocomposites have enhanced nonlinear optical response than pristine materials highlighting the strong potential of the nanocomposites for advanced optoelectronic and nonlinear optical applications.

This study investigates the impacts of etching time on the surface morphology and optical properties of nano-inverted pyramids (NIPs) on monocrystalline silicon (mono c-Si) wafers using cost-effective copper-assisted chemical etching (CACE) process. By varying the etching time, we aim to optimize the texturing conditions to achieve the lowest average reflection and the highest broadband light absorption in the mono c-Si absorber within 300–1100 nm wavelength region. The results demonstrate that the etching time significantly influences the formation of the NIPs. After 7 min of etching, dense NIPs have been formed on the surface with root mean square roughness (RMS) roughness of 197 nm, leading to the lowest average reflection (R_avg) of 7.95% and the highest light absorption of 92.05%. Furthermore, the average absorption enhancement at wavelength of 600 nm improves significantly when compared to the planar mono c-Si (reference); 1.45 for 7 min of etching. The findings provide valuable insights into the development of NIPs by CACE process, paving the way towards realizing high-efficiency photovoltaic (PV) devices in the future.

The synthesis and optical properties of silver nanoparticles (AgNPs) derived from water hyacinth were simulated using a computational framework integrating reduction kinetics, particle size distribution modeling, and quantum confinement theory. The reduction of silver ions to metallic silver followed pseudo-first-order kinetics, with Ag⁰ concentration increasing from 0 to approximately 997 µM over 120 min. Nanoparticles exhibited a lognormal size distribution with mean diameters ranging from 40 to 100 nm, a number-weighted mean of 90.3 nm, an intensity-weighted Z-average of 91.7 nm, and a dispersity index of 0.08, indicating uniform growth. Simulated UV-Vis spectra showed a size-dependent surface plasmon resonance (SPR) peak shifting from 392 nm for 10 nm particles to 421 nm for 50 nm particles, with absorbance increasing from 0.21 to 2.25 A.U. over 150 min. Bandgap energies decreased from 3.12 eV for smaller nanoparticles (~ 15 nm) to 3.07 eV for larger particles (~ 21 nm), reflecting reduced quantum confinement effects. Temperature-dependent simulations demonstrated that higher temperatures (25–125 °C) accelerated Ag⁺ reduction and particle growth, producing nanoparticles between 10 and 50 nm, with rapid nucleation at 125 °C causing slight broadening of the size distribution. Collectively, these results highlight the strong correlation between nanoparticle growth kinetics and optical properties, showing that computational modeling can effectively predict and optimize synthesis conditions to achieve desired plasmonic and electronic characteristics for applications in catalysis, sensing, and photonics.