Applied Physics A最新文献

In this paper, we numerically investigate the design of an all-dielectric terahertz metasurface sensor with an ultra-high Q-factor, utilizing the concept of bound states in the continuum (BIC). The proposed metasurface consists of silicon-based cylindrical disks arranged as metamolecules. It is observed that two resonant modes are formed at 3.79 THz and 4.19 THz under symmetric conditions. By introducing a local asymmetry parameter (α) to break the structural symmetry, a leaky channel emerges, converting the ideal BIC into a quasi-BIC (q-BIC). This results in a sharp resonance at 4.06 THz with a Q-factor of 1.5 ×(:{10}^{4}). The numerically evaluated sensing performance demonstrates a high refractive index sensitivity of 1.0746 THz/RIU and a figure of merit (FOM) of 10854.56/RIU over a refractive index range of 1.00-1.15. Tuning the asymmetry further enhances the FOM up to 41330.77/RIU. The proposed metasurface finds strong potential for high-precision sensing, detection, and imaging in the terahertz frequency regime.

A metal-insulator-metal (MIM) parallel plate thin-film capacitor of ceramic dielectric was fabricated using an n-type silicon wafer substrate and characterized electrically. The ferroelectric perovskite BST36 (Ba_0.36, Sr_0.64)TiO₃ thin film dielectric was deposited via the RF magnetron sputtering technique, and the film is employed as a dielectric for the parallel plate ceramic capacitor. A molybdenum disilicide (MoSi₂) thin film has been deposited via the DC magnetron sputtering technique, and the sheet resistance was 5.611 Ωcm^− 2, after thermal processing. It has been used as a bottom metal contact for the device. While indium (In), copper (Cu), and silver (Ag) were deposited via the thermal evaporation technique and employed as top contact electrodes for the device. Molybdenum disilicide (MoSi₂) has been used again as a top contact electrode as well as a bottom electrode. The capacitor was electrically characterized at room temperature under a 10 VDC bias and 1 MHz frequency. Measurements of dielectric loss, dielectric constant, and capacitance density were depended on the device structure and electrode material. The results of the MIM parallel plate capacitor structure of Ag/BST/MoSi₂/n-Si exhibited the highest capacitance density achievement of 405 nFcm^− 2 with a dielectric loss of 0.048. An optimal recorded dielectric loss was 0.024 at 10 VDC for the device structure In/BST/MoSi₂/n-Si. The MoSi₂/BST/MoSi₂/n-Si a full parallel-plate ceramic capacitor device structure had a capacitance density of 47 nFcm^− 2, a dielectric constant of 22.3; and a dielectric loss of 0.035.

A novel plasmonic bandpass filter is proposed, comprising an infinity-shaped resonator integrated with metal-insulator-metal (MIM) waveguide structures. The proposed profile enables tunable spectral filtering in the near-infrared region. Owing to its unique structure, the resonator supports three distinct resonant modes, producing a characteristic triple-peak transmission spectrum spanning the wavelength range of (:0.8-3:mu:m). Numerical simulations confirm that the spectral response of the proposed waveguide-consisting resonance positions, bandwidth and transmission intensities-can be precisely matched by adjusting the resonator’s geometric parameters. This filter demonstrates a high transmission efficiency (more than 0.8) and a desirable quality factor at the subwavelength-scale, which indicates its originality and importance. The tunable narrowband performance in a wide spectral window highlights its potential for diverse applications in optical sensing, biomedical imaging, spectral filtering, optoelectronic systems as well as astronomical instrumentation.

This work demonstrates the simple, economical, and rapid synthesis of magnesia oxide (Mn₂O₃), copper oxide (CuO), and their compound Mn₂O₃/CuO composite, employing fundamental green practices. The as-synthesized Mn₂O₃, CuO, and Mn₂O₃/CuO have been evaluated using X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and field-emission scanning electron microscopy (FESEM). The presence of distinct Mn₂O₃ and CuO phases, as well as the interphase between them, is evident in the TEM micrographs. Using the Tauc plot from absorption spectra, the energy bandgaps of pure Mn₂O₃, CuO, and the Mn₂O₃/CuO composite were estimated to be 2.6, 2.1, and 3.2 eV, respectively. The obtained materials were investigated for their photoluminescence (PL) and chromaticity characteristics to understand interfacial charge-transfer behavior. The PL spectra reveal broad blue - green emissions with main peaks located at 414 –437 nm for Mn₂O₃, 414 –439 nm for CuO, and a slightly red-shifted, intensified band at 435 nm for the Mn₂O₃/CuO composite. The corresponding CIE 1931 chromaticity coordinates (x ≈ 0.31, y ≈ 0.58) confirm a vivid green emission region, indicating improved color purity and radiative efficiency. These results demonstrate that coupling Mn₂O₃ with CuO tailors the electronic band alignment, suppresses non-radiative losses, and promotes strong visible luminescence, making the Mn₂O₃/CuO nanocomposite a promising candidate for green light - emitting and optoelectronic devices.

The demand for antibacterial surfaces has intensified since the recent pandemic, underscoring the need to prevent microbial adhesion on high-contact surfaces. Metallic and metal oxide nanostructures exhibit intrinsic antibacterial properties, motivating the development of scalable, cost-effective fabrication routes for functional coatings. In this study, copper oxide (CuO) thin films were deposited by magnetron sputtering and further nanostructured via glancing angle deposition (GLAD). The films exhibited pronounced antibacterial efficacy, inactivating Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) with efficiencies over 98% after 8 h of exposure. Increasing the deposition angle enhanced surface roughness and hydrophobicity, which directly correlated with higher bacterial inactivation. Longer exposure further improved antibacterial performance, demonstrating time-dependent activity. These results establish GLAD-fabricated CuO thin films as a promising, industrially scalable strategy for next-generation antimicrobial surface coatings.

Developing stable and efficient electrode materials is requisite for improving energy-storage performance. In this study, we compare the charge retention behaviour of pristine NiO nanoparticles, Ni-MOFs prepared with single and dual organic linkers, and their corresponding derived and composite structures. The materials were synthesized through a solvothermal route and characterized to confirm structural and morphological features. Their electrochemical response was evaluated in alkaline medium using standard supercapacitor testing methods. The outcomes show a clear progression in retention performance linked to the choice and number of linkers. Pristine NiO exhibits a retention of 68%, while mono-linker and double-linker Ni-MOFs improve this to 74% and 84%, respectively. MOF-derived NiO provides 78% retention, and the corresponding composites show 72% for mono-linker Ni-MOF@NiO, 84% for the double-linker system, and a maximum of 86% for the MOF-derived NiO@NiO. These trends demonstrate that ligand multiplicity and structural integration with NiO significantly enhance charge stability. Inclusive, the work highlights a straightforward strategy for designing MOF-based hybrid electrodes with improved retention for next-generation supercapacitors.

Reliable solid-state dosimeters are crucial for industrial and medical sterilization processes that require accurate monitoring of high gamma doses. In this work, thin polystyrene films with 0.2% methyl red (MR/PS) were produced and assessed under 60Co irradiation in the 10–30 kGy range. The films demonstrated a strong and highly linear dose-response at 475 nm, enabling precise measurement of accumulated dose, even though discoloration only became noticeable after 25 kGy. The excellent post-irradiation stability necessary for dosimeter storage and transportation outside of controlled environments was confirmed by the optical response, which stayed constant for two months after exposure and also showed very little variation under combined thermal and humidity conditions (20–40 °C and 20–45% RH). Mechanical testing revealed a radiation-induced strengthening effect due to crosslinking at 10–15 kGy; chain scission and reduced ductility were noted at higher doses (> 20 kGy). Young’s modulus increased by ≈ 16–21%, and the UTS increased by ≈ 30% at 10 kGy and ≈ 21% at 15 kGy, respectively. However, elongation gradually decreased up to ≈ 64% at 30 kGy, indicating a shift from reinforcement to degradation with increasing dose. These results were supported by FTIR and FESEM analyses, which revealed chemical structural changes and a change from smooth to cracked surfaces as the material progressed from mechanical stabilization to degradation. Overall, the MR/PS film exhibits clear, stable, and quantifiable optical and mechanical behavior, supporting its use as a dependable and reasonably priced dosimeter for high-dose gamma sterilization applications.

Doped ceria electrolytes are extensively studied and applied in intermediate-low temperature solid oxide fuel cell (IT-SOFC). Ce_0.79Gd_0.2-xCa_xCu_0.01O_2-δ electrolytes were synthesized by the ultrasonic-assisted sol-gel self combustion sintering method. The experimental results demonstrate that incorporating 1.0 mol% Cu into gadolinium-doped ceria (GDC) enables a reduction in sintering temperature by 500 °C, while Ca co-doping effectively increases oxygen vacancy formation, achieving a dense electrolyte with comparable ionic conductivity. Among these, the Ce₀.₇₉Gd₀.₁₅Ca₀.₀₅Cu₀.₀₁O_2-δ electrolyte demonstrated the highest conductivity, showing a tenfold increase compared to conventional Ce_0.79Gd_0.2-xCa_xCu_0.01O_2-δ electrolytes, with a conductivity of 0.054 S·cm⁻¹ at 800 °C and an activation energy of 0.88 eV.

A novel functionalized quinoline derivative, (E)-N’-(7,7-dimethyl-2-oxo-4-phenyl-2,3,4,6,7,8-hexahydroquinazole-5(1 H)-ylidene) isonicotinohydrazide, is developed and produced for potential therapeutic and nonlinear optical (NLO) uses. The structural elucidation is supported by FT-IR, UV-vis, NMR, and mass spectrometry, and the results are supported by DFT calculations at the B3LYP/6-31G(d, p) level. AIM analysis is used to analyze intramolecular interactions. NLO investigations indicate significant hyperpolarizability (β = 5.498 × 10⁻³⁰ esu), with values higher than those of urea. Frontier Molecular Orbital, MEP, and TD-DFT simulations in solvents yield a band gap of 3.80 eV, which has excellent electrical and optical properties. The NBO and Fukui analyses reveal stable donor-acceptor interactions and reactive regions. The SwissADME examination validated drug-likeness, and molecular docking revealed efficient interaction with tuberculosis target proteins, indicating anti-TB activity. These findings suggest that the compound not only possesses promising electronic characteristics but also demonstrates potential therapeutic applications. Overall, the molecule combines high biological activity with improved NLO responsiveness, making it a viable option for both therapeutic and photonic applications.

This work presents a theoretical and numerical investigation of the optical properties and slow-light behavior of CdS@ITO core–shell quantum dots (CSQDs) designed for operation in the 1310 nm and 1550 nm telecom bands. Using quasi-static electrodynamics, Maxwell–Garnett effective medium theory, and the Drude–Sommerfeld model, we demonstrate that the ITO shell supports low-loss infrared plasmonic resonances with extinction coefficients below (kappa < 0.06). Hybrid exciton–plasmon coupling between the CdS core and ITO shell produces strong local field enhancement ((|F|^{2}> 1000)) and pronounced normal dispersion, enabling slow-light behavior with group velocities as low as (v_{g} approx 0.05c). Geometric tuning of the core radius (3–5 nm) and shell thickness (6–8 nm) enables precise alignment of the plasmonic resonance with standard telecom wavelengths. Finite element simulations confirm intense field localization at the CdS/ITO interface and enhanced internal fields within the CdS core, supporting Kerr-type nonlinear effects relevant for optical modulation. Parametric mapping of extinction, refractive index, and group index further demonstrates robust spectral tunability and low-loss performance across the near-infrared region. These findings identify CdS@ITO CSQDs as promising, CMOS-compatible nanostructures for compact optical delay lines, all-optical modulators, and other integrated photonic components operating within the telecom band.