Applied Physics A最新文献

This work investigates the tunable optical response of cylindrical core/shell quantum dots (CCSQDs) and their inverted counterparts (ICCSQDs) under different oxide environments. Using the effective mass approximation and density matrix formalism, the effects of core radius, height, and optical intensity on the linear, third-order nonlinear, and total optical absorption coefficients, as well as refractive index changes, are analyzed for intersubband transitions (1s–1p, 1p–1d, 1d–1f). The results indicate that oxide-induced dielectric modulation significantly alters resonance intensities and spectral positions, providing a pathway to tailor nonlinear optical behavior for next-generation optoelectronic and photonic devices.

Green fabrication of calcium hydroxide nanoparticles in the presence of clove oil and surfactants is an innovative approach towards conservation of archaeological stone materials. The purpose of the current study is to determine the effectiveness of calcium hydroxide-based consolidants on archaeological stone conservation. Nanostructured calcium hydrates (NCH) were prepared using antioxidants from syzygium aromaticum L as an eco-friendly strategy. Calcium hydrates have plate-like crystals; however, they form spherical nanosized particles in the presence of surfactants. The effect of nature of the head group and hydrophobicity of surface-active agent on the particle size and homogeneity of the system was studied. The system was thoroughly analyzed using several techniques. The average effective diameter obtained by dynamic laser light scattering was between 82 and 191 nm. The transmission electron microscopy images revealed the sizes ranging between 40 and 75 nm. The crystallite sizes calculated using the X-Ray Diffraction data were between 25 and 44 nm. It was concluded that NCH synthesized by the addition of anionic and nonionic surfactants had relatively smaller sizes compare to those synthesized by the addition of cationic and zwitterionic surfactants as evident from above results. Before using the synthesized Nano hydrates for stone conservation, their antimicrobial activity and capability of degrading contaminants through aid of diffused light were studied as possession of these traits enhances the effectiveness of consolidants in archeological conservation. Thus, these Nano Calcium hydrates can be effectively applied for Conservation of archaeological stone Monuments as they are expected to have enhanced optical, mechanical and thermal properties.

Graphical abstract

In this paper, the influence of the target plate thickness, constraint conditions and filling medium on the cutting performance of the linear shaped charges is studied. Firstly, an explosion cutting experiment was conducted on a 6061-T6 aluminum alloy target plate using QV45 lead linear shaped charges, and the cutting performance of the linear shaped charges and the optimal stand-off distance 2.3 mm were obtained. Subsequently, a numerical simulation model was established and the material parameters of the simulation model were calibrated using experimental results. Finally, the effects of target plate thickness, constraint conditions, and filling medium on the cutting performance of QV45 linear shaped charges were analyzed through numerical simulations. The results show that all three will have obvious influence on the penetration of the target plate. At a stand-off distance of 0 mm, the maximum thickness of the target plate that can be cut is 6.8 mm. When the limit cutting thickness corresponding to different stand-off distances is exceeded, the thicker the target plate, the lower the penetration depth of the linear shaped charges. Reduced constraints also degrade the cutting performance of linear shaped charges. For a 10 mm thick target plate cut with QV45 linear shaped charge, when the bottom normal of the target plate is constrained, the maximum penetration depth reaches 7.63 mm; when the target plate is fully constrained on both sides of the surface, the penetration depth is 7.23 mm; when the target plate is fully constrained on one side of the surface, the penetration depth decreases to 7.19 mm; when the target plate is not constrained, the minimum penetration depth is only 6.93 mm. The study also found that when the stand-off distance space is completely filled with lubricant, the penetration depth decreases by approximately 40.4%; when the stand-off distance space is completely filled with water, the penetration depth decreases by approximately 32.6%. The results of this paper can provide guidance for the application of linear shaped charges in specific configurations.

In this work, the critical behavior and magnetic phase transitions of La_0.6Dy_0.1Sr_0.3Mn_−xBi_xO₃ (:(text{x}:=:0,:0.01,:0.03,:0.1)) manganites were systematically investigated. using an iterative fitting procedure based on the Kouvel–Fisher method, critical exponents (β; γ) were determined to be (1.1972; 0.4895), (1.3347; 0.4960), (1.1190; 0.3969) and (1.0743; 0.3890) for (:text{x}=0,:0.01,:0.03:text{a}text{n}text{d}:0.1), respectively. The refined approach ensured improved accuracy by minimizing discrepancies between critical temperatures derived from spontaneous magnetization and inverse susceptibility. The results revealed a crossover in critical behavior, with the exponents deviating from mean-field values, suggesting the presence of short-range magnetic interactions. Through the Landau theory framework, temperature-dependent coefficients(:text{a}left(text{T}right)) and (:text{b}left(text{T}right)) were extracted, confirming the stability of the second-order magnetic phase transition. Numerical simulations based on the Landau equation successfully reproduced experimental magnetization isotherms and magnetic entropy changes, showing good agreement, particularly at high fields. This combined experimental and theoretical analysis offers a comprehensive understanding of the influence of Bi substitution on the magnetic criticality and phase transition nature in these manganites.

In this study, CdO thin films with pure and volume ratios of (1.5% and 1.5%) B and Ga separately and dual-doped were coated on ITO substrate using electrodeposition method. Structural, optical and morphological properties of pure, B and Ga dual-doped CdO films coated on ITO were investigated. XRD measurements revealed that the crystal structure of CdO was disrupted and the crystal size decreased in the B and Ga dual-doped CdO films. As a result of optical measurements, it was observed that the optical band gap decreased as the doping ratio increased. As a result of morphological measurements, it was observed that the surface of all film was homogeneous. Spectroscopic ellipsometry was used to determine that the refractive index, extinction coefficient, dielectric constants, and dissipation factor were determined to change with the concentration of B and Ga dual doping. Refractive index values ranged from 0.8 to 2 and extinction coefficient values from 0.05 to 1.2. The dielectric constant values also show significant variation in the visible region.

This study investigates the dielectric and electrical properties of zinc ferrite (ZnFe₂O₄) nanoparticles synthesized via a sustainable myco-mediated route using Oyster mushroom extract as a bio-capping agent. Structural analysis confirmed crystallite sizes ranging from 16 to 28 nm, demonstrating that fungal phytochemicals effectively modulate particle size and microstructural parameters. The dielectric constant of the nanoparticles was found to be remarkably high (~ 24,854 at low frequencies) with comparatively low dielectric loss, both strongly dependent on frequency, temperature, and particle size. The dielectric dispersion was well-explained by the Cole–Cole model, indicating poly-dispersive relaxation behavior. AC conductivity, interpreted through Jonscher’s power law, revealed distinct conduction pathways: non-overlapping small polaron tunneling (NSPT) for pristine ZnFe₂O₄ and correlated barrier hopping (CBH) for the green-synthesized samples. Electrical modulus analysis further confirmed short-range charge carrier mobility with non-Debye relaxation. Temperature-dependent DC conductivity followed Arrhenius behavior, with activation energies decreasing systematically with increasing particle size, highlighting thermally activated conduction. The synergy of ultra-high dielectric constant, low dielectric loss, and tunable conduction mechanisms underscores the potential of green-synthesized ZnFe₂O₄ nanoparticles for capacitors, memory storage devices, and smart sensors.To the best of our knowledge, this is the first report on dielectric properties of green-synthesized ZnFe₂O₄ nanoparticles, where Oyster mushroom extract not only enables an eco-friendly fabrication route but also provides precise control over dielectric performance through particle size engineering.

A high-performance room temperature ammonia (NH₃) gas sensor based on ZnO/Zn₂SnO₄ composite was synthesized by a one-step hydrothermal method by combining simply prepared zinc oxide (ZnO) with zinc stannate (Zn₂SnO₄), which has a high gas-sensitive performance at room temperature. The experimental results show that the response value of ZnO/Zn₂SnO₄ for 1000 ppm NH₃ is 4364.6, and the response/recovery time is 1.4 s/1.2 s, respectively, and a minimum detection limit of 0.16 ppm. This is better than that of pure Zn₂SnO₄, which has a response value of 151.8, and it is difficult to reach the equilibrium during the adsorption process. Thus, the response/recovery time of ZnO/Zn₂SnO₄ is faster than that of the current metal oxide semiconductor-based gas sensors. This is due to more oxygen vacancies and oxygen radicals on the ZnO/Zn₂SnO₄ surface. In addition, the synergistic effect between ZnO and Zn₂SnO₄ heterojunction accelerates the carrier migration efficiency and improves the gas-sensitive performance. Thus, the ZnO/Zn₂SnO₄ sensor combines the advantages of room-temperature operation and the simplicity of preparation, and at the same time broadens the application of Zn₂SnO₄ in the sensor field.

Tin selenide (SnSe) thin films were co-electrodeposited onto ITO/glass substrates from an aqueous solution containing tin(II) dichloride (SnCl₂) and selenium dioxide (SeO₂) as precursors, with ethylene diamine tetra-acetic acid (EDTA) as a complexing agent at 50 °C. The electrochemical behavior and co-deposition potentials of Sn, Se, and SnSe were analyzed using cyclic voltammetry. The influence of deposition potential on the structural, morphological, compositional, and optical properties of SnSe films was examined through X-ray diffraction, Raman spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, diffuse reflectance spectroscopy, and UV-Vis-NIR spectroscopy. The films consist of randomly arranged nanosheets and exhibit an absorption coefficient exceeding 10⁴ cm^− 1 in the visible range, and an optical band gap between 1.2 and 1.45 eV. The optimal sample showed the highest purity of the SnSe phase and the most desirable stoichiometric composition among all the prepared samples.

Formation of laser-induced periodic surface structures (LIPSS) on metal thin films deposited on soda-lime glass is investigated using a femtosecond (fs) laser source with third harmonic generation (THG) producing a 343 nm UV beam. In this study, a bilayer of chromium (30 nm) and silver (100 nm) was chosen as metal thin films, sputtered onto a glass substrate to enhance the UV light absorption on the dielectric material surface. The variation in repetition rate (f) and pulse energy (E) of the laser irradiation was investigated while process time is fixed to 1 s, with parameters ranging from 10 kHz to 250 kHz and the pulse energy increasing from 1.5 µJ to 3 µJ. The experimental observation reveals the formation of LIPSS on both metal films and dielectric glass substrates exhibiting low spatial frequency LIPSS (LSFL) upon irradiation with linearly polarized femtosecond laser pulses (τ = 300 fs at 1030 nm) in air environment. With the pulse energy of 1.5 µJ, and for all frequencies, no surface modification was observed. When the pulse energy was increased to 2.2 µJ with a 100 kHz repetition rate, the bilayer metal films were ablated, and LIPSS were formed on the dielectric glass substrate at the center of the laser spot, oriented perpendicular to the laser beam polarization. Spatial period of LSFL_⊥ on glass is about 240 nm where the the spatial period of the LSFL_II on silver reach 330 nm therefore, around the value of the wavelength of the incident UV wavelength (343 nm). Upon increasing f to 250 kHz and energy to 3 µJ, the glass surface undergoes texturing or ablation due to elevated threshold fluence and the higher number of pulses achieved.