Applied Physics A最新文献

To enhance the sluggish oxygen evolution process (OER), an exceedingly productive, cost-effective and conspicuous electrocatalyst must be developed. A hydrothermal process was used to fabricate MnCr₂O₄/rGO composite which is effective for water splitting. Numerous analytical approaches were utilized to judge functionality, crystalline structure, thermal durability, morphology and surface area of described material. Furthermore, electrochemical analysis for the MnCr₂O₄/rGO composite was performed using nickel foam (NF) as base to assess its electrocatlytic nature. Electrochemical analysis demonstrated that prepared composite exhibits an excellent overpotential (200 mV) and tafel slope value (38 mV dec⁻¹). MnCr₂O₄/rGO nanocomposite has an excellent stability. The electrochemical observations suggested that adding rGO into MnCr₂O₄ directed to an increased surface area lowering resistance and promoting fast electrolyte ion binding. The composite (MnCr₂O₄/rGO) manufactured by this method can be used for a variety of energy storing and conversion purposes.

Bi₃NbTiO₉ (BNT) nanoparticles were successfully synthesized via a controlled wet-chemical co-precipitation route using high-purity precursors, followed by calcination at 800 °C. X-ray diffraction (XRD) and Rietveld refinement confirmed the formation of a single-phase orthorhombic Aurivillius-type layered perovskite structure with the A2₁am space group, while the average crystallite size was estimated to be 45 nm. Raman spectral analysis revealed distinct vibrational modes corresponding to the (Bi₂O₂)²⁺ layers and (TiO₆/NbO₆) octahedral slabs, indicative of a non-centrosymmetric structure favorable for ferroelectric polarization. Field-emission scanning electron microscopy (FESEM) demonstrated nearly spherical, uniformly dispersed nanoparticles, and XPS analysis verified the oxidation states Bi³⁺, Nb⁵⁺, and Ti⁴⁺, along with surface oxygen vacancies beneficial for photocatalytic processes. Optical studies using UV–Vis diffuse reflectance spectroscopy (DRS) showed a strong absorption edge around 380 nm with a direct band gap of 2.56 eV. The photocatalytic performance of BNT was evaluated through Rhodamine B (RhB) dye degradation under visible light irradiation, achieving an efficiency of ~ 36% within 70 min, following pseudo-first-order kinetics with a rate constant of 0.0009950 min^− 1. The moderate yet promising photocatalytic efficiency is attributed to efficient electron–hole pair generation, oxygen-vacancy-assisted charge separation, and structural stability. These findings demonstrate that Bi₃NbTiO₉ nanoparticles are potential multifunctional materials for visible-light-driven photocatalytic and optoelectronic applications.

Circular dichroism (CD) represents a crucial optical response of chiral dielectric nanostructures, finding extensive utilization in biochemistry, chiral sensing, biological detection, and pharmaceutical chemistry. In the past, numerous metasurfaces could only operate under a single band and specific incident angles, limiting their practical applicability. Herein, we introduce an oblique Si bar into the pure grating structure, endowing the metasurface with chiral characteristics. It is revealed that this metasurface can generate four intense CD peaks (or valleys) at 1443 nm, 1475 nm, 1488 nm, and 1649 nm under normal incidence. Notably, within an incident angle range of 40 degrees, the resonance peaks I-III of this chiral grating metasurface can sustain stable resonance wavelengths and linewidths. To further broaden the applications of the nanostructure, the relationship between wavelength and refractive index is investigated. These findings provide novel perspectives for the design and manipulation of planar chiral materials exhibiting multi-band CD and angular robustness, and also expand the application of chiral structures in refractive index sensors.

This work provides a detailed theoretical analysis of the optical properties of nanostructures, focusing on the influence of disk size, temperature and hydrostatic pressure. Correlated and uncorrelated excitons are examined in the framework of the effective mass approximation using a variational method. The analysis covers quantum disks with radii in the range (R=3)–(10~textrm{nm}), hydrostatic pressures between 0 and (40~textrm{kbar}), and temperatures from 4 to (300~textrm{K}), allowing a comprehensive exploration of excitonic and optical responses under realistic experimental conditions. The study focuses on key optical properties, including emission wavelength, interband absorption coefficient and photoionization cross section. Numerical results indicate that reducing the disk size improves quantum confinement, leading to significant changes in emission and absorption spectra. Variations in temperature and hydrostatic pressure have a significant impact on optical responses, leading to changes in emission wavelength and absorption intensity. Analysis of electron-hole correlations reveals clear distinctions between bound and unbound excitonic transitions, with correlated excitons exhibiting higher binding energies and more pronounced spectral features. These results provide important information for the design and optimization of quantum disk-based optoelectronic devices, such as tunable LEDs, photodetectors and nanoscale photonic components. To the best of our knowledge, this is the first work to simultaneously examine the combined influence of excitonic correlation, hydrostatic pressure, temperature, and disk size on emission wavelength, interband absorption coefficient and photoionization cross section of GaAs/AlAs quantum disks

This study systematically investigates how A-site doping with ions of varying radii (Gd, Sm, Nd) tunes the structure and magnetocaloric properties of Ruddlesden-Popper phase La_1.3A_0.1Sr_1.6Mn₂O₇. Rietveld refinement confirms a tetragonal structure (I4/mmm). FT-IR and XRD reveal doping-induced lattice distortions and octahedral alterations. XPS confirms the Mn⁴⁺/Mn³⁺ ratio of 0.42, optimizing electronic interactions. The Curie temperature decreases with decreasing ionic radius: Tc = 83.11 K (Nd), 75.21 K (Sm), 66.90 K (Gd). The magnetic entropy change reaches 3.02 J/(kg·K) for Sm doping at 5 T, and a relative cooling power of 217.43 J/kg is achieved for Gd. Critical behavior follows the mean-field model, indicating long-range magnetic order. These results demonstrate that ionic radius-controlled lattice distortion is an effective strategy for enhancing magnetocaloric performance in Ruddlesden-Popper manganites.

This study reports the rapid and solvent-free synthesis of nickel oxide (NiO) nanoparticles using an atmospheric-pressure plasma jet method. This approach provides a green alternative to conventional chemical routes. X-ray diffraction (XRD) analysis confirmed the formation of high-purity cubic NiO nanoparticles with an average crystallite size of 17.87 nm. Energy-dispersive X-ray (EDX) spectroscopy verified the elemental composition. Morphological characterization using atomic force microscopy (AFM) and field-emission scanning electron microscopy (FESEM) revealed spherical and well-dispersed particles with average diameters of 96.24 nm (grain size) and 91.7 nm (particle size), respectively. UV-Vis spectroscopy yielded an optical band gap of 3.70 eV, indicating suitability for UV-active applications. The combination of high purity, appropriate band gap, and favorable morphology suggests these nanoparticles are promising for use in optoelectronics, catalysis, and biomedical applications.

This work investigated the effect of arc deposition strategy on the interface characteristics and mechanical properties of 316 L/Inconel625 laminated structures fabricated by CMT + P wire arc additive manufacturing. Four distinct strategies were designed to control the thermal history and remelting behavior at periodic heterogeneous interfaces. All strategies yielded interfaces with sound metallurgical bonding, primarily characterized by columnar dendrites and equiaxed grains of γ-austenite. The solidification mode shift in the 316 L layer, where the remelting of the former deposited Inconel625 layer promoted the formation of δ-ferrite. Elemental diffusion and the width of the interfacial transition zone were directly governed by the arc direction relative to the interface, with vertical multi-layer deposition (VMD) promoting the widest intermixing. Consequently, mechanical anisotropy varied significantly. The horizontal multi-layer deposited (HMD) sample showed the strongest anisotropy with a vertical-direction tensile strength of only 345.7 MPa, while the LGD-Ss sample achieved the highest strength of 644.2 MPa in the welding direction. These results establish a clear process-microstructure-property relationship, demonstrating that arc scanning path is a critical factor in control interface microstructure and mitigating mechanical anisotropy in multi-material WAAM components.

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This study investigates the influence of nanostructured tungsten trioxide (WO₃) films on the surface properties of transparent electrodes used in organic photovoltaics, specifically indium tin oxide (ITO) and fluorine-doped tin oxide (FTO). The aim is to improve their compatibility with the conductive polymer PEDOT: PSS used as a hole-transport layer (HTL). We show that pulsed laser deposition (PLD) parameters, particularly the number of laser pulses, influence surface architecture, wettability, and optical behaviour of WO₃. The X-ray diffraction investigation reveals that thicker layers adopt a monoclinic structure. The integration of PEDOT: PSS with nanostructured WO₃ layers could help mitigate degradation caused by PEDOT: PSS acidity, creating interfacial conditions that have been associated in the literature with improved device stability and performance. Optical measurements show that thicker WO₃ films enhance absorption in the ultraviolet and near-infrared regions while maintaining high transmittance in the visible range. Additionally, the surface morphology of the WO₃ layer significantly improves electrode hydrophilicity, reducing the water contact angle and enabling uniform PEDOT: PSS deposition without changing HTL thickness. The nanostructured WO₃ film acts as an interfacial modifier that preserves HTL thickness, an important parameter for organic photovoltaic cells and other optoelectronic devices, requiring stable interfaces and efficient charge transport. These insights contribute to the optimization of transparent electrodes for enhanced efficiency in organic photovoltaic applications.

Nanocrystalline yttria stabilized zirconia (YSZ) was synthesized using sol–gel and co-precipitation methods with yttria concentrations ranging from 2 to 8 mol%. YSZ thin films were subsequently deposited onto glass substrates using spin coating from the prepared precursor solutions. Comprehensive characterization of the YSZ samples was performed using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and I-V measurement. X-ray diffraction and Raman spectroscopy confirmed that increasing yttria content promotes phase stabilization, with a predominantly cubic fluorite structure achieved at 8 mol% yttria. SEM analysis revealed well-defined crystalline grains, although minor surface microcracks were observed, while elemental analysis verified the intended yttria doping levels. TEM and selected area electron diffraction (SAED) further confirmed the nanocrystalline nature of the material, with measured lattice spacings consistent with the cubic fluorite phase. Electrical I–V measurements performed at 450 °C showed that 4 mol% YSZ exhibits the highest ionic conductivity, corresponding to the lowest electrical resistance among all compositions. This enhanced conductivity at moderate doping arises from an optimal balance between oxygen-vacancy concentration and reduced defect clustering. Overall, the results demonstrate that yttria concentration plays a crucial role in controlling phase stability, lattice strain, and defect chemistry, which collectively govern oxide-ion transport. Notably, 4 mol% YSZ emerges as a promising composition for high-temperature ionic applications, offering improved performance for solid oxide fuel cells, oxygen sensors, and thermal barrier coatings.

In this research, hybrid epoxy nanocomposites incorporating chitosan (CS) and functionalized multi-walled carbon nanotubes (MWCNTs) were developed using a manual lamination approach. Initially, the optimal CS content was established to maximise mechanical performance by synthesising CS/epoxy nanocomposites with various volume fractions of CS (0 to 12% in steps of 3%). Based on this, a fixed CS concentration (3%) was maintained while varying MWCNT loading (0.1–0.5% by volume) to fabricate the hybrid CS/MWCNT/epoxy nanocomposites, along with a control sample with 0.1% MWCNT. The resulting materials were evaluated, including tensile and flexural strength, morphological (SEM and EDS) inspection, FTIR spectroscopy, and dynamic mechanical analysis. Among all formulations, the CS3CN1E hybrid composite (3%-CS and 0.1%-MWCNT) showed optimal performance with a tensile strength of 35.74 MPa, load capacity of 2.68 kN, and enhanced strain (1.28 mm/mm) with an improved flexural strength (10.3%), modulus (21.3%) and ILSS (22.5%) over the control sample. FTIR and DMA results confirmed a better molecular interaction, structural ordering, and viscoelastic behaviour, making CS3CN1E suitable for structural applications of low-load bearing components. Based on their properties, it was understood that a slight modification in the constituents may also enhance the possibility of use in biomedical applications (implants and medical devices).