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过滤筛选
- 2018
- arbitrary coupling coefficients
- Dielectric resonator
- filtering
- coupler
- filtering balun
- dual-band
- dual-mode dielectric resonator (DR)
- Electronic Science and Technology
- Nantong University
- Sun Yat-Sen University
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The Dependence of Resonance Frequency to Landing Angle in Reciprocal Scattering Phenomena of the Waves From an Elliptical Plasma Dielectric Antenna
摘要： Scattering of an electromagnetic plane wave in transverse electric mode which is obliquely incident to an elliptical plasma antenna with a dielectric rod is comprehensively investigated. The field solutions of the incident, transmitted, and the scattered waves will be derived in terms of Mathieu and modified Mathieu functions. Using asymptotic expansions of Mathieu functions, the scattering cross section per unit length is obtained. It will be shown that in such an elliptical plasma antenna, the backscattering cross section depends on the incident angle and the bistatic scattering cross section varies with scattering angle significantly. Such effects are not seen in antennas with circular cross section due to the circular symmetry in them. The validation of the presented formulations and numerical computation will be examined with the circular case that is an asymptotic well-known case. The graphs of backscattering cross section, scattering pattern, and their corresponding to the polarized charge densities are presented. The dependence of the backscattering cross section and the scattering pattern upon the density and geometrical dimension of the plasma and dielectric are investigated. In addition, it will be shown that the resonance frequencies, under which the plasma antenna response will be maximum, essentially depend on the incident angle of the incident wave.
关键词： dielectric rod,resonance frequency,polarized charge density,Backscattering cross section,scattering pattern,elliptical plasma antenna
更新于2025-09-23 15:22:29
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Polydiacetylene capacitive artificial nose
摘要： Polydiacetylenes are a class of conjugated polymers exhibiting unique color and fluorescence properties and employed as useful sensing vehicles. Here we demonstrate for the first time that the dielectric properties of polydiacetylenes can be exploited for vapor sensing. Specifically, electrodes coated with polydiacetylenes, embedded within a porous polyvinylpyrrolidone (PVP) matrix, exhibit significant capacitance transformations upon exposure to different vapors. The capacitive response of the polydiacetylene/PVP films depended upon both the structures of the diacetylene monomers, and the extent of ultraviolet irradiation (i.e. polymerization), underscoring a unique sensing mechanism affected by conjugation, structure, and dielectric properties of the polydiacetylene/polymer matrix. Importantly, the variability of polydiacetylene structures allow vapor identification through an array-based pattern recognition (i.e. artificial nose). This study opens new avenues for applications of polydiacetylene systems, particularly pointing to their dielectric properties as powerful sensing determinants.
关键词： polydiacetylene,polyvinylpyrrolidone,artificial nose,dielectric properties,capacitive vapor sensing
更新于2025-09-23 15:22:29
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Generation of polarization-sensitive modulated optical vortices with all-dielectric metasurfaces
摘要： Optical vortices (OVs) created from helical modes of light have extensive applications in optical manipulation, imaging and optical communications. Moreover, modulated optical vortices (MOVs) with modified wavefronts could provide new opportunities for fractionating particles and actuating microelectromechanical systems. Traditional devices for generating MOVs include spatial light modulators, spiral phase plates etc. However, such bulky devices are difficult to be applied to high-level integrated optical systems. Besides, other MOV generators are typically static and polarization-insensitive. Here, we proposed an all-dielectric metasurface to generate polarization-sensitive MOVs. The intensity patterns of the OVs can be modulated by adding a tangential modulation factor in the phase profile. Independent manipulation of two orthogonal polarizations was adopted via tailoring the geometric parameters of silicon (Si) pillars. We experimentally demonstrated that the metasurface could generate a doughnut and an actinomorphic vortex beams for different polarization inputs. In addition, the intensity pattern of the MOVs can be dynamically tuned by adjusting the polarization angle. This work can benefit optical manipulation and can be further extended to visible and near-infrared bands.
关键词： propagation phase,all-dielectric metasurfaces,mid-infrared,polarizations,modulated optical vortices
更新于2025-09-23 15:22:29
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Lead-free Ag <sub/> 1-3 <i>x</i> </sub> La <sub/><i>x</i> </sub> NbO <sub/>3</sub> Antiferroelectric Ceramics with High Energy Storage Density and Efficiency
摘要： Environmentally benign lead-free bulk ceramics with high recoverable energy density (Wrec) are very attractive in advanced pulsed power capacitors. In this work, composition engineering was adopted by La3+ modification to improve the energy storage performance of Ag1-3xLaxNbO3 ceramics. It was found the antiferroelectric (AFE) phase was stabilized after La3+ substitution, as a result of the reduced tolerance factor t. Significant improvement of Wrec and energy storage efficiency (η) were achieved with value of 3.12 J/cm3 and 0.63 for x=0.02 at an electric field of 230 kV/cm, more than 1.5 times the value of pure AgNbO3 (Wrec=1.9 J/cm3, η=0.40). The excellent energy storage properties are resulted from the increased antiferroelectric-ferroelectric phase transition electric field (EF), ferroelectric-antiferroelectric phase transition electric field (EA) and breakdown electric field (Eb). The enhanced Eb was ascribed to the decreased grain size and increased electrical resistivity upon La3+ modification. The feature makes Ag1-3xLaxNbO3 a potential candidate for energy storage applications.
关键词： energy storage,ferroelectricity/ferroelectric materials,lead-free ceramics,dielectric materials/properties
更新于2025-09-23 15:22:29
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Nano-structural investigations of porous silica coated carbonaceous spheres and dielectric properties of its organosilicone hybrid film
摘要： In this research, a series of carbonaceous spheres samples were synthesized by hydrothermal carbonization of glucose and cyclodextrin, and coated with mesoporous silica. The unique nano-structure of such carbonaceous spheres samples was fully characterized by DLS, XRD, SEM, TEM, Raman spectroscopy and infrared spectroscopy techniques. Such carbonaceous spheres samples were then blended with organosilicone in order to prepare a series of hybrid films. The influence of the added silica coated carbonaceous spheres on the dielectric property of these hybrid film samples was thoroughly investigated. The results indicate that the silica coated carbonaceous spheres are amorphous and have a typical core-shell structure. Such nano-structure and aggregation behavior in the organosilicone matrix can introduce more interfaces into the hybrid organosilicone film samples, and have notably affected the dielectric property of the hybrid organosilicon film samples. The dielectric constant and dielectric loss of the hybrid film samples could be kept relatively low if the introduced interfaces were blurred enough to avoid the interfacial polarity.
关键词： Carbonaceous spheres,Films,Nanostructure,Dielectric properties,Silicones
更新于2025-09-23 15:22:29
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Examination of dielectric strength of thin Parylene C films under various conditions
摘要： The breakdown voltage of the biocompatible polymer Parylene C was determined after storage in 60°C saline solution and treatment by autoclave. It occurred that both, storage at 60°C in saline solution and autoclaving, lead to distinct decrease of dielectric strength by approximately 50%.
关键词： Parylene C,dielectric strength,insulation,encapsulation,implant
更新于2025-09-23 15:22:29
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Structure and multiferroic properties of ternary (1?x)(0.8BiFeO3-0.2BaTiO3)-xK0.5Na0.5NbO3 (0?≤?x?≤?0.5) solid solutions
摘要： The ternary (1?x)(0.8BiFeO3-0.2BaTiO3)-xK0.5Na0.5NbO3 (0 ≤ x ≤ 0.5) solid solutions have been successfully synthesized by a solid-state reaction route. X-ray diffraction and Rietveld refinement studies reveal the phase transition from the rhombohedral and tetragonal phases to the single tetragonal phase with x increasing. The average grain size decreases initially and then increases as x increases, whereas the remnant magnetization shows an opposite trend and reaches the maximum value of ~2.09 emu/g at x = 0.3. An enhanced remnant polarization of ~8.6 μC/cm2 appears at x = 0.3 due to the structure distortion and the decrement of defects. Moreover, the remanent polarization and the relative permittivity reach the maximum value of ~20.14 μC/cm2 (10 Hz) and ~644 (1 kHz) at x = 0.5, respectively, and the corresponding dielectric loss decreases to the lowest value of ~0.022 (1 kHz). These results indicate that the properties of ternary BFO-BTO-KNN solid solutions can be modulated by adjusting the K0.5Na0.5NbO3 content to adapt to different application needs.
关键词： Microstructure,Dielectric loss,Phase transition,Multiferroic properties
更新于2025-09-23 15:22:29
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Improvement of Thin Film Adhesion Due to Bombardment by Fast Argon Atoms
摘要： A new hollow cathode sputtering system is used for beam-assisted deposition of thin films on dielectric substrates. A copper target placed at the hollow cathode bottom is uniformly sputtered by argon ions from the glow discharge plasma filling the cathode. Through an emissive grid, sputtered copper atoms leave the cathode together with accelerated argon ions. On their way to the substrate, the ions—due to charge exchange collisions—turn into fast argon atoms bombarding the growing film. With increasing argon ion energy, continuous bombardment results in the film adhesion improvement and reduction of the deposition rate down to zero, at an energy of about 2 keV. The pulsed bombardment does not influence the film deposition rate, and results in a monotonic growth of the film adhesion up to 20 MPa when increasing the fast atom energy up to 10 keV.
关键词： neutral beam assisted deposition,adhesion improvement,thin films,dielectric substrates
更新于2025-09-23 15:22:29
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Interface Modulation of Core-Shell Structured BaTiO3@polyaniline for Novel Dielectric Materials from Its Nanocomposite with Polyarylene Ether Nitrile
摘要： The core-shell structured polyaniline-functionalized-BaTiO3 (BT@PANI) nanoparticles with controllable shell layer thicknesses are developed via in-situ aniline polymerization technology and characterized in detail. The results prove that the PANI shell layer with the adjustable and controllable thicknesses of 3–10 nm are completely stabilized on the surface of the BaTiO3 core. In addition, the BT@PANI nanoparticles are regarded as the hybrid nanofillers to prepare PEN/BT@PANI nanocomposite films with a PEN matrix. The research results indicate that the surface functionalized nanoparticles facilitate the compatibility and dispersibility of them in the PEN matrix, which improves the properties of the PEN/BT@PANI nanocomposites. Specifically, the PEN/BT@PANI nanocomposites exhibit thermal stability, excellent permittivity-frequency, and dielectric properties-temperature stability. Most importantly, the energy density of nanocomposites is maintained at over 70% at 180 °C compared with that at 25 °C. All these results reveal that a new way to prepare the high-performance PEN-based nanocomposites is established to fabricate an energy storage component in a high temperature environment.
关键词： dielectric properties,in-situ polymerization,nanoparticles,nanocomposites
更新于2025-09-23 15:22:29
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</sub> ) Interlayer
摘要： Electrical and dielectric properties of Au/n-Si metal–semiconductor structures with high dielectric have been examined by capacitance/conductance–voltage (C/G–V) measurements in the frequency range of 5–500 kHz at room temperature. Voltage-dependent profiles of interface states (Nss) and resistance (Ri) were extracted from the C and G data using the low–high-frequency capacitance and Nicollian–Brews methods, respectively. The real and imaginary components of the complex dielectric constant (ε', ε''), electric modulus (M', M''), and ac conductivity (σac) were calculated from the C and G data. All parameters have a strong relation with frequency and voltage, especially at low frequencies due to Maxwell–Wagner relaxation and Nss. The observed peaks in the Nss–V and Ri–V plots can be ascribed by the special distribution of Nss at M/S interface. These results confirmed that [2% graphene cobalt-doped (Ca3Co4Ga0.001Ox)] interlayer has high-dielectric constant and can be used an interlayer instead of the traditional SiO2 at M/S interface to increase their capacitance or more charges/energy storage and reduce both the values of Nss and series resistance (Rs). The values of σ are almost constant at lower–intermediate frequencies, but they start to increase at high frequencies that are corresponding to the dc and ac conductivity, respectively.
关键词： electrical properties,nanostructures,Dielectric properties,graphene,polymer
更新于2025-09-23 15:22:29