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- 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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Dielectric, electrical and impedance study of single perovskite Pb(Ni1/3Mn1/3W1/3)O3
摘要： A multiferroic material Pb(Ni1/3Mn1/3W1/3)O3 with ferroelectric and ferromagnetic properties at room temperature is designed for multifunctional applications. A orthorhombic perovskite crystal structure has been assigned for the present perovskite according to the X-ray diffraction patterns. At 1 kHz, dielectric constant (er) increases from 1655 at 298 K to its ?rst maximum 3514 at 457 K referred as magnetic transition. The high values of er in the low frequency range show better dispersion, and with the increase in frequency, a gradual decrease in the er values was observed. The contribution of grain and/or electrode/interface effects in the resistive/capacitive properties was ascertained by the Nyquist plots. An equivalent circuit has been suggested consisting of resistive and capacitive components (R, C, Q) estimates the bulk (grain) and grain boundary resistance and capacitance. The activation energy was found to be greater than 0.2 eV, supporting the conduction mechanism due to hopping of charge carriers.
关键词： Solid-state reaction,Multiferroic material,Dielectric response,Electrochemical impedance spectroscopy,Ceramics
更新于2025-09-09 09:28:46
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Improvement of dielectric breakdown strength and energy storage performance in Er2O3–modified 0.95Sr0.7Ba0.3Nb2O6-0.05CaTiO3 lead-free ceramics
摘要： In this study, 0.95Sr0.7Ba0.3Nb2O6-0.05CaTiO3-x wt. % Er2O3 ceramics (SBNCTEx; x = 0-5) were synthesized using traditional solid-state method, and we investigated the microstructure, energy storage properties as well as the relationship between dielectric breakdown strength and interfacial polarization. As compared with pure 0.95Sr0.7Ba0.3Nb2O6-0.05CaTiO3 ceramics, the Er2O3 dopants suppressed the grain growth of SBNCTEx, and the doped ones showed the dense microstructure. The secondary phase was found for x ≥ 1 according to the EDS results, and the influence of the secondary phase on relative dielectric breakdown strength has also been studied. The dielectric breakdown strength increased from 18.1kV/mm to 34.4 kV/mm, which is good for energy storage. The energy storage density of 0.28J/cm3 and the energy storage efficiency of 91.4% were obtained in the SBNCTE5 ceramics. The results indicate that SBNCTE ceramics can be used as energy storage capacitors.
关键词： Impedance,Er2O3 addition,Dielectric breakdown strength,Energy storage
更新于2025-09-09 09:28:46
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Composition-dependent xBa(Zr0.2Ti0.8)O3-(1-x)(Ba0.7Ca0.3)TiO3 bulk ceramics for high energy storage applications
摘要： This work reports the composition dependent microstructure, dielectric, ferroelectric and energy storage properties, and the phase transitions sequence of lead free xBa(Zr0.2Ti0.8)O3-(1-x)(Ba0.7Ca0.3)TiO3 [xBZT-(1-x)BCT] ceramics, with x = 0.4, 0.5 and 0.6, prepared by solid state reaction method. The XRD and Raman scattering results confirm the coexistence of rhombohedral and tetragonal phases at room temperature (RT). The temperature dependence of Raman scattering spectra, dielectric permittivity and polarization points a first phase transition from ferroelectric rhombohedral phase to ferroelectric tetragonal phase at a temperature (TR-T) of 40 0C and a second phase transition from ferroelectric tetragonal phase - paraelectric pseudocubic phase at a temperature (TT-C) of 110 0C. The dielectric analysis suggests that the phase transition at TT-C is of diffusive type and the BZT-BCT ceramics are a relaxor type ferroelectric materials. The composition induced variation in the temperature dependence of dielectric losses was correlated with full width half maxima (FWHM) of A1, E(LO) Raman mode. The saturation polarization (Ps) ≈ 8.3 μC/cm2 and coercive fields ≈ 2.9 kV/cm were found to be optimum at composition x = 0.6 and is attributed to grain size effect. It is also shown that BZT-BCT ceramics exhibit a fatigue free response up to 105 cycles. The effect of a.c. electric field amplitude and temperature on energy storage density and storage efficiency is also discussed. The presence of high TT-C (110 0C), a high dielectric constant (εr ≈ 12285) with low dielectric loss (0.03), good polarization (Ps) ≈ 8.3 μC/cm2) and large recoverable energy density (W = 121 mJ/cm3) with an energy storage efficiency (η) of 70 % at an electric field of 25 kV/cm in 0.6BZT-0.4BCT ceramics make them suitable candidates for energy storage capacitor applications.
关键词： spontaneous polarization,Raman spectroscopy,dielectric constant,lead free ceramics,Energy storage capacitors,fatigue
更新于2025-09-09 09:28:46
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Peculiarities of band structure of one-dimensional photonic crystals
摘要： In this paper, the peculiarities of the band structure of one-dimensional photonic crystals are studied, when the periodic (quasiperiodic) medium is inhomogeneous in relation to both the dielectric and magnetic properties. It is shown that the photonic band gap does not appear at small angles of incidence, in the case when the modulation depths of the dielectric permittivity and magnetic permeability coincide. The possibilities of obtaining photonic bandgaps in the terahertz radiation region are considered. The features of the band structure of photonic crystal with different spatial periods of the dielectric permittivity and magnetic permeability are investigated. It is shown that in this case, four PBGs appear in each diffraction reflection order.
关键词： Dielectric permittivity,Band structure,Magnetic permeability,Photonic crystals,Terahertz radiation
更新于2025-09-09 09:28:46
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Effect of PbO–B2O3–BaO–SiO2 glass additive on dielectric properties of Ba0.5Sr0.5TiO3 ceramics for radio-frequency applications
摘要： In this work, the effects of PbO–B2O3–BaO–SiO2 (PBBS) glass addition (in increasing wt%) into Ba0.5Sr0.5TiO3 (BST0) ceramic on sintering, phase, and dielectric properties of BST0 are studied. The Ba0.5Sr0.5TiO3 (BST0) ceramic was synthesized by the conventional solid-state reaction method, and the PbO–B2O3–BaO–SiO2(PBBS) glass was formed by melting and quenching process. The PBBS glass with different weight percentages (3, 5, 8 and 10 wt%)is added to BST0 ceramic (BST3, BST5, BST8, and BST10, respectively) as a sintering aid to reduce the sintering temperature. Addition of glass helps in better sintering at lower temperatures with the presence of liquid phase at the respective sintering temperatures. The results of liquid phase-sintered ceramics are compared with the BST0 ceramic sintered at 1523 K. The BST10 with 10 wt% glass showed the lowest sintering temperature of 1148 K. Rietveld refinement analysis of BST0 ceramic confirmed the formation of single phase with cubic crystal structure. X-ray diffraction patterns of all liquid phase-sintered ceramics showed that the glass has minimal reaction with the BST0 ceramic and does not affect the crystal structure. Dielectric characterization was performed within the temperature range 20–450 K and frequency range 1 kHz to 1MHz. It is revealed that the transition temperature shifted with different weight percentage of glass addition. All the compositions exhibit the paraelectric phase at room temperature. Dielectric properties were also measured in the microwave frequency range 8.5–11 GHz at room temperature.BST10shows the stable and highest dielectric constant (average value of εr = 27) with lowest dielectric loss (tanδ = ~0.121). Fourier transform infrared (FTIR) and Raman spectroscopy confirmed the formation of desired compositions by detecting molecular vibrations and chemical bonding. The synthesized ceramic is a low-cost candidate and can have potential uses in the radio-frequency applications.
关键词： Dielectric properties,Glass,Sintering,Transition Temperature,Calcination
更新于2025-09-09 09:28:46
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Sharpening emitter localization in front of a tuned mirror
摘要： Single-molecule localization microscopy (SMLM) aims for maximized precision and a high signal-to-noise ratio. Both features can be provided by placing the emitter in front of a metal-dielectric nanocoating that acts as a tuned mirror. Here, we demonstrate that a higher photon yield at a lower background on biocompatible metal-dielectric nanocoatings substantially improves SMLM performance and increases the localization precision by up to a factor of two. The resolution improvement relies solely on easy-to-fabricate nanocoatings on standard glass coverslips and is spectrally and spatially tunable by the layer design and wavelength, as experimentally demonstrated for dual-color SMLM in cells.
关键词： localization precision,metal-dielectric nanocoatings,dual-color SMLM,Single-molecule localization microscopy
更新于2025-09-09 09:28:46
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Towards epitaxial graphene p-n junctions as electrically programmable quantum resistance standards
摘要： We report the fabrication and measurement of top gated epitaxial graphene p-n junctions where exfoliated hexagonal boron nitride (h-BN) is used as the gate dielectric. The four-terminal longitudinal resistance across a single junction is well quantized at the von Klitzing constant RK with a relative uncertainty of 10?7. After the exploration of numerous parameter spaces, we summarize the conditions upon which these devices could function as potential resistance standards. Furthermore, we offer designs of programmable electrical resistance standards over six orders of magnitude by using external gating.
关键词： p-n junctions,quantum resistance standards,gate dielectric,hexagonal boron nitride,epitaxial graphene
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Novel low dielectric loss polyimide film: synthesis and high frequency electrical properties
摘要： The thioether structure was introduced into the poly (N, N’- phenoxyphenyl pyromellitimide) (PMDA-ODA), owing to the extremely low dielectric loss of polyphenylene sulfide (PPS) in high frequency. Novel polyimide film containing 60% sulfide was synthesized through thermal imidization. The properties of these polyimide films morphology, thermal, dielectric characteristics and high frequency surface discharge lifetime, were studied. The films exhibited good thermal stability, having a mass loss less than 50% in decomposition temperature at 800 ?C. The phenyl sulfide containing polyimide films showed a lower dielectric loss tangent and longer lifetime in the effect high frequency high voltage surface discharge. The novel polyimide is more suitable in the insulation application of high frequency power electronic devices.
关键词： lifetime,high frequency,polyimide,phenyl sulfide,dielectric loss
更新于2025-09-09 09:28:46
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The study of undulator radiation of transversal oscillator
摘要： We study the radiation intensity for a charged transversal oscillator moving around a dielectric cylinder. Similar to the case of coaxial circular motion, under certain conditions for the parameters of the trajectory and dielectric cylinder, strong narrow peaks appear in the angular distribution of the radiation intensity in the exterior medium for a given harmonic. Comparing to the case of a uniform coaxial circular motion, for a transversal oscillator new peaks may appear. The oscillations serve as a mechanism for the control of the spectral-angular characteristics of the radiation intensity.
关键词： spectral-angular characteristics,transversal oscillator,dielectric cylinder,undulator radiation
更新于2025-09-09 09:28:46
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The Role of B-site Substitution on the Structural and Dielectric Properties of Samarium Orthoferrite Polycrystals
摘要： Polycrystalline samples of SmFeO3, SmFe0.5Co0.5O3, and SmFe0.5Cr0.5O3 were prepared by the conventional solid state reaction method. Powder x- ray diffraction pattern confirmed the formation of orthorhombic structure without any impurity phase. Dielectric and impedance properties of the sintered samples were studied as a function of temperature and frequency ranging from 300 K to 550 K and 100 Hz to 50 MHz respectively. The dielectric studies showed interesting properties like dielectric anomaly around spin reorientation temperature suggesting that the magnetic and electric order parameter may be coupled. The behavior of AC conductivity with temperature was explained by hopping mechanisms and the activation energy was found decreased for the doped samples. Nyquist and electric modulus spectra revealed the grain and grain boundary contributions of the sintered samples. The experimental results suggest that the spin reorientation can be tuned in the samarium orthoferrites by changing the B-site ion.
关键词： Dielectric Properties,Orthoferrites,Impedance Spectra,Perovskites,Multiferroic
更新于2025-09-09 09:28:46