Topic
Dielectric loss
About: Dielectric loss is a research topic. Over the lifetime, 20296 publications have been published within this topic receiving 349254 citations.
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TL;DR: In this article, the authors fabricated one-dimensional porous Co3O4 and Co/CoO nanofibers by calcination of cobalt(II) oxalate dehydrate precursors in an environment filled with air and N2, respectively.
Abstract: In this study, we fabricated one-dimensional porous Co3O4 and Co/CoO nanofibers by calcination of cobalt(II) oxalate dehydrate precursors in an environment filled with air and N2, respectively. The porous configurations of Co3O4 and Co/CoO nanofibers are determined by the calcination temperatures, which can effectively tune complex permittivity and impedance match. The minimal reflection loss of porous Co3O4 nanofibers is −23.8 dB at 11.4 GHz with a thickness of 2.0 mm, which results from good impedance match, dielectric loss (dipole polarization) and one-dimensional shape effect (point discharge as an antenna receiver, and long microwave travel distance due to multiple reflections and scattering). For the porous Co/CoO nanofibers, in comparison with Co3O4, due to the existence of magnetic Co, they exhibit better microwave absorption properties. The minimal RL value is −48.4 dB at 16.1 GHz, and the effective absorption (RL below −10 dB) can reach 4.2 GHz (13.8–18 GHz) with a thickness of only 1.5 mm. Besides, in terms of the above mentioned absorption mechanisms of porous Co3O4, the magnetic loss (natural and exchange resonance) and interfacial polarization between Co and CoO also contribute to the microwave absorption. These one-dimensional porous Co3O4 and Co/CoO nanofibers are proved to be efficient and lightweight absorbers with promising applications.
93 citations
TL;DR: In this paper, the authors demonstrated that polymer composites with much improved dielectric constant while maintaining ultra-low Dielectric loss could be achieved via using hybrid filler and controlling the dispersion of conductive filler in polymer matrix.
93 citations
TL;DR: In this article, the nanosized base metal-electrode multilayer ceramic capacitors (BME MLCCs) were prepared by chemical coating method and the well-coated BaTiO3 particles were obtained by adjusting an appropriate pH value.
Abstract: The base-metal-electrode multilayer ceramic capacitors (BME MLCCs) for future application require much thinner dielectric layers (<1 μm). Therefore, the grain size and uniformity of BME MLCC powders should be effectively controlled. In this paper, the nanosized BME MLCC powders were prepared by chemical coating method. The well-coated BaTiO3 particles were obtained by adjusting an appropriate pH value. Transmission electron microscopy, energy-dispersive spectroscopy, X-ray photoelectron spectrum were utilized for the study of microstructures and element analysis. The high-performance X7R dielectric ceramics were produced in reducing atmosphere by “two-step” sintering method at a low temperature of 950°C. The dielectric constant at room temperature could reach ∼2400, with low dielectric loss below 1.0% and high insulation resistivity ∼1012Ω·cm. The ceramic grains were very homogenous with the average size below 150 nm.
93 citations
TL;DR: In this paper, flexible polymer based composites containing multi-walled carbon nanotubes (MWCNTs) have been reported to have high dielectric constant and low breakdown strength, which prohibits their practical use in electronic and electric industry.
Abstract: Flexible polymer based composites containing multi-walled carbon nanotubes (MWCNTs) have been reported to present high dielectric constant. However, the composites generally exhibit high dielectric loss and low dielectric breakdown strength, which prohibits their practical use in electronic and electric industry. MWCNTs were coated with a continuous layer of TiO2 nanoparticles (TiO2@MWCNTs) by a simple hydrothermal process and TiO2@MWCNTs/poly(vinylidene fluoride) (PVDF) composites were prepared by a solution casting method. Compared to the pristine MWCNTs/PVDF composites, the TiO2@MWCNTs/PVDF composites presented enhanced dielectric constant and lower dielectric loss. Additionally, the breakdown strength of the TiO2@MWCNTs/PVDF composites was also improved, which is favorable for enhanced ferroelectric properties in the composites.
93 citations
TL;DR: In this paper, the hollow-structured BaTiO3 frameworks with hierarchical interfaces in epoxy composites were constructed to improve the dielectric energy-storage performance of the composite.
Abstract: Dielectric polymer composites are promising candidates for pulsed power capacitors. Enhanced dielectric performance is usually achieved at the expense of high filler loadings. Herein, we report the realization of significantly enhanced dielectric performances in epoxy composites with ultralow BaTiO3 loadings via constructing hollow-structured BaTiO3 frameworks with hierarchical interfaces in epoxy. An enhanced dielectric permittivity of 22 @10 kHz, which is about 5 times that of the epoxy matrix, is achieved in the composite with merely 5 vol% BaTiO3, while the dielectric loss keeps low (tanδ ≈ 0.032 @10 kHz). Meanwhile, a greatly improved energy density which is about 250% that of the epoxy matrix and a high discharge efficiency (η = 89.7%) are achieved simultaneously. It is believed that, the hollow-structured BaTiO3 frameworks with hierarchical interfaces leads to strengthened interfacial polarization and ensures continuous transmission of polarization, which collectively improve the dielectric energy-storage performance.
93 citations