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Journal articles on the topic 'Dielectrical permittivity'
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1
Zang, Chong Guang, and Xian Peng Cao. "PANI / MWNTs / EP Composite Microwave Absorbing Coatings Dielectrical and Microwave Absorbing Properties Analysis." Applied Mechanics and Materials 303-306 (February 2013): 2477–80. http://dx.doi.org/10.4028/www.scientific.net/amm.303-306.2477.
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In this paper, the polyaniline (PANI) coated multi-walled carbon nanotubes (MWNTs) was prepared in situ polymerization. Adding PANI/MWNTs into epoxy resin（EP）, we got PANI / MWNTs / EP composite microwave absorbing materials. Through testing permittivity 、permeability and reflection loss of materials, the paper showed the effect of PANI/MWNTS to the dielectrical and microwave absorbing properties of materials.The results showed： PANI/MWNTs had great effect on dielectrical and microwave absorbing properties of materials. But the imaginary permeability was close to 0. That indicated that it mainly consumed electromagnetic wave by dielectric loss. In 200-1000MHZ, materials had better absorbing property and lower reflection loss (-13.6).
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Abd, Abeer. "Studying the mechanical and electrical properties of epoxy with PVC and calcium carbonate filler." International Journal of Engineering & Technology 3, no. 4 (2014): 545. http://dx.doi.org/10.14419/ijet.v3i4.3425.
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In the present research composite material was prepared from epoxy and PVC reinforced with calcium carbonate as a filler material with different percent weight ratios (0.6,1.2,1.8 and 2.4) g.The effect of different weight ratios of calcium carbonate particles and PVC different content on electrical permittivity , dielectrical loss constant, hardness ,young modulus and compression strength were studied. Electrical properties of these composites were investigated by using Fourier transform infrared spectroscopy (FTIR) to study the bonds which enhanced the insulating properties of epoxy material compounded with filler and PVC. The inclusion of CaCO3 in epoxy and (PVC) polymer matrices greatly enhances the physical and mechanical properties of the composite.The experimental results also show that sample (5) compounded with 2.4 g of Calcium Carbonate has the minimum dielectric loss therefore it had the best insulating properties. The compression strength, young modulus, hardness decrease with filler content increase and PVC compound decreased. The maximum electrical permittivity in sample (3) compounded with 1.2 g of calcium carbonate and 4.8 g of PVC. Cost also can be reduced by the addition of filler material.
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Marjanovic, Milos, Dragana Dimitrijevic, Vesna Paunovic, and Zoran Prijic. "Microstructural and dielectrical characterization of Ho doped BaTiO3 ceramics." Serbian Journal of Electrical Engineering 11, no. 1 (2014): 35–46. http://dx.doi.org/10.2298/sjee131129004m.
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The Ho doped BaTiO3 ceramics, with different Ho2O3 content, ranging from 0.01 to 1.0 wt % Ho, were investigated regarding their microstructural and dielectric characteristics. Doped BaTiO3 were prepared using conventional solid state reaction and sintered at 1380?C for four hours. SEM analysis of Ho/BaTiO3 doped ceramics showed that the low doped samples exhibit mainly fairly uniform and homogeneous microstructure with the grain size ranged from 20-40 ?m. In the samples with the higher dopant concentration the abnormal grain growth is inhibited and the grain size ranged between 2-10 ?m. Measurements of dielectric properties were carried out as a function of temperature up to 180 ?C at different frequencies. The samples doped with 0.01wt % of Ho, exhibit the high value of dielectric permittivity (?r = 2160) at room temperature. A nearly flat permittivity-response was obtained in specimens with higher additive content. Using a Curie-Weiss law and modified Curie-Weiss law the Curie constant (C), Curie temperature (Tc) and a critical exponent of nonlinearity (g) were calculated. The Curie temperature of doped samples were ranged from 128 to 130?C. The Curie constant for all series of samples decrease with increase of dopant concentration and the lowest values were observed on samples doped with 0.01 wt % of holmium.
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Zhang, Yu, and Chuan Guo Ma. "Preparation and Electrical Properties of Aligned Carbon Nanotubes/Epoxy Resin Composites Induced by a Low Magnetic Field." Advanced Materials Research 189-193 (February 2011): 1340–43. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.1340.
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Aligned carbon nanotubes(CNTs)/epoxy resin(EP) composites were prepared under a low magnetic field (B<500mT) induction. The effect of different magnetic fields on the electrical and dielectrical properties of composites was investigated. The results show that the CNTs are aligned with rod-like aggregations instead of single CNTs when the magnetic field direction is vertical to the casting direction of samples, then electric conductivity, permittivity, dielectric loss of the composite are improved. And a larger magnetic field intensity and a bigger mould capacity can help the effect of magnetic field induction. However the CNTs are seriously aggregated and the electrical properties of composites change worse when the magnetic field direction is parallel to the casting direction of samples.
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Setrajcic, Jovan, Ljubisa Dzambas, and Stevan Armakovic. "Particularities in physical characteristics of molecular crystalline nanofilms." Zbornik Matice srpske za prirodne nauke, no. 119 (2010): 115–25. http://dx.doi.org/10.2298/zmspn1019115s.
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In this paper, the alterations and changes in dielectrical properties of different nanofilm molecular crystals, caused by the presence of boundaries were theoretically investigated and analyzed. By combined analytical and numerical calculations, allowed exciton states were found, and their spatial distribution along the axis limit (by layers of film) and the surface localization was examined. The relative permittivity of the observed ultrathin film was determined, and the impact of (five) boundary parameters on resonant absorption phenomenon: discrete (by frequencies) and selective (by layers of film) was examined. The conditions for the emergence of single-resonant absorption lines were found.
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Cao, Xian Peng, and Chong Guang Zang. "Study on Electromagnetic Properties of Ni-MWNTs Filling High Dielectrical EP Composites." Advanced Materials Research 706-708 (June 2013): 274–78. http://dx.doi.org/10.4028/www.scientific.net/amr.706-708.274.
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In this paper, we got Ni-MWNTs through pretreatment of MWNTs and electroless plating of nickel, and observed the Ni-MWNTs and MWNTs with TEM and FTIR. In addition, we prepared Ni-MWNTs/EP and MWNTs/EP composites. The volume resistivity、permittivity and permeability of composites were measured. Results showed that the volume resistivity of Ni-MWNTs/EP was higher than MWNTs/EP’s when volume fraction was lower than 8%. The ε" of Ni-MWNTs/EP was larger than MWNTs/EP’s. It indicated that Ni-MWNTs/EP had better electromagnetic energy storing and consumption capacity. And the permeability of Ni-MWNTs/EP would increase with the increasing of Ni-MWNTs. Ni-MWNTs/EP had some ferromagnetism.
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Ionete, Eusebiu Ilarian, Artur Visse, Radu Dorin Andrei, Mirela Irina Petreanu, Stefan Ionut Spiridon, and Roxana Elena Ionete. "Electrical and Dielectrical Properties of Composites Based on Alumina and Cyclic Olefin Copolymers." Materials 17, no. 21 (2024): 5349. http://dx.doi.org/10.3390/ma17215349.
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Understanding the performance of polymer dielectrics at different temperatures is becoming increasingly important due to the rapid development of electric cars, electromagnetic devices, and new energy production solutions. Cyclic olefin copolymers (COCs) are an attractive material due to their low water absorption, good electrical insulation, long-term stability of surface treatments, and resistance to a wide range of acids and solvents. This work focused on the dielectric and electrical properties of cyclic olefin copolymer (COC)/Al2O3 composites over a wide range of temperature and frequency domains, from room temperature to cryogenic temperatures (around 125 K). Permittivity, electrical conductivity, and electrical modulus are given consideration. A composite of up to 50% Al2O3 mixed with COC was prepared via a conventional melt-blending method. The final samples were formed in sheets and processed using injection and extrusion moldings. It was found that formulations with Al2O3 concentrations ranging from 10 to 50% resulted in higher electrical conductivity while maintaining the viscosity of the composite at a level acceptable for polymer-processing machinery. Our data show that COC/alumina composites present substantial potential as materials for high-frequency applications, even at the regime of cryogenic temperatures.
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Tsai, B., H. Xue, E. Birgersson, S. Ollmar, and U. Birgersson. "Dielectrical properties of living epidermis and dermis in the frequency range from 1 kHz to 1 MHz." Journal of Electrical Bioimpedance 10, no. 1 (2019): 14–23. http://dx.doi.org/10.2478/joeb-2019-0003.
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Abstract We determine the in-vivo dielectric properties—resistivity and relative permittivity—of living epidermis and dermis of human skin soaked with a physiological saline solution for one minute between 1 kHz and 1 MHz. This is done by fitting approximate analytical solutions of a mechanistic model for the transport of charges in these layers to a training set comprising impedance measurements at two depth settings on stripped skin on the volar forearm of 24 young subjects. Here, the depth settings are obtained by varying the voltage at a second inject on the electrical-impedance-spectroscopy probe. The model and the dielectric properties are validated with a test set for a third depth setting with overall good agreement. In addition, the means and standard deviations of the thicknesses of living epidermis and dermis are estimated from a literature review as 61±7 μm and 1.0±0.2 mm respectively. Furthermore, extensions to resolve the skin layers in more detail are suggested.
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Dzubenko, L. S., P. P. Gorbyk, A. A. Sapyanenko, and N. M. Rezanova. "The influence of carbon-containing, magnetic and nano-dispersed additions on structure and electrophysical properties of polypropylene-based composite monofibers." Surface 13(28) (December 30, 2021): 197–205. http://dx.doi.org/10.15407/surface.2021.13.197.
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There were PP- and iron-containing, fibrous, carbon- and nanodispersed-addition-based composite fibers prepared. There were addition content equals of 5.0%mass. There were blend of isotactic PP and addition homogenized in melt with one-screw lab extruder. There were zonal temperature on extruder equals of 230-250 o C. There were strangs receiving in bath of water and threated with knife granulation. Then, there were granules drying on air during 5h, and, then in thermal vacuum oven at 80±5 o C during 3h. Then, there are monofiber of 1 mm’s diameter formed on lab stand. Then, from one formed those others monofibers of different values of spinneret drawing (Фв, %). There were Фв for monofibers equals of 300 and 500%. Then, there were formed monofibers threated with thermoorientational drawing process at 150 oC. Then, there were monofibers of Фв value, which equals of 300%, drawn till draw degree λ=6, but, those others of Фв value, which equals of 500% - to λ=4. It is succeed, for composite monofibers, that orientational drawing process has had realized, until to the same value, as well as for one of virgin PP. But, when at formation and thermoorientational drawing processes, there were placing much number of breaks, as compared with monofiber of pure PP. When studying the structure with SEM technique, there was revealed microfibrillar structure of composite monofiber. When using optical microscopy, then there was determined irregularity for distribution of addition’s particles, leading to disproportional distribution of tension values at loading. It is revealed, for composite monofiber, at given value for content of addition, that electrical conductivity phenomenon is absent here. There are real ε’and imaginal ε’’ parts of complex dielectrical permittivity phenomenon, on frequency of 9 GHz, equals of 2.1 and 0.2, accordingly. It is established, that pure, non-drawn and composite monofiber itrinsically have satisfactory magnetic properties (σs=0.5 Gs∙cm3/g, Hc= 695 E). There are real μ’ and imaginal μ’’ parts of complex magnetical permittivity phenomenon equals of 1.1 and 0.02, accordingly.
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Kryszyn, Jacek, and Waldemar Smolik. "2D MODELLING OF A SENSOR FOR ELECTRICAL CAPACITANCE TOMOGRAPHY IN ECTSIM TOOLBOX." Informatics Control Measurement in Economy and Environment Protection 7, no. 1 (2017): 0. http://dx.doi.org/10.5604/01.3001.0010.4604.
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Electrical capacitance tomography is used to visualize a spatial distribution of dielectrical permittivity of materials placed in a tomographic sensor. An image is reconstructed from measurements of mutual capacitances of electrodes placed around the examined volume. This technique is characterized by very high temporal resolution – it is possible to achieve even few thousands of images per second. One of drawbacks of the method is low spatial resolution. Electrical capacitance tomography is mainly used in industry, e.g. for multiphase flow visualization. One of important elements of a tomographic system is a sensor which parameters influence quality of measurements and therefore affects quality of reconstructed images. In the Division of Nuclear and Medical Electronics a Matlab toolbox called ECTsim was developed. It is used for modelling of sensors, simulations of electrical field and image reconstruction. In this article we present the latest improvement which is modelling of a sensor using algebra of sets. Using primitive elements like rectangle and sector of a ring it is possible to perform operations like union, intersection and difference of two elements with a designed language. With such tools it is easy to prepare complex models of tomographic sensors which have different geometries. In this paper we show two models of sensors with different geometry in order to show how ECTsim solves forward problem.
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Raszewski, Zbigniew, Stanisław Kłosowicz, Jerzy Zieliński, and Rafał Mazur. "Dielectric properties of liquid crystals." Bulletin of the Military University of Technology 72, no. 4 (2023): 15–54. http://dx.doi.org/10.5604/01.3001.0054.7909.
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In the paper, dielectric properties of liquid crystals, especially the nematic phase, arediscussed. An outline of the development of theories describing these properties is presented. Thestatic theory of dielectric permittivity of anisotropic nematic liquid crystals on Onsager, Maier andMeier approach is discussed in details. In this view, anisotropic properties of dielectric permittivityof nematics as well parameters describing these properties are presented.Keywords: material science, liquid crystals, nematics, dielectric permittivity, electron polarisability,constant and induced dipole moment of molecule, vectors of electric field intensity, induction andpolarisation in nematic phase.
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Gojayev, E.M.1 Aliyeva Sh.V.2 Mammadova S.I.3 Babayev U.T.4 &. Aliyeva B.V.5. "BIOLOGICAL ORIGIN FILLERS AND METAL NANOPARTICLES EFFECT ON DIELECTRIC AND ELECTRICAL PROPERTIES OF LDPE+X VOL%FB BIOCOMPOSITES." GLOBAL JOURNAL OF ENGINEERING SCIENCE AND RESEARCHES 6, no. 1 (2019): 9–15. https://doi.org/10.5281/zenodo.2531588.
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The presented work presents the results of studying the temperature dependences of the dielectric constant and tangent of the dielectric loss angle and specific volume resistance of biocomposites LDPE + x vol% FB and bionanocomposites LDPE + x vol% FB +1 vol% Cu in the temperature range 290 - 390K.It was revealed that with an increase in the volume content of a bio-filler, the dielectric constant increases, and the specific resistance and dielectric loss decreases. It was revealed that with a change in the volume content of the filler of biological origin of the metal nano particle and temperature, it is possible to control the optimal values of the dielectric and electrical parameters of the studied biocomposites.
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Modes, Christina, Stefan Malkmus, and Frieder Gora. "High K Low Loss Dielectrics Co-Fireable with LTCC." Active and Passive Electronic Components 25, no. 2 (2002): 141–45. http://dx.doi.org/10.1080/08827510212346.
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Rapid growth in the application of LTCC technology for RF wireless is clearly driven by the trend of miniaturization and mobile communication systems. This technology provides the possibility of integration of passive components in a cost effective way. Heraeus has implemented compatible high permitivity and low loss dielectrics with NPO performance into modified Heraeus CT700 low temperature co-fired ceramic tape system. The majority of commercially available microwave dielectrics show increasing firing temperatures>200 °Cwhich make them incompatible with Ag metallizations or show high dielectric loss which limit their usage in RF wireless applications. This development work demonstrates the integration of a low loss, high permittivityε=60dielectric tape into a conventional Ag bearing LTCC structure. The concept of a dual sintering process is introduced and the resultant mechanical benefits with regard to tape fired shrinkage are explained in detail. Permittivity and dielectric loss data at RF for the new structure are presented. These high K and low loss dielectrics along with a comprehensive material system developed by Heraeus will support customers in meeting the challenges of reducing cost and enhancing the performance of RF devices for high frequency applications.
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Zheng, Xianghe, and Jianyou Zhou. "Modeling the Effect of Material Viscoelasticity on the Dielectric Permittivity of Deformed Elastomers." Polymers 16, no. 1 (2023): 113. http://dx.doi.org/10.3390/polym16010113.
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Elastomers, as a typical category of soft dielectrics, have shown great potential for developing stretchable electronics and soft transducers. However, the performance of dielectric elastomers (DEs) is susceptible to the dielectric permittivity of the material, whether as insulators or actuators. On the other hand, experiments suggest that the material viscoelasticity significantly influences the dielectric permittivity of DEs. Based on the theory of finite-deformation viscoelasticity, this work adopts the Brillouin function to develop a modeling framework to examine the effect of material viscoelasticity on the dielectric permittivity for the first time. A comparison of the data fitting results between the models with and without consideration of the material viscoelasticity is presented. Simulation results also reveal that the viscous network of the elastomer exerts a mitigation effect on the decrease in the dielectric permittivity when the material is deformed. Furthermore, it is found that the loading rate is a key parameter that strongly affects the dielectric permittivity, mainly through the inelastic deformation.
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Zhu, Linwei, Yujie Yang, Yuchao Li, et al. "Remarkably enhancing dielectric permittivity and suppressing loss of PVDF via incorporating metal nanoparticles decorated glass fibers." Journal of Physics D: Applied Physics 57, no. 20 (2024): 205503. http://dx.doi.org/10.1088/1361-6463/ad27c8.
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Abstract Dielectrics with high permittivity and low dielectric loss have so far received considerable attention because of their wide applications in various electronic devices. However, the enhanced permittivity of dielectrics is always accompanied by an increase in loss. In this work, targeting at enhancing the permittivity of poly(vinylidene fluoride) (PVDF) without elevating loss, gold nanoparticles (Au NPs) decorated glass fibers (GF) are incorporated into the PVDF, forming a unique design of Au@GF/PVDF composites. The effects of gold nanoparticle content, calcination temperature, and hot-pressing pressure on the dielectric properties are studied. Interestingly, for the composite with gold sputtering time of 3 min, a remarkable dielectric enhancement of 430% (i.e. from 7.8 to 33.5 at 10 kHz) along with an obvious loss suppression of 56% (i.e. from 0.0353 to 0.0198) are concurrently achieved. It is believed that, the increase in permittivity is mainly attributed to the Maxwell–Wagner–Sillars effect of effective micro-capacitors and cluster polarization of gold nanoparticles while the suppressed loss is originated from the intrinsic low loss of GF and the Coulomb-blockade effect of gold nanoparticles. This work offers a promising strategy to simultaneously enhance the permittivity and suppress the loss of dielectric materials.
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Lee, Don Kyu. "Analysis of the Characteristics on Dielectric Barrier Discharges Depending on the Relative Permittivity and Frequency." Applied Mechanics and Materials 875 (January 2018): 113–16. http://dx.doi.org/10.4028/www.scientific.net/amm.875.113.
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Various studies are being conducted on the application of DBD (Dielectric barrier discharges). The internal dielectric has a very important characteristic on DBD, thus we analyze of the characteristics on dielectric barrier discharges depending on the relative permittivity and frequency. Through simulation, the discharge voltage was calculated based on relative permittivity and frequency of real used dielectrics (Green sheet, Down dielectric, white dielectric). We investigate that increased relative permittivity and fast frequency occur the decrease of the firing voltage. Also, we investigate the frequency dependence of the dielectric constant and dielectric loss of dielectric layers measured at a frequency region of 100Hz to 10MHz. In a condition of drive within 1MHz, with regard to the change of real and imaginary part according to frequency, it has quite stable dielectric constant in the condition of drive within 1MHz.
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Luo, Tianhuan, Bo Li, Qian Zhao, and Ji Zhou. "Dielectric Behavior of Low Microwave Loss Unit Cell for All Dielectric Metamaterial." International Journal of Antennas and Propagation 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/291234.
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With a deep study of the metamaterial, its unit cells have been widely extended from metals to dielectrics. The dielectric based unit cells attract much attention because of the advantage of easy preparation, tunability, and higher frequency response, and so forth. Using the conventional solid state method, we prepared a kind of incipient ferroelectrics (calcium titanate, CaTiO3) with higher microwave permittivity and lower loss, which can be successfully used to construct metamaterials. The temperature and frequency dependence of dielectric constant are also measured under different sintering temperatures. The dielectric spectra showed a slight permittivity decrease with the increase of temperature and exhibited a loss of 0.0005, combined with a higher microwave dielectric constant of ~167 and quality factorQof 2049. Therefore, CaTiO3is a kind of versatile and potential metamaterial unit cell. The permittivity of CaTiO3at higher microwave frequency was also examined in the rectangular waveguide and we got the permittivity of 165, creating a new method to test permittivity at higher microwave frequency.
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Petzelt, Jan. "Infrared and THz spectroscopy of nanostructured dielectrics." Processing and Application of Ceramics 3, no. 3 (2009): 145–55. http://dx.doi.org/10.2298/pac0903145p.
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Results achieved using the infrared/THz spectroscopy of various inhomogeneous dielectrics in the Department of Dielectrics, Institute of Physics, Prague, during the last decade are briefly reviewed. The discussion concerns high-permittivity ceramics with inevitable low-permittivity dead layers along the grain boundaries, relaxor ferroelectrics with highly anisotropic polar nano-regions, classical matrix-type composites, core-shell composites, filled nanoporous glasses, polycrystalline and epitaxial thin films, heterostructures and superlattices on dielectric substrates. The analysis using models based on the effective medium approach is discussed. The importance of depolarizing field and of the percolation of components on the effective ac dielectric response and the excitations contributing to it are emphasized. .
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Yokomizo, Satoshi, Takuya Hoshina, Hiroaki Takeda, et al. "Evolution of Internal Stress and Influence on Dielectric Properties by Number of Dielectric Layers in MLCC." Key Engineering Materials 445 (July 2010): 31–34. http://dx.doi.org/10.4028/www.scientific.net/kem.445.31.
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We researched the phenomenon that the permittivity of dielectric layers in multilayer ceramic capacitor (MLCC) increases with the number of dielectric layers. Finite element method (FEM) shows that the internal residual stress in MLCC was generated by the difference of thermal expansion coefficient between internal electrodes and dielectric layers. We developed a electric measurement system with applying external stress for understanding the stress influence on dielectric properties. The compressive stress along electric field increased the polarization. The polar nano regions (PNRs) in shell composition dielectrics were easily influenced by stress. Based on these results, the relationship between the number of dielectric layers and their permittivity in MLCCs was explained.
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Voronov, S. O., and Yu M. Poplavko. "Nonlinearity and Controllability of Dielectric Permittivity." Ukrainian Journal of Physics 70, no. 2 (2025): 125. https://doi.org/10.15407/ujpe70.2.125.
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Among the various materials used in electronics, an important place is occupied by the functional (smart) dielectrics. In this paper, we study dielectric nonlinearity and the possibility of an electrical control over the permittivity. In ionic compounds, this nonlinearity is conditioned by different electronegativities of neighboring ions, while the controllability of permittivity is determined by a change in the rigidity of atomic bonds under a controlling electric field influence. The relevance of this problem is due to the fact that microelectronics uses very thin dielectric layers, in which the electrical strength increases significantly allowing the use of nonlinearity. Moreover, in ferroelectrics, the electric field activates the orientation of domains, which significantly increases the permittivity, and, conversely, decreases it, when the reorientation of domains is suppressed by a bias electric field. The rate of nonlinear change in permittivity and its electrical control are important for use in electronics. So, the applicability limits of these properties are assessed using dielectric spectroscopy.
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Li, Wei, Zhonghua Yao, Hua Hao, Minghe Cao, and Hanxing Liu. "High-Permittivity and Bias-Voltage-Insensitive (Ba,Sr,Ca)TiO3·0.03(Bi2O3·3TiO2) Ceramics with Y5U Specification." Crystals 13, no. 12 (2023): 1627. http://dx.doi.org/10.3390/cryst13121627.
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Class II ceramics are a material with high permittivity but low reliability of their capacitance and bias voltage due to high the temperature sensitivity of their dielectric permittivity. In this work, a BST-based (Ba0.9−xSrxCa0.1)TiO3·0.03(Bi2O3·3TiO2) (x = 0.2, 0.25, 0.3, 0.35, 0.4) composition with Y5U characteristics was investigated through compositional control to develop high-permittivity and voltage-stable ceramic compositions. Sr doping can increase the breakdown strength (Eb) but decreases the Curie temperature (Tc). The composition at x = 0.3 can obtain optimal comprehensive electrical properties, with high permittivity of 4206, low dielectric loss of ~0.009, and moderate breakdown strength (Eb) of 77.6 kV/cm, which meets Y5U specifications. Typically, a low bias-voltage dependence of capacitance is confirmed with a variation rate of 7.64% under 20 kV/cm. This strategy provides a promising candidate for high-permittivity Class II ceramic dielectrics that can be used in this field.
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MARACHEVSKY, VALERY N. "CASIMIR ENERGY AND REALISTIC MODEL OF DILUTE DIELECTRIC BALL." Modern Physics Letters A 16, no. 15 (2001): 1007–16. http://dx.doi.org/10.1142/s0217732301004078.
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The Casimir energy of a dilute homogeneous nonmagnetic dielectric ball at zero temperature is derived analytically for the first time for an arbitrary physically possible frequency dispersion of dielectric permittivity ε(iω). A microscopic model of dielectrics is considered, divergences are absent in calculations because an average interatomic distance λ is a physical cutoff in the theory. This fact has been overlooked earlier, which led to divergences in various macroscopic approaches to the Casimir energy of connected dielectrics.
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Ren, He, and Wei-Feng Sun. "Characterizing Dielectric Permittivity of Nanoscale Dielectric Films by Electrostatic Micro-Probe Technology: Finite Element Simulations." Sensors 19, no. 24 (2019): 5405. http://dx.doi.org/10.3390/s19245405.
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Finite element simulations for detecting the dielectric permittivity of planar nanoscale dielectrics by electrostatic probe are performed to explore the microprobe technology of characterizing nanomaterials. The electrostatic force produced by the polarization of nanoscale dielectrics is analyzed by a capacitance gradient between the probe and nano-sample in an electrostatic detection system, in which sample thickness is varied in the range of 1 nm–10 μm, the width (diameter) encompasses from 100 nm to 10 μm, the tilt angle of probe alters between 0° and 20°, and the relative dielectric constant covers 2–1000 to represent a majority of dielectric materials. For dielectric thin films with infinite lateral dimension, the critical diameter is determined, not only by the geometric shape and tilt angle of detecting probe, but also by the thickness of the tested nanofilm. Meanwhile, for the thickness greater than 100 nm, the critical diameter is almost independent on the probe geometry while being primarily dominated by the thickness and dielectric permittivity of nanomaterials, which approximately complies a variation as exponential functions. For nanofilms with a plane size which can be regarded as infinite, a pertaining analytical formalism is established and verified for the film thickness in an ultrathin limit of 10–100 nm, with the probe axis being perpendicular and tilt to film plane, respectively. The present research suggests a general testing scheme for characterizing flat, nanoscale, dielectric materials on metal substrates by means of electrostatic microscopy, which can realize an accurate quantitative analysis of dielectric permittivity.
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Gunawan, Vincensius. "The Lateral Surface Phonon Modes in Bi-layer Dielectrics with Different Values of Permittivity." International Journal of Scientific Research and Management (IJSRM) 12, no. 11 (2024): 96–99. http://dx.doi.org/10.18535/ijsrm/v12i011.pe01.
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Surface phonon polaritons were electromagnetic waves that propagated at the surface of dielectrics. These polaritons had many attentions since the frequency can reach in the order of terahertz. Hence, it can be employ in terahertz technology. One of the general method to study polaritons was by solving Maxwell's equations. The results were dispersion relation which showed the characteristic of the polaritons. In this study, we analyze polaritons of a bilayer dielectric which was comprised of two dielectrics which had different permittivities. We set the thickness of each dielectric was smaller than the wavelength so that we could use effective medium method. In this approximation, we can treat a multilayer system as a single effective medium medium. We also assumed that the surface modes propagated across the thickness of each dielectric. It was found that when the resonant frequency of the two dielectrics were considerably wide, then we had two branches of surface polaritons. In this result, each branch represented each dielectric. The interesting results appeared when there was intersection of the the frequencies near resonant frequency of the dielectrics. In this condition, we found only one branch of surface modes.
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Fu, Yijia, Wendong Li, Man Xu, Chao Wang, Liyuan Zhang, and Guanjun Zhang. "Dielectric Properties and 3D-Printing Feasibility of UV-Curable Resin/Micron Ceramic Filler Composites." Advances in Polymer Technology 2022 (February 27, 2022): 1–14. http://dx.doi.org/10.1155/2022/9483642.
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To prepare high-permittivity composite materials for dielectrically functional gradient materials (d-FGMs) by the stereolithographic 3D-printing technique, three ceramic powders (i.e., alumina, barium titanate, and strontium titanate) are selected as functional fillers for a UV-curable resin matrix. The viscosity and UV curing depth of the uncured slurry are tested for feasibility of 3D printing. Comprehensive electrical properties, including volume resistivity, permittivity, dielectric loss, and breakdown strength of the cured composites are measured. The effects of the filler types, morphologies, particle sizes, and volume fractions on the UV curing characteristics of the slurry and dielectric properties of cured composites are systematically analyzed. The experimental results show that spherical fillers with large particle sizes, smooth surfaces, and high permittivity are conducive for reducing the slurry viscosity, increasing curing depth and adjusting the composite’s permittivity over a wide range. We believe that the proposed strategy for material system establishment can improve the 3D printability of high-permittivity composites and promote other applications of the d-FGMs by the stereolithography technique.
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Eshtemirovich, Eshquvatov Husan, Asatov Uralbay Toshniyozovich, Xolboyev Yunusali Xasanovich, and Shukurov Ahmadjon Raxmatovich. "STUDY OF DIELECTRIC PERMITTIVITY AND CONDUCTIVITY IN THE IONOSPHERE." American Journal of Applied Science and Technology 03, no. 03 (2023): 58–64. http://dx.doi.org/10.37547/ajast/volume03issue03-11.
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The ionosphere is so named because it is a region in the atmosphere where ions exist. In most areas of the atmosphere, molecules are in a combined state and remain electrically neutral. In the ionosphere, however, solar radiation (mainly ultraviolet light) is so intense that when it strikes gas molecules they split-ionize and an electron is set free. What remains is a positive ion (a molecule that is “missing” an electron) and a free electron. Although ions give their name to the region, free electrons actually affect radio waves. The number of electrons starts to increase at an altitude of about 30 km, but the electron density isn’t sufficient to affect radio waves until about 60 km. We often think of the ionosphere as having a number of distinct layers.
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Giannoukos, Georgios, Mart Min, and Toomas Rang. "Relative complex permittivity and its dependence on frequency." World Journal of Engineering 14, no. 6 (2017): 532–37. http://dx.doi.org/10.1108/wje-01-2017-0007.
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Purpose This paper aims to give a brief overview of dielectric properties, relative complex permittivity and its dependence on frequency. The significance of different approaches to complex permittivity is also discussed. Design/methodology/approach The different mechanisms of polarization are then presented. Dielectric measurements are given, and an RC parallel-equivalent circuit is used to simulate a parallel plate capacitor, and the way in which the impedance of the circuits is affected by frequency is illustrated in their respective diagrams. The way in which dielectric properties change with time is also discussed. Findings The goal of this paper is to give an overview of the characteristics of the dielectrics and how frequency affects the relative complex permittivity and to present different approaches to and equations for the relative complex permittivity, such as that of Debye, Cole–Cole, Cole–Davidson and Havriliak–Negami. In addition, three mechanisms of polarization, namely, electronic, atomic and bipolar, are presented. The most common dielectric characterization device, a capacitor with parallel plates between which the dielectric material under study is located, is also discussed. Ohmic and dielectric losses of a non-ideal capacitor are accounted for. Furthermore, this paper studies the equivalent circuits of a non-ideal parallel plate capacitor, those being a resistor and an ideal capacitor connected either in series or in parallel. Originality/value Finally, dielectric responses to both time and to stepwise excitation are given.
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Zhu, Congcong, Kun Li, Xiaoxu Liu, et al. "Enhanced Dielectric Performance in PVDF-Based Composites by Introducing a Transition Interface." Polymers 17, no. 2 (2025): 137. https://doi.org/10.3390/polym17020137.
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Polymeric dielectrics have garnered significant interest worldwide due to their excellent comprehensive performance. However, developing polymeric dielectric films with high permittivity (εr) and breakdown strength (Eb) and low dielectric loss (tanδ) presents a huge challenge. In this study, amorphous aluminum oxide (Al2O3, AO) transition interfaces with nanoscale thickness were constructed between titanium oxide (TiO2, TO) nanosheets and polyvinylidene fluoride (PVDF) to manufacture composites (PVDF/TO@AO). TO@AO nanosheets showed favorable dispersion in the polymer-based composites. Improved permittivity, suppressed dielectric loss, and enhanced breakdown strength were achieved by introducing AO coating with intermediate permittivity onto TO nanosheets to build a transition interface. The transition interface efficiently depressed the mobility of the charge carrier and electric conduction of the PVDF/TO@AO composites. As a result, the PVDF-based composite with 1 wt% TO@AO showed superior comprehensive performance, including high εr of ~12.7, low tanδ of ~0.017, and exceptional Eb of ~357 kV/mm. This strategy supplies a novel paradigm for the application of fabricating dielectric films with excellent comprehensive performance.
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Patsidis, Anastasios C., Panagiotis Dimitrakellis, Evangelos Gogolides, and Georgios C. Psarras. "Dielectric Response of ZnO/PMMA Nanocomposites with Atmospheric Pressure Plasma-Modified Surfaces." Materials 17, no. 16 (2024): 4063. http://dx.doi.org/10.3390/ma17164063.
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In this work, the effect of etching the surface of polymer matrix nanocomposites with atmospheric pressure plasma targeting to achieve enhanced dielectric properties was investigated. Polymer nanocomposites, with varying reinforcing phase content, were modified by atmospheric-pressure plasma resulting in an increase in the surface filler’s concentration. Polymethyl methacrylate (PMMA) matrix nanocomposites reinforced with zinc oxide (ZnO) nanoparticles were prepared and dielectrically studied as a function of the nanoparticle content and the plasma modified surfaces. The electrical response of the composite systems was studied by means of Broadband Dielectric Spectroscopy (BDS) over a wide range of temperatures and frequencies. The dielectric permittivity increased with the embedded phase content and with plasma surface treatment. Energy density followed the same trend as dielectric permittivity, and the plasma-treated nanocomposite with the higher ZnO content exhibited approximately 27% higher energy density compared to the unreinforced matrix.
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BUNOIU, M., G. E. IACOBESCU, G. PASCU, L. CHIRIGIU, and I. BICA. "Magnetically active composites with relatively giant dielectric permittivity." Romanian Reports in Physics 75, no. 3 (2023): 503. http://dx.doi.org/10.59277/romrepphys.2023.75.503.
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"Magnetically active composites based on silicone rubber, silicone oil, carbonyl microparticles, graphene nanopallets and fabric, as a reinforcing element, are manufactured. For a constant amount of carbonyl iron microparticles and silicone oil, and for different ratios between the amounts of silicone rubber and graphene nanopalets, three composite samples are prepared. Using the plane capacitor method, the relative permittivity of the composites is determined. It is shown that by using graphene nanopallets, composites with giant values of relative dielectric permittivity can be obtained and that the relative dielectric permittivity values are sensitive to the magnetic force induced by the static magnetic field superimposed on the medium-frequency electric field. Using the model of the dipolar magnetic approximation and elements of the theory of dielectrics in medium frequency electric fields, the mechanisms participating in the obtained effects are described."
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Guduloglu, Utku, Sedat Kurnaz, Turgay Seydioglu, Gizem Bekar, and Ozgur Ozturk. "Frequency Dependent Negative Dielectric Behavior in Parylene C Based Composite Films." Journal of Advanced Applied Sciences 3, no. 1 (2024): 32–39. http://dx.doi.org/10.61326/jaasci.v3i1.254.
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Dielectric materials are an important research topic for many applications today. Polymers are among the prominent dielectrics due to their durability, high ionic conductivity and low dielectric losses. This study investigates the dielectric properties of Parylene C (PAC)-based composite films. Capacitance and dissipation factor values are measured. Dielectric permittivity and losses are calculated. Negative capacitance and negative dielectric constant are observed, and resonant frequency values are compared. Activated carbon doping significantly impacts the resonant frequencies of the films. Doped samples exhibit higher positive and negative resonant frequencies (2.2560 MHz and 2.2593 MHz) compared to undoped counterparts (2.1952 MHz and 2.2015 MHz). Polarization further increases resonant frequencies, alongside dielectric permittivity and dissipation factor with permittivity experiencing a more pronounced increase. Post-polarization, doped samples display resonant frequencies of 2.3727 MHz and 2.3761 MHz, while undoped samples reach 2.3658 MHz and 2.3727 MHz. A comprehensive analysis of impedance, resistance, and reactance values reveals insights into the composite film's behavior. Crucially, throughout the measurements, the composite films display a consistent inductive response at frequencies above their resonance frequencies. Understanding the mechanisms behind this inductive response could open up new possibilities for the use of these films in advanced electronic devices and circuits.
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GEYER, B., G. L. KLIMCHITSKAYA, and V. M. MOSTEPANENKO. "RECENT RESULTS ON THERMAL CASIMIR FORCE BETWEEN DIELECTRICS AND RELATED PROBLEMS." International Journal of Modern Physics A 21, no. 25 (2006): 5007–42. http://dx.doi.org/10.1142/s0217751x06034227.
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We review recent results obtained in the physics of the thermal Casimir force acting between two dielectrics, dielectric and metal, and between metal and semiconductor. The detailed derivation for the low-temperature behavior of the Casimir free energy, pressure and entropy in the configuration of two real dielectric plates is presented. For dielectrics with finite static dielectric permittivity it is shown that the Nernst heat theorem is satisfied. Hence, the Lifshitz theory of the van der Waals and Casimir forces is demonstrated to be consistent with thermodynamics. The nonzero dc conductivity of dielectric plates is proved to lead to a violation of the Nernst heat theorem and, thus, is not related to the phenomenon of dispersion forces. The low-temperature asymptotics of the Casimir free energy, pressure and entropy are derived also in the configuration of one metal and one dielectric plate. The results are shown to be consistent with thermodynamics if the dielectric plate possesses a finite static dielectric permittivity. If the dc conductivity of a dielectric plate is taken into account this results in the violation of the Nernst heat theorem. We discuss both the experimental and theoretical results related to the Casimir interaction between metal and semiconductor with different charge carrier density. Discussions in the literature on the possible influence of spatial dispersion on the thermal Casimir force are analyzed. In conclusion, the conventional Lifshitz theory taking into account only the frequency dispersion remains the reliable foundation for the interpretation of all present experiments.
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MARACHEVSKY, VALERY N. "CASIMIR ENERGY OF A DILUTE DISPERSIVE DIELECTRIC BALL: REALISTIC MICROSCOPIC MODEL." International Journal of Modern Physics A 17, no. 06n07 (2002): 786–89. http://dx.doi.org/10.1142/s0217751x0201011x.
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The Casimir energy of a dilute homogeneous nonmagnetic dielectric ball at zero temperature is derived analytically within a microscopic realistic model of dielectrics for an arbitrary physically possible frequency dispersion of dielectric permittivity ε(iω). Divergences are absent in calculations, a minimum interatomic distance λ is a physical cut-off. Casimir surface force is proved to be a attractive. A physical definition of the Casimir energy is discussed.
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Felinskyi, S. G. "Negative dielectric permittivity of nonmagnetic crystals in the terahertz waveband." Semiconductor Physics Quantum Electronics and Optoelectronics 15, no. 1 (2012): 83–88. http://dx.doi.org/10.15407/spqeo15.01.083.
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Yin, Peng, Peitao Xie, Qingyang Tang, et al. "Enhanced dielectric energy storage properties in linear/nonlinear composites with hybrid-core satellite C/SiO2@TiO2 nanoparticles." Applied Physics Letters 122, no. 13 (2023): 132905. http://dx.doi.org/10.1063/5.0143758.
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Polymer dielectrics for electrostatic capacitors possess well-recognized advantages, including ultrahigh power density, excellent processability, and unique self-healing capability. Nevertheless, the negative coupling relationship between dielectric permittivity and breakdown strength in dielectrics always constrains the enhancement of energy density, which cannot satisfy the ever-increasing requirements for integrated and miniaturized technologies. Here, a kind of C/SiO2@TiO2 triphase nanoparticle (CST NP) with a hybrid-core satellite structure is prepared and introduced into nonlinear poly(vinylidene fluoride-co-hexafluoropylene) [P(VDF-HFP)] matrix to improve permittivity and polarization. Benefited from the intensified interfacial polarization induced by CST NPs, a high permittivity of ∼18.8, which is approximately 219% that of pure P(VDF-HFP) (∼8.6), is obtained at 10 kHz. Meanwhile, a linear PEI film with high breakdown strength is stacked with the CST/P(VDF-HFP) composites, forming linear/nonlinear CST/P(VDF-HFP)-PEI bilayer composites. Eventually, a high breakdown strength of ∼503.9 kV/mm, a high energy density of ∼4.26 J/cm3, and a high efficiency of ∼91% are simultaneously achieved in the bilayer composite with merely 0.75 wt. % nanoparticles. The linear/nonlinear bilayer structure incorporated with hybrid-core satellite nanofillers offers an effective strategy to design high-performance dielectric energy storage materials.
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Biju, Anjitha, Maria Joseph, V. N. Archana, Navya Joseph, and M. R. Anantharaman. "High Dielectric Constant Liquid Dielectrics Based on Magnetic Nanofluids." Journal of Nanofluids 12, no. 4 (2023): 1141–50. http://dx.doi.org/10.1166/jon.2023.1973.
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Magnetic nanofluids are increasingly finding new applications. They can be employed as liquid dielectrics. The advantage of having a liquid dielectric is that high dielectric constant can be achieved by a judicious choice of the base liquid. The dielectric constant can be tuned with the help of an external magnetic field too. Superparamagnetic iron oxide nanoparticles were dispersed in polar carriers, namely water, polyvinyl alcohol, ethylene glycol, and a nonpolar carrier like kerosene to obtain stable magnetic fluids after ensuring the crystallographic phase purity along with appropriate magnetic characteristics of the dispersant. The fluids were then subjected to dielectric studies using an automated homemade dielectric setup. The dielectric permittivity and dielectric loss at different frequencies with and without an external magnetic field were evaluated. The studies indicate that magnetic nanofluids based on polar carriers are excellent liquid dielectrics over a wide range of frequencies with the incorporation of iron oxide nanoparticles. The application of an external magnetic field enhances the dielectric constant considerably. These magnetic nanofluids can be employed as liquid dielectrics for applications. It has been found that kerosene based magneto fluids have a low dielectric constant while Polyvinyl alcohol based fluids exhibit the highest dielectric constant.
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Raengthon, Natthaphon, Connor McCue, and David P. Cann. "Relationship between tolerance factor and temperature coefficient of permittivity of temperature-stable high permittivity BaTiO3–Bi(Me)O3 compounds." Journal of Advanced Dielectrics 06, no. 01 (2016): 1650002. http://dx.doi.org/10.1142/s2010135x16500028.
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The temperature coefficient of permittivity ([Formula: see text]) of BaTiO3–Bi(Me)O3 solid solutions were investigated. It was determined that as the tolerance factor was decreased with the addition of Bi(Me)O3, the [Formula: see text] shifted from large negative values to [Formula: see text] values approaching zero. It is proposed that the different bonding nature of the dopant cation affects the magnitude and temperature stability of the permittivity. This study suggests that the relationship between tolerance factor and [Formula: see text] can be used as a guide to design new dielectric compounds exhibiting temperature-stable high permittivity characteristics, which is similar to past research on perovskite and pyrochlore-based microwave dielectrics.
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Tonkoshkur, A. S., and A. Ye Shcherbak. "APPLICATION FOR DATA PROCESSING AND ANALYSIS OF MEASUREMENT DATA OF THE CONCENTRATION-DEPENDENT DIELECTRIC PERMITTIVITY OF TWO-COMPONENT COMPOSITES." System technologies 1, no. 156 (2025): 89–96. https://doi.org/10.34185/1562-9945-1-156-2025-10.
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The article presents the results of using computer technologies for data processing and analysis in dielectric measurements, structural control, and properties of polymer composite materials and heterogeneous dielectrics. The algorithm used allows the identification of the structure of non-homogeneous dielectrics with conductive inclusions by analyzing the experimental concentration dependence of static dielectric permittivity. It helps to determine whether their structure corresponds to known models of matrix systems or statistical mix-tures. The developed application can be seen as part of the software for creating an auto-mated system for scientific research in the field of electronics of heterogeneous structures and materials, and it can also be used autonomously.
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Tumarkin, A. V., E. N. Sapego, A. G. Gagarin, et al. "Structural and Electrical Properties of Glass-Ceramic Ferroelectric Composite Materials." Journal of the Russian Universities. Radioelectronics 25, no. 3 (2022): 86–95. http://dx.doi.org/10.32603/1993-8985-2022-25-3-86-95.
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Introduction. Materials exhibiting high dielectric permittivity are relevant for use in modern ultrahigh-frequency electronics. Among them, ferroelectrics with high dielectric nonlinearity present particular interest. The electrical strength of ferroelectric materials can be increased using modern composite structures based on mixing ferroelectries and linear dielectrics - materials exhibiting simultaneously low dielectric permittivity and high electrical strength. This approach provides for the opportunity of creating new multicomponent materials with previously unattainable properties and adjusting their component composition, inclusion size and electrical properties across a wide range. In this work, on the basis of porous potassium-iron-silicate glass (KFS) obtained by ion exchange, glass-ceramic materials containing barium titanate were synthesized for use at ultrahigh frequencies.Aim. Production of glass composites by low-temperature sintering of pre-synthesized BaTiO3 (BTO) and potassium-iron-silicate glass, as well as characterization of their structural and electrical properties at ultrahigh frequencies (microwave).Materials and methods. The crystal structure and phase composition of the obtained films were studied by X-ray diffraction using a DRON-6 diffractometer by the emission spectral line CuKα1 (λ = 1.5406 Å). The dielectric permittivity (ε) of microwave samples was evaluated by the Nicholson-Ross method at room temperature using an Agilent E4980A LCR-meter.Results. According to X-ray diffraction analysis, the synthesized samples are a mixture of KFS glass, ferroelectric BaTiO3 and dielectric barium polytitanates; the ratio of the latter determines the electrical properties of the composites. Depending on the content of barium titanate, the studied samples demonstrate a dielectric constant from 50 to 270 at a dielectric loss level of 0.1...0.02. The samples subjected to annealing in an oxygen medium showed an increase in dielectric permittivity by 10.25 % and an increase in controllability with a decrease in dielectric losses by an average of two times.Conclusion. The composite composition of 70 wt % BTO /30 wt % KFS was found to be the most promising in terms of structural and electrical properties. This composite showed an increase in dielectric permittivity by 25 % and a significant increase in nonlinearity, at the same time as reducing losses by more than two times as a result of annealing in an oxygen medium.
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Zapata-Londoño, J., F. Umaña-Idárraga, J. Morales-Guerra, S. Arias-Gómez, C. Valencia-Balvin, and E. Reyes-Vera. "Differential microwave sensor based on microstrip lines loaded with a split-ring resonator for dielectric characterization of materials." Journal of Physics: Conference Series 2118, no. 1 (2021): 012004. http://dx.doi.org/10.1088/1742-6596/2118/1/012004.
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Abstract In this work, we propose a microwave sensor that allows the characterization of dielectric materials based on a differential configuration. A microstrip permittivity sensor of the surrounding material is proposed using a split ring-resonator to measure differentially. The geometry was optimized and was numerically analyzed using CST STUDIO. The numerical analysis of the metamaterial unit cells is carried out first, to determine the operating band. After that, the metamaterial cell was employed to design the differential microstrip permittivity sensor. The obtained results reveal that the proposed sensor has the capability to characterize different materials whose relative dielectric permittivity’s are in the range of 9.8 to 80 with great performance. The device has a total size of 86 mm × 60 mm and operates around 3 GHz. In this band, the sensor reaches a sensibility of 2.89 MHz and a Q-factor of 70.15. Thus, this work shows a compact, reusable, label-free, and non-destructive microwave sensing device and paves the way for high accuracy sensing of the dielectric properties of different materials due to its high- Q-factor as well as high sensitivity.
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Brezeanu, M., M. Badila, Gheorghe Brezeanu, et al. "Theoretical Study of an Effective Field Plate Termination for SiC Devices Based on High-k Dielectrics." Materials Science Forum 527-529 (October 2006): 1087–90. http://dx.doi.org/10.4028/www.scientific.net/msf.527-529.1087.
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A classical implementation of the field plate technique is the oxide ramp termination. This paper presents improvements of the breakdown voltage for both SiC JBDs and SBDs, obtained by using high-k dielectrics. A study regarding the influence of the dielectric permittivity and thickness on the off-state performances of the diodes is included. It is shown that Si3N4 is to be preferred to SiO2 for the dielectric ramp. Termination efficiencies up to 96% are reported.
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Yuste-Sanchez, Vanesa, Francisco Gonzalez-Gonzalez, Mario Hoyos, Miguel A. López Manchado, and Raquel Verdejo. "Dielectric Properties of All-Organic Coatings: Comparison of PEDOT and PANI in Epoxy Matrices." Journal of Composites Science 4, no. 1 (2020): 26. http://dx.doi.org/10.3390/jcs4010026.
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The technological demands imposed on dielectrics and electrical insulation materials are being increasing with the transition from traditional to smart grids. Epoxy resin/conductive polymer (CP) blends with high dielectric permittivity have been prepared by means of a straightforward methodology. Poly(3,4-ethylenedioxythiophene) (PEDOT) and polyaniline (PANI), doped with p-tosylate and ammonium peroxide sulfate (APS), respectively, were synthesized and blended with an epoxy matrix. The addition of 3 wt % of PEDOT and PANI results in permittivity values of 68.9 and 9.5, respectively at 0.1 Hz—1300 and 111 times higher than pure resin. Hence, PEDOT is more effective than PANI at improving the permittivity of the epoxy resin. Moreover, the material retains the electrical insulation of the resin and exhibits a slight increase in thermal conductivity.
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Rahman, Md Wahidur, Chandan Joishi, Nidhin Kurian Kalarickal, Hyunsoo Lee, and Siddharth Rajan. "High-Permittivity Dielectric for High-Performance Wide Bandgap Electronic Devices." ECS Meeting Abstracts MA2022-02, no. 32 (2022): 1210. http://dx.doi.org/10.1149/ma2022-02321210mtgabs.
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In this presentation, we will review recent work on the integration of high permittivity dielectrics with wide and and ultra-wide bandgap semiconductor devices to obtain improved high power and high frequency applications. We will first discuss the use of such structures for vertical power devices. The high permittivity dielectrics help to reduce surface fields and therefore prevent tunnel leakage from Schottky barriers [1]. Insertion of high permittivity dielectrics can also enable better field termination in high voltage vertical devices [2]. We will discuss recent results using such high permittivity dielectrics in vertical device structures based on Gallium Oxide, leading to high vertical electric fields up to 5.7 MV/cm being sustained in the structure. We will discuss the application of these high permittivity dielectrics for three-terminal high frequency [3] and high voltage [4,5] wide bandgap transistor applications. In lateral transistors built from wide and ultra-wide bandgap semiconductors, gate breakdown and non-uniform electric fields lead to average device breakdown fields that are significantly lower than material limits. We will show how high permittivity dielectrics inserted between the gate and drain can prevent gate breakdown, and also create much more uniform electric field profiles. An analytical model to explain this will be presented and compared with 2-dimensional device simulations. Finally, we will show experimental results for lateral devices from the high Al-composition AlGaN [6], -Ga2O3[7], and AlGaN/GaN [8] material systems, where in each case, we are able to achieve state-of-art breakdown performance for devices such as lateral Schottky diodes and transistors. For example, we have achieved up to 8.3 MV/cm field in high Al-content AlGaN devices, >5.5 MV/cm in -Ga2O3-based transistors, and >3 MV/cm lateral electric field in AlGaN/GaN HEMTs. The high breakdown fields also enable us to achieve state-of-art switching figures of merit in these devices. The authors acknowledge funding from NNSA ETI Consortium, AFOSR GAME MURI Program (Program Manager Dr. Ali Sayir), AFOSR (Program Manager Dr. Kenneth Goretta) NSF ECCS- and the DARPA DREAM program (Program Manger Dr. YK Chen), managed by ONR (Program Manager Dr. Paul Maki) for support of the work. References [1] Xia, Zhanbo, et al. "Metal/BaTiO3/β-Ga2O3 dielectric heterojunction diode with 5.7 MV/cm breakdown field." Applied Physics Letters 115.25 (2019): 252104. [2] Lee, Hyun-Soo, et al. "High-permittivity dielectric edge termination for vertical high voltage devices." Journal of Computational Electronics 19.4 (2020): 1538-1545. [3] Xia, Zhanbo, et al. "Design of transistors using high-permittivity materials." IEEE Transactions on Electron Devices 66.2 (2019): 896-900. [4] Kalarickal, Nidhin Kurian, et al. "Electrostatic engineering using extreme permittivity materials for ultra-wide bandgap semiconductor transistors." IEEE Transactions on Electron Devices 68.1 (2020): 29-35. [5] Hanawa, Hideyuki, et al. "Numerical Analysis of Breakdown Voltage Enhancement in AlGaN/GaN HEMTs With a High-k Passivation Layer." IEEE Transactions on Electron Devices 61.3 (2014): 769-775. [6] Razzak, Towhidur, et al. "BaTiO3/Al0. 58Ga0. 42N lateral heterojunction diodes with breakdown field exceeding 8 MV/cm." Applied Physics Letters 116.2 (2020): 023507. [7] Kalarickal, Nidhin Kurian, et al. "β-(Al0.18Ga0.82)2O3/Ga2O3 Double Heterojunction Transistor With Average Field of 5.5 MV/cm." IEEE Electron Device Letters 42.6 (2021): 899-902. [8] Rahman, Mohammad Wahidur, et al. "Hybrid BaTiO3/SiNx/AlGaN/GaN lateral Schottky barrier diodes with low turn-on and high breakdown performance." Applied Physics Letters 119.1 (2021): 013504.
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Zhou, R., and L. Shafai. "Directivity enhancement by layered radomes." Canadian Journal of Physics 73, no. 7-8 (1995): 444–51. http://dx.doi.org/10.1139/p95-064.
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Single and layered radomes are often used to protect radiating elements. A two-dimensional analysis is used to investigate their influence on the antenna directivity and radiation patterns. Image-theory and integral-equation methods are used to formulate the problem for a line source and layered dielectrics of finite length over a ground plane, and solved numerically using the moment method. It is shown that, for a sufficiently long single-layer slab, the directivity enhancement is approximately equal to the square root of its relative permittivity. Properly truncating the slab can even improve the directivity. The optimum length of a finite dielectric slab is determined to maximize the directivity. For multilayer slabs, the directivity enhancement is much greater and they can be used with low-permittivity dielectrics to simulate a single-layer one of higher permittivity. Frequency dependency of the enhanced gain is also studied. Useful information for how to incorporate the radome parameters into the antenna design and use it for gain or directivity enhancement is provided.
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Park, Se Yeon, Moonjeong Jang, Wooseok Song, Sun Sook Lee, Dae Ho Yoon, and Ki-Seok An. "Boosted dielectric performance of organic–inorganic nanocomposites based on BaTiO3 via 2D TiO2 templates." Functional Composites and Structures 3, no. 4 (2021): 045009. http://dx.doi.org/10.1088/2631-6331/ac4279.
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Abstract Organic–inorganic hybrid dielectrics composed of nanoscale ceramic fillers in polymer matrices have attracted considerable attention because they can overcome the inherent limitations such as the low dielectric constant, high dielectric loss, and low film density associated with mechanically flexible pristine polymer materials. Barium titanate (BaTiO3), a representative perovskite-based material with a high permittivity, is suitable for applications as nanofillers in nanocomposite dielectrics. X-ray diffraction combined with Raman analysis suggest that a two-step hydrothermal synthesis, which uses synthesized TiO2 nanosheets as a template, is an effective method for the synthesis of pure BaTiO3 nanoparticles compared with other methods. Ultrasonic treatment is employed to disperse BaTiO3 nanoparticles with different concentrations in polyvinyl alcohol (PVA) polymer, and the dielectric performance of the nanocomposite films has been examined. In this study, 20 wt% BaTiO3–PVA nanocomposite dielectric showed superior capacitance and dielectric constant performance, i.e. five times higher than that of the pristine PVA.
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Yin, Changchun, and Greg Hodges. "Influence of displacement currents on the response of helicopter electromagnetic systems." GEOPHYSICS 70, no. 4 (2005): G95—G100. http://dx.doi.org/10.1190/1.1993710.
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For the purpose of shallow-earth geophysical mapping, progressively higher frequencies have been developed for helicopter electromagnetic (HEM) systems. However, concern has been expressed about the vulnerability of high-frequency EM signals to the influence of the displacement current, especially the phase shift of the HEM signal resulting from the finite speed of light that describes the propagation of the EM wave in free space. In this paper we investigate the influence of the displacement current and the finite speed of light on HEM responses, based on a full solution of the EM field for a conductive, magnetically, and dielectrically polarizable earth half-space and an overlying half-space of air with free-space dielectric permittivity. We calculate the amplitude change and the phase shift of the HEM signal and the change in the apparent resistivity. We find that the displacement current, when both the air and the earth half-space assume the free-space dielectric permittivity, has a small influence on the HEM signal, while substantial influence may occur when the earth is dielectrically polarizable. The finite speed of the EM propagation in free space does not result in significant phase changes in the HEM signal.
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Chi, Xiaohong, Wenfeng Liu, Shengtao Li, and Xiaohong Zhang. "The Effect of Humidity on Dielectric Properties of PP-Based Nano-Dielectric." Materials 12, no. 9 (2019): 1378. http://dx.doi.org/10.3390/ma12091378.
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Nano-dielectrics are sensitive to humidity and easily degraded in damp environment because of the high surface energy of nanoparticles. In order to study the effect of humidity on the dielectric properties of nano-dielectric, polypropylene (PP) was modified by polyolefin elastomer (POE) and nano-SiO2, and the samples with obvious filling concentration were pre-selected by breakdown strength for damp aging. The aging experiments were carried out in different relative humidity. The dielectric properties of new, hygroscopic saturation and samples after drying were measured and analyzed. It is found that the breakdown strength of hygroscopic saturation nano-dielectrics decreased obviously compared with new samples, and it was difficult to recover after drying. The damp degradation resulted in different changing trends of permittivity of PP and nano-dielectric, but there were relaxation loss peaks of water in both of them. The influence of damp degradation on the trap distribution was studied by thermally stimulated depolarization currents (TSDC), and it was found that the traps level introduced by water molecules was different in PP and nano-dielectrics. All experiment results showed that the performance of nano-dielectrics degraded obviously in humid environment, and it was difficult to recover even after complete drying because of the existence of bounded water molecules in nano-dielectrics.
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Li, Jinxing, Hiroya Nishikawa, Junichi Kougo та ін. "Development of ferroelectric nematic fluids with giant-ε dielectricity and nonlinear optical properties". Science Advances 7, № 17 (2021): eabf5047. http://dx.doi.org/10.1126/sciadv.abf5047.
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Superhigh-ε materials that exhibit exceptionally high dielectric permittivity are recognized as potential candidates for a wide range of next-generation photonic and electronic devices. In general, achieving a high-ε state requires low material symmetry, as most known high-ε materials are symmetry-broken crystals. There are few reports on fluidic high-ε dielectrics. Here, we demonstrate how small molecules with high polarity, enabled by rational molecular design and machine learning analyses, enable the development of superhigh-ε fluid materials (dielectric permittivity, ε > 104) with strong second harmonic generation and macroscopic spontaneous polar ordering. The polar structures are confirmed to be identical for all the synthesized materials. Furthermore, adapting this strategy to high–molecular weight systems allows us to generalize this approach to polar polymeric materials, creating polar soft matters with spontaneous symmetry breaking.
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Kohler, Fabian, Monika Farina, Michal Schulz, Holger Fritze, and Jürgen Wilde. "Assembly and interconnection technology for high-temperature bulk acoustic wave resonators." Journal of Sensors and Sensor Systems 11, no. 1 (2022): 83–97. http://dx.doi.org/10.5194/jsss-11-83-2022.
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Abstract. A sensor based on a piezoelectric single crystal enables operation even under harsh environmental conditions. In addition to the sensor element, the packaging technology is crucial for sensor performance. In this paper, a suitable assembly and interconnection technology concept of Ca3TaGa3Si2O14 (CTGS) resonators for high-temperature applications is presented as a platform for future sensor assemblies. The concept described here has already been functionally tested as a temperature sensor (Schulz et al., 2021). The concept includes a sapphire base plate, a housing lid, and a spacer made from aluminium oxide (Al2O3). The substrate is metallised with platinum manufactured into thin film and thick film technology. The ceramic components are fused with glass solder. The connection of the resonator to the conductive tracks is realised by thermosonic bonding with 25 µm platinum wire. Initially, the stability of the metallisation must be investigated before subsequent electrical testing under high temperature. Diffusion processes play a major role in this temperature range, and the stability of the layer is a necessary condition for subsequent investigations. A suitable set of bonding parameters and the strength of the platinum bonds prior to and after thermal load is analysed. Shear tests are used to evaluate the quality of the ceramic materials fused with glass solder after thermal ageing. The dielectrical properties of sapphire and glass solder such as the isolation resistance, the relative permittivity, and the loss factor at high temperatures are evaluated using interdigital structures. The loss factor is measured on both bare interdigital structures and the samples coated with glass solder to make an estimation about the conductive behaviour up to 1000 ∘C. A ceramic lid for the sensor housing is attached by a high-temperature stable glass solder. Since platinum conductors are fed through this glass solder connection, the electrical conductivity of the glass solder is characterised at high temperature. Furthermore, the hermeticity of the assemblies is verified by means of helium leakage tests. These investigations are the basis for the implementation of an assembly and interconnection technology that is suitable for reliable operation under extreme temperature conditions. The packaging technology also offers further possibilities for pressure or chemical sensors that can withstand high-temperature loads.
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Blahovec, J. "Dielectric properties of deformed early potatoes." Research in Agricultural Engineering 54, No. 2 (2008): 113–22. http://dx.doi.org/10.17221/3104-rae.
Full textAbstract:
The permittivity of potato tissue was studied during uniaxial compression of cylindrical specimens prepared from two early varieties. Both the real and the imaginary permitivity components were determined repeatedly during the loading and unloading tests. The analysis of the results obtained shows that small differences exist between the permittivity of the late and early potato varieties. The differences are concentrated mainly at frequencies higher than 1 kHz with a maximum between 10 and 100 kHz. The effect of deformation is concentrated into frequencies between 1 and 100 kHz. The effect of deformation on the permittivity values can be divided into reversible and irreversible parts. The results obtained in the loading/unloading tests give some more information on the proportion of both parts.