Dielectric loss

About: Dielectric loss is a research topic. Over the lifetime, 20296 publications have been published within this topic receiving 349254 citations.

Polyhedral Oligosilsesquioxane‐Modified Boron Nitride Nanotube Based Epoxy Nanocomposites: An Ideal Dielectric Material with High Thermal Conductivity

Abstract: Dielectric polymer composites with high thermal conductivity are very promising for microelectronic packaging and thermal management application in new energy systems such as solar cells and light emitting diodes (LEDs). However, a well-known paradox is that conventional composites with high thermal conductivity usually suffer from the high dielectric constant and high dielectric loss, while on the other hand, composite materials with excellent dielectric properties usually possess low thermal conductivity. In this work, an ideal dielectric thermally conductive epoxy nanocomposite is successfully fabricated using polyhedral oligosilsesquioxane (POSS) functionalized boron nitride nanotubes (BNNTs) as fillers. The nanocomposites with 30 wt% fraction of POSS modified BNNTs exhibit much lower dielectric constant, dielectric loss tangent, and coefficient of thermal expansion in comparison with the pure epoxy resin. As an example, below 100 Hz, the dielectric loss of the nanocomposites with 20 and 30 wt% BNNTs is reduced by one order of magnitude in comparison with the pure epoxy resin. Moreover, the nanocomposites show a dramatic thermal conductivity enhancement of 1360% in comparison with the pristine epoxy resin at a BNNT loading fraction of 30 wt%. The merits of the designed composites are suggested to originate from the excellent intrinsic properties of embedded BNNTs, effective surface modification by POSS molecules, and carefully developed composite preparation methods.

Theory of Dielectrics: Dielectric Constant and Dielectric Loss

Abstract: Physicists, chemists, and electrical engineers are all interested in the properties of dielectric materials, though with different purposes in mind. This book is intended to give a systematic account of the theory of dielectric properties, and thus to provide a background against which applications can be made. It seldom requires the reader to have a knowledge of mathematics greater than is implied by an acquaintance with calculus, and the reader is assumed to have a certain elementary knowledge of atomic and molecular physics, statistical mechanics, and electrostatics.

Carbon nanotube composites with high dielectric constant at low percolation threshold

Abstract: In this letter, the dielectric properties of the untreated multiwall carbon-nanotubes∕poly(vinylidene fluoride) (MWNT∕PVDF) composites are studied. Towards low frequencies, the dielectric constant of a composite with about 2.0vol% of MWNT increases rapidly and the value of the dielectric constant is as high as 300. However, by a calculation, the percolation threshold of the MWNT∕PVDF composites is only 1.61vol% (0.0161 volume fraction) of MWNT. Both the large aspect ratio and the high conductivity of the MWNT may lead to the low percolation threshold of the MWNT∕PVDF composites. For the percolation composite, the dielectric loss value is always less than 0.4, irrespective of the frequency. Therefore, the experimental results suggest that the dielectric properties of MWNT∕PVDF composites may be improved significantly without the chemical functionalization to carbon nanotubes.

Novel Ferroelectric Polymers for High Energy Density and Low Loss Dielectrics

Abstract: The state-of-the-art polymer dielectrics have been limited to nonpolar polymers with relatively low energy density but ultralow dielectric losses for the past decades. With the fast development of power electronics in pulsed power and power conditioning applications, there is a need for next-generation dielectric capacitors in areas of high energy density/low loss and/or high temperature/low loss polymer dielectrics. Given limitations in further enhancing atomic and electronic polarizations for polymers, this Perspective focuses on a fundamental question: Can orientational polarization in polar polymers be utilized for high energy density and low loss dielectrics? Existing experimental and theoretical results have suggested the following perspectives. For amorphous polar polymers, high energy density and low loss can be achieved below their glass transition temperatures. For liquid crystalline side-chain polymers, dipole mobility is so high that they saturate at relatively low electric fields, and only li...

Development of a "laminated waveguide"

Abstract: A waveguide of new structure has been developed for millimeter-wave applications. The dielectric waveguide is constructed with sidewalls consisting of lined via-holes and edges of metallized planes. This structure can be manufactured by lamination techniques, so we refer to the waveguide as a "laminated waveguide". The laminated waveguide can be embedded in a substrate and is able to be wired in three dimensions. The transmission characteristics are evaluated using a glass-ceramic substrate of dielectric constant, /spl epsiv//sub r/=5, and loss, tan /spl delta/=0.0008. Insertion loss per unit length of the guide is estimated to be less than 0.5 dB/cm at 83 GHz. Furthermore, it was confirmed that the laminated waveguide is suitable to feeding lines for a small sized plane array antenna. By electromagnetic simulation, it has been confirmed that fundamental structures, such as bends, branches, power dividers, and interconnections between upper and lower layers can be realized with sufficient performances.