Continuous carbon fiber polymer–matrix composites in unprecedented antiferroelectric coupling, as enabled by stacking composites with positive value (up to 400) and negative value (down to -600) of the electric permittivity, provide exceptionally high through-thickness permittivity up to 78,000 (B2.0 MHz), corresponding to a capacitance of 370 lF/m. The high capacitance is consistent with the e...

Randomly distributed carbon fibers (CFs) reinforced epoxy resin composites are prepared by the pouring method, the dielectric properties of CF composites with different fiber content and length have been performed in the frequency range from 8.2 to 12.4 GHz. The complex permittivity of the composite increases with the fiber length, which is attributed to the decrease of depolarization field, an...

The relative permittivity (or static dielectric constant) of water and steam has been experimentally calculated at a relatively wide range of temperatures and pressures. Two separate functions for predicting the relative permittivity of water and steam in two distinct thermodynamic regions are evolved using genetic programming. A data set comprised of all of the most accurate relative permittiv...

Dielectric materials with high permittivity are strongly demanded for various technological applications. While polarization inherently exists in ferroelectric barium titanate (BaTiO3), its high permittivity can only be achieved by chemical and/or structural modification. Here, we report the room-temperature colossal permittivity (~760,000) obtained in xNd: BaTiO3 (x = 0.5 mol%) ceramics derive...

A number of studies have achieved the consensus that microwave thermal technology can regenerate the granular activated carbon (GAC) more efficiently and energy-conservatively than other technologies. In particular, in the microwave heating industry, permittivity is a crucial parameter. This paper developed two equivalent models to establish the relationship between effective complex permittivi...

Recently, the existence of a perfect lens has been predicted, made of an artificial material that has a negative electric permittivity and a negative magnetic permeability. For optical frequencies a poormans version is predicted to exist in the sub-wavelength limit. Then, only the permittivity has to be negative, a demand that metals fulfill at optical frequencies. We propose a new measurement ...

The ideal relative permittivity of liquid mixtures is demonstrated to be a volume-fraction-weighted average of the pure-component relative permittivities. This generalised-thermodynamics result is used to define the molar electric dipole, permittivity, dielectric polarization and electric susceptibility of thermodynamically ideal liquid mixtures and the corresponding excess properties. A hyperb...

The present paper reports the results of an extensive numerical analysis of electromagnetic fields in random dielectric materials. The effective permittivity of a two-dimensional (2-D) dielectric mixture is calculated by FDTD simulations of such a sample in a TEM waveguide. Various theoretical bounds are tested in light of the numerical simulations. The results show how the effective permittivi...

When the permittivities, or dielectric properties, of granular or powdered solid materials are important, some reliable relationship between the permittivity and the bulk density of the air-particle mixture is required. Examples of such applications include radio-frequency or microwave dielectric heating of these materials and the use of correlations between permittivity and water content of hy...

Effective complex permittivity measurements of materials are important in microwave engineering and microwave chemistry. The BP (Back Propagation) neural network computational module has been applied to microwave technology and becomes a useful tool recently. A neural network can be trained to learn the behavior of an effective complex permittivity of material under microwave irradiation in an ...