INVESTIGATION OF THE FREQUENCY-TEMPERATURE RELATIONSHIP OF THE DIELECTRIC PERMITTIVITY OF THE PZT PIEZOCERAMICS IN THE LOW FREQUENCY RANGE

A new instrument designed for frequency‐domain sounding in the depth range 0–10 m uses short coil spacings of 5 m or less and a frequency range of 300 kHz to 30 MHz. In this frequency range, both conduction currents (controlled by electrical conductivity) and displacement currents (controlled by dielectric permittivity) are important. Several surface electromagnetic survey systems commonly used (generally with frequencies less than 60 kHz) are unsuitable for detailed investigation of the upper 5 m of the earth or, as with ground‐penetrating radar, are most effective in relatively resistive environments. Most computer programs written for interpretation of data acquired with the low‐frequency systems neglect displacement currents, and are thus unsuited for accurate high‐frequency modeling and interpretation. New forward and inverse computer programs are described that include displacement currents in layered‐earth models. The computer programs and this new instrument are used to evaluate the effectiveness of shallow high‐frequency soundings based on measurement of the tilt angle and the ellipticity of magnetic fields. Forward model studies indicate that the influence of dielectric permittivity provides the ability to resolve thin layers, especially if the instrument frequency range can be extended to 50 MHz. Field tests of the instrument and the inversion program demonstrate the potential for detailed shallow mapping wherein both the resistivity and the dielectric permittivity of layers are determined. Although data collection and inversion are much slower than for low‐frequency methods, additional information is obtained inasmuch as there usually is a permittivity contrast as well as a resistivity contrast at boundaries between different materials. Determination of dielectric permittivity is particularly important for hazardous waste site characterization because the presence of some contaminants may have little effect on observed resistivity but a large effect on observed permittivity.

Download Full-text

Dielectric Properties of Ternary ( ) ( )x ( ) x ZnO MgO PO 30 2 5 70− (x = 5, 8, 13) Glasses

Malaysian Journal of Fundamental and Applied Sciences ◽

10.11113/mjfas.v5n1.285 ◽

2014 ◽

Vol 5 (1) ◽

Author(s):

S. F. Khor ◽

Z. A. Talib ◽

W. M. Daud ◽

H. A. A. Sidek ◽

W. M. M. Yunus ◽

...

Keyword(s):

Dielectric Properties ◽

Dielectric Permittivity ◽

Empirical Data ◽

Loss Factor ◽

Low Frequency ◽

Frequency Range ◽

Melt Quenching ◽

Dipolar Relaxation ◽

Temperature Range

(ZnO)30(MgO)x(P2O5)70-x glasses of the composition x = 5, 8 and 13 mol % have been prepared by melt quenching technique. The dielectric permittivity (89) and loss factor (8:) were measured in the frequency range from 0.01 Hz to 1 MHz and in the temperature range 303 to 573 K . From the results there are evidence of dipolar relaxation occurring between 103 – 106 Hz while at low frequency the spectrum is dominated by dc conduction which manifested by the 1/@ slope of loss factor plot. Value of the relaxing frequency (@p) plotted against 1/T shows one electrical transportation mechanism. The empirical data was sufficiently fitted by using Harviliak-Negami equation.

Download Full-text

Permittivity and Loss of Composites of Epoxy Resin and Kevlar Fibres

Advanced Composites Letters ◽

10.1177/096369359500400405 ◽

1995 ◽

Vol 4 (4) ◽

pp. 096369359500400 ◽

Cited By ~ 1

Author(s):

G.M. Tsangaris ◽

G.C. Psarras

Keyword(s):

Dielectric Permittivity ◽

Epoxy Resin ◽

Filler Content ◽

Low Frequency ◽

Interfacial Polarization ◽

Dielectric Behaviour ◽

Frequency Range ◽

Wide Range ◽

Dielectric Permittivity And Loss

The dielectric behaviour of composites with epoxy resin and kevlar fibres is investigated in a wide range of frequency and temperature. Dielectric permittivity is increasing with filler content and temperature, being always higher in the low frequency range. Dielectric permittivity and loss of the composites is mostly affected by interfacial polarization arising from inhomogeneities at interfaces introduced by the filler.

Download Full-text

Ionic Space Charge Relaxation and High Dielectric Permittivity in Polyethylene Oxide

MRS Proceedings ◽

10.1557/proc-548-353 ◽

1998 ◽

Vol 548 ◽

Cited By ~ 5

Author(s):

A. Wagner ◽

H. Kliem

Keyword(s):

Relative Humidity ◽

Dielectric Permittivity ◽

Space Charge ◽

Polyethylene Oxide ◽

Transition Probability ◽

Low Frequency ◽

Frequency Range ◽

Molecular Weights ◽

Thermally Activated ◽

High Dielectric

ABSTRACTThin films (0.3μm to 11.2 μm) of Polyethylene Oxide (PEO) with molecular weights from 6 × 103 to 4 × 105 were prepared from aqueous solutions by a spin technique as AI-PEO-AI structures, or as AI-PEO-Si structures. Dielectric measurements (capacitance and loss angle) were carried out in a frequency range 3 mHz ≤ f ≤ 1 MHz in atmospheres of different relative humidity (0% r.h. to 75% r.h.) and at different temperatures (293 K to 323 K). The nominal dielectric permittivity exhibits a remarkable dependence on the sample thickness and the relative humidity. We find a true volume polarization in the high frequency range and a thermally activated relaxation process in the low frequency range, whose time constant is shifted towards high frequencies with increasing r.h.. It is considered that due to the absorbed dipolar water molecules chemical bonds within the sample are broken and quasi-free ions are generated. These ions move through the sample to the electrode interfaces and form an ionic space charge. We assume that at the PEO-Al interface an oxide layer is formed, which is impermeable for these ions. The transit times and the drift velocities of the ions are almost independent of the electric field strength in the low-field limit. Therefore we conclude that the movement of the ions can be described by a multiwell potential model, where the transition probability between neighbored wells is thermally activated.

Download Full-text

Microstructure and Electrical Properties of Calcium Copper Titanate Ceramics

Materials Science Forum ◽

10.4028/www.scientific.net/msf.561-565.551 ◽

2007 ◽

Vol 561-565 ◽

pp. 551-555 ◽

Cited By ~ 1

Author(s):

Lai Jun Liu ◽

Hui Qing Fan

Keyword(s):

Electrical Properties ◽

Dielectric Permittivity ◽

High Frequency ◽

Low Frequency ◽

Wide Frequency Range ◽

Frequency Range ◽

Cell Parameters ◽

Grain Sizes ◽

Calcium Copper Titanate ◽

Titanate Ceramics

The effect of stoichiometry, i.e. Ca/Cu ratios (CaCu3xTi4O12, x = 0.8, 0.9, 1.0, 1.1 and 1.2) on the microstructure and electrical properties was investigated. The grain sizes of CaCu3xTi4O12 composition increased sharply with the increase of copper, from ~1 μm with x = 0.8 to ~50 μm with x = 1.2. The real part of dielectric permittivity changed dramatically, the pellet with x = 1.0 had the highest dielectric permittivity ~160, 000 at 1 kHz. Furthermore, the dielectric permittivity of all pellets was impressively large values (between 10, 000 to 1, 000,000 at 100 Hz) and was nearly constant over a wide frequency range between 100 Hz to ~100 MHz. However, the dielectric permittivity of CaCu3xTi4O12 composition is not consistent with the amount of copper and cell parameters and grain sizes. Impedance spectroscopy exhibited that the CaCu3xTi4O12 composition had two semicircle at least at high frequency (~ 107 Hz) and low frequency (<100 Hz), respectively. The grain and grain boundary of the compositions had different impedance and relaxation behavior.

Download Full-text

RELATIONSHIP OF LOW-FREQUENCY DIELECTRIC PERMITTIVITY WITH THE CONDUCTIVITY OF LOW-SALTED SAND SAMPLES

RADIO COMMUNICATION TECHNOLOGY ◽

10.33286/2075-8693-2020-46-85-94 ◽

2020 ◽

pp. 85-94

Author(s):

P. P. Bobrov ◽

T. A. Belyaeva ◽

E. S. Kroshka ◽

O. V. Rodionova

Keyword(s):

Dielectric Permittivity ◽

Specific Conductivity ◽

Low Frequency ◽

Calculated Data ◽

Coarse Sand ◽

Relaxation Processes ◽

Regression Equations ◽

Dielectric Characteristics ◽

5 Ghz ◽

Relationship Of

The results of experimental measurements of the complex dielectric permittivity (CDP) of sand and powders of quartz granules saturated with a saline solution with a conductivity from 0 to 0.77 S/m are presented. The measurements were carried out at the frequencies from 1 kHz to 5 GHz. It is shown that in the frequency range from 10 kHz to 100 MHz, the dielectric characteristics can be modeled by three relaxation processes. The parameters of these processes are described by the Debye and Cole-Cole formulas. For two low-frequency processes, regression equations that relate the parameters of the processes with the specific conductivity of the samples at a frequency of 5 kHz are found. Using the obtained equations and the results of CDP measuring at a frequency of 1 GHz, the calculated CDP spectra of coarse sand samples were obtained. The average deviations of the calculated data from the experimental ones were from 10 to 30 %.

Download Full-text

The effect of shape and sizes of particles of wet quartz powders on complex dielectric permittivity in the frequency range of 10 kHz – 10 GHz

Journal of Physics Conference Series ◽

10.1088/1742-6596/2140/1/012004 ◽

2021 ◽

Vol 2140 (1) ◽

pp. 012004

Author(s):

P P Bobrov ◽

E S Kroshka ◽

O V Rodionova

Keyword(s):

Dielectric Permittivity ◽

High Frequency ◽

Experimental Studies ◽

Low Frequency ◽

Dielectric Permeability ◽

Complex Dielectric Permittivity ◽

Particle Sizes ◽

Frequency Range ◽

High Concentration ◽

River Sand

Abstract The results of experimental studies of complex dielectric permeability of river sand and powders of granules of fused quartz with narrow distributions of particles in size at the frequencies from 10 kHz to 10 GHz are presented. The granule particles are spheres and the sand particles are irregularly shaped. The samples were moistened with distilled water and NaCl salt solution with conductivity of 0.1 and 0.77 S/m. It has been shown that the shape of the particles affects the complex dielectric permittivity (CDP) in the low frequency part of the range only when proportion of the solution is small and its concentration is weak. At full saturation of the samples with the solution and its high concentration, as well as in all cases at frequencies above 100 MHz, the influence of the particle shape is small. In the mid-frequency part of the range (from units to tens of megahertz) in a sample of quartz granules with small particles, there is a strong relaxation process, leading to a significant increase in the real part of the CDP. A similar, but slight increase is observed in samples of sand with larger particles. In the high-frequency range, the effect of the shape and particle sizes is very weak.

Download Full-text

Study on low-frequency dielectric behavior of the carbon black/polymer nanocomposite

Journal of Materials Science Materials in Electronics ◽

10.1007/s10854-021-07242-1 ◽

2021 ◽

Author(s):

H. Shivashankar ◽

Kevin Amith Mathias ◽

Pavankumar R. Sondar ◽

M. H. Shrishail ◽

S. M. Kulkarni

Keyword(s):

Energy Storage ◽

Dielectric Properties ◽

Dielectric Loss ◽

Dielectric Permittivity ◽

Carbon Black ◽

Low Frequency ◽

Clean Energy ◽

Polymer Materials ◽

Filler Concentration ◽

Frequency Range

AbstractRecently, polymer-based dielectric materials have become one of the key materials to play an essential role in clean energy production, energy transformation, and energy storage applications. The end usage is the energy storage capability because it is a trade-off between dielectric permittivity, dielectric loss, and dissipation factor. Hence, it is of prime importance to study the dielectric properties of polymer materials by adding filler material at a low-frequency range. In the present study, polydimethylsiloxane/carbon black nanocomposites are prepared using the solution cast method. The dielectric properties, such as dielectric constant, dielectric loss, and dissipation factors due to the concentration of filler particles and low-frequency effect on the nanocomposites, are examined. Also, different empirical models are used to estimate the dielectric permittivity of polymer nanocomposites. The low-frequency range of 100 Hz to 1 MHz and the effect of varying volume fractions of carbon black show a significant change in the dielectric properties. It is found that the nanocomposites have a higher dielectric permittivity than the base polymer material. It is also observed that an increase in filler concentration increases the dielectric permittivity, which is confirmed with an empirical model.

Download Full-text

Electromagnetic Properties of Carbon Gels

Materials ◽

10.3390/ma12244143 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4143 ◽

Cited By ~ 1

Author(s):

Jimena Castro-Gutiérrez ◽

Edita Palaimiene ◽

Jan Macutkevic ◽

Juras Banys ◽

Polina Kuzhir ◽

...

Keyword(s):

Electrical Conductivity ◽

Dielectric Permittivity ◽

Low Frequency ◽

Microwave Frequency ◽

Power Laws ◽

Wide Frequency Range ◽

Electromagnetic Properties ◽

Frequency Range ◽

Carbon Gels ◽

Electrical Conductivities

The electromagnetic properties of various carbon gels, produced with different bulk densities, were investigated in a wide frequency range (20 Hz–36 GHz). The values of dielectric permittivity and electrical conductivity at 129 Hz were found to be very high, i.e., more than 105 and close to 100 S/m, respectively. Both strongly decreased with frequency but remained high in the microwave frequency range (close to 10 and about 0.1 S/m, respectively, at 30 GHz). Moreover, the dielectric permittivity and the electrical conductivity strongly increased with the bulk density of the materials, according to power laws at low frequency. However, the maximum of microwave absorption was observed at lower densities. The DC conductivity slightly decreased on cooling, according to the Arrhenius law. The lower activation energies are typical of carbon gels presenting lower DC electrical conductivities, due to a higher number of defects. High and thermally stable electromagnetic properties of carbon gels, together with other unique properties of these materials, such as lightness and chemical inertness, open possibilities for producing new electromagnetic coatings.

Download Full-text