scholarly journals Dielectric Behaviour of Disperse Ice Microcrystals in The Frequency Range 105 to 10-2 Hz

1978 ◽  
Vol 20 (83) ◽  
pp. 359-365 ◽  
Author(s):  
C. Lafargue ◽  
C. Bourgeois ◽  
G. Evrard
Keyword(s):  
Activation Energy ◽  
Dielectric Properties ◽  
Activation Energies ◽  
Dielectric Behaviour ◽  
Ageing Effect ◽  
Frequency Range ◽  
Low Frequencies

Abstract Dielectric properties of ice microcrystals have been studied in the frequency range 3 x 105 to 10-2 Hz. Two separated dispersions are revealed : the Debye dispersion of ice and another dispersion at very low frequencies. Both dispersions present an ageing effect, with decreasing activation energy for the Debye dispersion and with increasing activation energy for the second one. It is shown in this paper that the sum of these activation energies retains a constant value of (1.05±0.02) eV.

scholarly journals Dielectric Behaviour of Disperse Ice Microcrystals in The Frequency Range 105 to 10-2 Hz

1978 ◽  
Vol 20 (83) ◽  
pp. 359-365
Author(s):  
C. Lafargue ◽  
C. Bourgeois ◽  
G. Evrard
Keyword(s):  
Activation Energy ◽  
Dielectric Properties ◽  
Activation Energies ◽  
Dielectric Behaviour ◽  
Ageing Effect ◽  
Frequency Range ◽  
Low Frequencies

AbstractDielectric properties of ice microcrystals have been studied in the frequency range 3 x 105 to 10-2 Hz. Two separated dispersions are revealed : the Debye dispersion of ice and another dispersion at very low frequencies. Both dispersions present an ageing effect, with decreasing activation energy for the Debye dispersion and with increasing activation energy for the second one. It is shown in this paper that the sum of these activation energies retains a constant value of (1.05±0.02) eV.

scholarly journals Dielectric Properties of Deep Ice Cores with Air-Hydrate Inclusions (Abstract)

1988 ◽  
Vol 10 ◽  
pp. 210
Author(s):  
Shinji Mae ◽  
Takeo Hondoh ◽  
Masayoshi Nakawo ◽  
C.C. Langway
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Dielectric Properties ◽  
Time Variation ◽  
Volume Fraction ◽  
Ice Cores ◽  
Frequency Range ◽  
Temperature Range ◽  
The Core

Air-hydrate inclusions have been found in deep ice cores from Dye 3, Greenland, which were taken in August 1981. Although the concentration of the air-hydrate crystals decreased with time, when the core was stored at a temperature of −50 °C, they still existed to an appreciable extent in 1985. An ice specimen was cut out from the Dye 3 core at a depth of 1500 m, where the volume fraction of the hydrate crystals was about 10−3 by volume. Its dielectric properties were measured in September 1985, in a frequency range of 30-20 × 103 Hz and temperature range of −20° to −90°C. The activation energy obtained for the relaxation time of the Debye dispersion was about 0.2 eV, which is much smaller than that of pure ice. The measurement was repeated once a month for about a year, and the sample was stored at a temperature of −10 °C between measurements. The time variation of the dielectric properties has been discussed in relation to the deterioration of the air-hydrate crystals.

scholarly journals Dielectric and Conduction Processes and Behaviours in Ni0.3Zn0.7Fe2O4

2016 ◽  
Vol 846 ◽  
pp. 311-317
Author(s):  
Mohd Noor Mat ◽  
M.K. Halimah ◽  
Wan Mohd Daud Wan Yusoff ◽  
H. Mansor ◽  
H. Nizam ◽  
...  
Keyword(s):  
Activation Energy ◽  
Zinc Oxide ◽  
Iron Oxide ◽  
Dielectric Properties ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Peak Frequency ◽  
Frequency Range ◽  
Dielectric Relaxation Process ◽  
Frequency Relaxation

Dielectric relaxation and conductivity of Ni0.3Zn0.7Fe2O4 (NZF) were studied in the frequency range between 0.01 Hz to 3 MHz and temperature range within 313 K to 473 K. The sample was prepared by mixing Zinc Oxide, Nickel Oxide and Iron Oxide and sintered at 1573 K for 10 hours long. Dielectric properties were studied using Novo Control Dielectric Spectrometer. Dielectric relaxation and conductivity phenomena were discussed using an empirical model to key out the dielectric relaxation process. Analyze peak frequency relaxation process consist of four slopes to explain the dielectric relaxation process. The conductivity of the sample indicates an activated process and activation energy of dc conductivity is 0.44 ± 0.01 eV.

Dielectric Behaviour of Ice Microcrystals Dispersed within Suspensions: A DTC Study

1982 ◽  
Vol 37 (9) ◽  
pp. 1000-1004 ◽  
Author(s):  
P. Pissis ◽  
L. Apekis ◽  
C. Christodoulides ◽  
G. Boudouris
Keyword(s):  
Dielectric Properties ◽  
Relaxation Mechanism ◽  
Dielectric Behaviour ◽  
Frequency Range ◽  
Temperature Range ◽  
Dielectric Absorption

Abstract The dielectric properties of water-in-oil (W/O) suspensions have been studied by means of the depolarization thermocurrent (DTC) method in the temperature range of 85-250 K. Two predominant peaks have been observed at about 140 and 225 K. Evidence has been obtained that the peak at 140 K and the dielectric absorption observed by many investigators at sub-zero temperatures in the kHz frequency range are due to the same relaxation mechanism.

Investigation of dielectric behavior of the PVC/BaTiO3 composite in low-frequencies

2018 ◽  
Vol 32 (09) ◽  
pp. 1850110 ◽  
Author(s):  
A. Berrag ◽  
S. Belkhiat ◽  
L. Madani
Keyword(s):  
Dielectric Properties ◽  
Dielectric Behavior ◽  
Index Formula ◽  
Response Analysis ◽  
Frequency Response Analysis ◽  
Frequency Range ◽  
Low Frequencies ◽  
X Ray ◽  
Space Charges ◽  
Loss Index

Polyvinyl chloride (PVC) is widely used as insulator in electrical engineering especially as cable insulation sheaths. In order to improve the dielectric properties, polymers are mixed with ceramics. In this paper, PVC composites with different weight percentages 2 wt.%, 5 wt.%, 8 wt.% and 10 wt.% were prepared and investigated. Loss index ([Formula: see text]) and dielectric constant ([Formula: see text]) have been measured using an impedance analyzer RLC. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) equipped with energy dispersive X-ray (EDX) have been used as characterization techniques. The incorporation of BaTiO3 does not modify the crystallinity and the morphology of the PVC but reduces the space charges, therefore the dielectric losses. The frequency response analysis has been followed in the frequency ranges (20–140 Hz and 115–1 MHz). Relaxation frequencies have been evaluated in each frequency range. Experimental measurements have been validated using Cole–Cole’s model. Experimental results show well that BaTiO3 as a filler improves the dielectric properties of PVC.

scholarly journals Dielectric Properties of Deep Ice Cores with Air-Hydrate Inclusions (Abstract)

1988 ◽  
Vol 10 ◽  
pp. 210-210
Author(s):  
Shinji Mae ◽  
Takeo Hondoh ◽  
Masayoshi Nakawo ◽  
C.C. Langway
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Dielectric Properties ◽  
Time Variation ◽  
Volume Fraction ◽  
Ice Cores ◽  
Frequency Range ◽  
Temperature Range ◽  
The Core

Air-hydrate inclusions have been found in deep ice cores from Dye 3, Greenland, which were taken in August 1981. Although the concentration of the air-hydrate crystals decreased with time, when the core was stored at a temperature of −50 °C, they still existed to an appreciable extent in 1985.An ice specimen was cut out from the Dye 3 core at a depth of 1500 m, where the volume fraction of the hydrate crystals was about 10−3 by volume. Its dielectric properties were measured in September 1985, in a frequency range of 30-20 × 103 Hz and temperature range of −20° to −90°C. The activation energy obtained for the relaxation time of the Debye dispersion was about 0.2 eV, which is much smaller than that of pure ice.The measurement was repeated once a month for about a year, and the sample was stored at a temperature of −10 °C between measurements. The time variation of the dielectric properties has been discussed in relation to the deterioration of the air-hydrate crystals.

scholarly journals Static and Dynamic Dielectric Properties of Mesogenic n-Nonyloxycyanobiphenyl (9OCB)

2007 ◽  
Vol 62 (1-2) ◽  
pp. 61-66
Author(s):  
Grzegorz Czechowski ◽  
Jan Jadżyn
Keyword(s):  
Activation Energy ◽  
Phase Transitions ◽  
Dielectric Properties ◽  
Dielectric Relaxation ◽  
Rotational Diffusion ◽  
Short Axis ◽  
Frequency Range ◽  
Static Permittivity ◽  
Anomalous Temperature ◽  
Smectic A

The dielectric properties of n-nonyloxycyanobiphenyl in the isotropic (I), nematic (N) and smectic A (SA) phases were investigated. The dielectric relaxation spectra, recorded in the frequency range 50 kHz - 100 MHz, were analyzed with use of the Cole-Cole equation. An anomalous temperature behavior of the static permittivity, the rotational diffusion exponent and the activation energy of mesogenic molecules rotating around their short axis, observed in the vicinity of the phase transitions, are discussed.

MEASUREMENT OF ELECTRICAL ACTIVATION ENERGY IN BLACK CVD DIAMOND USING IMPEDANCE SPECTROSCOPY

2002 ◽  
Vol 16 (28n29) ◽  
pp. 4487-4492
Author(s):  
HAITAO YE ◽  
OLIVER A. WILLIAMS ◽  
RICHARD B. JACKMAN
Keyword(s):  
Activation Energy ◽  
Deep Level ◽  
Diamond Films ◽  
Activation Energies ◽  
Electrical Activation ◽  
Capacitance Measurement ◽  
Free Standing ◽  
Low Frequencies ◽  
Wide Range ◽  
Diamond Grain

Dc current-voltage (I-V) measurement, Hall measurement, Deep-level transient-spectroscopy (DLTS), and flatband capacitance measurement have been used to investigate electrical activation energies in diamond. However, the deviations still exist in the published activation energies obtained by these methods. In this paper, we report the first measurement of impedance on free-standing diamond films from 0.1Hz to 10MHz up to 300°C. A wide range of CVD materials have been investigated, but here we concentrate on 'black' diamond grown by MWPECVD. The Cole-Cole (Z′ via Z″) plots are well fitted to a RC parallel circuit model and the equivalent Resistance and Capacitance for the diamond films have been estimated using the Zview curve fitting. The results show only one single semicircle response at each temperature measured. It was found that the resistance decreases from 62 MΩ at room temperature to 4 KΩ at 300°C, with an activation energy around 0.15eV. The equivalent capacitance is maintained at the level of 102 pF up to 300°C suggesting that the diamond grain boundaries are dominating the conduction. At 400°C, the impedance at low frequencies shows a linear tail, which can be explained that the AC polarization of diamond/Au interface occurs.

LOW TEMPERATURE STUDIES OF THE DIELECTRIC AND ELECTRICAL PARAMETERS OF GLASSY Se90Ge10-xInx

2002 ◽  
Vol 09 (03n04) ◽  
pp. 1379-1385
Author(s):  
S. ABOU EL-HASSAN
Keyword(s):  
Activation Energy ◽  
Dielectric Properties ◽  
Low Temperature ◽  
Localized States ◽  
Frequency Range ◽  
Electrical Parameters ◽  
Cbh Model ◽  
Correlated Barrier Hopping ◽  
Density Of Localized States ◽  
Different Temperatures

The dielectric properties of the system Se 90 Ge 10-x In x (x = 2, 4 and 6 at. %) were studied in the temperature range of 78–273 K and in the frequency range of 400 Hz–20 kHz. The density of localized states N(E) and the activation energy of hopping wk for the samples were deduced at different temperatures. The exponents s, m1 and m2 of the equations σ ac (ω) = Aωs, ε′ = Bωm1 and ε′′ = Cωm2 have been deduced for the samples. The composition and temperature dependence of s, m1, m2, wk and N(E) have been determined. The results are interpreted in terms of the correlated barrier hopping (CBH) model and the concept of localized states.

scholarly journals Dielectric Properties of La0.4Ca0.6Mn0.4Ti0.6O3 Ceramic Oxide

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Walter Charles Primus ◽  
Abdul Halim Shaari ◽  
Wan Mohd. Daud Wan Yusoff ◽  
Zainal Abidin Talib ◽  
Mazni Mustafa
Keyword(s):  
Dielectric Properties ◽  
Imaginary Part ◽  
Dielectric Behaviour ◽  
Circuit Modeling ◽  
Electrical Behaviour ◽  
Low Frequencies ◽  
Ceramic Oxide ◽  
Trapping Mechanism

The dielectric properties of La0.4Ca0.6Mn0.4Ti0.6O3 ceramic oxide was investigated under various temperatures. A Debyelikebehaviour was observed although the dc conduction effects at low frequencies almost overlapping the relaxationpeak in the imaginary part. This feature of dielectric behaviour was explained using trapping mechanism. An equivalentcircuit modeling was proposed to represent the electrical behaviour of this sample using universal capacitor, C*(4) =B(i4)n-1. The circuit modeling is consisting of two series of dispersive capacitors in parallel with conductance and highfrequency capacitance.

Sign in / Sign up

Export Citation Format

Share Document