Investigating the dielectric properties and low-frequency relaxation process of TlGaSe2 crystals

2017 ◽  
Vol 31 (12) ◽  
pp. 1750134 ◽  
Author(s):  
Oktay Samadov ◽  
Oktay Alakbarov ◽  
Arzu Najafov ◽  
Samir Samadov ◽  
Nizami Mehdiyev ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Relaxation Time ◽  
Constant Electric Field ◽  
Low Frequency ◽  
Constant Field ◽  
Impedance Spectra ◽  
Ionic Contribution ◽  
Frequency Relaxation ◽  
Average Relaxation Time ◽  
Diagram Analysis

The dielectric and impedance spectra of TlGaSe2 crystals have been studied at temperatures in the 100–500 K range in the alternating current (AC [Formula: see text]1 V). It has been shown that the conductivity of TlGaSe2 crystals is mainly an ionic characteristic at temperatures above 400 K. The well-defined peak at the frequency dependence of the imaginary part of impedance [Formula: see text] is observed in the 215–500 K temperature range. In a constant field, there occurs a significant decrease in electrical conductivity [Formula: see text] in due course. The ionic contribution to conductivity (76% at [Formula: see text]) has been estimated from a kinetic change in electrical conductivity [Formula: see text] under the influence of a constant electric field. The diagram analysis in a complex plane [Formula: see text] has been conducted by applying the method of an equivalent circuit of the substation. It has been determined that the average relaxation time of the electric module of the sample is [Formula: see text].

scholarly journals Physical Meanings of Fractal Behaviors of Water in Aqueous and Biological Systems with Open-Ended Coaxial Electrodes

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2606
Author(s):  
Shin Yagihara ◽  
Rio Kita ◽  
Naoki Shinyashiki ◽  
Hironobu Saito ◽  
Yuko Maruyama ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Relaxation Time ◽  
Relaxation Process ◽  
Fractal Analysis ◽  
Biological Systems ◽  
Polymer Networks ◽  
Dispersion Systems ◽  
Dispersion State ◽  
Frequency Relaxation ◽  
Average Relaxation Time

The dynamics of a hydrogen bonding network (HBN) relating to macroscopic properties of hydrogen bonding liquids were observed as a significant relaxation process by dielectric spectroscopy measurements. In the cases of water and water rich mixtures including biological systems, a GHz frequency relaxation process appearing at around 20 GHz with the relaxation time of 8.2 ps is generally observed at 25 °C. The GHz frequency process can be explained as a rate process of exchanges in hydrogen bond (HB) and the rate becomes higher with increasing HB density. In the present work, this study analyzed the GHz frequency process observed by suitable open-ended coaxial electrodes, and physical meanings of the fractal nature of water structures were clarified in various aqueous systems. Dynamic behaviors of HBN were characterized by a combination of the average relaxation time and the distribution of the relaxation time. This fractal analysis offered an available approach to both solution and dispersion systems with characterization of the aggregation or dispersion state of water molecules. In the case of polymer-water mixtures, the HBN and polymer networks penetrate each other, however, the HBN were segmented and isolated more by dispersed and aggregated particles in the case of dispersion systems. These HBN fragments were characterized by smaller values of the fractal dimension obtained from the fractal analysis. Some examples of actual usages suggest that the fractal analysis is now one of the most effective tools to understand the molecular mechanism of HBN in aqueous complex materials including biological systems.

Effect of changing water salinity on complex conductivity spectra of sandstones

Geophysics ◽  
2011 ◽  
Vol 76 (5) ◽  
pp. F315-F327 ◽  
Author(s):  
Andreas Weller ◽  
Katrin Breede ◽  
Lee Slater ◽  
Sven Nordsiek
Keyword(s):  
Electrical Conductivity ◽  
Relaxation Time ◽  
Pore Space ◽  
Internal Surface ◽  
Imaginary Component ◽  
Fluid Composition ◽  
High Porosity ◽  
Equal Concentration ◽  
Fluid Chemistry ◽  
Average Relaxation Time

We analyzed the influence of pore fluid composition on the complex electrical conductivity of three sandstones with differing porosity and permeability. The fluid electrical conductivity ([Formula: see text]) of sodium and calcium chloride solutions was gradually increased from 25 mS/m to 2300 mS/m. The expected linear relation between [Formula: see text] and the real component of electrical conductivity ([Formula: see text]) of the saturated samples was observed. The imaginary component ([Formula: see text]) exhibits a steeper increase at lower salinities that flattens at higher salinities. For a glauconitic sandstone and a high porosity Bunter sandstone, [Formula: see text] approaches an asymptotic value at high salinities. Sodium cations result in larger values of [Formula: see text] than calcium cations in solutions of equal concentration. Debye decomposition was used to determine normalized chargeability ([Formula: see text]) and average relaxation time ([Formula: see text]) from spectral data. The behavior of [Formula: see text] is comparable to [Formula: see text] as both parameters measure the polarizability. At lower salinity, the relation between [Formula: see text] and [Formula: see text] approximates a power law with an exponent of [Formula: see text]. The average relaxation time shows only a weak dependence on [Formula: see text]. The normalized chargeability of sandstone samples can be described by the product of the pore space related internal surface and a quantity characterizing the polarizability of the mineral-fluid interface that depends on fluid chemistry. We introduce a new parameter, the specific polarizability, describing this dependence. We propose relations between polarizability and fluid chemistry that could be used to estimate pore space internal surface across samples of varying [Formula: see text]. We observe a consistent maximum polarizability for quartz dominated siliceous material.

Effect of zirconia doping on the electrical behavior of yttria

1996 ◽  
Vol 11 (2) ◽  
pp. 422-429 ◽  
Author(s):  
C. C. Wang ◽  
V. D. Patton ◽  
S. A. Akbar ◽  
M. A. Alim
Keyword(s):  
Low Frequency ◽  
Transference Number ◽  
Electrical Behavior ◽  
Plane Analysis ◽  
Impedance Plane ◽  
Identical Response ◽  
Heavily Doped ◽  
Ionic Contribution ◽  
Frequency Relaxation ◽  
Electrical Data

The ac electrical behavior of yttria doped with a zirconia concentration ranging from 0.15 to 20 mole % is investigated in the temperature range of 800 to 1300 °C. The ac electrical data, obtained in the range from 5 Hz to 13 MHz, indicated two distinct relaxations when analyzed in the impedance plane. These relaxations are attributed to lumped grains and trapping within grain boundaries, including possible electrode/sample effects. The admittance plane analysis revealed a semicircular relaxation in the low-frequency region, indicating identical response to that of the low-frequency relaxation of the impedance plane. The incorporation of zirconia into yttria is found to lower the activation energy of conduction in the grains and enhance ionic contribution to the overall electrical conduction. The PO2 studies and transference number measurements near atmospheric region indicate that p-type conduction dominates for the lightly doped yttria. An ionic contribution to the conduction processes becomes significant in heavily doped samples at/near atmospheric PO2.

Radio and Electrical Measurements on Glacial Streams

1987 ◽  
Vol 33 (114) ◽  
pp. 239-242
Author(s):  
M. E. R. Walford
Keyword(s):  
Electrical Conductivity ◽  
Water Channel ◽  
Water System ◽  
Low Frequency ◽  
Water Channels ◽  
Radiative Loss ◽  
Radio Waves ◽  
Electrical Measurements ◽  
Water Conductivity ◽  
Glacier Surface

AbstractWe discuss the suggestion that small underwater transmitters might be used to illuminate the interior of major englacial water channels with radio waves. Once launched, the radio waves would naturally tend to be guided along the channels until attenuated by absorption and by radiative loss. Receivers placed within the channels or at the glacier surface could be used to detect the signals. They would provide valuable information about the connectivity of the water system. The electrical conductivity of the water is of crucial importance. A surface stream on Storglaciären, in Sweden, was found, using a low-frequency technique, to have a conductivity of approximately 4 × 10−4 S m−1. Although this is several hundred times higher than the conductivity of the surrounding glacier ice, the contrast is not sufficient to permit us simply to use electrical conductivity measurements to establish the connectivity of englacial water channels. However, the water conductivity is sufficiently small that, under favourable circumstances, radio signals should be detectable after travelling as much as a few hundred metres along an englacial water channel. In a preliminary field experiment, we demonstrated semi quantitatively that radio waves do indeed propagate as expected, at least in surface streams. We conclude that under-water radio transmitters could be of real practical value in the study of the englacial water system, provided that sufficiently robust devices can be constructed. In a subglacial channel, however, we expect the radio range would be much smaller, the environment much harsher, and the technique of less practical value.

scholarly journals Broadband dielectric spectroscopy for monitoring temperature-dependent chloride ion motion in BiOCl plates

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Adrian Radoń ◽  
Dariusz Łukowiec ◽  
Patryk Włodarczyk
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Spectroscopy ◽  
Low Frequency ◽  
Chloride Ion ◽  
Ion Source ◽  
Chloride Ions ◽  
Ion Concentration ◽  
Broadband Dielectric Spectroscopy ◽  
Free Chloride ◽  
Structure Rebuilding

AbstractThe dielectric properties and electrical conduction mechanism of bismuth oxychloride (BiOCl) plates synthesized using chloramine-T as the chloride ion source were investigated. Thermally-activated structure rebuilding was monitored using broadband dielectric spectroscopy, which showed that the onset temperature of this process was 283 K. This rebuilding was related to the introduction of free chloride ions into [Bi2O2]2+ layers and their growth, which increased the intensity of the (101) diffraction peak. The electrical conductivity and dielectric permittivity were related to the movement of chloride ions between plates (in the low-frequency region), the interplanar motion of Cl− ions at higher frequencies, vibrations of these ions, and charge carrier hopping at frequencies above 10 kHz. The influence of the free chloride ion concentration on the electrical conductivity was also described. Structure rebuilding was associated with a lower concentration of free chloride ions, which significantly decreased the conductivity. According to the analysis, the BiOCl plate conductivity was related to the movement of Cl− ions, not electrons.

Low-Frequency Relaxation Phenomena in α-LiIO3: The Nature and Role of Defects

2002 ◽  
Vol 168 (1) ◽  
pp. 76-84 ◽  
Author(s):  
Y. Mugnier ◽  
C. Galez ◽  
J.M. Crettez ◽  
P. Bourson ◽  
C. Opagiste ◽  
...  
Keyword(s):  
Low Frequency ◽  
Relaxation Phenomena ◽  
Frequency Relaxation

Dynamics of Ferroelectric and Nematic Liquid Crystals Confined in Porous Matrices

1994 ◽  
Vol 366 ◽  
Author(s):  
Fouad M. Aliev
Keyword(s):  
Liquid Crystals ◽  
Heterogeneous Media ◽  
Volume Fraction ◽  
Low Frequency ◽  
Pore Wall ◽  
Polar Molecules ◽  
Average Pore ◽  
Surface Polarization ◽  
The Difference ◽  
Frequency Relaxation

ABSTRACTWe performed dielectric spectroscopy measurements to study dynamics of collective modes of ferroelectric (FLC) and molecular motion of nematic (NLC) liquid crystals with polar molecules confined in silica macroporous and microporous glasses with average pore sizes of 1000 Å (volume fraction of pores 40%) and 100 Å (27%) respectively. For FLC the Goldstone and the soft modes are found in macropores. The rotational viscosity associated with the soft mode is about 10 times higher in pores than in the bulk. These modes are not detected in micropores although low frequency relaxation is present. The last one probably is not connected with the nature of liquid crystal but is associated with surface polarization effects typical for two component heterogeneous media. The difference between the dynamics of orientational motion of the polar molecules of NLC in confined geometries and in the bulk is qualitatively determined by the total energy Fs of the interaction between molecules and the surface of the pore wall, which is found Fs ≈ 102erg/cm2.

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