Dielectric relaxation of lithium and sodium perchlorates in 1,2-dimethoxyethane and propylene carbonate

1981 ◽  
Vol 59 (7) ◽  
pp. 1051-1060 ◽  
Author(s):  
Hubert Cachet ◽  
Mohamed Fekir ◽  
Jean-Claude Lestrade
Keyword(s):  
Dielectric Properties ◽  
Ethyl Acetate ◽  
Dielectric Relaxation ◽  
Propylene Carbonate ◽  
Complex Permittivity ◽  
Ion Pairs ◽  
Conductivity Measurements ◽  
Frequency Range ◽  
Dielectric Data

The complex permittivity of LiClO4 and NaClO4 solutions in 1,2-dimethoxyethane (DME) has been measured in the frequency range 0.140–123.2 GHz. The data have been analysed according to a model for the reorientation of ion pairs given in a previous paper. The dielectric data are supplemented by conductivity measurements in a broad concentration range (10−4–1 mol/L) which evidence the large extent of salt association. The main result is that the solvation of Li+ and Na+ by DME cannot be described as simply as in the case of other solvents, such as tetrahydrofuran or ethyl acetate, as far as the dielectric properties are concerned: while the assumption of rigidly bound solvating molecules was acceptable for the latter solvents, some freedom in the reorientation of these molecules has to be taken into account for the case of DME. LiClO4 solutions in propylene carbonate (PC) + benzene and PC + DME mixtures have also been studied. The data, for the latter, can be qualitatively interpreted under the assumption that PC molecules take the place of DME molecules in the solvation sheath, even at low PC concentration.

scholarly journals A.C conductivity and dielectric properties of (PVA/ PEO) blends doped with MWCNTs

2019 ◽  
Vol 14 (30) ◽  
pp. 64-72
Author(s):  
Ahmad A. Hasan
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Properties ◽  
The Other ◽  
Poly Vinyl Alcohol ◽  
Conductivity Measurements ◽  
Frequency Range ◽  
Maximum Value ◽  
Multi Walled Carbon Nanotube ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene

A.C electrical conductivity and dielectric properties for poly(vinyl alcohol) (PVA) /poly (ethylene oxide) (PEO) blends undopedand doped with multi-walled carbon nanotube (MWCNTs) withdifferent concentrations (1, and 3 wt %) in the frequency range(25x103 - 5x106 Hz) were investigated. Samples of (PVA/PEO)blends undoped and doped with MWCNTs were prepared usingcasting technique. The electrical conductivity measurements showedthat σA.C is frequency dependent and obey the relation σA.C =Aωs forundoped and doped blends with 1% MWCNTs, while it is frequencyindependent with increases of MWCNTs content to 3%. Theexponent s showed proceeding increase with the increase of PEOratio (≥50%) for undoped blends samples, while s value for dopedblends exhibits to change in different manner, i.e. s increases andreach maximum value at 50/50 PVA/PEO, then decreases forresidual doped blends samples with 1% MWCNTs on the other handthe exponent s decrease and reach minimum value at 50/50PVA/PEO for samples doped with 3% MWCNTs, then return toincrease. The results explained in different terms.

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.

AN INVESTIGATION ON THE DIELECTRIC PROPERTIES OF POLYANILINE-BASED NANOCOMPOSITE

2010 ◽  
Vol 24 (15) ◽  
pp. 1669-1674
Author(s):  
J. JIANG ◽  
L. H. AI
Keyword(s):  
Dielectric Properties ◽  
Imaginary Part ◽  
Complex Permittivity ◽  
Room Temperature ◽  
In Situ Polymerization ◽  
Dissipation Factor ◽  
Frequency Range ◽  
The Real ◽  
Tan Δ

Polyaniline/ LiNi 0.5 Gd 0.08 Fe 1.92 O 4 nanocomposite was synthesized by an in-situ polymerization of aniline in the presence of LiNi 0.5 Gd 0.08 Fe 1.92 O 4 particles. The dielectric properties of the as-prepared polyaniline-based nanocomposite were investigated using an Agilent E4991A RF Impedance/Material Analyzer at room temperature in the frequency range from 1 MHz to 1 GHz. The real (ε') and imaginary part (ε″) of complex permittivity, and dissipation factor ( tan δ) were found to be frequency-dependent, which decreased with increasing of frequency. It was shown that ε', ε″ and tan δ of the nanocomposite were lower than those of pristine polyaniline. In order to investigate the dielectric process in detail, the complex electric modulii derived from the complex permittivity were analyzed as a function of the frequency.

Dielectric relaxation of nonionic microemulsion: influence of the salinity

2001 ◽  
Vol 79 (1) ◽  
pp. 49-58
Author(s):  
G Delbos ◽  
M Keita ◽  
T K Bose
Keyword(s):  
Dielectric Properties ◽  
Dielectric Relaxation ◽  
Relaxation Frequency ◽  
The Other ◽  
Spectral Amplitude ◽  
Microemulsion System ◽  
Frequency Range ◽  
Amplitude Increase ◽  
Nacl Concentration ◽  
Main Relaxation

Study of dielectric properties of a quaternary microemulsion system composed of water, oil, a nonionic surfactant, and an alcohol, in the frequency range 100 kHz – 15 GHz is reported as a function of salt (NaCl) concentration. Depending on the salinity, the decomposition of the dielectric spectra shows the presence of two or three main relaxation domains. The lower relaxation frequency and the corresponding spectral amplitude increase as a function of salinity. The other observed relaxation mechanisms are shown to be dipolar in origin.PACS No.: 97.22Gn

Dynamics of Benzonitrile, Propylene Carbonate and Butylene Carbonate: the Influence of Molecular Shape and Flexibility on the Dielectric Relaxation Behaviour of Dipolar Aprotic Liquids

2000 ◽  
Vol 214 (9) ◽  
Author(s):  
J. Barthel ◽  
R. Buchner ◽  
Ch.G. Hölzl ◽  
M. Münsterer
Keyword(s):  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Propylene Carbonate ◽  
Molecular Shape ◽  
Relaxation Processes ◽  
Relaxation Behaviour ◽  
Frequency Range ◽  
Relaxation Experiments

The results of dielectric relaxation experiments on benzonitrile, propylene carbonate and butylene carbonate, performed between 228.15 K and 338.15 K in the frequency range 0.1 ≤ ν /GHz ≤ 89 are presented. The spectra of the three liquids can be formally fitted with two relaxation processes. The long relaxation time, τ

Dielectric Relaxation in Binary and Ternary Mixtures of Ethanol, Water, and Benzene or n-Hexane

1985 ◽  
Vol 40 (6) ◽  
pp. 588-595 ◽  
Author(s):  
H. Utzel ◽  
M. Stockhausen
Keyword(s):  
Dielectric Relaxation ◽  
Complex Permittivity ◽  
Lower Order ◽  
Ternary Mixtures ◽  
Main Term ◽  
Frequency Range ◽  
Binary And Ternary Mixtures ◽  
Partially Miscible ◽  
Free Molecules

The complex permittivity of the partially miscible systems ethanol-water-benzene and ethanol-water- n-hexane has been measured in the frequency range from 20 MHz to 36 GHz at 20 °C. The results are described as superposition of Debye-terms, which are considered as physically significant and are ascribed to (i) higher, ill-defined, fluctuating self- and hetero-associates (main term), (ii) associates of lower order, relaxing by rotational tumbling, (iii) free molecules. The demultimerization by benzene appears to be more effective than by hexane.

DIELECTRIC PROPERTIES OF POLYVINYL ACETALS

1952 ◽  
Vol 30 (12) ◽  
pp. 940-947 ◽  
Author(s):  
B. L. Funt ◽  
T. H. Sutherland
Keyword(s):  
Dielectric Properties ◽  
Electrical Properties ◽  
Dielectric Relaxation ◽  
Relaxation Times ◽  
Dielectric Dispersion ◽  
Transition Temperatures ◽  
Free Energies ◽  
Frequency Range ◽  
Physical Picture ◽  
Electrical Relaxation

Measurements of dielectric dispersion in vinyl acetal and formal polymers were performed over the frequency range 0.050 to 100 kc. at temperatures between 25 and 135 °C. The results reflect the effects of internal plasticization on the electrical properties of the polymers. With increasing size of the substituent groups from formal to butyral the dispersion range is shifted to lower temperatures at a given frequency. Electrical relaxation times and transition temperatures were obtained and values of enthalpies, free energies, and entropies of activation were calculated. A tentative physical picture of the mechanism of dielectric relaxation in these polymers was also formulated.

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.

scholarly journals Influence of Radiation on the Dielectric Properties of XLPE Based Insulation Systems

2010 ◽  
Vol 61 (4) ◽  
pp. 229-234 ◽  
Author(s):  
Vladimír Ďurman ◽  
Jaroslav Lelák
Keyword(s):  
Dielectric Properties ◽  
Structural Changes ◽  
Low Frequency ◽  
Absorbed Dose ◽  
Frequency Range ◽  
Impedance Measurements ◽  
Motion Data ◽  
Dielectric Data ◽  
Insulation Systems ◽  
The Cross

Influence of Radiation on the Dielectric Properties of XLPE Based Insulation SystemsThe paper discusses the possibilities of acquiring and processing the dielectric data in the range of very low frequency (VLF) and also design and construction of an impedance analyzer for measurements in this frequency range. The impedance measurements in the VLF range were used for investigation of the influence of radiation on the cross-linked polyethylene cable dielectric. An expressive β-type relaxation process was found in this type of cable. Most of the dielectric response parameters of the process depend significantly on the absorbed dose of radiation. The analysis of the process parameters showed that the most probable reason of the structural changes in cross-linked polyethylene was additional cross-linking. The results also proved that the impedance measurements in the VLF range could be effectively used in practice for estimation of the absorbed dose in the cross-linked polyethylene cables stressed by radiation.t data only. In order to identify or classify motion, data processing in real time is needed.

The Dielectric Relaxation of Water on Addition of Ethylene Carbonate and some Related Substances

1989 ◽  
Vol 44 (1) ◽  
pp. 56-58
Author(s):  
M. Stockhausen ◽  
A. Lux
Keyword(s):  
Dielectric Properties ◽  
Aqueous Solutions ◽  
Dielectric Relaxation ◽  
Propylene Carbonate ◽  
Ethylene Carbonate ◽  
Related Substances ◽  
Hydration Model

Abstract The dynamic dielectric properties of diluted aqueous solutions of propylene carbonate, ethylene carbonate (EC). 4-butyrolactone and cyclohexanone (CH) have been measured at 20 °C. On assuming normal solute relaxation, the water relaxation can be described by two superimposed Debye type contributions, which may be interpreted in terms of a hydration model. Qualitatively, the influence on the water relaxation increases from EC to CH.

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