Dielectric relaxation studies. III. Allyl bromide and allyl ethers in liquid state

1981 ◽  
Vol 59 (11) ◽  
pp. 1690-1695
Author(s):  
M. Jeyaraj ◽  
J. Sobhanadri
Keyword(s):  
Dielectric Relaxation ◽  
Allyl Bromide ◽  
Relaxation Times ◽  
Activation Parameters ◽  
Relaxation Mechanism ◽  
Microwave Frequencies ◽  
Allyl Ethers ◽  
Dielectric Data ◽  
Permittivity Measurements ◽  
Allyl Compounds

Complex dielectric permittivity measurements are reported at radio and microwave frequencies for four allyl compounds in the temperature range 30–70 °C. The analysis of dielectric data in terms of Cole–Cole arc, multiple relaxation times, and Higasi's distribution function reveals that the overall molecular rotation is the dominant relaxation mechanism in these unsaturated compounds. The activation parameters are evaluated assuming dielectric relaxation to be a rate process.

Dielectric relaxation of some aliphatic ester molecules in solutions

1979 ◽  
Vol 57 (7) ◽  
pp. 1035-1038 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Relaxation Times ◽  
Activation Parameters ◽  
Dielectric Absorption ◽  
Aliphatic Ketones ◽  
Dielectric Data ◽  
Aliphatic Ester ◽  
Aliphatic Esters ◽  
Intramolecular Rotation

The dielectric absorption of several aliphatic esters has been examined in the microwave region over a range of temperatures in n-heptane, cyclohexane, and benzene. The relaxation times and the thermodynamic parameters have been determined using the measured dielectric data. The values of the relaxation time for those solutions for which there are available known data agree well with other determinations. The relaxation times and the various molar activation parameters have been discussed in terms of dipole reorientation by molecular and intramolecular rotation. It would appear that the relaxation behavior of aliphatic esters is similar to that for other aliphatic molecules, such as aliphatic ketones studied previously.

Relaxation processes of some simple aliphatic molecules in dilute solutions

1977 ◽  
Vol 55 (4) ◽  
pp. 297-301 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Carbon Tetrachloride ◽  
Dielectric Relaxation ◽  
Thermodynamic Parameters ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Dilute Solutions ◽  
Microwave Region ◽  
Nonpolar Solvents ◽  
Dielectric Data ◽  
Intramolecular Rotation

The dielectric relaxation processes of acetone, cyclohexanone, 4-methyl-2-pentanone, and 4-heptanone in dilute nonpolar solvents, n-heptane, cyclohexane, benzene, and carbon tetrachloride have been studied in the microwave region over a temperature range 10 to 60 °C. The relaxation times and the thermodynamic parameters for the activated states have been determined using the measured dielectric data. The results have been discussed in terms of dipole reorientation by molecular and intramolecular rotation and compared, wherever possible, with other similar studies on aliphatic molecules.

The dielectric relaxation of some diols in p-dioxane solution

1978 ◽  
Vol 56 (3) ◽  
pp. 352-354 ◽  
Author(s):  
J. Crossley
Keyword(s):  
Dielectric Constant ◽  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Alkyl Group ◽  
Relaxation Times ◽  
Dielectric Dispersion ◽  
Dioxane Solution ◽  
Microwave Frequencies ◽  
Dielectric Absorption ◽  
Dielectric Constant And Loss

Dielectric constant and loss data at up to nine microwave frequencies have been obtained for 1-butanol, 1,4-butanediol, 1,7-heptanediol, 1,8-octanediol, 1,10-decanediol, and 1,12-do-decanediol at 25 °C, and for 1,6-hexanediol at 15, 25, 40, and 55 °C, in p-dioxane. In each case the dielectric dispersion is adequately described by a Cole-Cole distribution. The relaxation times for the diols are almost independent of the length of the alkyl group. An intramolecular relaxation process appears to be primarily responsible for the dielectric absorption.

Dielectric Relaxation Studies of Mixtures of N-Methylacetamide and Ethanol in Benzene Solutions Using Microwave Absorption Technique

2007 ◽  
Vol 62 (3-4) ◽  
pp. 213-217 ◽  
Author(s):  
Raman Kumar ◽  
Vir Singh Rangra ◽  
Dhani Ram Sharma ◽  
Nagesh Thakur ◽  
Nainjeet Singh Negi
Keyword(s):  
Dielectric Relaxation ◽  
Relaxation Process ◽  
Binary Mixtures ◽  
Benzene Solution ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Activation Parameters ◽  
Single Frequency ◽  
Dielectric Relaxation Process ◽  
Free Energy Of Activation

Using standard standing wave microwave X-band techniques, and by following Gopala Krishna’s single frequency (9.90 GHz) concentration variational method, the dielectric relaxation times (τ) and dipole moments (μ) of binary mixtures of different molar concentrations of ethanol (EtOH) in binary mixtures of N-methylacetamide (NMA) and ethanol in benzene solutions at 25, 30, 35 and 40 ◦C have been calculated. The activation parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process of binary mixtures containing 30 mol% of EtOH have been calculated at 25, 30, 35 and 40 ◦C and compared with the corresponding viscosity parameters. A good agreement between the free energy of activation from these two sets of values shows that the dielectric relaxation process, like the viscous flow, can be treated as a rate process. From relaxation time behaviour of NMA and EtOH binary mixtures in benzene solution, solute-solute and solute-solvent types of the molecular association have been predicted.

Dielectric relaxation of acetyl- and benzoyl-acetones

1989 ◽  
Vol 67 (5) ◽  
pp. 804-808 ◽  
Author(s):  
R. K. Khanna ◽  
Abha Bhatnagar
Keyword(s):  
Dielectric Relaxation ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Weight Fraction ◽  
Relaxation Mechanism ◽  
Relaxation Processes ◽  
Dielectric Absorption ◽  
Molar Polarization ◽  
Distribution Parameters ◽  
Few Data

Dielectric absorption measurements are reported at radio and microwave frequencies (at six different wavelengths) for acetylacetone and benzoylacetone solutions in benzene, in a temperature range 25–60 °C. Analysis of dielectric data in terms of Cole–Cole arc plots and multiple relaxation processes reveals that, at higher temperatures, overall molecular relaxation is the dominant relaxation mechanism in these β-diketones. The observed relaxation times, distribution parameters, and dipole moments are in reasonable agreement with the few data reported for some temperatures, in the literature. The activation energy parameters are also evaluated assuming dielectric relaxation to be a rate process. Molar polarization vs. weight fraction (concentration) plots show anomalous behaviour for acetylacetone. Keywords: dielectric properties, dielectric losses, relaxation times, dipole moment, dielectric absorption and dispersion, microwave measurements.

scholarly journals AC – Conductivity Study of CdSe Nanorods

2018 ◽  
Vol 2 (1) ◽  
Keyword(s):  
Dielectric Relaxation ◽  
Relaxation Times ◽  
Complex Impedance ◽  
Relaxation Mechanism ◽  
Electrical Equivalent Circuit ◽  
Chemical Route ◽  
Polaron Hopping ◽  
Transmission Electron ◽  
Complex Impedance Plane Plot ◽  
Cole Model

The nanorods of cadmium selenide (CdSe) have been synthesized by soft chemical route using mercapto ethanol as a capping agent. The sample forms a rod like shape, confirmed by transmission electron microscope (TEM) measurement. Impedance spectroscopy is applied to investigate the dielectric relaxation of the sample at a various temperature region with varying frequency range. Grain and grain boundary effects both are present in the complex impedance plane plot and is analyzed by an electrical equivalent circuit consisting of a resistance and a constantphase element. Dielectric relaxation mechanism shows peak positions in the imaginary parts of the spectra and that is analyzed by Cole–Cole model. The temperature-dependent relaxation times obeys Arrhenius law having activation energy of 0.391 eV, which indicates that polaron hopping is responsible for conduction or dielectric relaxation in this material. The presence of two plateaus in the frequency-dependent conductivity spectra follows double-power law

Dielectric Relaxation of Alkyl Acetates in Aromatic and Aliphatic Solvents at Microwave Frequencies

1972 ◽  
Vol 50 (13) ◽  
pp. 1449-1452 ◽  
Author(s):  
G. P. Srivastava ◽  
P. C. Mathur ◽  
Mrs. Krishna
Keyword(s):  
Dielectric Relaxation ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Strong Interactions ◽  
Dielectric Relaxation Time ◽  
Methyl Ethyl ◽  
Microwave Frequencies ◽  
Aromatic Solvents ◽  
Nonpolar Solvents ◽  
Alkyl Acetates

The dielectric relaxation times and the dipole moments of methyl, ethyl, and amyl acetates are measured in six nonpolar solvents having different viscosities. The dielectric relaxation time is found to increase with the chain length in each nonpolar solvent. The relaxation times in aromatic solvents (benzene and p-xylene) are found to be higher than in carbon tetrachloride, even though the viscosity of the latter is more than that of the aromatic solvents This shows that the dielectric relaxation is not only due to the viscous resistance of the solvent but is also influenced by strong interactions between aromatic solvents and solute molecules.

Frequency Dependent Dielectric Permittivity Studies in Emeraldine Base and Weakly Doped Polyaniline and its Deriviatives

1999 ◽  
Vol 598 ◽  
Author(s):  
Nicholas J. Pintoa ◽  
Ghanshyam P. Sinha ◽  
Fouad M. Aliev
Keyword(s):  
Dielectric Permittivity ◽  
Dielectric Relaxation ◽  
Doping Level ◽  
Relaxation Times ◽  
Relaxation Mechanism ◽  
Emeraldine Base ◽  
Three Samples ◽  
Multiple Paths ◽  
Doped Polyaniline ◽  
Subsequent Diffusion

ABSTRACTWe report on a study of the complex dielectric permittivity in polyaniline (PAN), poly-o-toluidine (POT) and poly-o-ethylaniline (OPEA) in the undoped and weakly doped state in the frequency range 1 mHz upto 1 MHz. The doping concentration defined as y=[C1-]/[N] was chosen so that 0 ≤ y ≤ 0.07. OPEA with y=0.50 was also investigated. The objective of this work was to investigate the contribution of the mobile charge defects (polarons and bipolarons) on the conductivity and dielectric relaxation at such low doping levels. The three samples were chosen so as to compare the effects of introducing larger interchain disorder while maintaining a similar conduction mechanism. In all samples studied we observe the presence of a dielectric relaxation mechanism and the relaxation times depend on the doping level and disorder. The presence of a larger number of polarons as the doping level is increased leads to multiple paths for the system to relax leading to progressively non Debye like relaxation process. The results are interpreted in terms of creation and annihilation of polarons and bipolarons and their subsequent diffusion.

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