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.

Dielectric Relaxation of Bromoalkanes in Cyclohexane Solution

1972 ◽  
Vol 50 (13) ◽  
pp. 2031-2034 ◽  
Author(s):  
Sing Pin Tay ◽  
John Crossley
Keyword(s):  
Dielectric Constant ◽  
Dielectric Relaxation ◽  
Dipole Moments ◽  
Relaxation Times ◽  
Dielectric Constant And Loss ◽  
Distribution Parameters

Mean relaxation times, Cole–Cole distribution parameters and apparent dipole moments, obtained from dielectric constant and loss measurements at 2 MHz and 1.5, 2.0, 2.5, 9.3, 16, 24, 35, 70, and 145 GHz, are reported for 1-, 2-, and 4-bromooctane, 1-bromodecane, 1-bromododecane, 1-bromohexadecane, 1-bromooctadecane, and 1,10-dibromodecane in cyclohexane solution at 25 °C.

Dielectric studies. Part XIX. Molecular relaxation of some rigid molecules

1968 ◽  
Vol 46 (12) ◽  
pp. 2181-2185 ◽  
Author(s):  
J. Crossley ◽  
W. F. Hassell ◽  
S. Walker
Keyword(s):  
Dipole Moments ◽  
Relaxation Times ◽  
Major Axis ◽  
Distribution Coefficients ◽  
Solvent Interactions ◽  
Zero Distribution ◽  
Nonpolar Solvents ◽  
Dielectric Absorption ◽  
Local Environments ◽  
Distribution Parameters

The dielectric absorption at five microwave frequencies of solutions of seven rigid polar molecules in nonpolar solvents has been examined as also has cyclohexanone. Furan, pyridine, and thiophene have their dipole moments along the major axis and their dielectric absorption should be characterized by a single relaxation time. Unlike the monohalobenzenes, camphor, pentamethylene sulfide, tetrahydropyran, and s-trioxan, however, furan, pyridine, and thiophene have non-zero distribution coefficients at 25 °C, whereas for pyridine at 50 °C and cyclohexanone at 25 °C the value is zero. The non-zero distribution coefficients are to be related to either weak solute-solute or solute-solvent interactions, resulting in the polar molecule experiencing a variety of local environments. The observed relaxation times of furan, pyridine, and thiophene are comparable with those of other rigid molecules of similar shape and size. For such cases, even though the distribution parameters are not zero, it is not feasible to analyze the dielectric data into contributions from more than one relaxation process.

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.

Relaxation processes of quinoline, isoquinoline, and their mixtures

1980 ◽  
Vol 58 (1) ◽  
pp. 20-24 ◽  
Author(s):  
M. P. Madan
Keyword(s):  
Thermodynamic Parameters ◽  
Molecular Motion ◽  
Polar Solvent ◽  
Relaxation Times ◽  
Relaxation Processes ◽  
Polar Components ◽  
Dielectric Absorption ◽  
System A ◽  
Dielectric Data ◽  
Activated State

The dielectric absorption of quinoline, isoquinoline, and their binary mixtures has been studied in the microwave region over a range of temperatures in dilute benzene and n-heptane solutions. The relaxation times and the thermodynamic parameters for the activated state have been determined using the measured dielectric data. The results obtained have been discussed in terms of the molecular motion of the system. A relation has been proposed to represent the relaxation behavior of a system of two Debye-type polar components in a non-polar solvent. The relation has been tested by comparing the calculated values with those determined experimentally for a few systems consisting of similar, simple rigid polar molecules.

Dielectric loss measurements for Bis(pentane-2,4-dionato)oxovanadium(IV) in benzene and dioxan

1975 ◽  
Vol 28 (5) ◽  
pp. 1137 ◽  
Author(s):  
MJ Aroney ◽  
RL Angel
Keyword(s):  
Dielectric Loss ◽  
Complex Formation ◽  
Dielectric Relaxation ◽  
Dipole Moments ◽  
Relaxation Times

Dipole moments and dielectric relaxation times determined by dielectric loss measurements are reported for bis(pentane-2,4- dionato)oxovanadium(IV) as a solute in benzene and in dioxan. Evidence is presented for VO(acac)2,dioxan complex formation.

scholarly journals Квазистационарные процессы диэлектрической релаксации в тонких поликристаллических пленках PZT

2020 ◽  
Vol 62 (10) ◽  
pp. 1665
Author(s):  
В.В. Иванов ◽  
Е.Н. Голубева ◽  
О.Н. Сергеева ◽  
Г.М. Некрасова ◽  
И.П. Пронин ◽  
...  
Keyword(s):  
Electric Field ◽  
Dielectric Relaxation ◽  
External Electric Field ◽  
Annealing Temperature ◽  
Relaxation Times ◽  
Polarization Vector ◽  
Silicon Substrates ◽  
Relaxation Processes ◽  
Pzt Films

In this work, relaxation processes in polycrystalline PZT films formed on silicon substrates with a quasistatic change in the external electric field are studied. It is shown that dielectric relaxation is characterized by at least three relaxation times, which depend on the direction of self-polarization vector in the film, the magnitude of the polarizing field, and also on the annealing temperature of the PZT films.

ChemInform Abstract: APPARENT DIPOLE MOMENTS AND DIELECTRIC RELAXATION TIMES OF 1,4-BENZOQUINONE AND ITS DERIVATIVES IN SOLUTIONS

1975 ◽  
Vol 6 (8) ◽  
pp. no-no
Author(s):  
TOHRU NAGAI ◽  
HIROAKI TAKAHASHI ◽  
KENITI HIGASI ◽  
LESLIE E. SUTTON ◽  
DAVID WADDINGTON
Keyword(s):  
Dielectric Relaxation ◽  
Dipole Moments ◽  
Relaxation Times
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