DIELECTRIC RELAXATION OF SOME NEARLY SPHERICAL MOLECULES IN THE LIQUID AND SOLID PHASES

1967 ◽  
Vol 45 (12) ◽  
pp. 3815-3822 ◽  
Author(s):  
Abhai Mansingh ◽  
David B. McLay
Keyword(s):  
Dielectric Constant ◽  
Melting Point ◽  
Dielectric Relaxation ◽  
Solid Phase ◽  
Relaxation Times ◽  
Microwave Frequency ◽  
Debye Model ◽  
Index Of Refraction ◽  
Dielectric Relaxation Time ◽  
Rotator Phase

The dielectric constant and loss at a microwave frequency of 9 GHz and also the static dielectric constant at either 10 kHz or 200 kHz have been measured for the nearly spherical molecules Br3CNO2, Cl3CNO2, BrC(CH3)3, ClC(CH3)3, and ClSi(CH3)3 over a range of temperature from below the respective melting point to above this melting point. The measurements combined with the tabulated values for the optical index of refraction allow a determination of the dielectric relaxation times at each temperature if it is assumed that either the Debye theory or the modification of this theory by Cole and Cole is valid. In the cases of the five liquids, the data are consistent with the Debye model. In the solid phase, however, only Cl3CNO2 and ClSi(CH3)3 do not exhibit solid rotator phases, while each of the other three molecules exhibits at least one solid rotator phase. The results are consistent with the interpretation that each liquid has a single dielectric relaxation time but that the transition to a solid rotator phase involves a distribution of relaxation times which are only slightly different in value from the appropriate single value in the liquid phase.

Dielectric Relaxation Studies of Ternary Mixture of Dimethyl Phthalate and Heptanol in Benzene Solution in the Microwave Region

2015 ◽  
Vol 70 (7) ◽  
pp. 507-512
Author(s):  
A. Mushtaq Ahmed Khan ◽  
M. Subramanian
Keyword(s):  
Dielectric Constant ◽  
Dipole Moment ◽  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Benzene Solution ◽  
Microwave Frequency ◽  
Viscous Force ◽  
Dimethyl Phthalate ◽  
Flow Process ◽  
Relaxation Studies

AbstractThe molecular structure and molecular forces in liquids and solutions, in particular, have been investigated by dielectric relaxation studies. The nature and strength of the molecular interactions have been established as the main cause for the chemical behaviour of compounds. The dielectric behaviour of dimethyl phthalate with heptanol in benzene solution has been studied at a microwave frequency of 9.36 GHz at different temperatures 303, 308, and 313 K. Different dielectric quantities such as dielectric constant (ε′), dielectric loss (ε″), static dielectric constant (ε0), and dielectric constant at optical frequency (ε∞) have been determined. The relaxation time τ has been calculated by both Higasi’s method and Cole–Cole method. The dielectric relaxation process can be treated as a rate process just like the viscous flow process. The complex system investigated shows the maximum relaxation time values at high temperatures by both Higasi’s method and Cole–Cole method. The molar free energies of activation of dipole moment (ΔFτ) and viscous force (ΔFη) have also been reported. The excess dipole moment is also determined. The excess dipole moment is a qualitative index for the presence of a hydrogen bond in the ternary system. The value of Δμ obtained in our study indicates the presence of hydrogen bonds between the components of the mixture. The system investigated shows that the relaxation time value increases with the increase in the concentration of solute.

scholarly journals An Empirical Relation for the Evaluation of the Dielectric Relaxation Time of Certain Polar Liquids Using a Single Microwave Frequency

1974 ◽  
Vol 27 (1) ◽  
pp. 87 ◽  
Author(s):  
BS Sarma ◽  
V Venkateswara Rao
Keyword(s):  
Experimental Data ◽  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Concentration Factor ◽  
Empirical Relation ◽  
Microwave Frequency ◽  
Dielectric Constants ◽  
Dielectric Relaxation Time ◽  
Polar Liquids

An empirical relation is proposed for the determination of the dielectric relaxation time .. of polar liquids with nearly spherical molecules from measurements of the dielectric constants at a single microwave frequency. The relation is obtained by introducing a concentration factor as a parameter in the expression for .. derived by Eyring et al. (1941). Its validity for suitable polar liquids is demonstrated by comparison of results with previously reported values. Thermodynamic parameters for a number of liquids at various concentrations have also been evaluated from experimental data using the relation.

scholarly journals Dielectric Relaxation Studies Between Brompheniramine with 1-Butanol, 1-Pentanol and 1-Hexanol at 303K

2020 ◽  
Vol 17 (3) ◽  
pp. 230-235
Author(s):  
Sampandam Elangovan ◽  
Tilahun Diriba Garbi ◽  
Senbeto Kena Etana
Keyword(s):  
Dielectric Constant ◽  
Relaxation Time ◽  
Dielectric Relaxation ◽  
Intermolecular Interaction ◽  
Research Work ◽  
Liquid Mixtures ◽  
Time Domain Reflectometry ◽  
Dielectric Relaxation Time ◽  
Pharmaceutical Industries ◽  
Relaxation Studies

The dielectric relaxation studies are vital in analyzing the strength of the inter molecular interaction between the binary liquid systems [1-4]. Jyostna et al. [5] reported thermodynamic parameters of isoamyl alcohols and mono clinic aromatic liquid mixtures. Shakila et al. [6] studied the dielectric properties of aromatic alcohols and aliphatic amines at different temperatures. In general, dielectric relaxation time varies with the inter molecular forces acting between the molecules in the selected liquid mixtures. Brompheniramine is one of the critical compounds of an amine group with spectacular applications, including pharmaceutical industries [7]. Higher carbon chain length alcohols are having self associated and proton donating ability in the liquid mixtures. The variations in the dielectric constant (є’), dielectric loss (є’’), static dielectric constant (є0) and the dielectric constant at an optical frequency (є∞) with a range of brompheniramine concentrations with 1-butanol,1-pentanol and 1-hexanol systems are useful in the applied research and chemical industries. Moreover, the variations in the dielectric constant and dielectric relaxation time should be useful in the analysis of intermolecular interaction between the functional group of the selected liquid mixtures. This research work attempts to analyse the intermolecular interaction between the brompheniramine and 1-butanol,1-pentanol and 1-hexanol at 303K using time domain reflectometry techniques.

Correlation between the electron solvation time and the solvent dielectric relaxation times τ2 and τL1 in liquid alcohols and water: towards a universal concept of electron solvation?

1997 ◽  
Vol 75 (10) ◽  
pp. 1310-1314 ◽  
Author(s):  
Jean-Paul Jay-Gerin
Keyword(s):  
Relaxation Time ◽  
Simple Model ◽  
Dielectric Relaxation ◽  
Hybrid Model ◽  
Relaxation Times ◽  
Close Similarity ◽  
Dielectric Relaxation Time ◽  
Polar Liquids ◽  
Electron Solvation ◽  
Linear Alcohols

A simple model of electron solvation in polar liquids is presented, in which we attempt to link the electron solvation time τs to τ2, the time for reorientation of monomeric molecules, and to τL1, the longitudinal dielectric relaxation time of the solvent. It is shown that this model, which is suggested by the so-called hybrid model of electron solvation previously described for methanol, can satisfactorily account for electron solvation in all polar liquids, including linear alcohols (methanol to decanol), 1,2-ethanediol, H2O, and D2O, for which data are available from the literature. A close similarity is indeed obtained between our calculated values of τs and those measured experimentally. The observation of such a correlation supports a universal concept of electron solvation. Keywords: polar liquids, electron solvation time, solvent dielectric relaxation times, universal concept of electron solvation.

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.

scholarly journals Microwave Dielectric Study of Tetramethylurea andN, N-Dimethylacetamide Binary Mixture in Benzene

2011 ◽  
Vol 8 (3) ◽  
pp. 1378-1386
Author(s):  
V. Sharma ◽  
N. Thakur
Keyword(s):  
Dielectric Constant ◽  
Binary Mixture ◽  
Dielectric Relaxation ◽  
Benzene Solution ◽  
Microwave Frequency ◽  
Single Frequency ◽  
Rate Theory ◽  
Dielectric Study ◽  
Frequency Method ◽  
Dielectric Parameters

Dielectric relaxation of the binary mixture of tetramethylurea andN, N-dimethylacetamide has been studied at fixed frequency and temperature (9.88 GHz & 298 K respectively) in benzene solution. Different dielectric parameters like the dielectric constant (ε') and the dielectric loss (ε") at microwave frequency, static dielectric constant (ε0) and dielectric constant (ε∞) at optical frequency were determined. The values of relaxation time (τ(1), τ(2), τ(0)& τGK) have been calculated using higasi’s single frequency method and Gopala Krishna’s method. Using Eyring’s rate theory, the activation energies for the process of dielectric relaxation and viscous flow were calculated and compared. The study of dielectric properties of the binary mixture reveals the existence of the solute-solute type of molecular associations.

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.

scholarly journals Dynamics and Pretransitional Effects in C60 Fullerene Nanoparticles and Liquid Crystalline Dodecylcyanobiphenyl (12CB) Hybrid System

Nanomaterials ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 2343
Author(s):  
Sylwester J. Rzoska ◽  
Szymon Starzonek ◽  
Joanna Łoś ◽  
Aleksandra Drozd-Rzoska ◽  
Samo Kralj
Keyword(s):  
Dielectric Constant ◽  
Liquid Crystalline ◽  
Complex Dynamics ◽  
Solid Phase ◽  
Relaxation Times ◽  
C60 Fullerene ◽  
Strong Impact ◽  
Isotropic Liquid ◽  
Critical Relation ◽  
The Impact

The report shows the strong impact of fullerene C60 nanoparticles on phase transitions and complex dynamics of rod-like liquid crystal dodecylcyanobiphenyl (12CB), within the limit of small concentrations. Studies were carried out using broadband dielectric spectroscopy (BDS) via the analysis of temperature dependences of the dielectric constant, the maximum of the primary loss curve, and relaxation times. They revealed a strong impact of nanoparticles, leading to a ~20% change of dielectric constant even at x = 0.05% of C60 fullerene. The application of the derivative-based and distortion-sensitive analysis showed that pretransitional effects dominate in the isotropic liquid phase up to 65 K above the clearing temperature and in the whole Smectic A mesophase. The impact of nanoparticles on the pretransitional anomaly appearance is notable for the smectic–solid phase transition. The fragility-based analysis of relaxation times revealed the universal pattern of its temperature changes, associated with scaling via the “mixed” (“activated” and “critical”) relation. Phase behavior and dynamics of tested systems are discussed within the extended Landau–de Gennes–Ginzburg mesoscopic approach.

Sign in / Sign up

Export Citation Format

Share Document