Dielectric Relaxation of Mixtures of N-Methylacetamide and N,N-Dimethylformamide Solved in Benzene Using Microwave Absorption Data

The dielectric relaxation times τ and dipole moments μ of N-methylacetamide (NMA) mixed with N,N-dimethylformamide (DMF) in benzene solutions have been obtained using standard standing wave microwave techniques and Gopala Krishna’s single frequency (9.90 GHz) concentration variational method at 25, 30, 35, and 40 ◦C. The energy parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process of mixtures with equal amounts of NMA and DMF have been calculated and compared with the corresponding energy parameters (ΔHη , ΔFη , ΔSη ) for the viscous flow. On the basis of the observations it is found that the dielectric relaxation process can be treated as a rate process like the viscous flow. Solute-solute and solute-solvent types of the molecular associations have been predicted

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Dielectric Relaxation Studies of Binary Mixtures of N-Methylformamide and Tetramethylurea in Benzene Using Microwave Absorption Data

Zeitschrift für Naturforschung A ◽

10.1515/zna-2008-3-419 ◽

2008 ◽

Vol 63 (3-4) ◽

pp. 230-236

Author(s):

Rajesh Kumar ◽

Nagesh Thakur

Keyword(s):

Dielectric Relaxation ◽

Viscous Flow ◽

Relaxation Process ◽

Binary Mixtures ◽

Single Frequency ◽

Dielectric Relaxation Time ◽

Absorption Data ◽

Flow Process ◽

Dielectric Relaxation Process ◽

Energy Parameters

The dielectric relaxation time (τ ) and dipole moment (μ) of binary mixtures of different molar concentrations of N-methylformamide (NMF) in binary mixtures of NMF and tetramethylurea (TMU) in benzene have been calculated at 25, 30, 35 and 40 ◦C using standard standing wave microwave techniques and following the single frequency (9.885 GHz) concentration variational method of Gopala Krishna. The energy parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process of binary mixtures containing 30 mol% of NMF have been calculated at different temperatures, and comparison has been made with the corresponding energy parameters (ΔHη , ΔFη , ΔSη ) for the viscous flow process. Based on these studies, it was inferred that the dielectric relaxation process can be treated as a rate process just like the viscous flow process. Solute-solvent and solute-solute molecular associations have been proposed.

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

Zeitschrift für Naturforschung A ◽

10.1515/zna-2007-3-415 ◽

2007 ◽

Vol 62 (3-4) ◽

pp. 213-217 ◽

Cited By ~ 1

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.

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Dielectric Relaxation Studies of Binary Mixtures of Ethanol and Chlorobenzene in Benzene Solution from Microwave Absorption Data

Zeitschrift für Naturforschung A ◽

10.1515/zna-2008-1-216 ◽

2008 ◽

Vol 63 (1-2) ◽

pp. 93-97 ◽

Cited By ~ 3

Author(s):

Vimal Sharma ◽

Nagesh Thakur

Keyword(s):

Dielectric Relaxation ◽

Viscous Flow ◽

Relaxation Process ◽

Binary Mixtures ◽

Benzene Solution ◽

Single Frequency ◽

Variation Method ◽

Dielectric Relaxation Time ◽

Dielectric Relaxation Process ◽

Energy Parameters

Dielectric relaxation of different molar concentrations of ethanol (C2H5OH) in binary mixtures of ethanol and chlorobenzene in benzene solutions has been studied at 9.883 GHz by using standard standing microwave techniques and Gopala Krishna’s single frequency concentration variation method at different temperatures (25 °C, 30 °C, 35 °C, and 40 °C). It was found that the dielectric relaxation time varies linearly with variation in the molar concentration of ethanol in the whole concentration range of the binary mixture. Based upon these results the absence of solute-solute and the presence of solute-solvent type of molecular associations could be assumed. The energy parameters for the dielectric relaxation process of binary mixtures containing 50 mol% of ethanol have been calculated at the given temperatures. Comparison has been made with the corresponding energy parameters for viscous flow processes. It was found that the dielectric relaxation process can be treated as the rate process like the viscous flow process.

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Dielectric Relaxation Study of Ethanol in Benzene from Microwave Absorption Data

Zeitschrift für Naturforschung A ◽

10.1515/zna-2007-7-809 ◽

2007 ◽

Vol 62 (7-8) ◽

pp. 406-408 ◽

Cited By ~ 1

Author(s):

Vimal Sharma ◽

Nagesh Thakur ◽

Dhani Ram Sharma ◽

Nainjeet Singh Negi ◽

Vir Singh Rangra

Keyword(s):

Dielectric Relaxation ◽

Viscous Flow ◽

Relaxation Process ◽

Benzene Solution ◽

Single Frequency ◽

Variation Method ◽

Dielectric Relaxation Time ◽

Absorption Data ◽

Flow Process ◽

Energy Parameters

The dielectric constant (ε’) and dielectric loss (ε″) of dilute solutions of ethanol in benzene havebeen measured at 9.883 GHz at 25, 30, 35 and 40 °C using standard microwave techniques. Thedielectric relaxation time (τ) and dipole moment (μ) at 25, 30, 35 and 40 °C have been calculated byusing the single frequency concentration variation method suggested by Gopala Krishna. It is foundthat the dielectric relaxation process can be treated as a rate process like the viscous flow process. Amonomer structure of C2H5OH in benzene solution has been inferred. Based upon these studies, thepresence of solute-solvent associations has been proposed. The energy parameters for the dielectricrelaxation process have been calculated and compared with the corresponding energy parameters ofviscous flow.

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Molecular Association of Tetramethylurea and Chlorobenzene Molecules in Microwave Frequency Range

Zeitschrift für Naturforschung A ◽

10.1515/zna-2010-1012 ◽

2010 ◽

Vol 65 (10) ◽

pp. 854-858

Author(s):

Vimal Sharma ◽

Nagesh Thakur

Keyword(s):

Relaxation Time ◽

Dielectric Relaxation ◽

Viscous Flow ◽

Relaxation Process ◽

Binary Mixtures ◽

Variation Method ◽

Dielectric Relaxation Time ◽

Flow Process ◽

Dielectric Relaxation Process ◽

Energy Parameters

The dielectric constant ε´ and dielectric loss ε´´ of the binary mixtures of tetramethylurea (TMU) and chlorobenzene (CB) have been calculated at 9.883 GHz by using standard standing microwave techniques. Gopalakrishna’s single frequency concentration variation method has been used to calculate dipole moment μ and dielectric relaxation time τ for different mole fractions of TMU in the binary mixture at different temperatures of 25 °C, 30 °C, 35 °C, and 40 °C. The variation of dielectric relaxation time with the mole fraction of TMU in the whole concentration range of the binary mixtures was found to be non-monotonic. The solute-solute and solute-solvent type of molecular associations may be proposed based upon above observations. Using Eyring rate equations the energy parameters ΔH, ΔF, and ΔS for the dielectric relaxation process and the viscous flow process have been calculated at the given temperatures. It is found from the comparison of energy parameters that, just like the viscous flow process, the dielectric relaxation process can also be treated as a rate process.

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Dielectric Relaxation of Binary Mixtures of Tetrahydrofuran and N-Methylformamide in Benzene Solution Using Microwave Absorption Studies

Zeitschrift für Naturforschung A ◽

10.1515/zna-2010-1-216 ◽

2010 ◽

Vol 65 (1-2) ◽

pp. 141-144 ◽

Cited By ~ 1

Author(s):

Raman Kumar ◽

Vir S. Rangra

Keyword(s):

Binary Mixture ◽

Dielectric Relaxation ◽

Relaxation Process ◽

Binary Mixtures ◽

Benzene Solution ◽

Relaxation Times ◽

Single Frequency ◽

Flow Process ◽

Dielectric Relaxation Process ◽

C 30

AbstractUsing standard standing wave microwave X-band technique and following Gopala Krishna’s single frequency (9.90 GHz) concentration variational method, the dielectric relaxation times τ and the dipole moments μ of dilute solutions of Tetrahydrofuran (THF), N-methylformamide (NMF), and THF+NMF binary mixtures in benzene solutions have been calculated at different temperatures (25°C, 30°C, 35°C, and 40°C). The energy parameters (ΔHε , ΔFε , ΔSε ) for the dielectric relaxation process for the THF+NMF binary mixture containing 30 mol% THF have been calculated at 25°C, 30°C, 35°C, 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 process can be treated as a rate process. From relaxation time behaviour of THF and NMF binary mixture in benzene solution, solute-solute types of the molecular association has been proposed.

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Dielectric Relaxation of Benzonitrile in Benzene

Zeitschrift für Naturforschung A ◽

10.1515/zna-2008-1209 ◽

2008 ◽

Vol 63 (12) ◽

pp. 813-818

Author(s):

Rajesh Kumar ◽

Nagesh Thakur ◽

Rajendra S. Bisht

Keyword(s):

Dielectric Relaxation ◽

Viscous Flow ◽

Single Frequency ◽

Dielectric Relaxation Time ◽

Relaxation Processes ◽

Flow Process ◽

Energy Parameters ◽

Different Temperatures ◽

Rate Processes ◽

Microwave Techniques

The dielectric constant, ε′ , and dielectric loss, ε″ , of dilute solutions of benzonitrile (C6H5CN) in benzene have been measured at 9.885 GHz at 25, 30, 35, and 40 °C using standard standing microwave techniques. Following the single frequency concentration variational method of Gopala Krishna, the dielectric relaxation time, τ , and the dipole moment, μ, at various temperatures have been calculated. It was concluded that dielectric relaxation processes can be treated as rate processes just like the viscous flow process. Based on the above studies, the monomer structure of benzonitrile in benzene has been inferred. The solute-solvent molecular association of benzonitrile in benzene has been found. The energy parameters ΔHε , ΔFε , ΔSε for the dielectric relaxation process of benzonitrile in benzene at different temperatures have been calculated and compared with the corresponding energy parameters ΔHη , ΔFη , ΔSη for the viscous flow process.

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Calculation of various relaxation times and conductivity for a single dielectric relaxation process

Solid State Ionics ◽

10.1016/0167-2738(90)90010-o ◽

1990 ◽

Vol 42 (3-4) ◽

pp. 213-221 ◽

Cited By ~ 152

Author(s):

W Cao

Keyword(s):

Dielectric Relaxation ◽

Relaxation Process ◽

Relaxation Times ◽

Dielectric Relaxation Process

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Dielectric Relaxation Studies of Silver Nanoparticles dispersed Liquid Crystal

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v8i3.1496 ◽

2015 ◽

Vol 8 (3) ◽

pp. 2176-2188 ◽

Cited By ~ 4

Author(s):

Keisham Nanao Singh

Keyword(s):

Activation Energy ◽

Silver Nanoparticles ◽

Liquid Crystal ◽

Dielectric Relaxation ◽

Relaxation Process ◽

Relaxation Times ◽

Low Frequency ◽

Bulk Liquid ◽

Molecular Rearrangement ◽

Relaxation Studies

This article reports on the Dielectric Relaxation Studies of two Liquid Crystalline compounds - 7O.4 and 7O.6 - doped with dodecanethiol capped Silver Nanoparticles. The liquid crystal molecules are aligned homeotropically using CTAB. The low frequency relaxation process occurring above 1 MHz is fitted to Cole-Cole formula using the software Dielectric Spectra fit. The effect of the Silver Nanoparticles on the molecular dipole dynamics are discussed in terms of the fitted relaxation times, Cole-Cole distribution parameter and activation energy. The study indicate a local molecular rearrangement of the liquid crystal molecules without affecting the order of the bulk liquid crystal molecules but these local molecules surrounding the Silver Nanoparticles do not contribute to the relaxation process in the studied frequency range. The observed effect on activation energy suggests a change in interaction between the nanoparticles/liquid crystal molecules.

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