Showing papers on "Relative permittivity published in 1972"
TL;DR: In this article, the authors measured the dielectric permittivity of pure decalin, and showed that the solvent as a viscoelastic medium with frequency-dependent viscosity can account for the broad dispersion region.
Abstract: The equilibrium dielectric permittivity of pure decalin and the dielectric permittivity and loss of dilute solutions of chlorobenzene, bromobenzene, toluene, tetrahydrofuran, 1‐fluoronaphthalene, 1‐chloronaphthalene, 1‐bromonaphthalene, and 1‐methylnaphthalene in decalin have been measured from 50 Hz to 100 kHz at several temperatures between −135 and −155°C The equilibrium dielectric permittivity of solutions shows no significant short‐range order tending to align the dipoles preferentially All the rigid molecules show a broad dispersion region which does not seem to be describable by any simple distribution function It is shown that the introduction of the solvent as a viscoelastic medium, with frequency‐dependent viscosity, can account for the broad dispersion region An additional region of dielectric absorption at relatively high frequencies appears to be present in all of these solutions The Arrhenius plots of the relaxation time are nonlinear, with the activation energy increasing from 25 kcal/
71 citations
TL;DR: The limiting high frequency permittivity e∞ of hexagonal ice, measured using a coaxial three terminal dielectric cell designed to minimize errors arising from differential thermal contraction, was described in this paper.
Abstract: The limiting high frequency permittivity e∞ of hexagonal ice, measured using a coaxial three terminal dielectric cell designed to minimize errors arising from differential thermal contraction, vari...
70 citations
TL;DR: In this article, the microstrip end effect as a function of width and substrate permittivity was calculated and the excess capacitance associated with the open end was determined using the method of moments.
Abstract: Calculated data, which extend the previous results of Farrar and Adams, are presented for the microstrip end effect as a function of width and substrate permittivity. With a quasistatic approximation, the excess capacitance associated with the open end was determined utilising the method of moments. Good experimental agreement was observed.
36 citations
TL;DR: In this paper, a modification of Onsager's model taking into account molecular anisotropy is proposed for mixtures of polar liquids, and two formulae giving the concentration dependence of the electric permittivity and its variations under the influence of strong electric fields (dielectric saturation) are derived.
Abstract: A modification of Onsager's model taking into account molecular anisotropy is proposed for mixtures of polar liquids. Two formulae giving the concentration dependence of the electric permittivity and its variations under the influence of strong electric fields (dielectric saturation) are derived.Comparison with experimental results for several mixtures shows that the variation of the dipole moments determined with these formulae over the whole range of concentration of a polar compound dissolved in a non-polar as well as in a polar solvent is less than 5 %. An application to the study of molecular association is proposed.
22 citations
TL;DR: The theoretical and practical considerations of a coaxial line cell which enables the permittivity of aqueous liquids to be measured up to 4 GHz and that of non-aqueous liquids at higher frequencies are given in this article.
Abstract: The theoretical and practical considerations are given of a coaxial line cell which enables the permittivity of aqueous liquids to be measured up to 4 GHz and that of non-aqueous liquids to be measured at higher frequencies. The paper includes brief details of the basic experimental and computational procedure used. The effects of wall loss are considered in detail and the appropriate corrections to the real as well as the imaginary part of the complex permittivity are explained.
21 citations
TL;DR: In this paper, the error in the determination of permittivity arising from the imperfection of beam-wave theory is estimated and it is further shown that by an improved method of analysing the experimental results, the effect of the imperfections in the theory is reduced and a great improvement in accuracy can be obtained.
Abstract: The accuracy of permittivity measurement using an open resonator has been studied. The error in the determination of permittivity arising from the imperfection of beam-wave theory is estimated. It is further shown that, by an improved method of analysing the experimental results, the effect of the imperfection in the theory is reduced and a great improvement in accuracy can be obtained.
20 citations
TL;DR: In this paper, a method for evaluating the conductivity and permittivity spectrum of materials by using time-domain reflectometry is presented, with emphasis on the asymptotic behavior for large values of time.
Abstract: A method is presented for evaluating the conductivity and permittivity spectrum of materials by using time-domain reflectometry. A theoretical analysis of the transient response is made, with emphasis on the asymptotic behavior for large values of time. The results of the asymptotic analysis are the basis of the presented method and are essential for the evaluation of the permittivity spectrum of conductive materials. Quite satisfactory experinental results are presented.
15 citations
TL;DR: In this article, a computer-based method for the direct conversion of step-response (transient) data (such as is obtained from the rate of discharge of a capacitor) into the frequency dependence of the complex relative permittivity was proposed.
Abstract: We report a satisfactory method for the direct conversion of step-response (transient) data (such as is obtained from the rate of discharge of a capacitor) into the frequency dependence of the complex relative permittivity. This computer-based method has no a-priori restriction on the shape of the loss peak or functional dependence of the decay response. In this it differs from a number of approaches described in the literature.1–4 The method herein described is compared to such other techniques for converting step-response data, and assessed in relation to the predicted behaviour for single and unresolved double Debye relaxations. The dielectric relaxation behaviour of a sample of poly(vinyl acetate) is also investigated using the described method of data analysis.
14 citations
TL;DR: In this paper, the relative permittivity of the n alkanes from n pentane to n decane has been measured over a range of pressures and temperatures and all the data for each alkane have been fitted by a polynomial to within better than 0.1%.
Abstract: Precision measurements of the relative permittivity of the n alkanes from n pentane to n decane have been made over a range of pressures and temperatures. All the data for each alkane have been fitted by a polynomial to within better than 0.1%. Results are compared where possible with those of other workers.
12 citations
TL;DR: In this paper, the relative permittivity prime and loss factor double prime for methylacrylate, ethylacetyl, methylacetyl-methacryl and ethylmethacetyl at different temperatures and frequencies have been determined.
Abstract: The relative permittivity prime and loss factor double prime have been determined for methylacrylate, ethylacrylate, methylmethacrylate and ethylmethacrylate at different temperatures and frequencies. The activation energies and relaxation times are estimated for these liquids. It has been observed that absorption maxima for these liquids are in the millimetre region. The dipole moments are also calculated using Onsager's equation and Rao's equation.
11 citations
TL;DR: In this paper, three-terminal measurements of capacitance and dissipation factor have been made on samples of d-camphor, dl-Camphor, and l-camphor at frequencies between 200 Hz and 10 kHz over the temperature range -196 degrees C to +20 degrees C.
Abstract: Three-terminal measurements of capacitance and dissipation factor have been made on samples of d-camphor, dl-camphor and l-camphor at frequencies between 200 Hz and 10 kHz over the temperature range -196 degrees C to +20 degrees C. The dielectric relaxation processes in d-camphor, below the transition temperature, have been studied and the change in the frequency of maximum dielectric loss, which occurs during the transition, has been estimated. It is believed that these results are the first to provide direct evidence of the increased freedom of molecular rotation which occurs during the transition. Electrical conduction appears to commence immediately on completion of the transition and increases with increasing temperature.
TL;DR: In this paper, the resonant frequencies of a simple straight microstrip resonator, short-circuited at both ends, are used to obtain the effective relative permittivity against frequency.
Abstract: The method uses the resonant frequencies of a simple straight microstrip resonator, short-circuited at both ends. It is excited by passing a current through one of the short circuits. Graphs of effective relative permittivity against frequency are given for resonators on alumina and quartz substrates, with an error of within only ±0.1%.
TL;DR: In this article, the frequency dependence of the complex permittivity of a series of solutions of tetra(n-butyl) ammonium bromide in 1,2-dichloroethane and pentan-3-one has been studied in the frequency range 0.4 to 3.0 GHz at four temperatures between 0 and 45°C.
Abstract: The frequency dependence of the complex permittivity of a series of solutions of tetra(n-butyl) ammonium bromide in 1,2-dichloroethane and pentan-3-one has been studied in the frequency range 0.4 to 3.0 GHz at four temperatures between 0 and 45°C. The dispersion of permittivity observed in the majority of cases cannot be adequately described by means of a single relaxation time. A non-zero distribution parameter must also be included, while the dispersion amplitude is not even an approximately linear function of electrolyte concentration. Possible loss mechanisms involving the rotational diffusion of ion-pairs and the translational diffusion of free ions have been considered in an attempt to interpret these observations.The electrical conductivity and permittivity of representative solutions in 1,2-dichloroethane have been measured between 1 and 100 MHz in addition to the real and imaginary permittivities of the pure solvents at frequencies up to 3 GHz. Density data for solutions of the salt in 1,2-dichloroethane are included and from these data, the partial molar volume of the solute has been evaluated.
TL;DR: In this paper, the authors considered the scattering of a compound particle by a bound system in the case of weak interaction and derived the Born cross-sections for positronium and muonium scattering by a polar nonmagnetic medium.
Abstract: The scattering of a compound particle by a bound system in the case of weak interaction is considered. The Born cross-sections for positronium and muonium scattering by a polar nonmagnetic medium were expressed by the complex permittivity function eαs(q, ω). The possibility of an experimental study of the frequency and wave vector dependence of the permittivity of homogeneous isotropic media using data on the scattering of leptonic atoms with spin transitions is investigated. The determination of Im {1/e∥(q, ω)} by small-angle thermal scattering data is also discussed.
[Russian Text Ignored].
01 Jan 1972
TL;DR: In this article, a technique was developed to interpret the measured admittance of an electrically short sheathed dipole probe in terms of the complex relative permittivity of the surrounding material.
Abstract: Motivated by a study of the electrical properties of deep polar ice, a technique was developed to interpret the measured admittance of an electrically short sheathed dipole probe in terms of the complex relative permittivity of the surrounding material. With the related analytical problem unsolved, the experimental study described herein provides new information for evaluating theoretical models as well as guidelines for the full-scale design of systems to measure the properties of ice or other materials in similar circumstances, and bounds on the measured sample volume. Reduction of the admittance data is accomplished with the aid of a three-element equivalent circuit resulting from a laboratory model study that is also described. Potential applications include measure-merit of the in situ properties of rock and naturally occurring ice masses surrounding deep drill holes. Preliminary results from the Antarctic ice sheet at Byrd Station are included by way of illustration.
TL;DR: In this paper, an unbalanced AC bridge is used to record the real or imaginary component of permittivity on a chart recorder over the frequency range from about 1 Hz to 1 MHz.
Abstract: The spectrometer uses an unbalanced AC bridge and records the real or imaginary component of permittivity on a chart recorder over the frequency range from about 1 Hz to 1 MHz. The measured sensitivity extends to values of loss tangent of about 10-3 although the ultimate sensitivity is expected to be higher. The spectrometer is intended primarily for use with solid samples with permittivities described by the Debye equations.
TL;DR: In this article, a formula is introduced, based on the consideration of the effective permittivity seen by a central particle in a powder, which determines the correct values of bulk permittivities over a large range when dielectric data for even a single packing fraction are available.
Abstract: An earlier method introduced by Yadav and Parshad for using Bottcher's equation for dielectric correlation between powder and bulk for wide ranges of permittivity and packing fractions has the limitation that dielectric data for a number of appropriate packing fractions are required. In the present work a formula is introduced, based on the consideration of the effective permittivity seen by a central particle in a powder, which determines the correct values of bulk permittivity over a large range when dielectric data for even a single packing fraction are available.
TL;DR: In this article, a method for determining both thickness and composition of a thin dielectric film containing a mixture of two materials, provided the refractive index and relative permittivity is known for each of the two components.
Abstract: Thickness and composition of thin dielectric films are frequently dependent upon the system deposition parameters. A method is described for determining both thickness and composition of a film containing a mixture of two materials, provided the refractive index and relative permittivity is known for each of the two components. A combination of scanning interferometry and capacitance measurements was used to test the method of the Si–SiO–SiO2 system, obtaining an over-all accuracy in thickness on the order of 250 A for film thickness on the order of 0.4 μ.
TL;DR: In this paper, a search oscillator, controlled by the second harmonic of the modulation signal provided for the frequency locking, was employed to extend the capability of the method to thicker dielectric films and/or larger permittivities.
Abstract: The permittivity of thin dielectric films can be measured with good accuracy by employing a method recently reported by the authors, whereby the microwave oscillator frequency is automatically locked to the resonant frequency of the test cavity perturbed by the sample, thus leading to a digital readout of the frequency. However, the method is satisfactory only when the frequency shift caused by the presence of the test sample does not exceed the frequency lock-in bandwidth. By employing a search oscillator, controlled by the second harmonic of the modulation signal provided for the frequency locking, this limitation is removed, thus extending the capability of the method to thicker films and/or larger permittivities.
TL;DR: In this article, a numerical method of determining characteristic impedances, propagation velocities and crosstalk parameters of coupled embedded (and unembedded or pure) microstrip lines from the relative permittivity of the substrate and geometrical data, such as the thickness of the strip conductor and that of the embedding layer, is presented.
Abstract: The letter gives a numerical method of determining characteristic impedances, propagation velocities and crosstalk parameters of coupled embedded (and unembedded or pure) microstrip lines from the relative permittivity of the substrate and geometrical data, such as the thickness of the strip conductor and that of the embedding layer. Some typical computed results are shown.
01 Jan 1972
01 Jan 1972
TL;DR: In this article, a simple microwave method for measuring the surface conductivity and permittivity of thin layers, such as epitaxial semiconductors on semi-insulating substrates, is proposed, and is shown to be of high accuracy at X band frequencies.
Abstract: A simple microwave method for measuring the surface conductivity and permittivity of thin layers, such as epitaxial semiconductors on semi-insulating substrates, is proposed, and is shown to be of high accuracy at X band frequencies.