Effective dielectric permeability and electrical conductivity of polycrystalline PbTe films with disturbed stochiometry

This paper presents the study of the effective dielectric constant and electrical conductivity of polycrystalline PbTe films with disturbed stoichiometry. It is shown that superstoichiometric additions of Te and Pb within the limits of solubility by doping with PbTe contribute to a change in a wide range of concentrations of electrically active impurities and, consequently, to an increase in the dielectric constant (ɛ), electrical conductivity (σ) and absorption coefficient (α), in addition, the excess of these components strongly affects the amount of polarization.

The effect of shape and sizes of particles of wet quartz powders on complex dielectric permittivity in the frequency range of 10 kHz – 10 GHz

The results of experimental studies of complex dielectric permeability of river sand and powders of granules of fused quartz with narrow distributions of particles in size at the frequencies from 10 kHz to 10 GHz are presented. The granule particles are spheres and the sand particles are irregularly shaped. The samples were moistened with distilled water and NaCl salt solution with conductivity of 0.1 and 0.77 S/m. It has been shown that the shape of the particles affects the complex dielectric permittivity (CDP) in the low frequency part of the range only when proportion of the solution is small and its concentration is weak. At full saturation of the samples with the solution and its high concentration, as well as in all cases at frequencies above 100 MHz, the influence of the particle shape is small. In the mid-frequency part of the range (from units to tens of megahertz) in a sample of quartz granules with small particles, there is a strong relaxation process, leading to a significant increase in the real part of the CDP. A similar, but slight increase is observed in samples of sand with larger particles. In the high-frequency range, the effect of the shape and particle sizes is very weak.

Determination of the complex dielectric permeability of liquid at the radiation frequency 32 GHz

Method and device for measuring the complex dielectric constant of liquids are described. The real part of the complex dielectric constant calculated from the conditions for the maximum and minimum of the measured interference dependence of the reflection coefficient on the layer depth. The imaginary part determined by selection to the maximum coincidence of the calculated and measured dependences of the reflection coefficient.

THE INFLUENCE OF THE SALTITY OF THE MOISTURIZING SOLUTION ON THE DIELECTRIC PERMEABILITY OF CLAYS IN THE FREQUENCY RANGE FROM 1 MHZ TO 8 GHZ

The article presents the results of measurements of the complex dielectric constant of clays saturated with NaCl solution of various concentrations in a wide frequency range. The measurements were carried out at positive temperatures. It was revealed that several relaxation processes are observed in the spectra. A model is proposed that makes it possible to take into account the relaxation processes and their dependence on the concentration of the salt solution. The concentration practically does not affect the parameters of the processes, in contrast to the temperature.

Design of liquid composite materials for shielding electromagnetic fields

This paper reports the principles of design and the examined protective properties of liquid materials for shielding the electric, magnetic, and electromagnetic fields over a wide frequency range. The materials were made on the basis of iron ore concentrate and a pigment additive, with water-dispersed and geopolymer paints used as a matrix. The tests of protective properties for the electrical and magnetic components of the electromagnetic field of industrial frequency showed that the electric field shielding coefficients at a concentration of the screening substance of 15−60 % (by weight) equaled 1.1−8.6; magnetic field – 1.2−5.3. The shielding coefficients of the material based on a water-dispersed paint are lower than those of a geopolymer one, which can be explained by the oxidation of an iron-containing component and a decrease in electrical conductivity. The shielding coefficients of the electromagnetic field with a frequency of 2.45 GHz are 1.2−7.9. The highest coefficients are inherent in the material with filler made of iron ore concentrate and titanium-containing pigment powder in a ratio of 1:1. To design materials with the required (predictable) protective properties, the relative magnetic, dielectric permeability of materials was calculated. It is shown that the obtained data are acceptably the same as the results from direct measurements of magnetic and dielectric permeability and could be used to calculate the wave resistance of the material and the predicted reflection coefficient of electromagnetic waves. Thus, there is reason to assert the need to build a database on the frequency dependence of effective magnetic and dielectric permeability in order to automate the design processes of composite materials with predefined protective properties.

RELATIONSHIP OF COMPLEX DIELECTRIC PERMEABILITY AND NMR CHARACTERISTICS OF DRILL CUTTINGS WITH ITS RESERVOIR PROPERTIES

The paper presents the results of experimental studies of the dielectric and NMR characteristics of drill cuttings. It is shown how the fluid distribution in the pore space changes at different stages of extraction and saturation. It is shown that it is possible to estimate the degree of saturation of samples by sequential interpretation the spectra of the dielectric and NMR characteristics.

Differential electrochemical impedance spectroscopy of the polymer proton electrolytes

A method of deriving standard electrochemical impedance spectroscopy (EIS) data such as Bode diagram, Nyquist diagram, and others from frequency dependence of the external impedance using numerical differentiation of the indicated dependence in quadratic coordinates is proposed, the method being named as the differential electrochemical impedance spectroscopy (DEIS). The method was tested experimentally on polyvinyl alcohol-based proton membranes doped with sulphated montmorillonite in granulated or dispersed states as an example. It is shown that DEIS data can be easier and with higher accuracy described by regular semicircles while leaving intact values of ohmic resistance. Very high values of dielectric permeability were obtained in the work enabling to develop condensers with high capacity based on highly conductive polymeric proton electrolytes.