Dielectric Material Parameters Research Articles

Versatile Landscape of Low-k Polyimide: Theories, Synthesis, Synergistic Properties, and Industrial Integration.

The development of microelectronics and large-scale intelligence nowadays promotes the integration, miniaturization, and multifunctionality of electronic and devices but also leads to the increment of signal transmission delays, crosstalk, and energy consumption. The exploitation of materials with low permittivity (low-k) is crucial for realizing innovations in microelectronics. However, due to the high permittivity of conventional interlayer dielectric material (k ∼ 4.0), it is difficult to meet the demands of current microelectronic technology development (k < 3.0). Organic dielectric materials have attracted much attention because of their relatively low permittivity owing to their low material density and low single bond polarization. Polyimide (PI) exhibits better application potential based on its well permittivity tunability (k = 1.1-3.2), high thermal stability (>500 °C), and mechanical property (modulus of elasticity up to 3.0-4.0 GPa). In this review, based on the synergistic relationship of dielectric parameters of materials, the development of nearly 20 years on low-k PI is thoroughly summarized. Moreover, process strategies for modifying low-k PI at the molecular level, multiphase recombination, and interface engineering are discussed exhaustively. The industrial application, technological challenges, and future development of low-k PI are also analyzed, which will provide meaningful guidance for the design and practical application of multifunctional low-k materials.

Boosting the Charge Density of Triboelectric Nanogenerator by Suppressing Air Breakdown and Dielectric Charge Leakage

AbstractCharge generation and charge decay are two essential factors that determine the surface charge density of a triboelectric nanogenerator (TENG). However, research mainly focuses on boosting charge generation, and little attention is paid to suppressing charge decay. Here, a strategy of suppressing charge decay, including the air breakdown and dielectric charge leakage, of TENG with high surface charge density (HCD‐TENG) is proposed by utilizing a dual dielectric layer. A series of parameters of different dielectric materials are tested with the assistance of a charge excitation TENG (CE‐TENG) to reveal the relationships between charge generation, air breakdown, and dielectric charge leakage in the atmospheric environment. Further, the phenomenon of dielectric charge leakage limiting the maximum output of TENG prior to air breakdown is observed for the first time. With the simultaneous suppression of the air breakdown and dielectric charge leakage, the output of TENG is enhanced to 2.2 mC m−2. This work not only provides new insight into the performance optimization and material selection of TENG, but also provides significant guidance for obtaining high‐output TENG in the future.

Calculation and Measurement of Dielectric Parameters of Ceramic and Ferroelectric Materials in the Microwave Range

Introduction. Determination of the electrophysical parameters of linear and nonlinear dielectric materials for use in microwave technology represents an important direction. Linear dielectrics are used as a basis for the substrates of microwave circuits, as well as volumetric elements for the construction of frequency selective or resonant structures that operate across a wide temperature range. Therefore, the issue of stabilizing the electrical parameters of such structures from temperature influences appears relevant. A possible solution lies in the use of a multilayer combination of dielectrics, both with linear and nonlinear properties. Due to their nonlinear properties, ferroelectrics find application in functional units with an electrical rearrangement of frequency and phase characteristics. Therefore, it is important to determine not only the relative permittivity of the material, but also the control coefficient in the RF– microwave wavelength ranges.Aim. Construction of computational mathematical models for layered bulk and film structures to determine the relative permittivity of linear and nonlinear dielectrics in the ultrahigh frequency range.Materials and methods. The construction of computational mathematical models for the analysis of complex layered structures was carried out on the basis of Maxwell’s equations and the Galerkin method using boundary conditions for electromagnetic field components.Results. An electrodynamic analysis of a two-layer volumetric disk resonator was performed, and numerical results of calculating the resonant frequency were obtained. A numerical analysis of a multielectrode half-wave resonator with a ferroelectric film (FEF) was carried out.Conclusion. The mathematical models created and the experiment performed made it possible to numerically evaluate the properties of linear and nonlinear dielectric bulk and film materials in the microwave range.

Primary standard for complex units of permittivity at frequency range 0.1–178.4 GHz GET 110-2023

The article is dedicated to research in the fi eld of measuring the dielectric parameters of materials. The aim of the research is to study promising methods for measuring the complex dielectric permittivity of weakly absorbing materials in the decimeter wavelength range, as well as the non-resonant method for measuring the dielectric parameters of materials with high dielectric losses. In order to achieve the set goal of improving the state primary standard of complex dielectric permittivity in the frequency range from 1 to 178.4 GHz, tasks were set to expand the frequency range to 0.1 GHz and the range of reproducible values of the dielectric loss tangent to 10–1. As a result of the improvement, new equipment was introduced into the composition of the standard, and new measurement methods were developed. To measure the complex dielectric permittivity of weakly absorbing materials in the decimeter wavelength range, a resonant measurement method in a coaxial resonator with a shortening capacitive gap and a measurement method in a bulk H011-resonator with dielectric fi lling were developed. To measure elevated dielectric losses up to 10–2–10–1, a measurement method using a non-resonant measuring transducer based on a shielded dielectric waveguide with a measured dielectric sample as such a waveguide has been developed. The developed methods are applied in the Primary standard of complex dielectric permittivity in the frequency range from 0.1 to 178.4 GHz, GET 110-2023. The frequency range of the standard is 0.1–178.4 GHz, the range of reproducible values of relative dielectric permittivity is 1.2–500, dielectric loss tangent 10–8–10–1. The scope of application of GET 110-2023 is metrological support of dielectric control in production of radio frequency cables, telecommunication equipment, electronic components, etc.

Thioether-Containing Zirconium(Alkoxy)Siloxanes: Synthesis and Study of Dielectric and Mechanical Properties of Silica-Filled Polydimethylsiloxane Compositions Cured by Them.

A number of thioether-containing zirconium siloxanes, differing in their composition and metal atom shielding degree with a siloxy substituent, were synthesized and characterized. Synthesis of such compounds made it possible to evaluate the effect of sulfur atoms' presence in the cured compositions on their dielectric properties, as well as to evaluate their curing ability and influence on mechanical characteristics compared to the sulfur-free analogs obtained earlier. Studying a wide range of compositions differing in their content and ratio of metallosiloxane and silica components revealed that such systems are still typical dielectrics. At the same time, the introduction of thioether groups can provide increased dielectric constant and conductivity in comparison with previously obtained sulfur-free similar compositions in the <102 Hz frequency range (dielectric constant up to ~10-30 at frequency range 1-10 Hz). As before, the dielectric parameters increase is directly determined by the silica component proportion in the cured material. It is also shown that varying sulfur-containing zirconium siloxanes structure and functionality and its combination with previously obtained sulfur-free analogs, along with varying the functionality and rubber chain length, can be an effective tool for changing the dielectric and mechanical material parameters in a wide range (tensile strength 0.5-7 Mpa, elastic deformation 2-300%), which determine the prospects for the use of such cured systems as dielectric elastomers for various purposes.

Grain boundary capacitance effect in Iron-based magnetic composites for superior C-band microwave absorption

Urgently, the absorbing bandwidth of magnetic materials is enormously limited in C-band by the exorbitant magnetic response. There are few reports about C-band absorber. In this paper, iron-based magnetic composites with large-angle grain boundaries (120°) were prepared by gelatinized starch assisted separation nucleation and solid phase sintering. Noteworthily, grain boundary capacitance layer is formed at the grain boundaries, effectively enhancing its dielectric parameters. This is facilitated to achieve balanced impedance matching. Therefore, the effective absorption bandwidth (EAB) of FFC-B covered the whole C-band (4–8 GHz). Natural resonance and impedance matching realized by grain boundary capacitance effect were confirmed to be the key to such wide EAB for FFC-B in C-band. This work explores the important role of grain boundary capacitance effect in regulating the dielectric parameters of iron-based magnetic materials, and provides a feasible strategy of grain boundary engineering for the low-frequency and wide EAB electromagnetic performance.

Recent progress in dielectric resonator antenna: Materials, designs, fabrications, and their performance

Dielectric resonator antenna (DRA) has secured an esteemed position in the field of antenna engineering technology due to its versatile features, including compactness, light-weight, low loss, high radiation efficiency, ease of excitation, diverse feeding techniques, multiple excitation modes, ease of integration with passive and active microwave integrated circuit components, a wide variety of available materials, simple fabrication techniques, and high degree of flexibility over wide frequency range. This article presents a comprehensive up-to-date review of research carried out in the field of DRA technology which includes an overview of DRA technology, its history, present status, and prospects. The basic parameters of microwave dielectric ceramic materials and the classification of materials based on utilization and material parameters are briefly discussed. The applications of DRA in different fields of science, engineering, and technology, overview of different reported DRA shapes, and the feeding techniques used to excite different modes of DRA are mentioned. Based on the control of DRA permittivity, shape/geometry, feeding techniques, and structural modifications, performance parameters engineering of DRA and its achievable performance in terms of low profile, compactness, high gain, wide beam, circular polarization, wide bandwidth, DRA decoupling methods for multiple input multiple output arrays, dielectric patch antenna, filtering DRA, and reconfigurable DRA are discussed. Different techniques used to attain and enhance the particular performance of DRA are highlighted. This review article also dilates upon the fabrication processes and characterization methods of DRA microwave dielectric ceramics, which play a very vital role in controlling the performance and properties of DRA.

Ultra-broadband wave-absorbing metamaterials with open-hole effect

In this paper, propose the open-hole effect, which can improve the absorption effect of electromagnetic absorbers in the X- and Ku-band by regularly opening certain shaped through-holes in the dielectric material. Based on this effect, an ultra-wideband metamaterial absorber with a special open-hole structure is designed and successfully prepared by numerical simulation, and the effective wavelength bandwidth (absorption > 90 %) covers X- and Ku-band. By optimizing the dielectric material and structural parameters of the absorber, an ultra-broadband metamaterial absorber with a thickness of 2.2 mm, a maximum absorption rate of 99.35 % and an effective absorption bandwidth of 11.6 GHz was obtained. Simulations of TE and TM waves at different angles show that the absorber has excellent electromagnetic wave absorption at different angles of incidence (θ < 30°).

Development of CO2 efficiency index for evaluating sustainability of microelectrical discharge drilling process

Recently, there has been a growing awareness of environmental issues, and the concept of sustainability has been introduced. This concept applies to different fields, including the manufacturing industry. This study focuses on the sustainability of the micro-electrical discharge machining (EDM) drilling process. In EDM technology, the critical aspects of sustainability are consumed energy, electrode wear, gas emissions, and generated waste. The operational conditions impact consumption and emissions. The aim of this study is to develop a CO2 efficiency index for evaluating the environmental–economic efficiency of the micro-EDM drilling process. The index was calculated as the emissions that occurred during machining and logistic activities divided by the added value, and it was expressed as the kg equivalent CO2 per unit money. For the emissions, all process activities that have an environmental impact were considered, such as transportation, absorbed energy generation, production of fumes by the dielectric during machining, and emissions attributed to the production of nonconforming pieces. The proposed index was applied to a medical case study in which titanium bone plates were produced for fractures of small body parts. It was found that the process performance significantly depended on the operation conditions of the dielectric fluid and electrode. The material removal rate (MRR) significantly influenced the index. Quality problems and scraping influenced the overall performance significantly, whereas dielectric management had a moderate effect. The optimum conditions were determined by varying the dielectric fluid, electrode material, and process parameters. Demineralized water was the best dielectric because it facilitated a high MRR, whereas hydrocarbon oil resulted in a high quality and a low scrap rate. Vegetable oil caused problems, resulting in a low MRR and poor quality. Further investigations should be conducted to improve its performance in microdrilling applications.

Electrical characteristics of wire-to-wire dielectric barrier discharges

A wire-to-wire dielectric barrier discharge (DBD) is a novel method of plasma generation that has been demonstrated as an effective ion source for electroaerodynamic ion propulsion devices. A wire-to-wire DBD comprises two parallel wires spaced less than a millimeter apart: an insulated high voltage wire forms the encapsulated electrode and a thin uninsulated wire forms the exposed electrode. This electrode arrangement is lightweight, simple to manufacture, and has low aerodynamic drag; these properties make it suitable for ion generation in atmospheric ion propulsion and other potential applications. We performed a parametric experimental exploration of this type of plasma source using a sinusoidal driving signal, measuring power draw and discharge characteristics over a range of electrical, geometric, and dielectric material parameters. We find that it has similar electrical characteristics to volume DBDs. We provide a model for predicting the power draw to within 0.9 W m−1 with a correlation of r 2 = 0.99 between model and experiments.

Comparative study of textile material characterization techniques for wearable antennas

A comparative study of Quarter-wavelength λ4 stub and ring resonator techniques for the characterization of four (4) different textile materials (Kente-Oke (M1), Sanya (M2), Alaari (M3) and Etu (M4)) are presented in this work for the first time. The materials characterized in this work are locally made handwoven textile called “Aso-Oke” in South-west, Nigeria. The simulation and measurement results are presented. The dielectric parameters of materials were found to be 1.68, 1.46, 1.32, 1.51 for M1, M2, M3, and M4 respectively, and corresponding loss tangent of 0.049, 0.061, 0.019, 0.059 using Ring resonator. In the same light, the permittivity of the material M1, M2, M3, and M4 are found to be 1.75, 1.75, 1.5, 1.5 respectively, and corresponding loss tangent of 0.5, 0.6, 0.2, 0.6 using Quarter-wavelength open end Stub resonator. Using the parameters extracted from characterization, the materials are used as the substrate for wearable antenna to validate the measured dielectric properties of the material under test (MUTs). The results of this work show that, stub technique is more accurate than the ring resonator techniques. This is because of the complexity of ring resonator technique which makes it prone to fabrication error compared to the simplicity of the stub resonator technique. However, stub resonator technique can be time consuming due to the manual adjustment of the relative permittivity of the material during simulation. It is observed from the results of this research that, the stub resonator results are comparable to the Ring resonator-based results. Hence, combining the two techniques by using the ring resonator to predict the region of the relative permittivity and then using the stub resonator technique to optimize the accuracy by varying the permittivity around the predicted region provided by ring resonator technique shall reduce the time consumed by Stub-resonator and increases the accuracy of the measurement.

Resonant properties of a multilayer strip-slot transition and its application for microwave measurements of dielectric properties of materials

Statement of the problem: One of the actual problems of applying radio materials at high and ultrahigh frequency ranges is the problem of increased requirements for the accuracy of assessing their dielectric properties. Currently, non-resonant and resonant methods are applied to assess the dielectric properties of radio materials at the frequency ranges indicated above. Non-resonant methods are expedient for application in non-destructive testing of large-area sheet materials. Their implementation requires the application of an expensive vector network analyzer. Resonant methods are applied with a limited amount of the test material or in its powder state. In the implementation of resonant methods the main investigated parameter is the displacement of the frequency of the electrical resonance. As a consequence, only the amplitude values of the transmission and reflection coefficients need to be known. This feature makes it possible to carry out microwave measurements for the resonant method applying a scalar network analyzer which has a lower cost compared to a vector network analyzer. That feature is an advantage in some cases. One of the promising directions in the development of the resonant measurement method is its implementation based on applying of a volumetric-modular technology. In particular its implementation that based on application of a multilayer strip-slot transition. The problem with this approach is the lack of researches in terms of the effectiveness of the application of the multilayer strip-slot transition as a device with a tunable frequency of electrical resonance. Aim: The aim of this article is to present a resonant method based on the application of the multilayer strip-slot transition as a basic measuring device. Such a design solution for the implementation of resonant microwave measurements has no analogues. This determined the conduction of current research. The task of which is to theoretically and experimentally substantiate the effectiveness of applying a multilayer strip-slot transition to implement the resonant method for measuring the dielectric properties of materials. Results: The results of theoretical and experimental studies of the resonance properties of the multilayer strip-slot transition are presented. Its application makes it possible to realize an original volume-modular device for the resonant method of measuring the dielectric parameters of materials in the microwave range of wavelengths. The theoretical research is based on the development of an equivalent circuit, which is presented in the form of a cascade connection of four-port networks. The results of mathematical simulation of the multilayer strip-slot transition prove the possibility of implementing on its basis the resonance method for measuring the dielectric parameters of materials in the microwave range of wavelengths. Experimental studies were carried out on a sample of a volume-modular device with the multilayer strip-slot transition. The test material was a powder representing barium hexaferrite BaFe10Ti2O19 partially substituted by titanium. The coincidence of the results of mathematical simulation and experimental studies of the frequency-selective properties of a multilayer strip-slot transition is more than 95%. The error in assessing the permittivity of the used powder material based on the results of theoretical and experimental studies does not exceed 4.5%. Practical significance: The results of the research showed the possibility of applying of the multilayer strip-slot transition as a basic element for the implementation of the resonance method for measuring the dielectric properties of materials. The advantages of the proposed design are compactness and the ability to measure the dielectric properties of powder materials using scalar network analyzers.

Nondestructive method of measurement of laminated plates dielectric parameters

The methods for measuring the parameters of dielectric materials of foil plates have been considered. It has been shown that for “non-destructive measurements” (i.e., without removing the metal foil from the dielectric plate), a method based on the excitation of electromagnetic oscillations in a rectangular plate considered as a resonator can be used. Based on the results of measurements of their resonant frequencies and Q-factors, the relative permittivity and the tangent of the dielectric loss angle of the material can be determined. The calculated relations obtained by the authors of the article in one of the early works using the electrodynamic model of a resonator with “magnetic walls” at the ends have been presented. The Q-factor of the resonator has been calculated by the perturbation method, taking into account the losses in the plate dielectric and metallization layers. The results of measurements for four samples from different dielectrics in the frequency range 200...1000 MHz have been presented. The experimental method has been described, in particular, the method of identifying the type of oscillation, the procedure for processing the measurement results. Due to the high sensitivity of the vector analyzer, measurements have been made with a possible small connection of the resonator (metallized plate) with the measuring circuit. This made it possible to minimize the influence of the coupling elements on the measured Qfactor of the oscillations and to consider this Q-factor close to its own. The presented results are in good agreement with the reference data for the materials. The conducted studies have shown the possibility of using a resonator model with “magnetic walls” at the ends for the analysis of electromagnetic oscillations in a foil dielectric plate and, accordingly, using the relations obtained in this case to determine the parameters of the dielectric plate. The conditions for using this model are the small thickness of the plate in comparison with its transverse dimensions and relatively low operating frequencies. The method, which is based on the calculated ratios of the electrodynamic model of the resonator with “magnetic” walls at the ends, provides a sufficiently high accuracy of determining the relative permittivity of the plate material, which led to the use of it (the method) in practice to control the parameters of foil dielectric plates intended for the manufacture of microwave and UHF-band microcircuits. The studies, the results of which have been presented in this paper, allow us to conclude that this method can also be recommended for determining the tangent of the dielectric loss angle of the plate material.

Evaluating the Accuracy of Reconstruction of the Electrical and Geometric Parameters of Multilayer Dielectric Coatings by a Multifrequency Radio-Wave Method for Slow Surface Electromagnetic Waves

One of the most important problems in the diagnostics of multilayer dielectric materials and coatings is the development of methods for quantitative interpretation of the results of monitoring the electrical and geometric parameters of these materials. Results are presented from a study of the potential informativeness of a multifrequency radio-wave method for slow surface electromagnetic waves for reconstruction of the electrical and geometric parameters of multilayer dielectric coatings. A simulation model is shown for evaluating the accuracy of reconstructing the electrical and geometric parameters of multilayer dielectric coatings. The model takes into account the electrical and geometric parameters of the coating, the level of noise in the measurement data, and the measurement bandwidth. Simulation modeling and experimental test data for the reconstruction of the relative dielectric constants and thicknesses of one- and two-layer equal-thickness dielectric coatings based on polymethyl methacrylate, ftoroplast (teflon) F-4D, and RO3010 for different values of the mean square deviation of the noise level in the measured attenuation coefficients for the field of a slow surface electromagnetic wave. The accuracy of the reconstruction of the geometric and electrical parameters of the layers is found to decrease as the number of estimated parameters and the noise level increase, as well as when the dielectric constant and thickness of the layers are reduced. Experimental data confirm the adequacy of the simulation model developed here. This model can be used for a specific measurement complex employing a multifrequency radio-wave technique for slow surface electromagnetic waves to estimate quantitatively the potential possible accuracy of reconstructing the geometric and electrical parameters of multilayer dielectric materials and coatings. A simulation model and experimental study of a multilayer dielectric coating show that for a measurement bandwidth of 1 GHz the errors in estimating the dielectric constants and thicknesses of the layers do not exceed 10% with a confidence coefficient of 0.95 for a mean square deviation of 0.003–0.004 in the noise level.

Simulation of electromagnetic field distribution in the measuring cell for determining the dielectric permittivity of materials at microwave frequencies

To determine the dielectric permittivity of materials in a wide frequency range with the automation of measurements and the necessary accuracy, measuring cells have been created to ensure the simplicity of the design of the waveguide path. In order to obtain information about the suitability of measuring cells based on irregular SHF waveguides for estimation of dielectric parameters of materials, we simulated the structure of electromagnetic field in the system consisting of two irregular waveguides and waveguide chamber placed between them using a three-dimensional electrodynamic simulation in Ansoft HFSS package environment. The distribution of the electric field was simulated when an empty polyethylene tube, a rod of fluoroplastic and a rod of textolite are placed in the measuring cell. It was demonstrated that high order modes fade out in irregular waveguide and do not affect the precision of obtained results, and significant edge effects were not detected. It allows one to utilize measuring cells based on irregular waveguides together with a scalar or vector network analyzer and using the partial filling of the waveguide method or the modified Nicholson – Ross – Weir method for measurements of dielectric permittivity  of materials. The results of modeling the dependence of the amplitude and phase of the reflection coefficient of the textolite and fluoroplastic on the frequency in Ansoft HFSS environment are given. The simulation results are compared with the results obtained experimentally. The frequency dependencies of  were obtained experimentally for test materials – textolite and fluoroplastic – in the frequency range of 25,95–37,50 GHz. The experimental data are in satisfactory agreement with the results of theoretical calculations and do not go beyond the boundaries specified by the measurement uncertainty.

Enhancement of electro-optical and dielectric parameters of a room temperature nematic liquid crystalline material by dispersing multi-walled carbon nanotubes

ABSTRACT We have prepared the composites of a room temperature nematic liquid crystal mixture by dispersing small fractions of Multi-Walled Carbon Nanotubes into its matrix. The electro-optical and dielectric properties of the prepared samples were investigated. The effect of Multi-Walled Carbon Nanotubes on various display parameters of host nematic liquid crystal mixture was observed. The variations in some of the display parameters like dielectric anisotropy, threshold voltage, splay elastic constant and activation energy have been observed for composite systems with respect to pure nematic liquid crystal mixture. Dispersion of Multi-Walled Carbon Nanotubes enhanced the nematic order of liquid crystal host, resulting in the improvement of dielectric and electro-optical parameters of studied composite systems.

Robust design of compact microwave absorbers and waveguide matched loads based on DC-conductive 3D-printable filament

The design concept of effective microwave absorbers and compact matched loads based on 3D-printable lossy nanocarbon-based composites with filler content above the percolation threshold is proposed. The DC-conductive (σDC = 0.39 S m−1) 3D-printable filament based on poly(lactic) acid filled with 12 wt.% of multiwalled carbon nanotubes was used. The electromagnetic properties of 3D-printed pyramidal regular structures were experimentally investigated and numerically simulated in 12–18 GHz (Ku-band) and 26-37 GHz (Ka-band) frequency ranges. Within the proposed model the structures under study were considered as graded refractive index material. The optimal geometrical parameters of designed microwave components were successfully evaluated using numerical modeling. Tested components demonstrate remarkable shielding efficiency (> 20 dB) within whole Ku- and Ka-bands and are suitable for practical application related to effective absorption of microwave radiation. The production of 3D-printable materials with controlled and predicted losses offers the possibility for miniaturization of 3D printed microwave components, such as absorbers and loads. The developed technique, estimating the geometrical parameters of the components vs dielectric properties of the conductive filament, could be used as a versatile platform for predesign of compact microwave devices taking into account constituent dielectric parameters of available printable materials and filaments.

Evaluation of the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings by the multi-frequency radio wave method of a slow surface electromagnetic waves

One of the most important diagnostic problems multilayer dielectric materials and coatings is the development of methods for quantitative interpretation of the checkout results their electrophysical and geometric parameters. The results of a study of the potential informativeness of the multi-frequency radio wave method of surface electromagnetic waves during reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings are presented. The simulation model is presented that makes it possible to evaluate of the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric coatings. The model takes into account the values of the electrophysical and geometric parameters of the coating, the noise level in the measurement data and the measurement bandwidth. The results of simulation and experimental investigations of reconstruction of the structure of relative permittivitties and thicknesses of single-layer and double-layer dielectric coatings with different thicknesses, with different values of the standard deviation (RMS) of the noise level in the measured attenuation coefficients of the surface slow electromagnetic wave are presented. Coatings based on the following materials were investigated: polymethyl methacrylate, F-4D PTFE, RO3010. The accuracy of reconstruction of the electrophysical parameters of the layers decreases with an increase in the number of evaluated parameters and an increase in the noise level. The accuracy of the estimates of the electrophysical parameters of the layers also decreases with a decrease in their relative permittivity and thickness. The results of experimental studies confirm the adequacy of the developed simulation model. The presented model allows for a specific measuring complex that implements the multi-frequency radio wave method of surface electromagnetic waves, to quantify the potential possibilities for the accuracy of reconstruction of the electrophysical and geometric parameters of multilayer dielectric materials and coatings. Experimental investigations and simulation results of a multilayer dielectric coating demonstrated the theoretical capabilities gained relative error permittivity and thickness of the individual layers with relative error not greater than 10 %, with a measurement bandwidth of 1 GHz and RMS of noise level 0,003–0,004.

Study of the dielectric parameters of biological liquids

Study of the dielectric parameters of different materials attracts great attention of researchers as these parameters allow knowing various characteristics of different materials and chemical substances. This article presents studies of dielectric loss tangent of albumin protein water solution. Measurements of the frequency dependence of dielectric loss tangent in the range 10–106 Hz were performed. The experimental results showed non-linear frequency dependences of the dielectric loss tangent.

Nonlinear optical and dielectric properties of TiO2 nanoparticles incorporated PEO/PVP blend matrix based multifunctional polymer nanocomposites

Poly(ethylene oxide) (PEO)/poly(vinyl pyrrolidone) (PVP) blend (50/50 wt%) and mixed-phase (anatase and rutile) titanium dioxide (TiO2) nanoparticles are used as organic host matrix and inorganic nanofiller, respectively, for the preparation of hybrid polymer nanocomposite (PNC) films (i.e. (PEO/PVP)–x wt% TiO2; x = 0, 1, 3, 5, 10, and 15) by solution casting method with deionized water as solvent. These PNC films are characterized by employing SEM, FTIR, XRD, UV–Vis, DSC, and DRS techniques. The effect of TiO2 nanofiller loading on the structural, morphological, thermal, optical, dielectric, and electrical properties of the PEO/PVP blend matrix, and also on the chain segmental dynamics of PEO in the PNC structures is investigated. It is revealed that the crystalline phase and spherulite morphology of PEO, and the polymer–polymer interactions in these PNC films have been primarily modified by the polymer–nanoparticle interactions. The optical energy band gap decreases, whereas UV absorbance enhances non-linearly with the increase of TiO2 concentration in the PNC films. The enthalpy of melting of the PEO irregularly reduces when the incorporated amount of TiO2 enhances in these films. The real part of complex permittivity and the dielectric loss tangent of these materials are found frequency independent in the range from 20 kHz to 1 MHz but these parameters increase non-linearly from ~ 1.6 to 2 and 0.006–0.008, respectively with the increase of TiO2 concentration up to 10 wt%, at 30 °C. The dominant contribution of interfacial polarization process increases the real part of complex permittivity of these PNC materials by about 1.3 times with the decrease of frequency from 20 kHz to 20 Hz which further enhances with the increment in the temperature of the film. The electrical behaviour of these materials has been examined by analyzing their ac electrical conductivity, complex impedance, and electric modulus spectra over the frequency range 20 Hz–1 MHz. The dc electrical conductivity of these PNC materials enhances nonlinearly with the increase of TiO2 loading in the PEO/PVP blend matrix. The optical and dielectric parameters of these flexible-type PNC materials confirm their multifunctional properties as UV absorber, optical energy band gap tuner, low permittivity tunable nanodielectric, electrical conductivity regulator, and novel host matrix for ion conducting materials. The results infer that these innovative technologically advanced engineered materials can be potential candidates for the next generation microelectronic devices.