Complex Electrical Conductivity Research Articles

A novel saturation calculation model of fractured-vuggy carbonate reservoir via multiscale pore networks: a case study from Sichuan Basin, China

Abstract Existing saturation models cannot effectively describe the specific fractured-vuggy carbonate reservoir in area A of the Sichuan Basin, southwestern China. This reservoir has got a wide pore size distribution, strong heterogeneity, high gas saturation and complex electrical conductivity mechanism. Hence, the present study attempted to establish a new saturation calculation equation for this carbonate reservoir based on the microscopic conductivity mechanism of the rock. Here, we first used the multiscale computed tomography (CT) scanning method to build multiscale digital rocks. Subsequently, we applied the maximum sphere algorithm to extract the pore space structure and constructed the multiscale pore network models. By using the cross-scale fusion method, four different pore configurations were determined. Then, the percolation theory was implemented to simulate the conductivity mechanism of the constructed pore network models. As a result, the fluid distribution characteristics and the resistivity variation trends of the different pore structures were obtained. The simulation results showed that the fracture system of the studied reservoir had a much greater effect than the vug system on the carbonate rock's electrical conductivity, and the conductivity was closely related to the fluid distribution. In addition, based on the simulation results, a new conductivity model was proposed that incorporates the coupling phenomenon of pores, vugs and fractures; and also a new saturation calculation equation for triple-porosity media was established. The observations indicated that the field application of the proposed equation had an acceptable performance with an error value of less than 2.56%. The results from the present study provide new insights into the evolution of electrical properties in triple-porosity carbonate systems.

Effect of alloying on the structure and electric properties of ZnFe2O4/ZnMn2O4 heterostructure nanocomposites

The heterostructure nanocomposite (1-x)ZnFe2O4/xZnMn2O4 (x = 0, 0.5, 0.8, 1) samples were prepared using the sol–gel method. The structural parameters and the percentages of the phases formed were determined utilizing the Rietveld method. Beside the two phases formed ZnFe2O4 (ZFO) and ZnMn2O4 (ZMO), a minor phase ZnO (3%) was observed in the sample x = 0.5. Analysis revealed phase percentages for composite samples different from intended (x) values due to the exchange of cations between the phases formed. The effect of composition ratio (x), as well as the frequency and temperature on the dielectric constant, dielectric loss, impedance spectroscopy and complex electric modulus and ac conductivity, was examined. The degree of correlation in each sample was also determined. Different conductivity mechanisms are found for different samples and frequency ranges. The 0.2ZFO-0.8ZMO sample disclosed higher conductivity and higher dispersion relative to other samples. The effect of temperature on the Cole–Cole plots was also studied.

Impedance characterization and microwave permittivity of multi-walled carbon nanotubes/BaTiO3/epoxy composites

Polymer composite materials with mixed fillers are widely investigated due to potentially superior properties they provide compared to a composite with a single filler. In this work, the electrical properties of multi-walled carbon nanotubes (MWCNT)/BaTiO3/epoxy composites are investigated using impedance measurements, modeling with equivalent circuit model, determining of alternating current conductivity in the range 10 Hz–2 MHz, permittivity measurements at frequencies 1–67 GHz, and temperature dependencies (77–290 K) of direct current conductivity. Measurements were processed to define the influence of filler combination (carbon nanotubes and BaTiO3) on dielectric properties of the epoxy composites. Nyquist diagrams indicate that all investigated composites have extensive conductive clusters. Permittivity increases monotonically with carbon nanotubes content with a steeper increase of the real part at lower frequencies. Alternating current conductivity has been determined to increase significantly at frequencies over 1 GHz. Temperature dependencies of direct current conductivity in the range 77–293 K exhibit a maximum near 180–220 K, which is shifted to the higher temperatures with the increase of carbon nanotubes content. The observed enhanced values of complex permittivity and electrical conductivity of three-phase MWCNT/BaTiO3/epoxy composites lead to a comparatively high microwave attenuation constant, which may be tuned by the carbon nanotubes content in the composite. It suggests that these composites might be perspective shielding and absorbing materials used for microwave applications.

GO-CNTs hybrids reinforced epoxy composites with porous structure as microwave absorbers

Foam structures with epoxy as the matrix and both carbon nanotubes (CNTs) and their hybrids with graphene oxide (GO-CNTs) as absorbers were fabricated, and their microwave absorbing and electromagnetic properties were investigated in the frequency range of 1–18 GHz. The fillers and bubbles were uniformly distributed in the composites. The complex permittivity and electrical conductivity of the composites increased as the fillers’ content increasing. The best performance of the reflection loss (RL) can be obtained for a foam structure with 0.5 wt% GO-CNTs, which had a RL peak value of −20dB with a −10 dB range of 5.3 GHz (10.8–16.1 GHz). Multi-layered structures were also discussed in this work, a RL peak value of −40dB with a −10dB range of 7.1 GHz (9.9–17 GHz) had been obtained by combining two foam structures, which are 2 mm thick 0.5 wt% GO-CNTs/epoxy and 1 mm thick 2.0 wt% GO-CNTs/epoxy. Furthermore, the −10dB range can reach 11.5 GHz (6.5–18 GHz) when combining 2.6 mm thick 0.5 wt% GO-CNTs/epoxy and 1.3 mm thick 2.0 wt% GO-CNTs/epoxy.

Dielectric dispersion study of binary mixtures of methyl ethers with water at 298.15 K using frequency domain technique

A precision LCR meter along with a liquid dielectric cell have been used to measure the capacitance and resistance of the binary mixtures of methyl ethers with water at 298.15 K in the frequency range of 20 Hz to 2 MHz. The measured values are used to compute the complex dielectric permittivity ε*(ω) . The parameters like complex electrical modulus M*(ω) , complex electrical conductivity σ*(ω) and loss tangent (tan δ ) are obtained from the complex dielectric permittivity values of the samples. The values of excess dielectric permittivity of the samples are calculated using the respective static dielectric permittivity values. The refractive indices of all the samples were measured using Abbe’s refractometer at 298.15 K. All these parameters are used to gain insight into the concentration dependent variation in dielectric and electrical properties of the binary mixtures. A dominance of electrode polarization effect in the lower frequency region is observed for all the samples studied here.

Investigation of effects on dielectric properties of different doping concentrations of Au/Gr-PVA/p-Si structures at 0.1 and 1 MHz at room temperature

In order to improve and detailedly investigate the dielectric properties of polymer interfaces of Metal–Polymer–Semiconductor (MPS) structures, three types of MPS were fabricated by doping 1, 3 and 5% graphene (Gr) into the polyvinyl alcohol (PVA) interface material. Capacitance–Voltage (C-V) and Conductance–Voltage (G/ω-V) measurements were used to analyze the dielectric properties of three types of MPS. Using C-V and G/ω-V data, series resistance (Rs) affecting device performance and interface properties besides basic dielectric parameters of each structure such as both the real and imaginary components of complex dielectric constant (e' and e''), complex electrical modulus (M' and M''), loss tangent (tanδ), and ac electrical conductivity (σac) were also calculated. The effect of graphene doping was examined for each parameter and obtained results were compared at both low (0.1 MHz) and high (1 MHz) frequencies. It was observed that e and e'' decreased with increasing graphene doping at both 0.1 and 1 MHz, while M' and M'' increased under same conditions. Moreover, both the M' and M'' vs V plots have two distinctive peaks between −2.0 V and 0.0 V due to a special density distribution of surface states between (Gr-PVA) and p-Si. The tanδ gradually increased with increasing graphene doping at only 0.1 MHz. As the doping ratio of graphene increases, the charge carriers in the structure generate more dipoles and create an earlier relaxation process. In other words, increasing the doping ratio helps to improve the series resistance effects in MPS structures. As a result, it was seen that the interfacial properties of MPS structures were improved by increasing the rate of graphene doping.

Complex Electrical Conductivity of Biotite and Muscovite Micas at Elevated Temperatures: A Comparative Study.

The unique physicochemical, electrical, mechanical, and thermal properties of micas make them suitable for a wide range of industrial applications, and thus, the interest for these kind of hydrous aluminosilicate minerals is still persistent, not only from a practical but also from a scientific point of view. In the present work, complex impedance spectroscopy measurements were carried out in muscovite and biotite micas, perpendicular to their cleavage planes, over a broad range of frequencies (10−2 Hz to 106 Hz) and temperatures (473–1173 K) that have not been measured so far. Different formalisms of data representation were used, namely, Cole-Cole plots of complex impedance, complex electrical conductivity and electric modulus to analyze the electrical behavior of micas and the electrical signatures of the dehydration/dehydroxylation processes. Our results suggest that ac-conductivity is affected by the structural hydroxyls and the different concentrations of transition metals (Fe, Ti and Mg) in biotite and muscovite micas. The estimated activation energies, i.e., 0.33–0.83 eV for biotite and 0.69–1.92 eV for muscovite, were attributed to proton and small polaron conduction, due to the bound water and different oxidation states of Fe.

Complex conductivity of rammed earth

Searching for recyclable materials of construction, in the objective of building sobriety and resilience, is a major issue of our current societies. Mudbricks of compacted rammed earth represent an ancient construction material with many advantages associated with its availability, cost of production, potential reuse, and with a very low carbon footprint. Moisture content affects the mechanical resistance of such materials, which could become mechanically weak above a critical value. Therefore, non-intrusive characterization techniques able to image the water content distribution of these materials is highly in demand. We apply a recently developed theory of complex electrical conductivity (alias induced polarization) to characterize core samples of rammed earth materials in the laboratory. Complex conductivity describes both the ability of a porous material to conduct an electrical current (characterized by the in-phase conductivity) and its ability to store reversibly electrical charges (characterized by two interconnected properties namely the quadrature conductivity and the normalized chargeability). Samples of rammed earth and clayey soils with different pore water salinities, saturations, and compaction states are measured with the complex conductivity method in the frequency range 100 mHz–45 kHz. The in-phase and quadrature conductivities of the complex conductivity of rammed earth are connected to the water content offering therefore a new non-intrusive tomographic technique to study the water content distribution in walls made of rammed earth. The data are all consistent with the so-called dynamic Stern layer model of complex conductivity for clayey materials. This new approach provides a general method to image the change in the water content of walls made of rammed earth, a task that electrical conductivity imaging cannot perform as a stand-alone technique.

Complex electrical conductivity as a new technique to monitor the coagulation-flocculation processes in the wastewater treatment of the textile Industry

In this paper, we have used complex electrical conductivity σ*(ω) as a new key factor for monitoring the efficiency of coagulation-flocculation processes. This process was applied of textile wastewater treatment by controlling the flocculants dosages through σ*(ω) measurements. Therefore, σ*(ω) is the best parameter that allows investigating and predicting the interactions at the molecular level between the fine colloidal particles in the wastewater and cationic polymer used for coagulation-flocculation. The variations of complex conductivity were modeled by the summation of Cole-Cole relaxation process and diffusion process, and the analysis of extracted parameters from the model allowed us to predict the dosage of the cationic polymer to achieve the flocculation process. The results showed that 10 mg/L as the optimal concentration to achieve the best flocculation process.

Significantly enhanced dielectric properties and chain segmental dynamics of PEO/SnO2 nanocomposites

Poly(ethylene oxide) (PEO) matrix- and tin oxide (SnO2) nanofiller-based polymer nanocomposite films were prepared by solution cast followed by melt press. The effect of SnO2 concentration (i.e. 1, 3, and 5 wt%) on the structure, dielectric permittivity, and chain segmental motion of PEO was investigated with X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and dielectric relaxation spectroscopy (DRS) techniques. Results reveal that the dispersion of SnO2 nanoparticles has enormously altered the contents of different crystallite phases of the PEO and some amount of the degree of crystallinity. The DRS study in the range of 20 Hz–1 MHz at 30 °C confirmed that the complex dielectric permittivity and electrical conductivity at lower frequencies increased largely on the dispersion of SnO2 nanoparticles in the PEO matrix which was attributed to the contribution of interfacial polarization effect, moreover, a significant increase was also noted in the molecular polarization at higher frequencies. The relaxation processes corresponding to Maxwell–Wagner–Sillars mechanism and PEO chain segmental motion were analysed from the electric modulus spectra. The chain segmental dynamics and dc electrical conductivity have nonlinearly enhanced with the increase in SnO2 content in the polymer structure. The temperature-dependent dielectric and relaxation behaviour of PEO-3 wt% SnO2 film was also reported. It was observed that the relaxation time and electrical conductivity of the film exhibited Arrhenius behaviour of low activation energies.

Study on electric modulus, complex modulus and conductivity properties of Nb/Sm, Gd doped barium titanate-lithium ferrite ceramic composites

The (90)BaTi(1−2x) YxNbxO3 + (10)Li0.5Fe2.5O4 (Y = Gd, Sm and x = 0, 0.05, 0.1) composites are prepared using the solid state method. The structural properties like X-ray diffraction (XRD), FESEM, electrical properties like electric modulus (M′), complex electric modulus (M″) and conductivity properties of doped and undoped composites have been discussed. The XRD studies confirm the tetragonal structure of all composites. FESEM studies reveal an increase in the average grain size of the (90)BaTiO3 + (10)Li0.5Fe2.5O4 composite upon doping with Gd/Nb and Sm/Nb. As and when the temperature of the sample is decreased, with frequency is similar but its conductivity has decreased. In the high frequency region, the frequencies beyond 100 MHz, the conductivity of all composites are not zero, which shows the existence of hopping of electrons to a new site. The real electric modulus (M′) of composites confirm the occurrence of dispersion in all composites at all temperatures. The imaginary electric modulus (M″) increases with frequency and exhibits a peak at a certain frequency. The relaxation time of all composites reveals the short range movement of charge carriers. The nearly same value of activation energy of all composites reveals that the distribution of energy barriers in the Gd/Nb and Sm/Nb doped 0.9BT0.1LF composites. The area of semicircles of all composites increase and the shift of the intercept of a semicircle towards the higher value of M′ represents an increase in the capacitance. The normalized scaling behavior of all composites is studied by plotting normalized parameters M″/M″maxVs Log (f/fmax).

Parameter of dielectric loss distribution in the new model for complex conductivity based on Havriliak–Negami formula

This paper is focused on the comparison of the results of various approximation models describing the frequency dependences of the dielectric constant [Formula: see text] and [Formula: see text], the tangent of the loss angle tg[Formula: see text] and the electrical conductivity [Formula: see text] and [Formula: see text] of nonlinear dielectrics. The classic ferroelectric material of the PZT system with [Formula: see text] was chosen as the object of study. Based on the analysis of temperature-frequency dependences of the “empirical” parameters [Formula: see text] and [Formula: see text], a regularity has been revealed that allows them to be calculated. A new relationship has been established through the parameter [Formula: see text], which allows to relate the temperature and frequency dependences of the complex electrical conductivity as [Formula: see text] and as [Formula: see text] in the Havriliak–Negami approximation models and in the new model for the description of the complex electrical conductivity [Formula: see text]. It is shown that [Formula: see text] is a parameter of the temperature-frequency distribution of dielectric losses. Using the obtained expressions, a new theoretical description of experimental spectra having a relaxation character was proposed. It has been proven that the use of the new model makes it possible to accurately describe the set of studied spectra, including the high and low frequencies, in the frequency range from [Formula: see text] to 108[Formula: see text]Hz.

Magnetic Structured Nickel Core-Shell @ Silica/PMMA Nanocomposites from Synthesis to Applications

Incorporating Ni@SiO2 nanoparticles on poly-methyl methacrylate (PMMA) can alter electrical, optical, and magnetic properties of Ni nanoparticles to be used for energy storage applications, photo electronic devices and spintronic applications. The Ni@SiO2/PMMA nanocomposite samples are prepared by casting method. The morphology of the prepared nanoparticles was examined through high resolution transition electron microscope revealed the formation of SiO2 coating on ni nanoparticles. Furthermore, the topography of nanocomposites was characterized by the field emission scanning electron microscope. We investigated the formation of crystalline phase of Ni nanoparticles through X-ray diffraction. The Complex dielectric permittivity, electrical conductivity, electric modulus and impedance spectra of the PNC films were investigated in the frequency range from 0.1 Hz to 10 MHz. The real and imaginary parts of the permittivity decrease with increasing frequency due to an increase in Ni@SiO2 content. All the nanocomposites showed relatively low conductivity values and high impedance that could be used for nano-dielectrics. UV–Vis spectrophotometer was used to measure optical properties such as transmittance, and absorbance at normal incidence in the wavelength range of 200–1100 nm. The transmittance was found to decrease while the absorbance increases with increasing Ni@SiO2 nanoparticles. The indirect optical band gap of the composite films was calculated, and it was sharply decreased. Magnetic hysteresis plots at room temperature of composites Ni@SiO2/PMMA were studied. All samples demonstrate ferromagnetic behavior with well pronounced magnetic hysteresis.

Synthesis, vibrational, thermal, mechanical and third-order nonlinear optical properties of sodium 4-methyl-3-nitrobenzoate monohydrate crystal for optical limiting applications✰

ABSTRACT A nonlinear optical (NLO) sodium 4-methyl-3-nitrobenzoate monohydrate (Na4M3N) single crystal was synthesized and grown by the slow cooling solution growth method using an ethanol-water (1:1) mixed solvent. Powder X-ray diffraction (PXRD) reveals the crystallinity of Na4M3N compound. The Na4M3N crystal was estimated with a single crystal XRD instrument and it was identified to be in the centrosymmetric space group (P21/c) having a monoclinic system. The vibrational, proton (1H) and carbon (13C) NMR spectral analysis substantiates the functional groups, hydrogen and carbons in the synthesized compound. The Hirshfeld surfaces analysis was executed to know the different type of interactions present in the crystal. From the UV–vis spectrum, the optical band gap and cut-off wavelength of the Na4M3N crystal are endowed to be 5.06 eV and 254 nm respectively. The Na4M3N crystal was subjected to a thermogravimetric as well as differential thermal analysis for discerning the thermal characteristics. The LDT value of crystal was endowed to be 5.8 GW/cm2 using Nd: YAG laser and the value is superior to that of KDP and Urea. The emission region of the compound was identified by the photoluminescence emission spectrum. The crystalline quality was again confirmed by lifetime measurements. The thermo-optic coefficient (dn/dt) was determined to be –3.5 × 10−5 K−1. The reverse saturable absorption observed by third-order NLO studies dictates the suitability for optical limiting applications. Vickers microhardness test showed that Na4M3N crystal was a soft material. The average etch pit density (3.2 × 103 cm−2) was determined from chemical etching studies. The complex dielectric constant, electric modulus and electrical conductivity values were measured as a function of frequency to get information on the conduction mechanisms.

Anisotropic complex electrical conductivity of black shale and mudstone from the Moffat Shale Group (Ireland)

ABSTRACTThe geological setting in the north of Ireland, especially concerning the origin of the Moffat Shale Group, has long been under discussion. Within the Tellus Programme of the Geological Survey Ireland, airborne electromagnetic measurements revealed high‐conductivity anomalies that have been interpreted as the response of a black shale. In order to petrophysically characterize the Moffat Shale, a laboratory study using material from two shallow boreholes was carried out. The study focuses on spectral induced polarization measurements on 23 oriented samples in the frequency range from 10−4 to 105 Hz.The sample material can be categorized into two groups. A mudstone‐like rock type shows weakly frequency‐dependent, porosity‐driven conductivities with a strong anisotropy. On the other hand, black shale samples are characterized by moderately anisotropic but strong polarization effects especially at low frequencies and a strong conductivity increase towards higher frequencies. The polarization in the black shale is controlled by the texture and volume fraction of the polarizable components. The spectral induced polarization data are processed by means of a Debye decomposition approach. The anisotropy of the complex electrical conductivity is determined by utilizing the foliation dip angle and assuming tilted transverse isotropic conditions. The relevance of the laboratory findings for airborne electromagnetic surveys is addressed with a synthetic one‐dimensional modelling study.

Investigation of Dielectric Properties, Electric Modulus and Conductivity of the Au/Zn-Doped PVA/n-4H-SiC (MPS) Structure Using Impedance Spectroscopy Method

Abstract The 50 nm thickness Zn-doped polyvinyl alcohol (PVA) was deposited on n-4H-SiC semiconductor as interlayer by electro-spinning method and so Au/Zn-doped PVA/n-4H-SiC metal-polymer-semiconductor (MPS) structure were fabricated. The real and imaginary parts of the complex dielectric constant (ε′, ε′′), loss-tangent (tan δ), the real and imaginary parts of the complex electric modulus (M′, M′′) and ac electrical conductivity (σ ac ) behavior of this structure were examined using impedance spectroscopy method in a wide range of frequency (1 kHz–400 kHz) and voltage (−1 V)–(+6 V) at room temperature. The values of ε′, ε′′, tan δ, M′, M′′ and σ ac are determined sensitive to the frequency and voltage in depletion and accumulation regions. The values of ε′ and ε′′ decrease with increasing frequency while the values of M′ and σ ac increase. The peak behavior in the tan δ and M′′ vs. frequency curves was attributed to the dielectric relaxation processes and surface states (Nss ). The plots of ln (σ ac ) vs. ln (f) at enough high forward bias voltage (+6 V) have three linear regions with different slopes which correspond to low, intermediate and high frequencies, respectively. The dc conductivity is effective at low frequencies whereas the ac conductivity effective at high frequencies. According to experimental results, the surface/dipole polarizations can occur more easily occur at low frequencies and the majority of Nss between Zn-doped PVA and n-4H-SiC contributes to the deviation of dielectric behavior of this structure.

An investigation on the conductivity, electric modulus and scaling behavior of electric modulus of barium titanate-lithium ferrite composite doped with Nb, Gd and Sm

The (90)BaTi(1-2x) RxNbxO3+(10)Li0.5Fe2.5O4 (R = Gd, Sm and x = 0, 0.05, 0.1) composites are prepared using solid state method. The structural properties like X-ray diffraction (XRD), FESEM electrical properties like electric modulus (M′), complex electric modulus (M″) and conductivity properties of doped and undoped composites have been discussed. The XRD studies confirm the incorporation of Gd and Sm in the composite. FESEM reveals an increase in the average grain size of composite upon doping with Gd/Nb and Sm/Nb. The conductivity and the real electric modulus (M′) of composites are increases steeply with increase in frequency at all temperatures. The real electric modulus (M′) of composites confirms the occurrence of dispersion in all composites at all temperatures. The imaginary electric modulus (M″) increases with frequency and exhibits a peak at a certain frequency. The peaks of complex electric modulus (M″) of composites have shifted towards higher frequency with temperature. The shift of the relaxation peak towards higher frequencies upon heating suggests the decrease in the relaxation rate of the process.

AC/DC conductivity and dielectric relaxation behavior of ionic solutions of 1-butyl-3-methylimidazolium chloride in methanol

The complex relative dielectric function, ε*(f) of solutions of 1-butyl-3-methylimidazolium chloride ([BMiM][Cl]) in methanol (MeOH) of varying concentration and temperature have been measured in lower (20 Hz–2 MHz) and microwave (200 MHz–20 GHz) frequency regimes using precision LCR meter and Vector Network Analyzer (VNA) respectively. Complex ac conductivity, σ*(f) of the liquid samples were determined from the measured low frequency ε*(f). DC conductivity, σdc of the samples were also determined. The influence of concentration and temperature variation on the complex permittivity and electrical conductivity of the solutions is discussed. σdc of pure [BMiM][Cl] and pure MeOH is significantly enhanced in diluted to moderately concentrated solution of [BMiM][Cl] in MeOH. Experimental values of σdc at different concentrations were fitted to the empirical Casteel-Amis (CA) equation. Static dielectric constant of ionic solutions was determined from complex permittivity measurements in the microwave frequency range, using which, information about the molecular interaction between [BMiM][Cl] and MeOH was revealed. Viscosity (η), molar conductivities (Λm), infinite dilution conductance (Λ0) and Walden product (W) of the solutions were also determined. Orientational relaxation behavior of the mixture solutions in microwave frequency region is not influenced by variation in concentration of [BMiM][Cl] in MeOH. Different contribution arising in the dielectric spectra are discriminated.

Exploring the Structural, Thermal and Dielectric Properties of PVA/Ni0.5Zn0.5Fe2O4 Composites

Nano-Ni0.5Zn0.5Fe2O4 embeded in polyvinyl alcohol (PVA) with different weight ratios (5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, 30 wt.%, 40 wt.% and 50 wt.%) were prepared by solution casting. The formation of PVA/Ni0.5Zn0.5Fe2O4 hyprid composite is confirmed through x-ray diffraction, scanning electron micrographs, transmission electron microscopy, and Fourier transform infrared spectroscopy analysis. Thermogravimetric analysis showed that the composite films have thermal stability higher than pure PVA. The complex dielectric constant (e*), electrical conductivity, electric modulus and impedance spectra of these polymer nanocompsites have been studied over the frequency range 1 Hz–20 MHz. The real permittivity (e′) of PVA polymer film enhanced while the real electric modulus (M′) decreased by the addition of Ni0.5Zn0.5Fe2O4 nanoparticles. The imaginary part of permittivity has the same trendline of e′ leading to the increase in its values. These aspects of PVA composites making it a promising material to be used in microwave absorbers depending on the dielectric loss.

On the Frequency-Voltage Dependence Profile of Complex Dielectric, Complex Electric Modulus and Electrical Conductivity in Al/ZnO/p-GaAs Type Structure at Room Temperature

On the Frequency-Voltage Dependence Profile of Complex Dielectric, Complex Electric Modulus and Electrical Conductivity in Al/ZnO/<i>p</i>-GaAs Type Structure at Room Temperature