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A series of (50 − x) P2O5–20B2O3–20CaO–10Na2O (x = 0–15 mol% MoO3) glass composition was prepared. Glass structure was analyzed using infrared absorption, UV–visible spectroscopy, electron spin resonance, density, and molar volume calculations. FTIR confirmed that Mo ions are contributed as MoO6 octahedral units in the glassy matrix, resulting in an increase in the pyrophosphate and BO3 groups at the expense of metaphosphate and BO4 units. UV–visible and ESR spectra detected Mo3+ and Mo5+ ions as species in the host glass due to the increase in MoO3 content. Broadband dielectric spectroscopy investigation on a broad range of frequencies and at different temperatures indicated that the enhancement of electrical conductivity of the prepared glasses due to molybdenum doping was prevented using confinement effect at the wells, causing demobilization of the charge carriers. Hence the dielectric spectra were caused by the mobility of charge carriers rather than the dynamics at the molecular scale. There is a clear correlation between the transport mechanism and dynamics at the interface of the charge carriers. Presently, the challenge is to understand if optimizing the accumulation of charges at the interfaces and electrodes is the origin of electrical storage energy.

The results showed that the annealing of polyvinyl alcohol (PVA) at 450 K has improved its electrical conductivity. Scientists had previously overlooked its great characteristics because of its insulating properties however, PVA showed a considerable increase in conductivity, making it a promising material for optoelectronic devices. The electrical and dielectric properties of PVA/n-Si heterostructure were investigated. The ideality factor, barrier height, and series resistance were measured at different temperatures using various approaches as Nord, Chueng, and the conventional method. A detailed analysis of Ac conductivity, real and imaginary parts of the impedance (Z’, Z“) were examined at different temperatures, voltages, and frequencies. The results showed that the value of the imaginary part of the impedance Z” changes with temperature, voltage, and frequency; however, the novelty here is that Z” only takes positive values if the frequency is set to a very low value, such as 10 Hz. The photocurrent properties were also studied confirming that PVA/n-Si structure is responsive to daylight illumination.

The present study examined polyvinyl alcohol, PVA, in its pure form without any additives. We investigated its application as a Schottky barrier device, which demonstrates the novelty of this research. We report the synthesis, current–voltage (I–V) and capacitance–voltage (C–V) characteristics, dielectric properties, x-ray diffraction of PVA/nSi. Several parameters, including the ideality factor (n), series resistance (Rs), barrier height (Φb), the saturation current (I0), and shunt resistance (Rsh) were estimated. It was found that the n values decrease with increasing temperature, setting the enhancement of the device features. (Φb) values tend to increase with temperature rise. Frequency, voltage and temperature dependence of electric modulus (( $$ M^{\prime}\& M^{\prime\prime} $$ ) was investigated, showing that $$ \left( {M^{\prime}} \right) $$ decreases with temperature (T) while the values of $$ (M^{'} $$ ) are increased with frequency (f). But at low frequencies $$ (M^{'} ) \,{\text{rises }}\,{\text{when }}\, T\, {\text{is }}\,{\text{raised}}. \,{\text{While }} $$ ( $$ M^{\prime\prime}) $$ tends to be reduced with increasing T at (f) = 10 and 103 Hz, with increases at (f) = 2 × 107 Hz. We observed semicircles in the Cole–Cole plots where the radii of curvature increased with temperature and voltage. I–V characteristic at different temperatures (298–423 K)

The aim of this work is to invent a novel technology for manufacture not only graphene oxide, but also conductive graphene oxide. This is the novelty in this technology, which is not available in any other method for preparing graphene oxide. This study describes a unique way for preparation of conductive nano-particles of graphene oxide, GO. The advantages of this technology is very simple, low cost, short time of preparation and can be manufacture a large amount of conductive GO by firing polyvinyl alcohol PVA on SiO2/pSi to preparation this assembly GO/SiO2/pSi as a Schottky barrier diode or Metal Oxide Semiconductor, MOS. Besides the pioneering in this article GO is deemed insulator, however with rising temperature through firing PVA, its conductivity remarkably enhances and the produced GO can be used as a conductor. The as-prepared sample has been characterized using different techniques (e.g. Scanning Electron Microscopy (SEM), Raman Spectroscopy, X-Ray diffraction (XRD) and Impedance Spectroscopy. Temperature, voltage and frequency dependences of M’, M’’, 1/C2, Rs, σac and tanδ of GO/SiO2//p-Si diodes were achieved in the varied ranges of voltage and frequency. I-V characteristic of GO/SiO2/pSi Schottky-diode is taken at different temperatures. The elementary factors of the diode such as barrier height (Φb), series resistance (Rs) and ideality factor (n), of GO/SiO2/pSi are also considered. The nyquist plot of M″(M′) at different voltages and temperatures were examined.

In this work, we presented a novel method to produce graphene oxide – nanoparticles. This method based on burning polyvinyl alcohol upon the surface of SiO2/p-Si surface. Graphene oxide, whatever its method of preparation, usually has lower values of electrical conductivity. Researchers perform a reduction process to improve its electrical conductivity. The new in our method is that, the prepared graphene oxide has high electrical conductivity. This is originated from raising the temperature to be about 400C during preparation giving save of effort, time and money. GO structure was confirmed using SEM, FTIR, Raman spectroscopy and XRD techniques. Electric properties for GO/SiO2/p-Si were done by using I-V measurement. Ideality factor, barrier height, series resistance, shunt resistance and resistance junction were all determined. Dielectric characteristics including variations of capacitance (C) and conductance (G) with voltage are studied. The complex permittivity (e*) and real part of conductivity (σac) in addition to loss tangent (tan δ) have indicated a strong function of temperature and applied voltage. The features of the (Z') , Z'' and σac'', σac' below the altering voltages and temperatures established a shape of semicircle having a semicircular center underneath the Z’ and σac' coordinate. The thickness of silicon oxide layer calculated for the sample was found to be 46 nm.

Textile fabrics possess multitude applications and a wide variety of highly technical uses. Microfiber is one of the most popular synthetic fibers. Its popularity is a result of special properties such as good resiliency, heat resistance, light weight, water proof and durability. In the present work, two woven fabrics were synthesized from polyester microfiber and then coated by calcium silicate/copper oxide-nanoparticles, (CaO3Si/CuO)-NPs, using low temperature plasma (dielectric barrier discharge) technique. The coated textiles were investigated by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX). A broadband dielectric spectroscopy (BDS) was employed to study the treatment conditions on the electrical and dielectric properties over a wide range of frequencies. The results showed that, the resistivity of the textile samples was remarkably enhanced upon coating with the (CaO3Si/CuO)-NPs) accompanied by a reduction of the static charges accumulated on the surface. These results made the plasma sprayed coated textiles promising for electrical applications like cables isolation as well as packing and packaging.

Electrochemical conductive hydrogels are being extensively explored in the fabrication of portable batteries and high-performance supercapacitors. Herein, the rational design of a new polyanionic electrically conductive hydrogels based on sodium alginate-g-poly(AM-co-ECA-co-AMPS) are described. rGO was incorporated into the hydrogel during the polymerization process generating rGO@ sodium alginate-g-poly(AM-co-ECA-co-AMPS) composite hydrogels to study the impact of rGO on the performance of the hydrogels. FT-IR, XRD, and SEM-EDX characterized the chemical composition, crystalline, and morphological structure of the new synthesized hydrogels. The electrochemical performance of as-synthesized hydrogels was investigated by cyclic voltammetry, galvanostatic, charge-discharge rate, and electrochemical impedance spectroscopy. The supercapacitor performance for ECH2.5 composite hydrogel showed a capacitance of 753 F. g

Epoxy resins are important industrial polymers due to their versatile properties and ease of preparation. They are used on a large scale in coating and adhesives applications. Epoxy resins are prepared by photo-curing technique or thermal curing method in presence of different hardeners. The first method is used for small areas while the latter is utilized mainly for coating applications. Graphene and its oxide have proved themselves as good fillers for epoxy resin since the formed composites demonstrated enhanced mechanical, thermal and electrical properties. This article gives insight view for synthesis techniques and properties of these composites with a deep discussion for electrical and dielectric investigations of epoxy resins loaded with threshold concentration of graphene oxide. A case study of dielectric properties of epoxy resin/modified graphene oxide composite, is presented in which effect of curing technique on dielectric behavior is explored. Although the amount of filler was kept at the threshold concentration (1% by weight) obvious change in the dielectric properties could be observed unlike the rest of properties.

Films of polyethylene oxide (PEO) filled with silicon dioxide (SiO2) were synthesized via casting method. The formation of the PEO/SiO2 nanocomposites was characterized by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) measurements. The XRD patterns confirmed that increasing SiO2 in semicrystalline PEO enhances the amorphousity and causes a disturbance in the crystalline phase. The influence of the SiO2 on the dielectric relaxation spectra of PEO in wide temperature and frequency ranges was investigated. Two molecular relaxation processes are observed: main (α-) and secondary (β-) relaxations. For the α-process, the process slowed down with adding SiO2 fillers reflecting an increase in the glass transition temperature, Tg. This trend was also verified by differential scanning calorimetry (DSC). The findings indicated that adding SiO2 restricted the motion of PEO segments, while such changes were not observed in the glassy state. Further, the attenuation of the electric field of the terahertz waves passed through PEO/SiO2 samples was evaluated. In the terahertz range, the resonant peaks of PEO originated from lattice vibration feature the complex dielectric function. These peaks were weakened broadened and red-shifted by increasing of SiO2 concentrations.

The optical, dielectric response, and ac-conductivity properties for six glasses of zinc lead-borate doped with different contents of Fe3+ (Fe2O3 = 0 to 10 wt%) have been investigated. UV–Vis spectra in 190–1100 nm wavelength have been carried out. Band gaps for optical energy (EOptical), Urbach’s energy (EU), index of refraction (n), steepness parameter (S), energy dispersion parameter of refractive index (Ed), single-oscillator energy (Eo), the dispersion refractive index (no), minimum reflectance wavelength (λo), and oscillator strength (So) were evaluated. Results reveal that the indirect energy gap varies from 2.57 to 1.01 eV, while the direct energy gap takes values from 2.80 to 1.45 eV. The EU values change from 0.232 to 0.966 eV for glasses with Fe2O3 = 0 and 10 wt%, respectively. Also, S and λo decrease with the enhancement of Fe2O3 content. The dielectric response and ac-conductivity of the prepared glasses were investigated by broadband dielectric spectroscopy, BDS, in the frequency range from 0.1 Hz to 10 MHz and at temperatures ranging between 300 and 430 K. Two trends of activation plot have been observed in the conductivity of the samples with low content of Fe2O3. Although these samples show a perfect insulation features, they obey an anomalous behavior at higher temperatures. Therefore, the investigated glasses can be applied in several optical and optoelectronic devices. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.

In this work, we intended to investigate the antimicrobial activity, biocompatibility, and study the electrical conductivity of the polypyrrole on the surface of the conducting hydrogel such as carboxymethyl cellulose-g-poly (acrylamide-co-acrylamido-2-methyl-1-propane sulfonic acid). Broadband dielectric spectroscopy was employed to follow up the electrochemical double layer that developed at the electrode surfaces. Biocompatible conducting hydrogel showed the establishment of the electrical double layer in a wide range of frequencies, and the DC-conductivity values were in top of the semiconductors range. The addition of polypyrrole not only diminishes the effect of water transformations on conductivity, but also manifests the permittivity’s value (from 1.7 × 106 to 2.4 × 108). In addition, it lowers the charging–discharging loss of energy. Comparing the prepared conductive hydrogels to the ionic liquids, it showed that hydrogels have more ability to be applicable in the energy storage systems. Also, the prepared hydrogels biocompatibility was tested against normal cell line (Vero cells) which recorded the excellent compatibility with cells. The antimicrobial activity was examined against some pathogens; (i) Gram-negative bacteria: Escherichia coli (NCTC-10416) and Pseudomonas aeruginosa (NCID-9016); (ii) Gram-positive bacteria: Bacillus subtilis (NCID-3610); (iii) unicellular fungi: Candida albicans (NCCLS-11) and (iv) filamentous fungi Aspergillus niger (ATCC-22342).

In this work, a detailed insight to the microstructure, morphology, surface topography, electrical and optical properties in visible and terahertz range was presented for polyethylene oxide (PEO)/silicon dioxide SiO2 nanocomposites. PEO-filled with various contents of SiO2 nanoparticles were synthesized via the solution cast technique. The polycrystalline nature of PEO/SiO2 films was affirmed by the selected area electron diffraction pattern (SAED) recorded by HRTEM measurement and it was found to nearly conformable with X-ray diffraction data. The energy-dispersive X-ray analysis (EDAX) proved the existence of SiO2 with wt% ranged from 0 to 5% as starting fillers. The high-resolution scanning electron microscope planar images indicated uniform distribution of SiO2 nanoparticles within the PEO films. The atomic force microscope 3D images depicted the surface changed from rough to smooth upon the filling with SiO2. The composite samples exhibit absorption spectra that extended from UV–Vis to near infrared regions. Based on Tauc's formula, it was found that the absorption edge shifted from 4.90 to 3.20 eV as the filler fraction increased from 0 to 5 wt%. The analysis of reflective index in the UV–Vis–NIR regions displayed decrement with increasing filler content. Moreover, the refractive index in Vis–NIR regions is good extension to that in THz region expressing the optical quality of studied films. The optical dispersion parameters were analyzed in the view of Wemple-Didomenico single oscillator and Sellmeier model. The values of nonlinear optical parameters (nonlinear susceptibility χ(3) and nonlinear refractive index (n2) were influenced by the filler fractions. Upon the rise of filler content, the conductivity values show slightly decrement.

Pure BST and doped BSTF (with BSTF2: Fe2O3 2 wt % and BSTF4: Fe2O3 4 wt %) ceramics were prepared by solid state reaction. XRD pattern showed the different phases were formed depend on the weight percent of Fe2O3. The crystal size and lattice parameters increased while the lattice strain decreased. The topography of the sintered samples shows increase of the grain size with increasing Fe2O3 ratio and hence enhances the compaction of ceramics. Broadband dielectric spectroscopy was employed to investigate the effect of magnetite nanoparticle on the dielectric properties of the pure BST ceramic. The interfacial polarization and the conductivity contribution reflect the high values of permittivity and its gradual increase as frequency decreases. The two BSTF samples show relaxation peak dynamic originated from presence of immobile species/electrons at low temperatures and defects/vacancies results from the formation of oxygen vacancies originates from the spontaneous change in oxidation states of Fe ions (Fe 3+/Fe2+) at high temperatures. The relaxation rate obeys Arrhenius law at high temperatures in case of BST sample with activation energy 225 kJ/mol. This high value of activation energy at higher temperatures reflects and confirms the slowed down of the dynamics at the interphase and the decoupling nature of the OH-dynamic and the interfacial polarization.

Fe2Cd1-xMnxO4 (x= 0, 0.25, 0.5, 0.75, 1) spinel ferrite nanoparticle samples were synthesized using a flash auto-combustion technique and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The inspection of dielectric and magnetic properties of the prepared ferrites was carried out by using broadband dielectric spectroscopy (BDS) and vibration sample magnetometer (VSM) measurements, respectively. X-ray diffraction analysis verified the formation of the main cubic phase with space group Fd3m and a decrease in lattice constants with the increase in Mn-content. FTIR study revealed the two characteristic absorption bands of spinel ferrites and their dependence on Mn-content was investigated and explained. Elastic moduli such as Longitudinal, transverse and mean elastic wave velocities (𝑉𝑙 , 𝑉𝑡 𝑉𝑚), bulk modulus (𝐵), rigidity modulus (𝐺), Young modulus (𝐸) and calculated Debye temperature (θD) have been studied and found to decrease with the increase in Mn-content. SEM analysis revealed nanoparticles agglomeration of uniform grains with increasing in the average grain size as Mn-content increased. The VSM measurements showed an increase in saturation magnetization (Ms) accompanied by a decrease in coercivity (Hc) as Mn-content increased. Dielectric investigations showed very high values of permittivity and dielectric loss at lower frequencies reflecting the combination of exchange of electrons between ferrous and ferric ions and ions’ transport. The ac-conductivity showed a plateau that yields the dc-conductivity (σdc) at lower frequencies followed by a characteristic frequency (νc) at which it tends out to follow a power law. The relation between these two parameters confirms the empirical BNN-relation.

We present the preparation of polystyrene-polyaniline composites by an emulsion polymerization technique. Polyethylene glycol and dodecylbenzenesulfonic acid were used as nonionic and anionic surfactants, respectively, for emulsion preparation. Fourier transform IR spectroscopy, UV–vis spectroscopy, and thermogravimetric analysis were used to characterize the composites obtained. Surface morphological investigations by scanning electron microscopy showed that the emulsion technique using polyethylene glycol produces the most homogeneously distributed composites. Thermal analysis in conjugation with broadband dielectric spectroscopy revealed that as the composite conductivity increased, the temperature at which the maximum degradation rate was achieved gradually decreased. The dielectric investigation showed the α-relaxation process in pure polystyrene has an activation energy of 10.8 kJ/mol and is accompanied by a dielectrically determined glass transition temperature of about 366 K. After addition of polyaniline, this α-relaxation process was masked by the conductivity contribution. Moreover, polyaniline prepared with the anionic surfactant had higher electrical conductivity than that prepared with the nonionic surfactant because of its ordering effect on the structure. Surprisingly, the dependence of the conductivity of the composites on temperature, regardless of the preparation method, has two different trends, and each can be attributed to a different mechanism of charge transport.

Nanocrystalline PbTe thin films were deposited on a glass substrate by thermal evaporation technique with two thicknesses namely, 45 and 250 nm. The structural studies revealed that the films have nanocrystalline cubic structure and the particle size was found to be 11 and 20.7 nm, for low and high thicknesses respectively. The FE-SEM study shows that the surface grains increase for higher thickness film. This indicates that samples lying under the strong regime of confinement for PbTe thin films. The optical properties confirm the occurrence of confinement process as the optical band gap are 1.67 and 0.9 eV for 45 and 250 nm films, respectively. The dielectric results indicated that the conductivity increases by about two orders of magnitude with increasing the thickness from 45 to 250 nm. Moreover, the permittivity shows a higher dispersion step at lower frequencies in both samples due to the hopping conduction mechanism in addition to the interfacial polarization in such heterogeneous structures. Another small dispersion step is noticed in case of the lower thickness. It is attributed to the polarization of the accumulated charge carriers near the grain boundaries interfaces. No indication of any electrode phenomena in both samples is shown here.

Nanocomposites of polymethyl methacrylate (PMMA)/cellulose nanocrystals (CNC) have been developed through physical mixing of different ratios of CNC with dissolved PMMA. Solvent exchange method has been carried out in order to increase the dispersion of CNC in the polymer matrix. The obtained composite films showed high transparency. Moreover, its barrier properties against water vapor were significantly increased. The nanocomposite films were further coated with a layer of polyaniline (PANI) which showed a negligible electrical conductivity as confirmed by electrical properties investigations, but imparted antioxidant properties on the coated films. The inhibition ability reached up to 45% after 4 h and did not decrease upon storage for 3 months. Moreover, the coated nanocomposite films showed good antimicrobial activities against food poisoning microorganisms. The obtained results indicate that such modified PMMA composites could be a promising candidate for active food packaging.

Novel glass-ceramics of the nominal molar compositions 20Fe2O3·20B2O3·(60-x)V2O5· (xNa2O or xSrO) (where x = 0 or 10) were prepared by traditional melt technique. Differential thermal analysis (DTA) was implemented to study the thermal behavior of the prepared glasses. Vanadium pentoxide (V2O5), iron vanadate (FeVO4), sodium vanadate (Na3VO4) and strontium vanadate (with different formulae) were crystallized and identified by X-ray diffraction (XRD) analysis under certain conditions of heat-treatment. Further characterization of glass and glass ceramics samples were performed using scanning electron microscope (SEM), density, electrical and dielectric measurements. In conclusion, our study elucidated that the substitution of vanadium by Na+ and Sr2+ ions enhanced the conductivity at 180 °C from 5.11 × 10−4 for unmodified glass to 2.93 × 10−3 and 1.03 × 10−2 S cm−1 for Na- and Sr-modified glasses.

This study provides insights about the influence of incorporation of silver nanoparticles or silver nanoparticles@polypyrrole composite on the thermal behavior, mechanical properties, and electrical conductivity of carboxymethylcellulose-g-poly(acrylamide-co-acrylamido-2-methyl-1-propane sulfonic acid) hydrogel prepared via graft copolymerization and cross-linking of acrylamidomethylpropanesulfonic acid and acrylamide into carboxymethyl cellulose. The hydrogel exhibited improved the thermal stability and mechanical properties, increased specific surface area, pore radius, and pore volum upon incorporation of silver nanoparticles. Meanwhile the addition of polypyrrole to the hydrogel negatively impacted the hydrogel thermal stability, surface area and mechanical properties. The electrical conductivity measurements were studied at range frequency range of 100 mHz to 10 MHz. The results revealed the remarkable enhancement of the dc conductivity for the hydrogel containing silver nanoparticles@polypyrrole. The dielectric properties of the composite containg hydrogel/silver nanoparticles@polypyrrole promise their utility as a green, cheap electrical conducting electrolyte in the fabrication of supercapacitors and energy storage devices.

The current work focuses on a cheap and simple preparation of highly conducting chitosan/hydroxyl ethylcellulose/polyaniline loaded with graphene oxide doped by silver nanoparticles (CS/HEC/PAni/GO@Ag) bionanocomposite as a biodegradable and biocompatible hydrogel for energy storage technology. Scanning electron microscopy (SEM) displays the compatibility of chitosan, hydroxyl ethyl cellulose, and polyaniline and a good distribution of GO@Ag-NPs in bionanocomposite hydrogels. X-ray diffraction (XRD) displayed the structure and existence of GO@Ag-NPs in the matrix. The swelling percentage and the antibacterial activities slightly increased with raising the content of GO@Ag-NPs. Also, the presence of both chitosan and cellulose improves the biodegradation of the fabricated bionanocomposites, which is increased by adding GO. Moreover, the incorporation of 5% GO@Ag-NPs in hydrogels enhances dc-conductivity by about 25 times from 3.37 × 10−3 to 8.53 × 10−2 S/cm. The fabricated hydrogels are inexpensive, eco-friendly, and have high capacitance and permittivity, and so they can store electrical energy.

This work studies the effect of composite formation between polyvinyl acetate (PVAc) and conductive polyaniline (PAni) on its conductivity mechanism. To achieve this goal, different concentrations of PAni in mini-emulsion of PVAc are prepared. The dynamic relaxation and electric conductivity are evaluated using broadband dielectric spectroscopy technique. The relaxation rate of the local reorientations (β-process) of ester group follows an Arrhenius relation with activation energy 39 kJ/mole. The coupling of the segmental dynamic (α-process) and terminal fluctuation (β′-process) occurs just above the calorimetric glass transition temperatures, Tg, of pure PVAc. This is reasonable since α-process that originated from a structural rearrangement became very slow below Tg which takes the polymer toward its equilibrium state. There is also decoupling of the charge carriers transport, and the segmental motion, the concept concluded in this manuscript, sounds reasonable if one thinks about the ion motion at T

A stable Sr4Fe6O13 was prepared as small crystallites by auto-combustion of a sol-gel in air followed by annealing the later at pertinent temperatures. A green sample, as annealed at elevated temperatures, yields a single Sr4Fe6O13 phase of tailored magnetic properties. The structural, morphological, magnetic and electrical properties were investigated by X-ray diffraction, transmission electron microscopy, vibrating sample magnetometer, and broadband dielectric spectrometer. Hard magnetic Sr4Fe6O13 properties arise with saturation magnetization Ms = 12.4 emu/g, coercivity Hc = 3956.7 Oe and squareness 0.512. Studies made at low temperatures reveals Ms decreasing on increasing temperature from 17.5 emu/g at 85 K down to 12.4 emu/g at 305 K, while Hc rises from 1483 Oe at 85 K to 1944 Oe at 305 K. The ac-conductivity follows the Jonscher relation. The dc-conductivity at high temperatures/low frequencies exhibits a plateau and it depends linearly on a characteristic frequency according to the Barton-Nakajima-Namikawa) relation.

The conducting polymer nanocomposites and bionanocomposites attracted greatly significant attention recently owing to their usage in diverse fields, particularly in electrical storage devices. Conducting hydrogel bionanocomposite based on magnetite nanoparticles (Fe3O4-NPs) was synthesized from chitosan/polyacrylic acid/polypyrrole. Furthermore, different ratios of Fe3O4-NPs were added to the synthesized biocomposites to improve the thermal and the electrical conductivity properties of the conducting bionanocomposites hydrogel. In addition, morphology and swelling percentage of the fabricated bionanocomposites hydrogel were investigated. The influence of the conductive polymer and the magnetite nanoparticles on enhancement the conductivity of the bionanocomposites is the main objective of this work. The broadband dielectric spectroscopy was employed to study the electrical and dielectric properties of the investigated samples. The addition of PPy increased the conductivity of the hydrogel by about four orders of magnitude. Furthermore, the effect of adding Fe3O4-NPs at ratios 1–5 wt% was at the satisfactory level.

Bionanocomposites hydrogel based on conducting polymers were successfully fabricated from chitosan/polyacrylic acid/polypyrrole (CS/PAA/PPy) as well as the magnetite nanoparticle (Fe3O4-NPs) was prepared via co-precipitation method. In addition, different ratios of Fe3O4-NPs were added to the prepared bionanocomposites to enhance the antimicrobial and the electrical conductivity of the prepared conductive hydrogel. Furthermore, the morphology, the swelling percent, antimicrobial activity and the dielectric properties of the prepared conducting bionanocomposites hydrogel were investigated. The antibacterial activities of the experienced microbes were improved with the increasing the loading of Fe3O4-NPs in conducting Bio-nanocomposites hydrogel. Moreover, the DC-conductivity was examined and our resulted indicated that the DC-conductivity was enhanced by increasing the loadings of Fe3O4-NPs compared to that of the pure CS/PAA as well as CS/PAA/PPy.

Composite of polystyrene (PS) and a biodegradable polymer, polycaprolactone (PCL), has been prepared by miniemulsion polymerization technique. In the procedures, different amounts of commercial PCL were added during polymerization of PS in presence of sodium lauryl sulfate (SLS) as a surfactant. Formation of PS and PS/PCL nanoparticles was confirmed by Transmission Electron Microscope (TEM) and their structure was investigated using Fourier Transform Infra-Red (FTIR)and UV spectrometry. Encapsulation of PCL particles yielded nanoparticles of gradual enlargement in size as revealed by zeta sizer. However, significant information about the molecular dynamics within the composite and charge mobility can be realized by Broadband dielectric spectroscopy (BDS). So that, BDShas been employed to investigate the electrical and dielectric behavior of the considered composites over a wide range of frequency and temperature. It was found that the dielectric properties of the composites seem to be mainly due to the PS shell with no significant effect for presence of PCL in the core. The linear decrease of the real part of conductivity of the prepared blends with decreasing frequency just like the perfect insulator confirmed the encapsulation feature of the structure. The new materials can find applications in packaging, household beside biomedical fields.

Smart textile is considered to be a new trend that can revolutionize the functionality of clothing. One of the most promising fields of smart textiles is in energy storage devices. Recently, many research efforts focus on supercapacitor as an energy storage device that can overlap the gap between conventional batteries and traditional capacitors. Activated carbon fiber (ACF) is one of the important candidate for this application. Different groups of non-woven polyester fabrics were prepared with and without adding the activated carbons. The effect of structure of the samples on the permittivity, dielectric loss as well as the ac-conductivity is investigated and interpreted. The mechanism of the storage of the charge carriers is given by two different capacities. The first one is the capacity of the electric double layer at the interface between the electrode and the dielectric material. The second is the capacity due to the redox or what is called pseudo capacity. In this work, the broadband dielectric spectrometer, BDS, is employed to study the effect of frequency in the range of 1mHz – 10 MHz and sometimes temperature (20 – 60 oC). The non-woven samples prepared with ACF showed the best results among the prepared nonwoven samples without activated carbon fibers and even nonwoven samples with carbon granules. This is due to the good electrical conductivity of activated carbon fiber used in the nonwoven samples.

Cellulose has attracted much attention as a potential substrate for low-cost, flexible electronics. Here, new cellulose-based films embedded with nano-silver (AgNs) and carbon (C) were successfully prepared. First, cellulose was oxidized to tricarboxy cellulose (TCC) using 2,2,6,6 tetramethylpiperidine-1-oxyl followed by periodate oxidation. Then, nano-silver was prepared by polyol method and carbon was prepared via a single-step from bagasse. The structure, thermal, morphology, mechanical properties, and broad-band were characterized by infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy with energy-dispersive X-ray, X-ray diffraction, and stress-strain relation. The results showed that the tensile strength and thermal stability of the films were improved. The temperature dependence of permittivity, ε′ of the TCC film, increased in two trends. However, TCC film shows non-conducting features, especially at lower temperatures; its nanocomposites films show a semiconducting behavior, and its ac-conductivity follows the empirical Jonscher law. Although the temperature dependence of dc-conductivity of the TCC/C, shows an Arrhenius behavior with low activation energy (≈3.74 kJ mol−1.), its investigated nanocomposites follow the well-known Vogel Fulcher Tamman equation according to the fragility of the prepared samples and/or the correlation between the interfacial polarization and conductivity.

Incorporation of graphitic carbon nitride (g-CN) in a conductive polymer matrix has been used for different applications. However, the conductivity behavior of the conjugated polymer in the presence of g-CN still needs thorough exploring. This work investigates the electric conductivity of polyaniline/g-CN nanocomposites synthesized via an in situ oxidative polymerization reaction. The chemical structure of the prepared materials was studied using Fourier-transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The electrical and dielectric parameters were measured and calculated through broadband dielectric spectroscopy. The temperature dependence of the permittivity shows different trends depending on the polarization and conductivity mechanisms. The DC conductivity of all samples varies only by one order of magnitude. Its value at 373 K increases from 0.21 mS/cm for 1% g-CN to 2.2 mS/cm for 5% g-CN. However, the DC conductivity reduces again to 1.6 mS/cm for the sample containing 7% g-CN. The charge carrier mobility has a dominant effect on the conductivity, and its activation behavior shows unusual characteristics.

In this article, we map the dielectric properties of manufactured metal-polymer-semiconductor (MPS) Schottky barrier diode consisting of aluminum (Al), polyvinyl alcohol (PVA), and n-type silicon (n-Si), under different conditions of applied frequency (1 Hz–20 MHz), voltage (-2–2 volts), and temperature (-50–90 °C). By tuning all these parameters, we could activate all possible polarization modes at the PVA/Si interface and reach tremendous values for the dielectric constant of our sample (e′ >3000) with a conveniently low dissipation factor (tan δ ≥ 30 °C. These promising values are motivating for using Al/PVA/n-Si Scottky diode structure in innovative energy storage applications.

The structure of carbon nanotube CNTs functioning as p-type material deposited over n-type silicon to produce heterojunction of Au/CNTs/n-Si/Al is presented in this study. This work explored the capacitance and conductance at various frequencies, temperatures, and voltages, the novelty here is that negative capacitance and conductance were observed at high frequencies in all temperatures and voltages, whereas capacitance appeared at both high and low frequencies, such as (2 × 107,1× 107,1 × 102,10) Hz. At high-frequency f = 2 × 107 Hz, the capacitance raises while the conductance decreases; at all temperatures and voltages, the capacitance and conductance exhibit the same behavior at particular frequencies such as 1 × 106,1 × 105,1 × 104,1 × 103 Hz, however their behavior differs at 2 × 107,1 × 107, 1 × 102 and 10 Hz. Investigating the reverse square capacitance with voltage yielded the energy Fermi (Ef), density surface of states (Nss), depletion width (Wd), barrier height, series resistance, and donor concentration (Nd).

Rhyodacite is a good source of major oxides, as these are contained in its essential mineral components, such as quartz, oligoclase, and albite. Thus, using natural rhyodacite and kaolin, dielectric self-glazing ceramic materials were prepared that exhibit excellent dielectric properties. The obtained materials were sintered at different temperatures to determine their vitrification ranges and optimal sintering temperatures. As well as determining the composition and microstructure of the phases obtained, their physical, thermal, and mechanical properties were also measured. The prepared materials exhibit low dissipation factors and stable dielectric constants at high frequencies, making them promising dielectric materials for use in high power circuits that operate at high speed.

An ex-situ approach was applied to prepare nanocomposites from hyperbranched poly(amidoamine) and modified kaolinite (Ka-DCA). The structure of the polymer and the corresponding nanocomposites was investigated by FTIR, DSC, SAXS and TEM. SAXS might suggest a partly exfoliated structure of the nanocomposites, which was supported by TEM. The molecular dynamics was studied by means of broadband dielectric spectroscopy (BDS). The dielectric spectra are dominated by a conductivity contribution at higher temperatures for all samples investigated. The obtained results further indicated that DC conductivity is increased by 4 orders of magnitude with increasing concentration of Ka-DCA nanofiller. Further, a significant separation between the conductivity relaxation time and that of segmental dynamics was observed. The decoupling phenomenon and the conductivity mechanism were discussed in detail. This study provides insights about the influence of the nanofiller on the structure and the conductivity contribution of nanocomposites of hyperbranched polymers including the decoupling phenomenon and fragility.

Cyanoethyl cellulose (CEC)/ magnetite (Fe

The chitosan/polyacrylic acid/polypyrrole/loaded with silver nanoparticles (CS/PAA/PPy/Ag-NPs) bionanocomposite as conductive, biodegradable, and biocompatible hydrogels were prepared by the casting method. Silver nanoparticles (Ag-NPs) were incorporated into the prepared bionanocomposite hydrogels to reinforce the electrical conductivity as well as the antimicrobial properties of the prepared hydrogels. The scanning electron microscopy revealed the compatibility of chitosan, polyacrylic acid, and polypyrrole, as well as Ag-NPs, were inserted in the polymer matrix and dispersed well on the superficies of the prepared bionanocomposites. X-ray diffraction displayed the presence of Ag-NPs into the polymer matrix. Also, the appearance of characteristic peaks in the Fourier transform infrared confirmed the compatibility of three polymers. Additionally, the swelling properties, antimicrobial activity as well as the electrical and dielectric characteristics of the fabricated bionanocomposites hydrogels were investigated. Moreover, the DC-conductivity was studied and our data designated that the DC-conductivity of the prepared bio-nanocomposites was improved by the existence of PPy more precisely than that of Ag-NPs. However, both were of high conductivity compared to that of the CS/PAA and found to follow the BNN universal relation. Also, The activation energy of about 55 kJ/mol of CS:2PAA hydrogel and reduce to about 15 kJ/mol in all the considered bionanocomposites after addition of Ag-NPs. Furthermore, the antibacterial activities of the knowledgeable microbes were improved as a result of the presence of Ag-NPs in bionanocomposites hydrogels.

The present work is concerned with the synthesis and studying the electrical and dielectric properties of Polyaniline (PANI)/Mn3O4/Reduced Graphene Oxide (RGO) nanocomposites using the Broadband Dielectric Spectroscopy technique. Polyaniline/Mn3O4 and polyaniline/Mn3O4/RGO nanocomposites were prepared using in-situ polymerization. To investigate the structural and morphology of the prepared samples, XRD, FTIR, HRTEM and SEM techniques were used. XRD results of pure Mn3O4 and PANI showed that PANI has crystallinity to some extent and the formation of Mn3O4 as a major phase with crystallite size ~20 nm is obtained. In case of nanocomposite samples, PANI/Mn3O4 and PANI /Mn3O4/RGO revealed a slight disappearance of the characteristic peaks of Mn3O4, which may be attributed to the covering of Mn3O4 surface by PANI. FTIR analysis of the nanocomposite samples indicated that the characteristic absorption peaks are shifted to higher wavenumbers compared with that of pure PANI confirming the interaction between PANI, graphene and Mn3O4. The morphological study of the samples revealed a porous surface of micro aggregates of Mn3O4 and PANI enveloped by RGO sheets and showed the distribution of Mn3O4 nanoparticle and PANI nanofibers on and between the thin sheets of RGO. The value of dc conductivity is rather high, and the prepared nanocomposites could be considered as synthetic metals from the conductivity point of view of such plastic electrode materials.

The aim of the paper has always been to explore the possibility of constructing new electronics devices based on Au/CNT/TiO2/SiO2/p-Si/Al multi-layers structure highlighting the appearance of negative dielectric constant (ε′) and dielectric loss tangent (ε′) at low frequencies in the range 5000–10 Hz. We have investigated the structural, electrical, and dielectric properties of this structure using different techniques like SEM, XRD pattern, Raman spectroscopy, I-V, and C-V measurements. At various temperatures, frequencies, and voltages, we present a detailed analysis of the dielectric constant and dielectric loss tangent. The highest dielectric constant combined with the lowest dielectric loss tangent would improve the use of Au/CNT/TiO2/SiO2/p-Si/Al structures in various electronic applications such as diodes, energy storage, and supercapacitor devices. In this study, the maximum dielectric constant values were around 4000, with dielectric loss tangents ranging from 0.08 to 0.32 at high and mid-frequency ranging from (2 × 107 − 105 Hz). The Col-Col diagram of ε′ as a function of ε′ of Au/CNT/TiO2/SiO2/p-Si/Al was also investigated.

The novel in this article is the appearance of negative capacitance at low frequency in this structure carbon nanotube/TiO2/SiO2/p-Si, which has not been studied yet in terms of its structural, electrical, and dielectric properties. The CNT/TiO2/SiO2/p-Si was synthesized as a metal oxide semiconductor (MOS) structure. The structural, electrical, dielectric, and capacitance were investigated by XRD, I-V, and C-V measurements. Besides the electrical properties, we present here a comprehensive study of capacitance and its variation with frequency, voltage, and temperature. Through this study, we can control and tune the capacitance in terms of its value as well as its signal polarity as positive or negative values the tunneling behavior and negative resistance were realized in I-V measurements. The capacitance vs temperature, voltage, and frequency was explored, it takes positive values reaching its maximum of about 2.12 × 10−9–2.4 × 10−7 F at high frequencies from 2 × 107–103 Hz, but at low frequency from 103–10 Hz, it takes high positive and negative values to reach 4 × 10−3–5 × 10−3 F respectively.

In this study, a nanostructure of graphene oxide films was deposited on the surface of silicon oxide to form a hybrid heterojunction diode. The characteristics of dielectric were studied in a wide range of frequencies under the influence of temperature in the range from 223 K to 363 K. The results showed lower and nearly constant values of the dielectric at high frequencies which can be understood under the conception of the inability of the dipole to rotate itself under the influence of high frequency. Moreover, the recorded large capacitance at low frequencies was attributed to the excess capacity value caused by the formed oxide layer. Also, the electrical properties in the dark and under the influence of light illumination were studied in a wide range of temperatures from 303 K to 448 K. The hybrid heterojunction diode exhibited a high rectification ratio at high voltage bias. The extracted series and shunt resistances showed a decrease with increasing temperature, which meant that the characteristics of the device enhanced at a higher temperature. The device also showed a remarkable light sensitivity and the transient photocurrent was detected, confirming the validity of the prepared device for photodiode applications.

Flexible transparent conductive electrodes represent the next generation electronics and are considered a vital part of the renewable energy technology. This article describes fabrication of a plastic ITO-free conductive electrode based on polyaniline/layered titanate nanocomposites using a layer-by-layer technique. Titanate nanowires (T-NWs) were first synthesized via a hydrothermal method in strong alkaline medium. The obtained NWs had length more than one micrometer and width of 100–120 nm. Modification of layered titanate using cetyltrimethyl ammonium bromide (CTAB), as cationic surfactant, was carried out through an ion exchange mechanism. T/CTAB-NWs were characterized using FTIR, XRD and the morphology was studied by TEM. Nanocomposites of polyaniline (PANI) and T/CTAB-NWs were prepared and well characterized using FT-IR, UV, XRD and TEM. The value of electrical conductivity of the prepared nanocomposite was found to be over two folds higher than that of pure PANI. Assembly of a flexible conductive electrode was prepared using multilayers of T/CTAB-NWs and PANI doped with camphor sulphonic acid (CSA). The transparency and photoelectrochemical properties of layer-by-layer (LBL) film of PANI–CSA and T/CTAB-NWs were investigated. The results confirmed the utility of the fabricated ITO-free conductive assembly as a photoelectrode for organic photovoltaic cells and flexible electronic devices.

Germanium bismuth-borate glasses with varying concentration of CuO of [(55-x)B2O3-20Bi2O3-5GeO2-20CaF2:xCuO] composition were prepared with melt-quenching method. The structure and thermal behavior of the samples were described through DTA, XRD, FTIR spectroscopy. The low energy of formation phases Bi44GeO68, CaGeO3 and CuGe3O9 were crystallized by the incorporation of CuO. [BO3] and [BO4] units are the main building groups of the glass matrix with some sharing of BiO6 and GeO4 units as FTIR analysis indicated. The electrical and dielectric characteristics were studied by broadband dielectric spectroscopy upon a wide-ranging of frequency (10-1 -107 Hz) and at temperatures 240 and 330 K. The heat-treated samples reveal higher conductivity than glass, by about three decades, at 330 K as the ratio of CuO increases to be in the range of semiconducting materials. The enhancement of dielectric properties of heat-treated samples over considered glass samples makes them better choices for the energy storage glass-dielectrics.

Cyanoethyl cellulose (CEC)/ magnetite (Fe3O4) flexible composite film with enhanced dielectric and magnetic properties was successfully prepared. CEC has been synthesized from micro crystalline cellulose (MCC). The effects of magnetite mass fraction on the morphology, microstructure, thermal stability, and antimicrobial activity of the as-prepared composite films were investigated. The Vibrating sample magnetometer (VSM) and broadband dielectric spectrometer was also employed to study the magnetic and dielectric properties, respectively. In addition to study the computational calculation of MCC, and CEC by DFT/ B3LYP/6-31G (d) basis sets. The results showed that, the sample that is magnetite free has a diamagnetic response to the applied magnetic field, however the other samples that is loaded with magnetite show super-paramagnetic behavior indicating that the particles’ sizes of the magnetite mostly below 20 nm. Also, antimicrobial activities of composite films against (G + ve), (G-ve), were investigated.

The presented article findings indicate an efficient method for obtaining graphene oxide and its enhancement for electronic devices. The structural checking for confirming the molecular, crystalline and morphology characterization was carefully included. The measurement of the dielectric characteristics was considered in a wide range of voltage bias, temperature, and frequency for obtaining valuable evidence about the electrical storage and dissipation properties of the device for prospective applications. The measured dielectric parameters showed a dispersion attitude under the influence of all the studied factors. The results confirmed a reduction in both capacitance and conductance with increasing the applied frequency. Remarkably, a negative capacitance influence was also detected in the studied frequency range in wholly investigated devices. The deviations in the dielectric behavior could be attributed to the rearrange of charges at the GO/Si interface and to the influence of series resistance. Additionally, the current-density voltage characteristics were investigated under influence of temperature to provide the option for the diode as a temperature sensor. Accordingly, the GO-based heterojunction provided the projections to produce low cost with a wide scale of device applications.

Composites of polyaniline (PAni)/polystyrene sulfonic acid were prepared in different ratios using in-situ polymerization method. Characterization of the formed composites’ structures was performed using FTIR, XRD, UV–vis also their thermal stability was investigated. Extensive study for the dynamic relaxation and charge transport mechanisms of the prepared composites was carried out by broadband dielectric spectrometer (BDS). Dielectric measurements illustrate the effect of annealing on the conductivity mechanism of the composites. The moisture enhances the conductivity abruptly when the atmosphere is ambient air. The unusual behavior was explained as an effect of the water molecules in the composites that behaves like bridges. On the other hand, the parameter playing the main role in the charge transport (conductivity) was found to be the mobility rather than the charge carrier’s density. The obtained results indicate the possibility of commercial utility of the prepared composites as anti-static packaging, anticorrosion shielding or as semi-conductors.

A blend of SBR/NBR (50/50) reinforced with a core-shell (nanotitanium dioxide/silica fume waste) in the presence of a silane coupling agent and polyethylene glycol as a dispersing agent was prepared. The new pigment is based on a nanotitanium dioxide shell comprising (15–20%) of the pigment precipitated on (85–80%) silica fume waste, this pigment combines the properties of both core and shell. The new core-shell pigment combines more than one constituent with different particle sizes The results of rheometric, mechanical, physical, and electrical studies revealed that the nanotitanium dioxide and silica interact chemically with the rubber by the formation of Ti–O–Si between nanotitanium and the silane coupling agent and Si–O–Si between the silica fume and silane coupling agent, doubling the effect of both components, which leads to drastic modification of the properties up to 9phr of pigment loading, indicating that this is the optimum loading, any further increase in the concentration can lead to decrease in the properties.

Novel nickel and copper phthalocyanine polymers, with uniformly carboxylic end groups and carbonyl groups as bridges linking the phthalocyanine units, were successfully prepared. Structural modelling and atomic absorption spectroscopy confirmed the network polymeric structure and suggested at least nine phthalocyanine units in each polymeric network. The dielectric properties of the prepared polymers were investigated over a wide range of frequencies at room temperature. The electric modulus formalism was used to study the conductivity relaxation in the prepared polymers. The collapsing of the real part of the conductivity function, σ’, at higher frequencies for both materials was observed indicating that the local molecular dynamics is due to the polymer conjugated backbone (functional and/or terminal groups) with no clear effect of the central metal.