Electric Modulus Studies Research Articles

Broadband Dielectric Spectroscopy: Unraveling Na+diffusion and mixed conduction in Na₂O-modified zinc phosphate glasses for electrode material applications

The fundamental understanding of electric charge (ion + polarons/electrons) transport and relaxation mechanism is essential for applications in solid state ionics. In present work, to study Na+ transport, the electrical conductivity of zinc phosphate glasses modified with Na2O has been investigated in temperature range 313K and 473K and frequency range of 100 mHz to 1 MHz. The experimental data of Nyquist plots is fitted with appropriate equivalent circuits at different temperatures which reveals presence of mixed conduction (polaronic + ionic) and Na+ diffusion (at 50 mol% Na2O) in studied glass samples. The values of frequency exponent (s) obtained from the fitting of experimental data of the real part of electrical conductivity with Almond–West equation (WAE) have been used to determine the conduction mechanism. The electric transport in studied glasses occurred via correlated barrier hopping and non-overlapping small polaron tunnelling conduction models depending on the glass composition and temperature range of investigation. Electric Modulus studies further supports the assertion of composition and temperature dependent conduction mechanisms. The activation energies determined from conductivity, electric modulus, and impedance measurements are found to be consistent, indicating a good correlation in the study.

Dynamics of charge carriers in La2CuO4 cuprates: Conductivity variation, scaling formalisms, and electric modulus study

In this work, we conducted a detailed investigation of the structural properties and the dynamics of the charges in the La2CuO4 Ruddlesden–Popper system that is prepared via the conventional solid-state process. Via the X-ray diffraction data and using the Rietveld refinement, we found that the compound exhibits a single crystallographic phase with a Bmab space group. The DC-conductivity investigation shows that the studied ceramic exhibits two electrical behaviors. Below 460 °C, the occurrence of a semiconductor behavior is attributed to the effect of the Variable range hopping conduction process. At high temperatures, the electrical nature of the material is linked to the thermally activated small polaron hopping conduction process via an activation energy Ea = 1.40 eV. Over the explored temperature range, conductivity spectra of the Ruddlesden–Popper are analyzed using the universal Double Jonscher power law. The dispersion region can be attributed to the coexistence of both hopping and tunneling processes. The conductivity spectra of the La2CuO4 Ruddlesden–Popper nicely follow the time-temperature superposition (TTSP) principle. This confirms that similar sources are responsible for relaxation and conduction processes. Using the Summerfield scaling approach, the superposition of the conductivity spectra into a single master curve confirms that the relaxation process is the microstructure's response independent. From the electrical modulus investigation, we found that the studied compound exhibits a non-Debye relaxation nature, over the explored temperature interval. Contribution of grain and grain boundary were resolved by complex modulus spectroscopy analysis. In addition, we found the absence of the electrode contribution at low frequencies. The correlation between both Z″ and the M″ peaks indicates that the conduction and relaxation processes are not related to the same origins.

Investigation of structural, dielectric and optical properties of the (Bi0.5La0.5Fe)0.5(Bi0.5Na0.5Ti)0.5O3perovskite for some electronic devices

This paper outlines the investigation of structural, dielectric, complex impedance and optical properties of lanthanum-modified (Bi[Formula: see text]La[Formula: see text]Fe)[Formula: see text](Bi[Formula: see text]Na[Formula: see text]Ti)[Formula: see text]O3 (BLF–BNT) single perovskite oxide synthesized by conventional solid-state reaction method. From Rietveld refinement, the crystal structure of the BLF–BNT ceramic has confirmed a tetragonal and the estimated average crystallite size is found to be 43.6[Formula: see text]nm. The dielectric properties of the La-doped BLF–BNT ceramic reveal the presence of Maxwell–Wagner-type dielectric dispersion. This suggests the occurrence of charge accumulation at grain boundaries and interfaces within the material. The complex impedance and complex electric modulus studies were employed to gain insight into the microscopic dielectric relaxations and conduction processes of the material. The electric modulus spectroscopy reveals the existence of nonDebye-type relaxation processes, including localized and long-range relaxation processes. The Nyquist and Cole–Cole plots show the semiconducting nature of the BLF–BNT ceramic. With the help of the Arrhenius method based on the imaginary portion of the electrical impedance and modulus, activation energies and relaxation times have been estimated. These parameters contribute to a deeper understanding of the electrical properties and conduction mechanisms within the material. Further, Raman spectroscopy, a nondestructive chemical analysis technique, was conducted to confirm the composition and structural integrity of the proposed system through its atomic vibrations. Also, the bandgap energy of the material has been estimated using Tauc’s relation and is found to be 1.69[Formula: see text]eV. This signifies that the BLF–BNT ceramic possesses a suitable bandgap for certain device applications, making it a promising candidate in various technological fields. Moreover, the overall comprehensive study of the proposed ceramic provides valuable insight and opens new possibilities for its potential applications in various electronic devices.

Valence band spectra and doping based alterations in band gap and electric modulus of Nd2NiMnO6

Here in this paper, extending our earlier study, we have investigated the electrical properties of Sr doped Nd2NiMnO6 through the study of electric modulus. Nd2NiMnO6 has been doped with Sr by replacing Nd and the doping has not induced any new phase as all the samples of Nd2-xSrxNiMnO6 (x = 0.0, 0.1, 0.3) show monoclinic phase. Valence band spectra have been determined through x-ray photoemission spectroscopy and the absence of spectral density at Fermi energy EF for all the three samples indicates the insulating behavior with the sample having doping concentration x = 0.1 being the highly insulating of all the samples. Modulus study has been carried out in order to investigate more about the electrical properties by studying the dependence of real and imaginary part of modulus on frequency and temperature. The variation of real and imaginary part of electric modulus with the concentration of dopant has also been observed. The modulus study reveals the relaxation phenomenon in all the three samples. Further, we have determined the band gap of three samples through UV-Visible spectroscopy and the variation in the value of band gap with changing concentration of dopant Sr is in accordance with the conductivity plots already discussed in our earlier studies.

Combined transport and dielectric models and experimental characterization based on impedance spectroscopy for studying the microstructural and transport properties of electro-ceramic perovskites

Collective investigations on the electrical resistivity, complex dielectric permittivity, complex impedance, conductivity, and electric modulus properties of La0.55Ca0.45Mn0.8Nb0.2O3 (LCMNO) are conducted. The impedance spectroscopy (IS) technique is reviewed to examine the electrical and dielectric responses of the material according to the carrier displacement, including core-shell structure, grain boundary effects, dielectric relaxation (local relaxation), and long-range conduction (non-local relaxation). This technique can correlate the electrical and dielectric responses with the ceramics’ microstructural effects (grain boundary and grain (core-shell) zones). For LCMNO, the electrical resistivity study confirms the presence of a metal-semiconductor transition at TM-SC=66 K. It points towards a gradual crossover from the thermally activated Small Polaron Hopping (SPH) to the Variable Range Hopping (VRH) process at low temperatures and for T> TM-SC. The dielectric results confirm the presence of various types of polarization effects. The occurrence of a dipolar reorientation is attributed to long-range electrical conduction. In addition, the accumulation of the activated charge carriers increases the Maxwell-Wagner polarization resulting from an internal barrier layer capacitor (IBLC) microstructure. The electric modulus study confirms the existence of a correlation between the mobile charge carrier’s motions. From the complex impedance, dielectric, and electric modulus, it is possible to label a material’s conductive and dielectric natures (non-Debye-relaxation-type).

Optical properties and electric modulus studies of TSP: CH3COONa based biopolymer electrolytes

The research of biopolymers for the creation of solid polymer electrolytes (SPE) for electrochemical devices has resulted from the green revolution. Various strategies have been used to build and characterise biopolymer-based membranes for proton and lithium-ion conduction. However, research on biopolymers based on sodium ions is uncommon in the literature. The solution cast approach is used in this work to create a SPE based on the biopolymer Tamarind Seed Polysaccharide (TSP) incorporated with sodium acetate (CH3COONa). UV–visible optical absorption spectroscopy in the wavelength range of 200–800 nm was used to investigate the optical characteristics. From the studies of optical absorption, optical transmission, optical absorption coefficient, refractive index spectrum, extinction coefficient spectra, direct energy bandgap, indirect energy bandgap, optical absorption edge, Urbach – energy, and optical dielectric loss were calculated. The comparative study of the optical dielectric loss to the optical bandgap showed that the direct allowed transition was the most probable electronic transition for the prepared films. The calculated optical bandgap (Direct allowed) was decreased for 80:20 film from 5.51 eV (for pure TSP) to 4.88 eV. The direct, indirect, and absorption edges for pure TSP were all high, and when the salt concentration of CH3COONa increased, the above characteristics progressively decreased. For 80 % TSP: 20 % CH3COONa concentration, a low direct and indirect energy bandgap value was obtained. Tangent loss and electric modulus experiment results were then presented using AC Impedance data. For the 80:20 film, the tangent energy loss revealed a minimum and the electric modulus spectra exhibited the zeroth tail is at its maximum.

Dielectric Property, AC Conductivity, and Electric Modulus Studies of Pristine and Green‐Synthesized ZnO Nanoparticles

Frequency‐dependent dielectric constant and dielectric loss of pristine and green‐synthesized (using Tabernaemontana divaricata flower extract) ZnO nanoparticles (NPs) are studied at different temperatures. Below 1 kHz frequency and at temperatures above 100 °C, ZnO NPs have giant dielectric constant values (≈3 × 104). At lower frequencies and at/below 100 °C, the nature of temperature dependence of dielectric constant for pristine and green‐synthesized ZnO NPs are reversed, and this anomalous temperature dependence is correlated with the in‐plane and out‐of‐plane thermal expansions of ZnO. A temperature‐dependent poly‐dispersive relaxation mechanism in ZnO has been observed. The electrical conduction mechanism is found to be significantly modulated by the use of flower extract. The electric modulus study suggests similar mechanism of electrical conduction and dielectric polarization followed in these materials. A plausible growth mechanism of the ZnO NPs in presence of the flower extract is explored. Variations in the dielectric constant, dielectric loss, conductivity, and polarization mechanisms of the ZnO NPs are understood as signatures of the capping effect of the phytochemicals present in the flower extract on the crystal growth and formation of grain boundaries.

Crystal structure, Hirshfeld surface analysis, conduction mechanism and electrical modulus study of the new organic-inorganic compound [C8H10NO]2HgBr4.

There has been a lot of interest in the development of a novel hybrid material based on mercury that has fascinating structural properties. In this paper, single crystals of [C8H10NO]2HgBr4 was successfully synthesized by the slow evaporation method at room temperature. In fact, the latter crystallizes in the orthorhombic system (Cmca space group) with cell parameters a = 20.824(2) Å, b = 15.352(1) Å and c = 13.700(1) Å and Z = 8. Its structure is constituted by one [C8H10NO]+ cation and one type of isolated anion [HgBr4]2- tetrabromomercurate(ii). The atomic arrangement presents an alternation of organic and inorganic layers along the a-axis. To maintain the cohesiveness of the structure, these components are joined via π⋯π interactions and hydrogen bonds (N-H⋯Br and N-H⋯O). A general network of hydrogen bonds ensures the interconnection of several entities. Greater knowledge of these interactions has been obtained based on the Hirshfeld surface analysis and 2D fingerprint plots. The analysis of complex impedance spectra shows that the electrical properties of the material are heavily dependent on frequency and temperature. The obtained results were analyzed by fitting the experimental data to an equivalent circuit model. The temperature dependence of conductivity and the relaxation frequency ωmax fulfill the Arrhenius relation and activation energies are estimated. The material follows Jonscher's universal dynamic law or here there is a decrease in the exponent 's' as the temperature increases. This result indicates that the Correlated Barrier Hopping (CBH) model represents the conduction mechanism. Besides, the non-Debye type conductivity relaxation is revealed by the electrical modulus analysis.

Complex dielectric and impedance analysis in Dy1-XPrXMnO3 compounds: Partial substitution effects

Synthesis and characterization of single phasic Dy1-xPrxMnO3 (DPMO) ceramic samples through solid-state reaction (SSR) method are reported in present study. XRD analysis confirmed the structural formation of DPMO and revealed lattice changes induced by Pr substitution that affect JT-distortion and tilting of MnO6 octahedra. Fine-grained microstructures with a micrometre-sized grain size were observed using FESEM images, which increased with increasing Pr concentration. The variation of activation energy in DPMO was found to be induced by modification in Mn–O bond distances. The dielectric behaviour of DPMO was significantly enhanced, which was explained using the UDR model fitting. Impedance analysis confirmed the existence of non-Debye type relaxation and negligible electronic polarization mechanisms in all DPMO samples. With the increase in temperature, a reduction in the magnitude of Z' was observed, indicating a decrease in the resistance of contributing electroactive components such as grains, grain boundaries, and electrode interfaces. Electric modulus studies revealed the existence of grain and grain boundary relaxation processes throughout the studied frequency and temperature range in DPMO compounds. Overall, the study provides deep insights into the effect of Pr substitution on the structural, electrical, and dielectric properties of DPMO and highlights the potential of DPMO for future electronic and energy device applications.

Dielectric Response and Electric Modulus Studies of Polythiophene/Reduced Graphene Oxide Nanocomposites

Chemical oxidation reactions were used to create composite materials made of polythiophene (PTh) and reduced graphene oxide with varying compositions. To describe the samples, Fourier transform infrared spectroscopy (FTIR) was used. The hydroxyl (OH) stretching vibrations of the -COOH functional group and adsorbed H2O molecules are responsible for the intense bands at 3386 cm-1 and 1302 cm-1. O-H vibrations can be attributed to absorption at a wavelength of 1610 cm-1. C-S bending mode of thiophene ring has produced the peak at 666 cm-1. The dielectric constant, tangent loss, and electric modulus with the applied AC frequency for the polythiophene/reduced graphene oxide composites were studied.

Investigation of electric transport in mixed conducting Na2O modified zinc borate glasses for electrode material using broadband dielectric spectroscopy.

The electrical conductivity of Na2O substituted zinc borate glasses has been studied in the frequency range of 10 mHz to 1MHz and in the temperature range from 313 to 573K. The conduction mechanism has been ascertained using the values of the frequency exponent (s) extracted from the fitting of experimental data of the real part of electric conductivity in light of the Almond-West equation. Depending on the glass composition, the ac conduction in the glasses happened via correlated barrier hopping and non-overlapping small polaron tunneling conduction models. The electric modulus studies support the assertion of composition dependent conduction mechanisms. Furthermore, electronic conduction and ionic conduction have been studied from impedance investigations. Equivalent circuit models were used to fit the Nyquist and Bode plots of each sample at the temperatures under consideration. It has been found that the activation energy values calculated from conductivity, electric modulus, and impedance measurements are more or less the same.

High-frequency electric modulus, impedance and conductance studies of gadolinium/niobium substituted barium titanate-lithium ferrite solids

Using conventional solid-state techniques, BaTiO3- Li0.5Fe2.5O4composites doped with Gd/Nb are prepared. Investigations are made on the electric and micro-structural characteristics of composites at high frequencies. The tetragonal structure without phase change is confirmed by the composites BTO, BTOLF, BGN-1, and BGN-2. Using FESEM micrographs, the grain size of the composite samples BTO, BTOLF, BGN-1, and BGN-2 was determined. The Impedance (Z′), Complex Impedance (Z′′), and Mod of Impedance (|Z |) of all composites exhibit dispersion among the samples in the frequency range between 1 MHz and 1 GHz. The capacitance (C′) of BGN-2 falls between BTOLF and BGN-1 as a result of the effect of grain size.Due to the Gd/Nb doping in BTOLF, the true part of the composite's conductance (YS′) peak migrated towards lower and higher frequencies. All composites experience a rise in frequency beyond 1 GHz and a sharp peak in both the real component of the electric modulus (M') and the imaginary part of the electric modulus (M'').

Variable range hopping transport and dielectric relaxation mechanism in GdCrO3 rare-earth orthochromite perovskite

The polycrystalline GdCrO3 (GCO) perovskite orthochromite was synthesized by the sol–gel auto-combustion method. The Rietveld refined X-ray diffraction (XRD) profile of GCO confirms that the orthorhombic phase crystallizes in perovskite crystal structure with space group Pbnm. The transmission electron microscopy and selected area electron diffraction divulge the polycrystalline nature of the perovskite chromite. The field emission scanning electron microscopy (FESEM) images reveal the microstructural polyhedral growth of grains separated by sharp grain boundaries. The chemical states of the ions present in the compound were investigated by X-ray photoelectron spectroscopy (XPS) studies, and the electrical pathways were identified. Complex impedance studies were carried out in the experimental frequency and temperature ranges of 40 Hz–4 MHz and 178–408 K, respectively. The equivalent circuit model (RGQG) (RGBQGB) resolves the impedance response into two contributions originating from the intra-grain and inter-granular micro-constituents of the material. The electrical conduction mechanism is based on the Mott variable range hopping model. The complex electric modulus studies demonstrate the short- and long-range mobility of the charge carriers and rule out the presence of electrode effects on the dielectric relaxation mechanism of the material. The decreasing pattern of dielectric permittivity with frequency is explained by the Maxwell–Wagner type of polarization. The frequency dependence of the loss factor exhibits the presence of thermally activated relaxation time distribution in the material.

Synthesis and electrical characterizations of (Sn0.8Ti0.2)O2 electronic material

ABSTRACT The ceramic composite electronic material of (Sn0.8Ti0.2)O2 has been synthesized through a cost-effective solid-state ceramic approach. The crystallographic tetragonal structure from the XRD spectrum, hydrophilic porous structure from SEM micrograph, dielectric, conductivity, and electrical modulus in addition to impedance spectroscopy over an extensive range of temperature and frequency have been elucidated. Hydrophilicity, superior dielectric response with significantly low dielectric loss, and enhanced capacitive behaviour draw the major attraction of this ceramic-based material system. The temperature-dependent conductivity spectrum evinces Arrhenius’s behaviour. The grain and grain boundary effects in the synthesized sample has been displayed through the Nyquist spectrum. The non-Debye type of relaxation mechanism has been established through an electric modulus study. The extensive study sketched out this composite as a potential capacitive electronic component for humidity sensor device applications. The investigated electrical parameters associated with the ceramic composite may enlighten the development of functional electronic devices.

Investigation of ion transport properties in Er–W co-doped La2Mo2O9 electrolytes

Here we present the structural, vibrational, dielectric as well as ionic transport properties in a series of La2-xErxMo1.7W0·3O9 (for 0 ≤ x ≤ 0.5). Stabilization of cubic β-phase at room temperature was achieved by doping, evident from XRD and conductivity plots. Raman analysis suggests a change in phase structure and deformation in Mo-polyhedra due to doping. Ionic conductivity of 10 mol% Er-doped sample was found to be 3.6 × 10−2 S/cm similar to that of pure La2Mo2O9 at 700 °C. Two different conduction mechanisms prevail: Arrhenius type below 450 °C and Vogel-Tammann-Fulcher (VTF) type above 450 °C. Dielectric constant and loss studies indicate the presence of two dielectric relaxations in the co-doped samples with different relaxation times attributed to the short-range diffusion of oxygen ions between different sites, i.e., O (1) ↔ O (2) and O (1) ↔ O (3). Electric modulus studies suggests that the relaxation mechanism is independent of temperature and composition.

Nanocrystalline Mn-doped Ni–Cu ferrites with a high cut-off frequency and initial permeability: Suitable for advanced electronic devices and biomedical applications

The microstructural and electromagnetic properties of Mn-doped Ni0.50-xMnxCu0.50Fe2O4 (x = 0.0, 0.10, 0.20, 0.30, 0.40) magnetic nanoparticles are studied. Compositions are produced by the combustion method, and samples prepared from these powders are sintered at different sintering temperatures. The Rietveld refinement of X-ray diffraction (XRD) data confirmed that all compositions have cubic spinel structures with an Fd-3m space group. The average crystallite size is within 8–65 nm measured by different methods. The porosity of the surface, average grain diameter, and grain distribution are measured using optical micrographs. The high cut-off frequency of 10 MHz is observed in the initial permeability as a function of frequency plots. The maximum Curie temperature of 855 K is found for the x = 0 sample. The maximum relative quality factor (2636) and lowest relative loss factor (0.04) are found for x = 0.4. The initial permeability as a function of frequency is also measured at liquid nitrogen temperature (77 K). The “law of approach to saturation (LAS)” is used for magnetization data and the highest saturation magnetization value 61 emu/g is obtained for x = 0.3. The "Jonscher universal power law" fitted the ac electrical conductivity with large dispersion at a higher frequency region and a small polaron hopping model is applicable in this case. The dielectric constant exhibit dispersive behavior at low frequency and follow Koop's as well as Maxwell-Wagner's two-layer models. At 100 Hz the maximum value of the dielectric constant is 2.8 × 105. Nyquist plot representation stated that the electrical conduction mechanism in these ferrites is mainly due to the influence of the grain and grain boundary effects. An electrical equivalent circuit is suggested to explain the impedance analysis. Electric modulus studies confirm the non-Debye type relaxation process of the compositions. Tuning all of the properties specifies that the synthesized magnetic nanoparticles may be an optimistic application for high-frequency electronic devices and biomedical applications.

Synthesis and investigation of the morphological, optical, electrical and dielectric characteristics of a disodium cobalt orthogermanate.

A sodium cobalt germanate material (Na2CoGeO4) was synthesized and studied. The X-ray powder diffraction pattern revealed a monoclinic crystal system with the Pn space group. The calculated value of the direct bandgap (Eg) was (3.89 ± 0.02) eV. Electrical measurements were undertaken in a frequency range from 40 Hz to 1 MHz and a temperature range from 403 K to 573 K. Nyquist plots revealed only a semicircle in the whole impedance spectra due to the effect of interior grains. The AC conductivity of Na2CoGeO4 was associated with the correlated barrier hopping (CBH) model. Studies of the complex electric modulus M*(ω) confirmed that the relaxation process was thermally activated.

Structural, electrical and dielectric properties of chitosan/polyaniline/vanadium-pentoxide hybrid nanocomposites

Chitosan/polyaniline/V2O5 hybrid nanocomposites were synthesized by an oxidative polymerization technique by varying V2O5 content and using (NH4)2S2O8 as an oxidizing agent. The structural and morphological properties were characterized by using Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). The characterization results corroborate the successful formation of the nanocomposites and reveal modifications in morphological features. The AC conductivity, dielectric, impedance, and electric modulus properties were studied in the frequency range of 10 Hz–8 MHz at room temperature. The AC conductivity and dielectric constant values of the chitosan/polyaniline matrix were remarkably improved with the addition of V2O5 nanoparticles. The AC conductivity of the CPAV-0.6 nanocomposite increased significantly at higher frequencies (5.78×10–3 S/m at 8 MHz). The CPAV-0.4 nanocomposite showed a drastic enhancement in dielectric constant values for lower frequencies (2×105 at 10 Hz). The prepared nanocomposites exhibited lower dielectric and tangent loss values at higher frequencies, implying that they are lossless materials at higher frequencies and have applicability in high-frequency devices. The relaxation time decreased with increasing V2O5 concentration (∼7.5×10–5 s for CPA and ∼2.5×10–5 s for CPAV-0.2 and CPAV-0.4), which is in good agreement with electrical results. The electrical results are further supported by the impedance and electric modulus studies. As a result of these improved properties, as-prepared nanocomposites in their optimum form are particularly helpful in energy storage and conversion devices, optoelectronic and biomedical applications, sensors, supercapacitors, and photovoltaic devices such as solar cells.

Dielectric, AC Conductivity, and DC Conductivity Behaviours of Sr2CaTeO6 Double Perovskite.

Relatively new double perovskite material, Sr2CaTeO6, has been prepared through conventional solid-state procedures. Structural, dielectric, and optical characteristics of this exquisite solid-state material were analysed in this study. The single-phase monoclinic P21/n structure of this prepared compound was well correlated with the literature review. Good distribution of grain sizes and shapes was observed in the morphological study of this compound. The discussions on its optical and dielectric properties are included in this manuscript. High dielectric real permittivity, low dielectric loss, and good capacitance over a range of temperatures possessed by this compound, as shown in dielectric and electrical modulus studies, indicated good potential values for capacitor applications. The Ro(RgQg)(RgbQgb) circuit fitted well with the impedance and electrical modulus plot of the compound. Its relatively high electrical DC conductivity in grain at high frequencies and its increasing value with the temperature are typical of a semiconductor behaviour. This behaviour might be attributed to the presence of minor oxygen vacancies within its lattice structure and provides a long-range conduction mechanism. A small difference between activation energy and Ea of DC conductivity indicates that the same charge carriers were involved in both grains and the grain boundaries’ long-range conduction. The electrical AC conductivity of this compound was found to contribute to the dielectric loss in grain structure and can be related to Jonscher’s power law. The presence of polarons in this compound was exhibited by non-overlapping small polaron tunnelling (NSPT) and overlapping large polaron tunnelling (OLPT) conduction mechanisms over a range of temperatures. Wide optical band gap and Eopt in the range of 2.6 eV to 3.6 eV were determined by using an indirect and direct allowed mechanism of electrons transitions. These values supported the efficient semiconducting behaviour of the grain in this material and are suitable for applications in the semiconductor industry.

Dielectric properties of hot-pressed Poly(vinylidene fluoride)/Functionalized carbon nanotube composites

This work reports the structural and dielectric properties of poly(vinylidene fluoride) (PVDF) composites with functionalized carbon nanotube (FCNT) prepared by the hot pressing method. XPS, SEM, TEM, and TGA techniques were employed to understand the extent of functionalization of CNT with acid treatment. Permittivity, Electric Modulus, and AC conductivity measurements of hot pressed samples are compared with samples prepared by the solvent casting method. It was found that the PVDF-FCNT composites were formed with more γ phases. Hot pressing the samples increases the overall polar phases, especially the β phase. The permittivity, electric modulus, and AC conductivity studies reveal the dielectric behavior and conductivity changes with hot pressing samples.