Conductivity Σac Research Articles

Evaluation of the electrical behavior of tungsten trioxide and cobalt oxide nanoparticles filled poly (ɛ-caprolactone) composite for optoelectronic devices

This study obtains the electrical characterization of nanocomposites comprising Poly(ɛ-caprolactone) (PCL), tungsten trioxide (WO3), and cobalt oxide (Co3O4) nanoparticles. The fabrication of these nanocomposites through a casting method aimed to enhance their electrical conductivity and dielectric properties. The AC conductivity (σac) was analyzed across varying frequencies, revealing a notable increase with the addition of Co3O4 nanoparticles, particularly up to the high content of Co3O4 nanoparticles. This enhancement is attributed to the formation of ion transport pathways and the increased amorphous regions within the PCL matrix. Dielectric properties were assessed through ε′ and ε'') measurements, which exhibited a decrease with increasing frequency, indicating the dielectric relaxation processes of the composite. The complex electric modulus analysis demonstrated a significant relationship between the real and imaginary components, suggesting potential ionic conductivity in the nanocomposites. Additionally, the Argand plot revealed a depressed semicircle, indicating a distribution of relaxation times, which further confirmed the enhancement of conductivity with raising laser ablation time. Overall, the results indicate that the addition of WO3 and Co3O4 nanoparticles significantly improves the electrical properties of PCL, making these nanocomposites suitable for various electrical applications.

Crystallographic Profiling, Core-Shell Electronic Configurations, and Investigations of Frequency-Dependent Dielectric Characteristics of Sb2O3-V2O5 Micro Ceramics

A series of V2-xSb2xO5-δ (Sb-V-O) ceramic powder samples with molar concentrations ranging from 0.05 to 0.08 were synthesized using a solid-state reaction method. Crystallographic analysis conducted through Rietveld refinement indicates that at a molar fraction of x=0.05, the orthorhombic V₂O₅ phase is observed. Conversely, at molar concentrations of x=0.06, 0.07, and 0.08, the orthorhombic phase of V2O5 and the tetragonal phase of SbVO4 are present simultaneously. X-ray photoelectron spectroscopy (XPS) was employed to ascertain the elemental oxidation states, revealing the presence of V5+, V4+, Sb3+ ions, and Sb0 metal atoms, along with O1s photoelectron peaks. The photoluminescence (PL) emission spectrum suggests transitions from a shallow donor level to the valance band. The room temperature AC conductivity and dielectric property results reveal a systematic decrease in the dielectric constant. The AC conductivity experimental data was accurately modeled using the Almond-West formalism, yielding high R2 values (0.9968–0.9986) and low chi-square errors (1.157×10⁻11–9.42×10⁻12) obtaining hopping frequency values for each composition (x = 0.05–0.08). AC conductivity (σac) decreased from 5.08×10⁻⁴ S/m to 2.40×10⁻⁴ S/m at 10 MHz, while DC conductivity (σdc) dropped from 7.22×10⁻⁵ S/m to 1.55×10⁻⁵ S/m. This reduction in conductivity is attributed to structural changes from Sb³⁺ substitution, which disrupts polaronic conduction by reducing the number of available O2⁻ ions and promoting SbVO₄ phase formation, hindering charge transport. The Sb₂O₃-V₂O₅ ceramics exhibit promising potential for energy storage applications, particularly in capacitors requiring high dielectric constants at low frequencies. At lower frequencies, grain boundaries inhibit conduction, enhancing dielectric constant values; at elevated frequencies, grain conduction predominates, lowering dielectric constant in accordance with Koop’s phenomenological theory, favoring applications in multi-layer ceramic capacitors. A notably higher dielectric loss factor (εr'') at low frequencies (10 Hz–1 kHz) indicates lossy behavior, beneficial for microwave absorption, while its stabilization above 10 kHz suggests minimal energy dissipation, ideal for high-frequency electronic and dielectric devices.

Novel ceramic materials based on industrial wastes within the CaO–MgO–Al2O3–SiO2 system

The use of solid waste and raw materials such as ceramic sludge, klin rollers, magnesite, and limestone to produce low cost refractory ceramics after sintering at 1300 °C for 2 h was studied. Sample D30 with a composition of, 30 % diopside and 70 % mullite, was selected to be treated at 1200 °C for 2 h to investigate the effect of temperature on phase evolution. Microstructure, morphology and physical properties were also studied. Several techniques including XRF, XRD, SEM, EDX, flexural strength, and dielectric properties were used for samples characterisation. Densification parameters, morphology and microstructure were studied in order to evaluate the influence of the formed phases on the properties of produced ceramic materials. The study showed that the bulk density increased with the formation of corundum and mullite phases and decreased with the formation of anorthite and spinel phases. Bulk density also increased at higher firing temperatures. In contrast, porosity and water absorption showed the opposite trend to density. The main phases developed after firing at 1300 °C for 2 h were corundum, spinel, mullite, and anorthite. Flexural strength values were increased by increasing the precipitation pecent of corundum and mullite phases, as well as with bulk density. But it decreased with increasing porosity and both anorthite and spinel contents; ranging between 8.00 and 11.00 MPa. Bulk density increased with increasing of mullite content and temperature, ranging from 1.72 to 2.00 g/cm3, while porosity and water absorption ratio decreased from 32.59 to 22.10 and from 19.66 to 10.98, respectively. The microstructure morphology was converted from coarse-grained to fine-grained with increasing anorthite and spinel phases by increasing the temperature. To investigate the effect of the phases precipitated from the diopside-mullite system on their dielectric properties, parameters such as permeability (ε’), dielectric loss (ε′′), alternating current conductivity (σac) and Modulus'' were measured at the frequency range from 10−1 Hz–106 Hz. There is no noticeable effect on any of the dielectric parameters by increasing the concentration of diopside (CaMgSi₂O₆). In addition, the conductivity indicated that all the samples are insulators (σdc ≈ 10 pS/cm at f = 0.1 Hz) without any noticeable effect of composition.

Fabrication and characterization of PVDF/PMMA nanocomposite membranes doped with graphene oxide (GO) for separation of CO2/CH4 from flue gas

This work focuses on developing polyvinylidene fluoride/polymethyl methacrylate (PVDF/PMMA) polymer blend nanocomposites incorporating varying concentrations of graphene oxide (GO) nanoparticles fabricated via casting solution processes. XRD and FT-IR confirmed GO-induced structural modifications in PVDF/PMMA blend. The addition of GO into PMMA/PVDF blend decreased and weakened the intensity of XRD peaks, suggesting that adding GO gradually reduces the crystallinity of the films. FT-IR verified miscibility and complex formation between the pristine polymer blend and the GO-filled nanocomposite. The incorporation of GO caused shifts in the optical absorption edge to lower wavelengths, causing a decrease in the optical bandgap energy (Eg). The real and imaginary parts of the dielectric permittivity (ε′ and ε′′), electric modulus (M′, M″), and AC conductivity (σac) have been measured from 0.1 Hz to 6 MHz. Both ε′ and ε′′ declined with rising frequency. The addition of different concentrations of GO generated charge transfer complexes in the polymer nanocomposites. SEM images show good homogeny with random dispersion of GO inside the polymer blend. The thermoluminescence (TL) glow curves for the nanocomposite samples irradiated 0.5, 1.0, 1.5, and 2 Gy doses show peak cantered at 207 °C. The peak position remained unchanged with increasing irradiation dosage. The dose-dependent linear growth in maximum peak height indicates radiation detection and monitoring capability.

Frequency and voltage dependent of electrical and dielectric properties of Ag/GO doped NiO/p-Si/Al MOS structures under darkness and light

At studying, we searched the frequency and voltage dependency of the electrical and dielectric traits of a nano-made NiO-contributed GO thin film enlarged on a p-type silicon substrate using sol-gel technique. The electrical and dielectric features of Ag/GO-NiO/p-Si were investigated by capacitance–voltage (C–V) and conductance–voltage (G/ ω–V) indications in the frequency interval of 10 kHz–1000 kHz below dark and illumination at ambient temperature. While the capacitance and series resistance (Rs) values decrease with increment of frequency and increment trend in conductance was observed with the increasement of frequency. These decrement/increment trend observed at greater frequencies are attributed to existence of interface state densities. After, the frequency dependence of dielectric constant (εʼ), dielectric loss (εʼʼ), loss tangent (tanδ), ac electrical conductivity (σac) and complex impedance (Z∗) of Ag/GO-NiO/p-Si structures were investigated in the frequency by means of the capacitance–voltage (C–V) and conductance-voltage (G/w-V) indications. The experimental findings showed that εʼ, εʼʼ and σac were strongly frequency dependent.

Investigation of the Dielectric Characteristics of Chromium-substituted Zinc and Cobalt Nanoferrite Systems

Abstract The series of Cr-substituted Zn and Co nanoferrite systems having the chemical composition CrxZnFe2–xO4 and CrxCoFe2–xO4 (0.0 ≤ x ≤0.5) were prepared by sol–gel technique. The present investigation aims to compare the impact of Cr3+ concentration on dielectric characteristics of Zn and Co-nanoferrite systems. The investigation of various dielectric characteristics was conducted using an LCR meter at 1kHz frequency and across the frequency range of 100Hz to 1MHz. The measurements were conducted at room temperature. In the case of both ferrite systems, the plots of frequency Vs dielectric constant (ε′) and AC conductivity (σac) show a common dielectric behavior of spinel ferrites. The plots of frequency Vs dissipation factor (D) of Cr- Cr-substituted zinc and Cobalt nanoferrite samples were observed to be unusual and display a relaxation peak at a particular frequency. In the current study, CrxZnFe2-xO4(x=0.2 and 0.3) and CrxCoFe2–xO4 (x=0.3) ferrite samples were found to exhibit very high values of dielectric constant. So these ferrites may be useful for a wide range of applications in electrical storage devices. According to LCR reports, all the Cr3+ substituted ferrite samples in both ferrite systems exhibit higher dielectric constant and AC conductivity values. Possible mechanisms that may be accountable for the outcomes are thoroughly scrutinized in this paper.

Structural, Dielectric, and Electrical Properties of Chitosan Composites Doped with Silver for Electrochemical Applications

AbstractIn this study, chitosan‐silver (Chs‐Ag) composites containing Ag in different concentrations (0.01–0.08 M) were prepared. The characterization and structure studies of the composites containing 0.01, 0.02, 0.04, and 0.08 M Ag were carried out, and then the dielectric properties of these composites were examined. The composites were characterized by Fourier transform infrared spectrophotometer (FTIR), scanning electron microscopy and energy dispersive spectroscopy (SEM‐EDS), and thermogravimetric analysis (TGA). The dielectric and electrical properties of these composites were investigated depending on the frequency at room temperature, and these properties were determined using an impedance analyzer. Spectroscopy revealed that the dielectric constant (ε′), dielectric loss (ε′′), and real (Z′) and imaginary (Z″) components of impedance are found to decrease with increased frequency for both Chs and Chs‐Ag (0.01M–0.08 M) composites. On the contrary, the AC conductivity (σac) of samples increased with increasing frequency. ε′ and ε′′ values of Chs were lower than when the Ag was added. The AC conductivity was improved by the addition of silver particles. The results show that the dielectric and electrical properties of Chs‐Ag samples were improved by using Ag as filler.

Weakly negative permittivity from three-dimensional printed polydimethylsiloxane/graphene films in the radio frequency band

Epsilon-negative materials (ENMs) has become a research hotspot due to their unique physical properties and practical applications in fields such as directional radiation and tunneling effects. In this work, weakly negative permittivity (from -50 at 10 kHz to -25 at 1 MHz) was realized from three-dimensional printed polydimethylsiloxane/graphene films. The dielectric properties including complex permittivity (ε', ε″), complex impedance (Z', Z″), alternating current conductivity (σac), and dielectric loss tangent (tanδ) were investigated. When graphene content reached 15 wt%, the interconnected graphene network was formed, resulting in negative permittivity. Theory calculations were further used to explore the mechanism. The electrons around carbon atoms showed significant delocalization. With the effect of the external electromagnetic field, the electrons on the surface of graphene could easily oscillate collectively, leading to negative permittivity. Differential charge density exhibited that interfacial electric fields were formed between polydimethylsiloxane and graphene, enhancing positive permittivity. Therefore, when the graphene content reached 15 wt%, the film exhibited weakly negative permittivity, which was the result of the mutual balance between the graphene conductive network and the interface electric fields.

Optimizing ZnSe nanorods with La doping for structural, electrical, and dielectric properties in device applications

Nano-materials, pure Zinc Selenide (ZnSe), and rare earth (Lanthanum) doped ZnSe (Zn1-xLaxSe, x = 0.00, 0.02, 0.04, 0.06) were synthesized via a facile and low-cost hydrothermal method. X-ray diffraction (XRD) demonstrated that the nanoparticles grow in cubic crystal phase with high degree crystallinity, and the measured crystallite size of La-doped ZnSe ranges from 31.95 to 31.11 nm. Mitigation in crystallite size was observed with the inclusion of La and enhancement in the lattice constant ‘a’ from 5.6565 Å to 5.6818 Å. Morphological study (FESEM) depicts synthesized materials' morphologies as nanorods. The FESEM images indicate the random distribution of the nanorods across the crystal lattice, regardless of the accumulation of the nanorods, showing lumps in the synthesized material sample. The estimated grain size of pure ZnSe nanorods ranges from 137.6 to 496.9 nm. Electrical features revealed that direct current (DC) electrical conductivity ‘σdc’ enhances with temperature, affirming the semiconducting behavior of the materials. Increased lanthanum content enhances the ‘σdc’ from 3.08 × 10–5 (Ω cm)-1 to 5.94 × 10–5 (Ω cm)-1 at 303 K while lessening the activation energy value from 0.134 to 0.104 eV. Dielectric features, including relative permittivity (ε'), loss factor or dielectric loss (ε''), tangent loss (tanδ), as well as AC conductivity (σac), indicate a direct proportionality with temperature, and elevated values of all the dielectric parameters are noted with La-doping. An increase in dielectric constant with doping concentration displayed that the prepared nanocrystals have valuable dielectric and capacitive behavior. The outcomes of electrical and dielectric features display that the prepared nanorods have vital characteristics for developing optoelectronic devices, solar cells, photocatalysts, and light-emitting diode applications.

Study of structural, dielectric properties of ZnFe2O4: effect of thermal annealing

Abstract We report structural, dielectric properties of sol-gel auto-combustion-synthesized ZnFe2O4 nano-ferrites (grain-size: 53.43 - 64.81 nm), and study the effect of thermal annealing on structural dielectric properties by X-ray diffraction (XRD), dielectric measurements. Results show that thermal-annealing shows: i) an increase of lattice parameter (aexp.), and on B-site: there is an increase of Zn2+ population with concurrent decrease of Fe3+ ions, ii) alterations of inversion-degree from 0.18 to 0.32, strengthening of A-O-B, A-O-A interactions, accompanied by a weakening of B-O-B super-exchange-interaction, iii) decrease of theoretical magnetization at 0 K (Ms(th)), iv) with increasing frequency, real-imaginary components (ε', ε'') of dielectric constant, and loss-tangent decreases, v) that at higher frequencies, ac conductivity (σac) shows a significant increase and exhibited a power law dependence, suggesting a typical of charge transport assisted by a hopping or tunneling processes. Results also reveal that polarizability strength decrease with annealing temperature, and correlated-barrier-hopping remains the dominant mechanism for conduction. Cole-Cole plots (ε', ε''), corresponding complex impedance (Z', Z'') data are indicative of the growing influence of grain boundaries on the dielectric properties for the studied samples. Observed improved-response of σac, recommends the potential-applications of the studied samples in high-frequency device applications.

On a detail examination of frequency and voltage dependence of dielectric, electric modulus, ac conductivity (σac) of the Al/DLC/p-Si structures between 2 kHz and 1 MHz

In this study, the frequency/voltage dependent profiles of the real/imaginary parts of the complex-dielectric (ε′, ε"), electric-modulus (M′, M"), impedance (Z′, Z"), loss-tangent (tanδ), ac electrical-conductivity (σac) and phase-angle (θ) were investigated in the frequency and voltage ranges of 2kHz/1 MHz and -2V/4V, respectively. The increase in ε′ and ε” values with decreasing frequency is attributed to surface-states (Nss), surface/dipole-polarizations at the diamond-like carbon (DLC)/Si interface. This behavior of ε′ and ε” is known as Maxwell-Wagner type polarization. The M''-V plot has clear peak for each frequency and its position shifts from −0.6V (at 2 kHz) to 1.65V (at 1 MHz) due to the relaxation process and Nss at low-mid frequencies. Values of ε′ and ε” changed from 16.27 to 8.12 and 456.93 to 8.73 for 3V in the range of 2 kHz and 1 MHz, respectively. Therefore, the fabricated Al/DLC/p-Si can be used as an alternative to insulators for further electronic-charging/energy-storage.

Research on cadmium-injected manganese ferrite made through the sol-gel method, focusing on its structure, magnetic properties, electrical conductivity, and electrochemical behavior

Cadmium was integrated into Manganese ferrite (Mn1-xCdxFe2O4) nanofine particles via the sol-gel method for potential sensing uses. The X-ray diffraction (XRD) revealed that the particles contained a cubic spinel structure and FTIR spectroscopy was employed to identify the metal-oxide (MO) stretching, bending and stretching vibrations. The purity of the samples and the surface feature were scrutinized using an energy dispersive X-ray (EDAX) spectrum and scanning electron microscope (SEM). The magnetic properties were examined as ferromagnetic found through a vibrating sample magnetometer (VSM). An LCR meter gives information on dielectric constants (ε’ & ε’’), loss (tanδ) with AC conductivity (σAC), and cyclic-voltammetry was used to evaluate the electrochemical properties, including voltage/current responses (V/I), Nyquist frequency, voltage/current response to SCR, and phase angle as a function of frequency. From the results the magnetic, dielectric, electrochemical behavior and etc., can be interpreted and discussed extensively.

Modification of Structural, Optical, and Electrical Properties of PVA/PVP Blend Filled by Nanostructured Titanium Dioxide for Optoelectronic Applications

The PVA/PVP/TiO2 films were prepared using different TiO2 concentrations by solvent casting technique. An analysis was conducted to investigate the influence of TiO2 on the characteristics of PVA/PVP blends. The FTIR, UV/visible spectroscopy, and electrical bridge circuits were used to characterize the prepared nanocomposite films. The structural changes of the nanocomposite relative to pure PVA/PVP are indicated by FTIR spectra. The optical studies demonstrate that by increasing the TiO2 concentration inside PVA/PVP blends, the band gaps reduce from 5.40 eV for PVA/PVP to 4.20 eV for PVA/PVP/TiO2 (10 wt%), also the refractive indices the nanocomposites increase from 1.2020 for PVA/PVP blend into 2.5380 for PVA/PVP/TiO2 (10 wt%). Also, the transmittance decreased from 97.6% for PVA/PVP blend to approximately 55.4% at the largest concentration of TiO2. Additionally, studies were conducted on the parameters, as well, ac conductivity (σ ac). The outcomes of dielectric parameters of the prepared films are enhanced by the doping of TiO2 with different concentrations and dielectric relaxation is observed. The hopping mechanism of PVA/PVP/TiO2 films is supported by the ac conductivity. It is found that adding 10 wt% TiO2 inside PVA/PVP matrix at 5 MHz increases the conductivity of the pure PVA/PVP blend by 4.46 times.

Finding the best frequency dependent performance of 3d transition metals (Co, Ni, and Mn) substituted nano magnetite for miniaturizing device applications

Ferrite samples with enhanced magneto-dielectric properties are more essential in electromagnetic applications. Therefore, a parent composition of Fe3O4 has been modified by substituting 3d transition metal elements (Co, Ni, Mn) at a single Fe atom using the co-precipitation synthesis method. The structural properties of the synthesized Fe3O4, NiFe2O4, CoFe2O4, and MnFe2O4 samples have been evaluated from the X-ray diffraction patterns. The surface morphology and microstructures of the studied samples were studied by field emission scanning electron microscopy and the average grain size of all the studied samples varied from 60.11 to 106.03 nm. The magneto-dielectric properties were analyzed by frequency dependent permeability (μ) and permittivity (ε) measurements for the range of 100 Hz to 100 MHz. The conduction process for the synthesized ferrites has been noticed from the ac conductivity (σac). The localized relaxation mechanism for the studied ferrites has been observed from the variation of imaginary portion of the electric modulus (M") and the impedance (Z"). Moreover, the mismatch (Z/ηο) between the impedance of the antenna substrates (Z) made of the studied samples and air (ηο) has been evaluated from the permeability and permittivity. Finally, NiFe2O4 has been derived as a suitable ferrite for miniaturizing devices over a frequency range of 10 kHz-6.5 MHz.

Investigation of thermal, optical properties, AC conductivity and broadband dielectric spectroscopy of poly(ethyl methacrylate)/poly(vinyl chloride) polymer blend

This work reports the structural, thermal, optical and electrical properties of PEMA, PVC and their polyblends. These properties are investigated by FTIR, TGA, UV/Vis and broadband dielectric spectroscopy. FTIR spectra showed that the characteristic bands of PEMA and PVC are affected by blending and displayed red and blue shifts confirming that an intermolecular interaction between PEMA and PVC is occurred. Thermal degradation kinetics of PEMA, PVC and its polyblend samples is investigated in details and the thermal properties of each decomposition stage are estimated. UV measurements analysis revealed that Urbach energy (EU) is increased while optical bandgap decreased upon increasing the PVC content. The indirect and direct band gap (Eig/Edg) values are decreased from (3.95/4.21) to (3.10/3.92) eV. Also, upon increasing the content of PVC, the lattice dielectric constant (εL) is increased from 2.71 to 7.83. Wemple-DiDomenico model is applied for investigating the refractive index dispersion and to calculate the oscillator and dispersion energies. It is observed that the linear/nonlinear parameters are increased nonlinearly with increasing the PVC content. χ(1), χ(3) and n2 values are found to increase from 0.104, 0.213 × 10−13 and 4.01 × 10−12 to 0.363, 31.26 × 10−13 and 5.33 × 10−12. These results make PEMA/PVC polyblend strong candidates for use in the development and design of advanced optoelectronic devices. AC conductivity (σac) and dielectric measurements are carried out at various temperatures in wide frequency range. Jonscher power law is applied and showed that the predominant conduction mechanism in our samples is overlapping large-polaron tunneling (OLPT). The dielectric constant and electrical impedance are found to be frequency and temperature dependent. The investigation of the electric modulus (M*) revealed that M′ is increased non-linearly with increasing the frequency, while M″ spectra displayed two different modes of relaxation. The interfacial polarization (IP) is observed in low frequency region, while, dipolar relaxation is detected in high frequency region.

Structural, micro-structural and physico-chemical studies of Polyvinylpyroledene (PVP) added Cobalt ferrite (CoFe2O4) nanoparticles

To understand the structural and physico-chemical behavior of magnetic nanoparticle (CoFe2O4) is necessary for the selection of materials for various technological applications. The structural parameters derived from X-Ray diffraction (XRD) such as hopping length of site A (LA) and site B (LB), bond length between two A sites (dLA), two B sites (dLB), A and B (dLAB) and some related lengths. The micro-structural and magnetic studies from Fourier transform infrared spectroscopy (FTIR) and vibration sample magnetometer (VSM) analysis such as force constant, bond lengths between cation – anion (p, q, r, s) and cation - cation (b, c, d, e, f), and the angles between the bonds (θ1, θ2, θ3, θ4, θ5) values and trends were studied and it is merely suitable for 7.5 and 12.5 %. In addition some mechanical behavior obtained through their stiff constant C11 and C12 such as Young's modulus, bulk modulus, rigidity modulus and etc., The dielectric and electrochemical behavior of CoFe2O4 measured through AC conductivity (σAC), resistivity (ρAC) and electric modulus (M’, M’’ and M*) electrochemical parameters (V/I, impedance) through LCR and Cyclic voltameter measurements. The obtained results were interpreted and discussed extensively.

Voltage-frequency dependence of the complex dielectric and electric modulus and the determination of the interface-state density distribution from the capacitance-frequency measurements of Al/p-Si/Al and Al/V2O5/p-Si/Al structures

The energy distribution of the interface states (Nss) and relaxation time (τ) are calculated from the capacitance-frequency (C-f) characteristics for Al/p-type Si/Al metal-semiconductor and Al/V2O5/p-type Si/Al metal–interfacial layer–semiconductor diodes with and without anodic surface passivation. The experimental results show that the density of the interface states and the relaxation times increase almost exponentially with the bias from the top of the valence band to the center of the gap for each diode produced. At the same time, using the C-f characteristics, the dielectric properties such as the dielectric constant (ε′), dielectric loss (ε″), dielectric loss tangent (tanδ), real and imaginary portions of the electric modulus (M’ and M″) and ac electrical conductivity (σac) are investigated in this study. The analysis was performed at room temperature, in the frequency range from 1 kHz to 10 MHz, and the voltage range from 0 to 0.24 V. The experimental results show that the ε′, ε″ and tanδ values decrease with increasing frequency while σac, M′ and M″ values increase. This results will show that dielectric parameters are strongly frequency dependent.

Comprehensive study on dielectric properties and proton conductivity of graphene oxide (GO) embedded PVdF/PVP membrane electrolytes

This article investigates how the presence of polyvinylpyrrolidone (PVP) affects the dielectric properties and proton conductivity of phosphoric acid (PA) doped PVdF/PVP-based composite polymer electrolytes supported by graphene oxide (GO). In the study, insights into the structural, morphological, and thermal characteristics of the proposed composite electrolytes are obtained using characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). Proton conductivity and dielectric measurements are carried out across a frequency and temperature range (20 Hz-1 MHz, 300–420 K). We conduct in-depth discussions on the dielectric properties, including AC conductivity (σac), dielectric permittivity (ε′), imaginary permittivity (ε″), and loss tangent (tanδ) of the polymer electrolytes. While GO enhances the thermomechanical properties, the highest proton conductivity values are observed for (PVdF70/PVP30)-GO and (PVdF50/PVP50)-GO electrolytes, reaching 4.4 × 10−5 and 6.1 × 10−4 S/cm respectively. The dielectric measurements revealed a significant increase in the dielectric constant (ε′) and dielectric loss (ε″) values for the composite membranes, especially at lower frequencies and higher temperatures. For instance, the (PVdF50/PVP50)-GO composite exhibited ε′ values of 8.8 × 106, 1.99 × 105, and 77.38 at frequencies of 20 Hz, 1 kHz, and 1 MHz, respectively, at 300 K, and 7.38 × 106, 2.76 × 104, and 430.5 at 420 K. The ε″ values at 300 K for the same composite were 16.18 × 106, 7.25 × 105, and 1.09 × 103, respectively, at the same frequencies. (PVdF50-PVP50)-GO exhibits the lowest relaxation time (τ) and the highest proton conductivity at ambient temperature. These findings underscore the intricate interplay between PVP content, dielectric properties, and proton conductivity, providing valuable insights for the advancement of polymer electrolyte materials. This study contributes to our understanding of PA-doped (PVdFx/PVPy)-GO electrolytes, with implications for electronic and energy storage devices.

Si/ZnO:Coumarin photocapacitor for electro and photonic applications

The present study first investigated the photocapacitance measurements of Al/p-Si/ZnO:Coumarin/Au metal-oxide-semiconductor MOS device at room temperature in the frequency range of 10 kHz-1MHz and bias voltage range of −5 V; +5 V. Based on photocapacitance analysis, Vbi, Na, Nss, Ef, Em, Δϕb, ϕb, Wd values were calculated for 10 kHz, 100 kHz and 1 MHz. For 1 MHz, Vbi value was 0.79 eV, Na value was 3.54x1015 cm−3, ϕb value was 0.99 eV and Wd value was 530 nm. Additionally, the dielectric constant (ε′), dielectric loss (ε″), electrical modulus (M′M″) and complex impedance (Z*), tangent loss (tanδ), ac conductivity(σac) and phase angle (φ) values of the device were also calculated. ε′ values were calculated 116 at 10 kHz, 58 at 100 kHz and 6 at 1 MHz. These ε′values indicate that the higher ZnO:Coumarin layer can store more charge carriers. This study has shown that materials produced by ZnO, a metal oxide semiconductor, doped with coumarin have the potential to be used in many optoelectronic devices, especially in photonic applications.

Influence of Ac-Signal Amplitude on the Dielectric Properties of Al-Tiw-Ptsi/N-Si Schottky Diodes

Influence of ac-signal amplitude on the dielectric properties of Al-TiW-PtSi/n-Si Schottky diode has been investigated at the room temperature and bias voltage in the range of -2V÷4V, when the amplitude of test signal (500 kHz) changed from 5mV to 1V. By the using impedance method have been obtained real ( εꞌ ) and imaginary (εꞌ) parts of dielectric constants and electric modul ( Mꞌ and Mꞌꞌ ) , loss tangent ( tanδ ), ac electrical conductivity ( σac ), the series resistance ( Rs ), On all dependences on voltage and amplitude of ac-signal , there is a jump in the value of the parameter in the range of voltage values 1-2V and 200mV It can be concluded that, at certain values, the amplitude of the ac-signal can significantly affect the interfacial polarization even at high frequencies.