Ac Conductivity Analysis Research Articles

In-situ polymerized boehmite/ cashew gum/ polyvinyl alcohol/ polypyrrole blend nanocomposites with tunable structural, electrical, and mechanical properties for enhanced energy storage applications

This study describes the successful synthesis of boehmite (BHM) nanofiller-reinforced ternary blend nanocomposite films composed of polyvinyl alcohol (PVA), cashew gum (CG), and polypyrrole (PPy) using in-situ polymerization with water as the environmentally friendly solvent. The blend nanocomposites were characterized using Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). FTIR analysis revealed chemical bonding between BHM and the biopolymer matrix at1071 cm-1. FE-SEM images exhibited a uniform distribution of BHM nanofillers within the CG/PVA/PPy matrix, particularly at a 10 wt% concentration. The addition of BHM significantly enhanced the thermal stability and the glass transition temperature of the nanocomposites. The temperature-sensitive AC conductivity, activation energy, and dielectric properties were examined using an impedance analyzer. AC conductivity analysis revealed reduced activation energy (1.277 × 10⁻5 eV at 7 wt% BHM) and increased dielectric constant (from 565.28 to 4411.22). The ternary blend nanocomposite demonstrated a significant 60.2 % increase in tensile strength, reflecting enhanced force resistance, while hardness values ranged from 26 to 30, classifying the films as soft and flexible. Overall, the study highlights significant enhancements in the morphological, electrical, thermal, dielectric, and mechanical properties of the nanocomposite films, emphasizing their promising potential for energy storage applications.

Ionic liquid supported chitosan-g-SPA as a biopolymer-based single ion conducting solid polymer electrolyte for energy storage devices

This article discusses the preparation of different grades of single-ion conducting quasi-solid polymer electrolytes (q-SPE) material (Chit-g-SPA-IL) based on biopolymer (chitosan), polyacrylic acid and DBU-acetate (DBUH+ AcO−) ionic liquid. Chit-SPA-60 %-IL exhibited the highest conductivity within the range of 10−4 S/cm. TGA analysis demonstrated the stability of electrolytes up to a temperature of 120 °C. SEM-EDS analysis unveiled the porous nature of the electrolyte and even distribution of ions throughout the matrix. It exhibited an electrochemical stability window (EWS) of 2.53 V with significant current density and an ionic transference number (ITN) of ~99.9 %. The temperature-dependent conductivity established an Arrhenius-type conduction mechanism with an activation energy of 0.149 eV for ion movement within the electrolyte matrix. The AC conductivity analysis emphasized the time-temperature independence of the ionic conduction mechanism. Dielectric analysis highlighted the capacitive nature of the electrolyte, underlining its substantial capacitance, while modulus studies indicated minimal influence from the electrode-electrolyte interface. Chit-SPA-60 %-IL at 30 °C included a self-diffusion coefficient of 4.57 × 10−5 m2/s, ionic mobility of 1.75 × 10−3 m2/Vs, and drift ionic velocity of 0.44 m/s. These findings makes SPE as a promising candidate for sodium-ion-based energy storage devices.

Electrical conductivity and relaxation mechanisms of nanocrystalline Ba0.75Ca0.2Cs0.05TiO3

Ca and Cs doped barium titanate lead-free ceramic with the formula Ba0.75Ca0.2Cs0.05TiO3 has been prepared by the solid-state reaction method. X-ray diffraction (XRD) confirms the crystallization of the sample in a tetragonal structure with a P4mm space group. The phase purity and grain morphology were evaluated using X-ray diffraction and scanning electron microscopy (SEM). The material exhibits a primary phase of Ba0.75Ca0.2Cs0.05TiO3 with a minor secondary phase of BaO2, and the average grain size is determined to be 1.66 μm. Using non-destructive complex impedance spectroscopy (CIS), we extensively studied the electrical behavior, including complex impedance (Z*), complex modulus (M*), electrical conductivity, and relaxation mechanisms, of Ba0.75Ca0.2Cs0.05TiO3 over a wide temperature (85 K–290 K) and frequency range. The ac conductivity analysis reveals that the dominant conduction mechanism is the non-overlapping small polaron tunneling (NSPT) model. The impedance analysis indicates a single semi-circle in the real and imaginary parts, suggesting a single relaxation mechanism. Additionally, the activation energy was calculated to be approximately 0.0489 eV. These findings contribute to the understanding of the structural and electrical properties of Ba0.75Ca0.2Cs0.05TiO3, highlighting its potential applications in electronic devices such as capacitors, thermistors, and ferroelectric random access memories (FRAMs).

Ionic liquid based NCPBE membranes for electrochemical capacitor applications: Structural, thermal and electrical transport properties

The current study focuses on the preparation and characterisation of imidazolium ionic liquid based plasticized nano-composite polymer blend electrolytes (NCPBEs). Semi-crystalline nature of the synthesized samples was observed using XRD analysis. ATR-FTIR results demonstrate the interaction among the carbonyl (CO) and hydroxyl (O–H) groups of polymers with ionic liquid (IL) and salt, NaI. Furthermore, thermo-gravimetric analysis (TGA) indicates multi-step decomposition process. Ion transport mechanism has been analysed using temperature dependent conductivity analysis, ac conductivity analysis and dielectric properties study. The sample containing 25 wt% IL i.e. NCPBE-25 has the ionic conductivity ∼9.30 × 10−4 Scm−1 with the optimum vale of charge carrier density, mobility, and ion diffusivity at 30oC. Ions are principal charge carriers in the present electrolytes. The sample NCPBE-25 has the electro-chemical stability window −3.6 to 1.5 V at room temperature. The fabricated electro-chemical capacitor has the specific capacitance, energy density and power density 363.27 Fg-1, 50.45 Whkg−1 and 18.16 kW/kg, respectively at the scan rate 5 mV/s.

Structural, Microstructural, and Electrical Properties Study of Pb(Sn0.45Ti0.55)O3 Ceramics

We undertook a comprehensive investigation of the the structural, dielectric, and electrical characteristics of Pb(Sn0.45Ti0.55)O3 ceramics prepared using the conventional solid-state route. A meticulous preparation protocol, involving solvating various precursors, was followed by extensive characterization employing X-ray diffraction, scanning electron microscopy, and dielectric studies. The synthesized sample features a single-phase tetragonal structure with P4mm symmetry. Using impedance spectroscopy, electrical transport properties of the polycrystalline Pb(Sn0.45Ti0.55)O3(PST) ceramic were studied in detail. Relaxation and conduction mechanisms of the material were inferred using complex impedance, complex electric modulus, and frequency dependent ac conductivity analysis. Impedance spectroscopy results reveal the range of frequencies in which the grain, grain boundary, and electrode effects are dominant. Above certain temperatures, the imaginary component of impedance (Z//) exhibits some resonant type peaks at different frequencies indicating relaxor nature of the sample. The activation energy obtained for both the relaxation and conduction process indicates the role of doubly-ionized oxygen vacancy in the conduction mechanism of the sample. The dielectric relaxation occurring at low frequency and high temperatures is related to the space charges associated with the ionized oxygen vacancies being trapped at the grain boundaries. The Cole-Cole plots confirm the poly-dispersive nature of dielectric relaxation in the sample.

Investigation of structural, morphological, and ionic conduction behaviour of Na+ substituted trimeric strontium silicate Sr3–3xNa3xSi3O9-δ (0.00 ≤ x ≤ 0.20)

Extensive research has been carried out to search new electrolytes for Solid Oxide Fuel Cells (SOFCs) in order to reduce their operating temperature in the intermediate temperature range (500 ̊C < t < 800 ̊C) for wide commercialization. Recently, alkali doped strontium silicates materials have been reported to show adequate ionic conductivity in the intermediate temperature range. Hence, in the present work, we have tried to synthesize trimeric Sr3–3xNa3xSi3O9-δ (0.00 ≤ x ≤ 0.20; SNS) system and did a comprehensive study on this system to examine its applicability as a solid electrolyte for electrochemical devices such as IT-SOFCs. The SNS system was prepared via solid state reaction route and characterized by means of XRD, FT-IR and Raman spectroscopy to authenticate the structural phase formation and to gather its spectroscopic traits. The optical Energy band gap of the system was calculated by means of UV-Visible absorption spectroscopy. Surface morphology, microstructure and elemental confinement of the system was examined via Scanning Electron Microscopy (SEM) and Energy dispersive spectroscopy (EDX) techniques. The ionic transport study of the system has been conducted via AC conductivity analysis and Electrical Impedance Spectroscopy (EIS) technique. The highest total conductivity ∼ 0.46×10−2 Scm−1 at 650 ºC was found for the composition Sr2.40Na0.60Si3O9-δ thru EIS method.

Low temperature dielectric study and photoconductive analysis of ZnO/NiO composite material

The sol-gel process was used to synthesize a ZnO–NiO composite material in this study. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the material, which confirmed the existence of both ZnO nanoparticles and NiO sheets in the composite. The composite material contained two distinct crystalline phases, the face-centered cubic phase of NiO and the hexagonal phase of ZnO. The composite's average crystallite size was determined to be 19.0 nm. The particle size of the composite material was calculated to be ∼121 nm. The band edge emission at 393 nm (3.15 eV) was measured using photoluminescence (PL) spectroscopy. The PL spectrum revealed other emissions as well. The dielectric properties of the material were studied at low temperatures in the frequency range of 20 Hz to 1 MHz, and it was found to have a low dielectric dissipation at high frequencies, making it suitable for use in high frequency microwave devices. Impedance data was fitted using Z-View software with a fitting error of <5%. Impedance spectroscopy revealed that the composite material had two dielectric relaxation processes related to the bulk and the grain boundary. Analysis of frequency dependent ac conductivity revealed Overlapping large-polaron hopping (OLPH) is responsible conduction mechanism in our case indicated by variation of temperature (200–280 K) dependent parameter “s” with temperature. Photoconductivity studies showed that the composite material had enhanced electrical conductivity and photoconductivity compared to pure ZnO and NiO. This makes it a promising candidate for use in optoelectronic applications such as solar cells, optical switches, and photodetectors. The responsivity of composite (0.86 mA/Watt) is found to be 10 times greater than that of the responsivity of NiO (0.085 mA/Watt).

Tunable energy bandgap of Fe-doped (Bi, Li) co-substituted barium titanate

In this work, a polycrystalline Ba0.96(½ Bi, ½ Li)0.04Ti(1-x) FexO3; (0 ≤ x ≤ 0.08) ceramics have been synthesised using a solid-state reaction method. The prepared systems were explored to detect the impact of Fe substitution on the energy bandgap of the ceramics. XRD patterns confirmed that there is a structural phase transition from tetragonal (P4 mm) to hexagonal (P63/mmc) phase as the concentration of Fe increases. Rietveld refinement was performed to obtain the lattice information. Furthermore, Raman spectroscopic analysis confirmed the structural information obtained from XRD study. The average bond length variations, strain evolutions, crystallite size, and theoretical density have been calculated from the structural analysis. It is found that the lower Fe concentration with the tetragonal phase showed a strong Jahn-Teller effect. Meanwhile, the higher concentration of Fe led to phase transition to hexagonal phase with fewer structural distortions. The optical band gap species were investigated through UV-Vis. Following the onset of defects induced by acceptor ions, an exciting band gap reduction up to 2.09 eV for the sample with x = 0.08 was attained. ESR and PL spectroscopies analyses showed that in the hexagonal phase region more defects are formed giving rise to promoting band gap narrowing. Furthermore, the ac conductivity analysis indicates the appearance of defect levels due to the formation of oxygen vacancies. This study demonstrates that the right choice of Fe content in the host material can tune the energy band gap significantly in the BLBTF system and may be exploited in photovoltaics in the visible region.

Synthesis and characterization of (1-x)Bi0.9Sm0.1FeO3 - (x)BaZr0.15Ti0.85O3 based solid solution: Temperature-dependent dielectric and impedance properties

Lead-free solid solution of (1-x) Bi0.9Sm0.1FeO3 − (x) BaZr0.15Ti0.85O3 (BSFO − BZT) (x = 0.0, 0.10, 0.15, 0.20, 0.25, 0.50) ceramics were prepared using solid-state reaction method. The structural, morphological, temperature-dependent dielectric properties and leakage current were investigated. The structural investigation revealed the formation of perovskite structure coexisting with tetragonal and rhombohedral phases within (BSFO–BZT) ceramics. The dielectric measurements (within 303 K-773 K) confirmed the existence of a morphotropic phase boundary at x = 0.15 for the (BSFO–BZT) system. The frequency and temperature dependent electrical behavior were explained using Ac conductivity and impedance analysis. The leakage current behavior for all these samples was investigated using both space charge-limited conduction (SCLC) for bulk and Schottky emission (SE) for limited interface conduction approach, whereas the pure BSFO sample was found to be dominated by ohmic conduction, while the BZT-doped samples were dominated by grain boundary-limited conduction.The sample (0.80)Bi0.9Sm0.1FeO3-(0.15)BaZr0.15Ti0.85O3 achieved largest dielectric constant 330 at 10 KHz along with a moderate leakage current density value of 3.54 × 10-5A/cm2 (which is quite lower than pure BSFO) proven its candidacy to develop a stable photovoltaic, multilayer actuators, and ferroelectric memory devices.

Enhanced electrical conductivity and charge conduction mechanisms in Nano-cubical Sunset Yellow dye incorporated with titanium dioxide nanoparticles

This manuscript focuses on the investigation of the effect of titanium dioxide nanoparticles doping on the electrical conductivity of Nano-cubical Sunset Yellow Dye. The successful preparation of the composite was confirmed through XRD analysis, and EDX analysis verified the composite's composition. DC conductivity measurements revealed two conduction mechanisms with activation energies of 0.683 eV and 0.466 eV for the dye without NPs at low and high-temperature regions, respectively, and 0.532 eV and 0.351 eV for the same regions in the presence of NPs. AC conductivity analysis showed single polaron hopping as the dominant charge conduction mechanism for both devices. The device with the dye-NP composite exhibited lower activation energy and improved conductivity compared to the dye-only device. The composite also displayed a higher density of localized states, and by incorporation of NPs reduced the hopping length, contributing to the enhanced conductivity of the composite device.

Temperature dependent magnetic and electrical transport properties of lanthanum and samarium substituted nanocrystalline nickel ferrite and their hyperthermia applications

Structural, optical, temperature dependent magnetic and electrical properties have been investigated for the nanocrystalline NiFe1.97RE0.03O4 (RE = La3+ and Sm3+) compound. Without any signs of a secondary REFeO3 phase, the Rietveld refinement reveals a single-phase spinel structure possessing cubic symmetry for current samples. The decrease in lattice constant has been observed as a result of RE ions substitution. The TEM micrographs reveal nanosized particles with an average size of 35 ± 3 nm and 32 ± 3 nm for La3+ and Sm3+ substituted samples. EDX spectra of both samples show good compositional homogeneity. HRTEM micrographs of both samples show well resolved lattice fringes and their inter-planar spacing matches with that obtained from the Rietveld analysis of the XRD patterns. The concentration of Fe2+ and Fe3+ ions has been estimated from the XPS spectra analysis and it is found to be ∼ 22% and 78% for NiFe1.97La0.03O4 and, 20% and 80% for NiFe1.97Sm0.03O4 compound. The optical energy band gap for rare earth substituted samples is found to be more than that of pure nickel ferrite. The value of saturation magnetization (Ms) and magneto-crystalline anisotropy constant (K1) estimated from the “Law of Approach to Saturation” equation for rare earth substituted samples are found to be less than that of pure nickel ferrite. However, an enhanced value of coercivity has been observed with RE substitution. ZFC (zero field cooling) and FC (field cooling) DC magnetization curves measured at 100 Oe in the temperature range of 60–400 K reveal a combination of weak and intermediate forms of magnetic interaction between the particles for both samples. Temperature dependent analysis of saturation magnetization and coercivity employing modified Bloch’s law and Kneller’s relation supports the nanomagnetic behavior of both samples. Under an AC magnetic field of 14.92 kA/m and frequency 337 kHz, the SAR and ILP values have been found to be ∼ 331 W/g and 4.22 nHm2/kg for NiFe1.97La0.03O4 and, ∼ 241 W/g and 3.21 nHm2/kg for NiFe1.97Sm0.03O4. The dielectric relaxation data have been analyzed at various temperatures ranging from 40 to 300 0C over the frequency range 100 Hz-1 MHz using electrical impedance spectroscopy. The dielectric constant for rare earth substituted samples is found to be more and their AC conductivity is observed to be less than that of pure nickel ferrite. The analysis of temperature dependent AC conductivity employing Jonscher’s power law suggests that the charge carrier’s conduction mechanism of both samples follows the small polaron hopping mechanism below 200 0C, thereafter; it follows the correlated barrier hopping mechanism. The activation energy estimated by imaginary impedance spectra is found to be 0.411 eV and 0.398 eV for NiFe1.97La0.03O4 and NiFe1.97Sm0.03O4 which is more than that of pure nickel ferrite. The Cole-Cole plots at different temperatures suggest the presence of non-Debye-type relaxation. The modeling of Cole-Cole plots with equivalent circuits for both samples confirms the contribution of both grain and grain boundary in electrical conduction. The estimated stretching exponential factor by fitting the modified KWW (Kohlrausch-Williams-Watts) equation to the imaginary modulus curve reveals relatively more dipole-dipole interaction in NiFe1.97Sm0.03O4 than that of the La3+ substituted sample.

Impedance Spectroscopy and AC Conductivity Analysis of (Ba1−kCak)(Zr0.1Ti0.9)O3, (0.140 ≤ k ≤ 0.160), Ceramics

Ceramic pellets of (Ba1−kCak)(Zr1−zTiz)O3, (k = 0.140–0.160, z = 0.9) were prepared via solid-state reaction technique followed by double sintering. The impedance measurements were carried out at different temperatures and frequencies (12–1000 kHz). The NTCR nature exhibits the semiconducting behavior of the prepared BCZT ceramics in the measured temperature range. The temperature also has a considerable impact on the relaxing process. The characteristics of Nyquist plots show that bulk and grain boundary effects exist in BCZT ceramics. The bulk conductivity indicates an Arrhenius-type thermally activated process. The observed impedance spectra, relaxation behavior, and AC conductivity of the prepared compositions of BCZT ceramics will extend the possibilities for using this compound in various optoelectronic applications.

Study of the effect of the substitution of Fe by Ti on the microstructure and the physical properties of the perovskite system La0.67Ca0.2Ba0.13Fe1-xTixO3 with x = 0 and 0.03 at low temperatures.

La0.67Ca0.2Ba0.13Fe1-xTixO3 samples (x = 0 and 0.03) were synthesized by the auto-combustion method. Analysis of XRD diffractograms revealed that these compounds crystallize in the cubic system with the space group Pm3̄m. The dielectric properties have been studied in the 102-106 frequency range and the 120-280 K temperature range. Analysis of AC conductivity shows that the conduction mechanisms are of polaronic origin and that they are co-dominated by the NSPT and OLPT models. The monotonic increase in conductivity with increasing temperature results from the reduction of defect centers and the increase in charge carrier mobility. Such variation is consistent with impedance variation at different frequencies and temperatures indicating semiconductor behavior. Nyquist diagrams are characterized by the appearance of semi-circular arcs. These spectra are modeled in terms of equivalent electrical circuits confirming the contribution of grains (Rg//CPEg) and grain boundaries (Rgb//CPEgb). The dielectric analysis showed an evolution of the dielectric constant in accordance with Koop's theory and the phenomenological model of Maxwell-Wagner. The low conductivity and the high values of the real permittivity at low frequency make our compounds potential candidates for energy storage and applications for electronic devices and microwaves.

Fabrication of a low-cost efficient novel Ti3AlC2 MAX phase / Polyvinyl alcohol / Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) polymer nanocomposite film for symmetric supercapacitor

ABSTRACT This work reports a systematic study of the electrochemical performance of the Ti3AlC2 MAX phase/PVA-PEDOT: PSS + DMSO polymer nanocomposite (PPM) films fabricated by the facile solution cast technique. A varying weight percentage of Ti3AlC2 MAX phase nanoparticles were dispersed in the polyvinyl alcohol (PVA)-[poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) + dimethyl sulfoxide)] (PEDOT: PSS + DMSO) polymer blend to fabricate the polymer nanocomposite films. The structural, morphological, optical, thermal, electrical, and electrochemical properties of the nanocomposite films were studied meticulously. The structural and morphological studies were done by using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction technique (XRD), and field emission scanning electron microscopy (FESEM). The optical properties of the PPM films were analyzed using the UV-Visible (UV-Vis) spectra. The thermal analysis of the PPM films was done from the thermogravimetric analysis (TGA) curves. The ac conductivity and dynamic mechanical analysis (DMA) were done to evaluate the electrical conductivity and mechanical properties of the PPM films. The performance enhancement of the polymer blend film by loading Ti3AlC2 MAX phase nanofiller was investigated. The nanocomposite film having the highest conductivity and the greatest mechanical strength was further considered for the electrochemical characterization. The nanocomposites reported a specific capacitance of 52.8 F/g and 1500 mF/g in 0.1 M HCl electrolyte at a scan rate of 20 mV/s in the 3-electrode system and 2-electrode system, respectively. The Nyquist plots and Bode plots were plotted from the electrochemical impedance spectroscopy (EIS) data. The Nyquist plots were analyzed from the simulated equivalent circuits. The facile fabrication method of the supercapacitor electrode with improved thermal and mechanical properties will be beneficial for their commercial electrochemical applications in the future.

Study of frequency dependence properties of CCTO-BT/polymer composites

In the current study, the calcium copper titanate (CCTO)/polymer, barium titanate (BT)/polymer, and CCTO-BT/polymer composites with variable volume fractions of CCTO and BT are fabricated using hand lay-up and compression molding processes. The composites are characterized for the frequency dependence on dielectric properties, conductivity, impedance spectroscopy, and electrical modulus. X-ray diffraction (XRD) patterns of CCTO-BT/polymer composite samples confirmed the presence of both CCTO and BT ceramic samples separately. The dielectric properties of hybrid CCTO-BT/polymer composites with 10 vol% CCTO 10 vol% BT, 12 vol% CCTO 8 vol% BT, and 8 vol% CCTO 12 vol% BT was found relatively better than those of the single ceramic filler reinforced polymer composites. AC conductivity analysis shows a significant improvement in the results of hybrid filler-filled CCTO-BT/polymer composites in comparison with single filler-filled polymer composites. Thus, impedance analysis confirms higher insulating properties for 8 vol% CCTO 12 vol% BT and 12 vol% CCTO 8 vol% BT hybrid CCTO-BT/polymer composites with respect to the single and other hybrid ceramic polymer composites. The analysis suggests the hybrid CCTO-BT/polymer composites to be adopted as a possible dielectric material for energy storage devices and other electronic applications.

Influence of LiNbO3 layer thickness on structural and dielectric properties of CoFe2O4\\LiNbO3 multiferroic bilayers prepared by laser ablation

Multiferroic bilayer thin films composed by LiNbO3 and CoFe2O4 were prepared by laser ablation over (100) platinum-covered Si substrates, to understand the influence of the LiNbO3 layer thickness on their structural, electric and dielectric properties. The films were dense and polycrystalline, presenting rhombohedral LiNbO3 and cubic spinel CoFe2O4 layers. The CoFe2O4 unit cell experienced compression along the growth direction of the films, whereas the LiNbO3 layer exhibited a structural distortion in its unit cell. These strain effects were due to the mechanical interaction between both layers and to the presence of a higher amount of point defects in the thinner LiNbO3 samples, which gradually relaxed as the LiNbO3 layer thickness increased. The DC conductivity and activation energies of LiNbO3, determined from low-frequency dielectric permittivity behavior, were found to be dependent on the layer thickness. Thicker LiNbO3 layers displayed bulk-like characteristics, with a transition from polaronic to ionic conduction with increasing temperature. In contrast, thinner LiNbO3 layer films displayed polaronic behavior up to higher temperatures, due to the formation of bound polarons associated with lithium defects during deposition. AC conductivity analysis revealed that the CoFe2O4 layer conductivity mechanism primarily involved hopping between ions located at octahedral sites in the ferrite. These findings provide valuable insights into structure-function relationships and dynamical behavior within multiferroic bilayer thin films, promoting their applicability for emerging magneto-electric technologies.

Characterization of BiFeO3–Al2O3 nano-composites: A study of structural, microstructural, electrical, and magnetic properties

Results: of the studies on the structural, magnetic, and electrical properties of BiFeO3–Al2O3 nanocomposites prepared using the sol-gel method have been reported. The X-ray diffraction results confirm bi-phase structure of the composites with the presence of some impurity phases of Bi25FeO40 and Bi24A12O39. Field emission scanning electron microscopy images revealed the crystalline nature composed of grain and grain boundaries of both the pure and composite samples. Energy-dispersive X-ray spectroscopy confirms the absence of unwanted components. Magnetic characterization reveals weak ferromagnetic behaviour of BiFeO3 and composites while diamagnetic behaviour of Al2O3. The maximum saturation magnetization in the pure BFO sample is ∼ 6 emu/gm, but this magnetization is lowered by up to 63% and is determined to be ∼ 3.8 emu/gm with the 30% addition of Al2O3 in the BFO matrix. Electrical measurements demonstrate that the addition of Al2O3 nanoparticles leads to a reduction in the dielectric constant, loss tangent, and ac conductivity. A.C. conductivity was found to follow Jonscher's universal power law and to be dominated by the correlated barrier hopping mechanism in the conduction process, according to frequency-dependent ac conductivity analysis. Additionally, impedance analysis reveals a field-induced excitation of charge carriers, resulting in a noteworthy reduction in sample impedance. Overall electrical properties have been discussed in the context of oxygen vacancies, secondary phases, defects, and disorder in details

Microstructure, AC conductivity and complex modulus analysis of Ca-ZnO nanoparticles for potential optoelectronic applications

In the present work, we investigate the conductivity characteristics and microstructure of Ca-doped ZnO (ZO_Ca) nanoparticles. ZO_Ca nanoparticles were created using a straightforward sol-gel manufacturing method and annealed at various temperatures. Powder X-ray diffraction analysis provided proof of the ZO_Ca nanoparticles' purity, crystalline nature, and hexagonal structure. Meanwhile, the transmission electron microscopy (TEM) was used to establish the morphology and shape of the ZO_Ca nanoparticles, and energy dispersive X-ray spectroscopy analysis was used to discover the components that make up the particles' makeup. Moreover, AC conductivity measurements have been used to examine the electrical characteristics of ZO_Ca nanoparticles. Reduced activation energy values demonstrate the material's appropriateness for photonics devices, and the small proportion of activation energy derived from AC conductivity and complex modulus measurements is an added benefit for the construction of optoelectronic devices.

Enhanced room temperature relative permittivity and low dielectric loss ferroelectric double perovskite for energy storage applications

The polycrystalline ceramic oxide, BaBi1.2Fe0.8TiO6 is synthesized by a mixed oxide method at 1000 °C. XRD and Rietveld's analysis suggests a tetragonal system and P4mm space group. The closely spaced dense micro grains of various shapes and sizes in scanning electron micrograph (SEM) image support the polycrystalline single-phase compound. The UV–Visible spectroscopy results in a convenient value of threshold wavelength (610 nm), absorption bandgap energy (2.23 eV), and reflectance bandgap energy (2.31 eV) which are good responses to the IR and visible range and its possible application in photocatalytic devices. The room temperature (RT) polarization loop shows non-zero remanent polarization, i.e. ferroelectric property of the compound. Relatively higher room temperature dielectric permittivity (ɛr = 2455) with low loss tangent (tanδ) = 0.247 at 100 Hz, phase transition (Td > 200 °C), and Curie (Tc > 470 °C) temperature values are supporting to be as good dielectric material for ceramic capacitors. Transport property shows lower RT current density is in order of 1E-9 at 300 V/cm. The compound follows the Arrhenius equation and results in imminent values of activation energy in ac conductivity (Ea = 0.847 eV at 100 Hz) and dc conductivity (Ea = 0.838 eV) analysis. Based on the results, the present compound is likely to be used as a dielectric material in ceramic capacitors, energy and memory storage devices, and photocatalytic devices.

Electrical transport phenomena and modulus behavior in lead-free Ba0.85Sr0.15Ti0.85Zr0.15O3 compound

In this work, the ceramic Ba0.85Sr0.15Ti0.85Zr0.15O3 is prepared using the conventional solid-state reaction method. The frequency dependence of the electrical conductivity, impedance, and electric modulus of Ba0.85Sr0.15Ti0.85Zr0.15O3 are investigated using numerous theoretical laws over a large temperature range. The X-ray diffraction (XRD) study confirms that this composition crystallizes in pseudo-cubic symmetry. In addition, it shows the good crystallization of our material. The appearance of semiconductor behavior is attributed to the activation of the small polaron hopping process. AC conductivity analysis confirms the presence of complex behaviors. Indeed, we found the contribution of several hopping and tunneling processes to the conduction properties. The Nyquist plots (Z” vs. Z’) confirm the important contribution of the microstructure to the transport and relaxation phenomena. The complex modulus analysis confirms the strong correlation between the movements of the mobile charge carriers and shows the thermal activation of the relaxation process in Ba0.85Sr0.15Ti0.85Zr0.15O3. As a result, the long-distance movement of the load carriers essentially determines the relaxation process at low frequencies. From the electric modulus results, it is observed that the system under study reveals a non-Debye character.