Complex Impedance Properties Research Articles

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.

Revealing the effects of electron beam irradiation on the structural, optical, thermal, and dielectric properties of PVC/Ag2WO4 nanocomposite films

Herein, rod-like shape of Ag2WO4 was synthesized using the co-precipitation approach. These rods were mixed with PVC using the solution casting process to create a PVC/Ag2WO4 nanocomposite film. The effect of exposing the PVC/Ag2WO4 nanocomposite film to varying doses of the electron beam (E-beam) irradiation (0, 25, 50, and 100) kGy on its structural, optical, thermal, electric modulus, complex impedance, and dielectric properties was investigated. XRD results showed that Ag2WO4 has mixed phases. The optical properties have been addressed. The thermal evaluations were performed at three distinct heating rates: 6, 8, and 10 °C/min. In the same context, the thermal activation energy (Ea) of the unirradiated PVC/Ag2WO4 nanocomposite films increased from 12.89 to 31.17 kJ/mol with the increase in E-beam irradiation doses. As a result, E-beam irradiation reduces the values of the real (ɛ′) and imaginary (ε″) components of PVC/Ag2WO4 nanocomposite films. The electric modulus analyses showed that the magnitude of the grain capacitance increased as the E-beam doses increased, while the magnitude of the grain boundary capacitance exhibited a decreasing trend. Meanwhile, a progressive reduction in the diameter of the two semicircular arcs for complex impedance analyses was observed as the doses of E-beam irradiation increase.

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).

Analyses of negative real permittivity behavior, AC conductivity and impedance properties of (YxEu1-x)Ba2Cu3O6.5 ceramics

In the present study, the dielectric, ac conductivity, and complex impedance properties of (YxEu1-x) Ba2Cu3O6.5 perovskite ceramics where x: 0; 0,4; 0,6; 1 have been examined from room temperature to 523 K between 1 Hz and 20 MHz frequency range. The ceramics have been synthesized by solid-state reaction method. The XRD analyses of the samples pointed out that they crystallize in an orthorhombic structure. While the highest orthorombicity factor has been observed for YBa2Cu3O6.5 ceramic, the reduced orthorhombicity in the other ceramics has been associated with the Eu substitution. On the other hand, the dielectric analyses of the samples have revealed a negative real permittivity (NRP) property of all ceramics regardless of the Eu substitution ratio and temperature. The origin of the NRP phenomenon has been explained based on the Drude model. However, it has been reported that the frequency interval at which the NRP is valid is maximum for x≥0.6 at high temperatures (T > 500 K). Additionally, both impedance and loss tangent spectra of the samples have been evaluated by establishing a correlation between NRP and the inductive character of the ceramics. The dc conductivity and the real component of complex impedance analyses imply the semiconducting nature and the negative thermal coefficient (NTC) of resistance of the ceramics. Ac conductivity analyses also indicate a pre-dominant CBH charge transport mechanism in the ceramics except for EuBa2Cu3O6.5.

Structural, conductivity, and complex impedance properties of the La0.7Ag0.3Mn1−xZnxO3 (x = 0 and x = 0.025) samples

In this paper, the structural and dielectric properties of La0.7Ag0.3Mn1−xZnxO3 (x = 0 and 0.025) manganite system are investigated. The x-ray diffraction analysis confirms that all compounds crystallized in the rhombohedral structure with R3̄C space group. The effects of Zn substitution on the crystal structure and the dielectric properties were studied by using the impedance spectroscopy technique at room temperature and over a wide range of frequencies. Electrical conductance curves are found to obey the Jonscher universal power law. We note a decrease in the conductivity when increasing the Zn content from x = 0 to x = 0.025. This behavior can be associated with the introduction of a very low concentration of a non-magnetic Zn ion, which distorts the octahedral MnO6 neighbor. The analysis of the complex impedance spectra reveals a single semicircular arc reflecting a non-Debye-type relaxation process. We conclude from the best fits that the equivalent circuit formed in our case is defined as a grain resistance Rg in series with a parallel combination of grain boundary resistance Rgb and constant phase element impedance (ZCPE).

Structural, impedance, and photoluminescence properties of Ho3+ substituted Na0·5Bi0·5TiO3

Complex impedance and photoluminescence properties have been investigated in Na0.5 Bi(1-x) HoxTiO3 x = 0, 0.5, 1, 2 and 3 mol %. The observation of semicircle in the higher temperature regime from the Nyquist plots confirms the Debye type relaxation. Overlapping of normalized Z″ and M″ peaks suggested the long-range relaxation of charge carriers. The grain resistance (Rg) decreased with temperature. The improved insulating character was found for a small concentration (0.5 mol %) of holmium substituted NBT. Additionally, photoluminescence emission peaks associated with the transitions in Ho3+ ions were observed in the visible range. Quenching in photoluminescence intensities was observed in the higher composition (3 mol % Ho3+ substituted NBT) which we surmise as due to the collective impact of concentration quenching and the emergence of higher symmetric orthorhombic phase (Pbnm) within lower symmetric (R3c + Cc) phase.

Effect of Ag doping on structural, optical, complex impedance and photovoltaic properties of SnO2 nanoparticles prepared by co-precipitation method for dye sensitized solar cell application

The pure SnO2 and Ag-doped snO2 nanoparticles (NPs) were prepared by co-precipitation method. The structural, electrical and optical properties of the material were systematically studied. The XRD patterns of both samples reveal that the presence of cassiterite tetragonal structure and GSAS fittings confirms the incorporation of Ag in SnO2 lattices. The SEM-EDS analysis reveals that the presence of spherical-shaped NPs with the expected elements. The Raman spectra of Ag-doped SnO2 NPs show that the two extra local disorder vibrational modes while comparing with pure SnO2. The UV-Vis spectroscopy result shows that the Ag doping reduces the optical band gap and increases Urbach tail energy with a reduced effective energy band gap in Ag-doped SnO2 NPs. The Photoluminescence spectrum confirms the presence of the defects like oxygen vacancies; however, these defects are increased by the Ag-doped SnO2 system. From the dielectric measurements, the conductivity of both samples followed Jonscher’s power law. The nonlinear least-square fittings on Nyquist plots of both samples suggested that the conduction process took place predominantly through grain boundary in SnO2 NPs whereas through grains in Ag-SnO2 NPs. This nature of band gap narrowing with increased conductivity in Ag-doped samples drives these samples for good solar cell activity applications. As expected, photovoltaic measurements show higher power conversion efficiency in Ag-doped SnO2 NPs. These results were discussed by correlating optical and dielectric properties of SnO2 and Ag-doped SnO2 NPs which gave a broad understanding for device fabrications successfully.

Synthesis and investigation on the microstructural and electrical proprieties of Ni0.1Co0.5Cu0.4Fe2O4 ferrite prepared using sol-gel route

In this work, the new polycrystalline spinel-type Ni0.1Co0.5Cu0.4Fe2O4 (NCCF) ferrite has been prepared via sol-gel method and analyzed using X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively for structural, morphological, and elemental analysis. The refinement of X-ray pattern via the Rietveld technique asserts that the prepared sample exhibits the formation of a mono-phase cubic spinel structure with a Fd3¯m space group. The modified Scherrer and Williamson Hall (W–H) equations were used to evaluate the average crystallite size in the NCCF. Dielectric and complex impedance properties have been investigated in frequency range 102 ≤ f ​≤ ​106 ​Hz and in temperature range 300 ​≤ ​T ​≤ ​400 ​K using spectroscopy impedance. The ac conductivity was modeled using Jonscher's power law from 300 ​K to 340 ​K and Jonscher's augmented equation from 350 ​K to 400 ​K. Moreover, the temperature dependence of the dc conductivity revealed a semiconductor-metal transition occurring in our sample at TSM ​= ​370 ​K. The dielectric constant was exhaustively investigated vs. frequency and temperature and was obtained according to Maxwell-Wagner polarization. Col-Col plot of impedance data was used to evaluate the grain and grain boundary contributions in the NCCF sample.

Synthesis and characterization of strontium-doped barium titanate thin film by dip and dry technique

Thin films of polycrystalline (Ba[Formula: see text][Formula: see text]TiO3 ([Formula: see text] = 0.2 and 0.3) with Perovskite structure were prepared by a dip and dry technique on a platinum-coated silicon substrate. The good quality thin films with uniform microstructure and thickness were successfully produced by dip-coating techniques annealed at 730[Formula: see text]C for 1 h. The resulting thin film shows a well-developed dense polycrystalline structure with more uniform grain size distribution. The BST thin films were characterized for their structural, Raman spectroscopy, morphological properties, and complex impedance properties. The dielectric constant-frequency curve showed the good dielectric constant and loss dielectric loss with low-frequency dispersion. The BST 0.3 thin film reveals that the dielectric constant and dielectric loss at a frequency of 1 kHz were 578 and 0.02, respectively. The obtained results on dielectric properties can be analyzed in terms of the Maxwell–Wagner model.

Electrochemical performance and complex impedance properties of reduced-graphene oxide/polypyrrole nanofiber nanocomposite

Reduced-graphene oxide/polypyrrole nanofiber (RGO/PPy-Nf) nanocomposite has been prepared as the electrode material of the supercapacitor. This nanocomposite was prepared via a facile two-step process, including exfoliation and reduction of graphene oxide by microwave irradiation (MRGO) and in situ polymerization pyrrole onto it. The morphological, structural, and porosity characterizations of this nanocomposite were shown the proper formation of RGO/PPy-Nf composite with a mesoporous structure. The high specific capacitance of 277 F g−1 was obtained for the RGO/PPy-Nf nanocomposite at a constant current density of 1 A g−1 in a 1 M H2SO4 solution electrolyte. This nanocomposite revealed the highest energy density of 38.5 Wh kg−1 with a corresponding power density of 500 W kg−1, and the capacitive retention of 95% after 1000 cycles. In evaluating the samples by electrochemical impedance spectroscopy, the values of capacitor response time revealed that the dominant mechanism in pristine PPy and MRGO is faradaic reactions and electrical double-layer capacitance (EDLC), respectively, and both mechanisms play a role in the RGO/PPy-Nf nanocomposite. Also, the relaxation time investigation revealed this nanocomposite exhibit an ideal capacitive behavior at very low frequency.

Grain size effect on microwave dielectric properties of Na2WO4 ceramics prepared by cold sintering process

In this work, cold sintering was adopted to prepare Na2WO4 ceramics with different grain sizes ranging from 0.632 μm to 17.825 μm. Their microstructures, complex impedance, and microwave dielectric properties were studied in-depth. It was found that samples with relative densities higher than 92% can be successfully synthesized by cold sintering process at a low temperature of 240 °C. However, their electrical properties have strong dependence on the grain size. Specifically, the resistance of grain boundaries decreases dramatically with the increase of grain sizes, while the quality factor has a positive correlation with the grain sizes of Na2WO4 ceramics. Excellent microwave dielectric properties, including permittivity = 5.80, Q × f = 22,000 GHz, and TCF = −70 ppm/°C, are obtained for Na2WO4 ceramics with a grain size of 4.477 μm prepared by cold sintering process.

Electrical properties of an n-order network with Y circuits

This paper introduces an n-order network model with Y circuits to investigate the electrical properties, and it is an entirely new question that has seldom been addressed in the academic world. We carry out the research by means of building an equivalent model. Firstly, we use Kirchhoff’s law to build a second-order nonlinear recurrence equation model. Secondly, by using variable substitution we transform the nonlinear equation into a linear difference equation. Thirdly, we name the process recurrence transformation of n-order network, called N-RT for short. Based on the linear difference equation, an analytical solution is offered to the problem of the equivalent resistance of the n-order network with Y circuits. This research is going to find specific application in many cases. What’s important, this paper further investigates the equivalent complex impedance of LC network and the electrical properties of complex impedance, and illustrates the oscillation and resonance characteristics of LC network with 3D graphs.

Understanding the effect of high energy γ-radiation induced on the structural and electrical behavior of Eu3+-substituted Mg–Cd nanoferrites

The nano-sized Mg1−xCdxEuyFe2−yO4 (0.0 ≤ x ≤ 1.0; y = 0.0, 0.1) ferrites are synthesized by combustion technique. All samples are subjected to γ-radiation of 60Co source with overall 310 kGy exposure dosage. The structural analysis of all the samples is done using XRD. The structural parameters of Mg–Cd–Eu nanoferrites before and after irradiation are estimated by applying Rietveld refinement to XRD data. Furthermore, the lattice parameters are found to be increasing with increase in Cd2+ ion content. The average crystallite sizes are found in the range of 12–38 nm. The morphology of the samples before and after gamma irradiations was observed by using SEM. The morphology of the samples confirms the porous nature after gamma irradiation and EDAX analysis confirms the composition details of the samples. XPS analysis of the samples confirms the oxidation state of all the elements. Dielectric constant, dielectric loss tangent, complex impedance, and AC conductivity properties are measured in the frequency range of 100 Hz–5 MHz at room temperature before and after gamma irradiation. The dielectric constants, dielectric loss tangent, and impedance increased with increasing concentration of Cd2+. The ac conductivity decreased with the increase in Cd2+ concentration. The dielectric constant and lattice parameter values have essentially decreased with substitution of Eu3+ ion and enhanced after gamma illumination because of the change of ferric particles into ferrous particles due to the ionizing impact of γ-illumination. The Cole–Cole plots reveal the existence of various electrical responses in the samples. Hence our results suggest that these materials are helpful for radio frequency application.

Influence of humidity on complex impedance and dielectric properties of iron manganite (FeMnO3)

Bulk samples of iron manganite with a cubic $$Ia\bar{3}$$ crystal structure were obtained by solid state synthesis (combination of milling and calcination) of starting hematite (Fe2O3) and manganese carbonate (MnCO3) powders followed by sintering green samples at 1000 °C for 4 h. Structural characterization performed by XRD and SEM analysis confirmed the formation of iron manganite in the form of a porous network of grains and pores with average particle size of 530 and 430 nm, respectively. The influence of humidity on complex impedance and dielectric properties was monitored in the relative humidity range 30–90% in a climatic chamber in the frequency range 42 Hz–1 MHz at working temperatures of 25 and 50 °C. At the lowest frequency of 42 Hz the impedance reduced with relative humidity from 57.9 (RH 30%) to 3.21 MΩ (RH 90%) at 25 °C, and from 23.3 (RH 30%) to 1.3 MΩ (RH 90%) at 50 °C that is approximately 20 times. Analysis of complex impedance using an equivalent circuit showed the dominant influence of grain boundaries. The influence of grains (bulk) was taken into account for higher relative humidity values (70% at 25 °C and 60% at 50 °C) that is related to the mechanism of water interaction with the sample surface. The dielectric constant and loss tangent decreased with increase in frequency in accordance with the Maxwell–Wagner type interfacial polarization mechanism and also increased with increase in relative humidity.

Induced effects of Zn+2 on the transport and complex impedance properties of Gadolinium substituted nickel-zinc nano ferrites

Abstract We report on the preparation and transport properties of Gadolinium substituted Ni ( 1 - x ) Zn x Gd y Fe ( 2 - y ) O 4 ( 0 ⩽ x ⩽ 1 , y = 0.1 ) nano particles using low temperature citrate precursor combustion method. The Rietveld refinement of PXRD data suggests the crystal structure of sample belongs to Fd-3m space group with an octahedral occupation of Gd+3 ions. FESEM micrographs show the existence of porosity in the samples. The dielectric studies reveal the good dielectric behaviour with high dielectric constant in Zn+2 substituted sample (x = 0.4). An increase in a . c conductivity observed in the Zn+2 substituted sample due to the hopping mechanism. The impedance spectroscopy of the samples shows the existence of high grain boundary resistance and an alternate switching of dielectric relaxation from non-Debye to Debye type. The activation energies and Curie temperature estimated using D. C. conductivity measurements drop linearly with an increase in Zn+2 concentration. We attribute the observed transport properties mainly to the hopping of Fe+2 ↔ Fe+3 ions.

Investigation of Complex Impedance and Modulus Properties of La or/and Ca Doped BaTiO3

Abstract BaTiO3 (BT), Ba0.99La0.01Ti0.9975O3 (BLT), Ba0.90Ca0.1TiO3 (BCT) and La0.01(Ba1-xCax)0.99Ti0.9975O3 (LBCT with x= 0.1) powders were successfully synthesized by sol-gel process through Destabilization of Colloidal Solution (DCS). Sintering of pressed powders was performed at 1300 °C for 4h. XRD analysis showed a good crystallization of the samples in the pure Perovskite structure, and allowed determination of the crystallite size. Microstructure morphology was analyzed using Scanning Electron Microscopy (SEM), and the grain size of the samples was estimated. Wide ranges of frequency (40Hz-1MHz) and temperature (ambient–500°C) dependence of the impedance relaxation were investigated. Both the Complex Impedance and Modulus studies have suggested the presence of dielectric relaxation effects in bulk and grain boundary in the materials. Conductivity spectra reveal the presence of hopping mechanism in the electrical transport process of the samples.

Anomalous freezing of dielectric polarons near magnetic ordering in multiferroic La0.5Bi0.5FeO3

A single-phase multiferroic (MF) La0.5Bi0.5FeO3 (LBFO) ceramic sample was prepared by the conventional solid-state reaction method. The crystallographic phase formation and morphological studies were carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The temperature-dependent magnetization exhibits weak ferromagnetic ordering near TC = 220 K. Complex dielectric and impedance properties of LBFO as a function of temperature and frequency were performed to understand the correlation between magnetic and dielectric properties. The analysis of electrical modulus spectrum reveals that the magnetic ordering imposes a change in the activation energy of dielectric polarons. The thermal fluctuations of magnetic moments activate the freezing of dielectric polarons with enhancement in temperature.

Structural and complex impedance properties of Zn2+ substituted nickel ferrite prepared via low-temperature citrate gel auto-combustion method

We report the productive synthesis of nanocrystalline zinc substituted mixed ferrite (Ni1−xZnxFe2O4 (0 ≤ x ≤ 1)) particles via low-temperature citrate gel auto-combustion method. The structure and microstructure of the particles, elemental analysis, and complex impedance properties are carried out by PXRD, FESEM, EDS and impedance spectroscopy respectively. The increased lattice parameters with Zn2+ concentrations suggest the substitution of Zn2+ ions to Ni2+. Dielectric constant, dielectric loss and AC conductivity were studied as a function of frequency infer a significant alteration in the dielectric constant, dielectric loss and A.C. conductivity and also showed that zinc substituted ferrites possess low tangent loss (≈ 10−2) at high frequencies. Further, the impedance spectroscopic studies reveal that Zn2+ substituted (x = 0.2, 0.8 and 1) samples attain non-Debye type dielectric relaxation.

Effect of distributive mass of spring on power flow in engineering test

Mass of spring is always neglected in theoretical and simulative analysis, while it may be a significance in practical engineering. This paper is concerned with the distributive mass of a steel spring which is used as an isolator to simulate isolation performance of a water pipe in a heating system. Theoretical derivation of distributive mass effect of steel spring on vibration is presented, and multiple eigenfrequencies are obtained, which manifest that distributive mass results in extra modes and complex impedance properties. Furthermore, numerical simulation visually shows several anti-resonances of the steel spring corresponding to impedance and power flow curves. When anti-resonances emerge, the spring collects large energy which may cause damage and unexpected consequences in practical engineering and needs to be avoided. Finally, experimental tests are conducted and results show consistency with that of the simulation of the spring with distributive mass.

High remnant polarization, high dielectric constant and impedance performance of Nb/In Co-doped Bi0.49La0.01Na0.49Li0.01TiO3-δ ceramics

The new ferroelectric oxides, Bi0.49La0.01Na0.49Li0.01Ti0.99(Nb1-xInx)0.01O3-δ (hereafter abbreviated as BLNLTN1-xIx), with x = 0.5–0.65 were fabricated using conventional solid state reaction method. The effects of Niobium (Nb) and Indium (In) as B-site substitutions on phase, microstructure, dielectric, ferroelectric, complex impedance and complex electric modulus properties were systemically analyzed. Hysteresis graphs indicated that BLNLTN0.5I0.5 comparatively have the highest remnant polarization (Pr) of about 49.83 µC/cm2. Moreover, the dielectric studies of BLNLTN0.5I0.5 showed the highest relative dielectric constant (εr) i.e. 4599.3 in comparison to all other compositions. In addition, it also indicated very small loss of <0.045 at 1kHz over a broad range of temperature i.e. room temperature (RT) to 380°C. By comparing BLNLTN0.5I0.5 with BNT, Pr and εr were increased 13.46% and 26.3%, respectively whereas coercive electric field (Ec) and tanδ were decreased 41.06% and 1.96%, respectively. The impedance analysis for BLNLTN0.5I0.5 revealed a gradual decrease in bulk resistance (Rb) with the increase in temperature. Also, it showed negative temperature coefficient of resistance (NTCR) property at 500–800°C and a polydispersive non-debye type relaxation at 800°C. The complex electric modulus analysis proved that effect is mainly due to the bulk grains. Their basic analysis i.e. XRD and SEM studies showed a single phase perovskite structure, spherical grain shape and decreasing average grain size trend with increasing x content. The overall analysis has confirmed the significance of Nb/In co-doping in Bi0.49La0.01Na0.49Li0.01TiO3-δ and showed it as a capable dielectric material for fabricating high-temperature ceramic capacitors.