Imaginary Parts Of Electrical Impedance Research Articles

Sol–gel synthesized (Bi0.5Ba0.5Ag)0.5 (NiMn)0.5O3 perovskite ceramic: An exploration of its structural characteristics, dielectric properties and electrical conductivity

This manuscript delves into the multifaceted exploration of the perovskite ceramic (Bi0.5Ba0.5Ag)0.5(NiMn)0.5O3, synthesized via the sol-gel technique. Unveiling the structural, morphological, dielectric, and electrical facets, the material's orthorhombic structure, affirmed through Rietveld-refined XRD data, showcases an average crystallite size of approximately 33 nm. Dielectric investigations illuminate the presence of Maxwell-Wagner-type dispersion, hinting at charge accumulation along grain boundaries and interfaces. Employing complex impedance and electric modulus analyses reveals microscopic dielectric relaxation intricacies and the material's conduction mechanisms. Electric modulus spectroscopy uncovers non-Debye-type relaxation, encompassing both localized and long-range processes. Nyquist plots attest to the ceramic's semiconducting nature. Applying the Arrhenius law to the imaginary part of electrical impedance and conductivity yields activation energies and relaxation times, significantly enriching our understanding of the material's electrical properties. This comprehensive scrutiny unravels the ceramic's potential applications, offering fresh insights for diverse device implementations.

Unveiling the high-temperature dielectric relaxation and conduction mechanisms in sol-gel derived LaFeO3 modified Sodium Bismuth Titanate ceramics

The lead-free NBT (Na0.5Bi0.5TiO3) ceramics doped with LaFeO3 having general chemical composition (1-x)Na0.5Bi0.5TiO3-(x)LaFeO3, where x = 0 and 0.05 (abbreviated as LFNBT0 and LFNBT5) were synthesized by sol-gel technique. These ceramics were characterized using X-Ray photoelectron spectroscopy to determine the elemental composition and chemical state of the samples whereas impedance spectroscopy was performed to investigate the electrical properties viz. dielectric constant, dielectric loss, impedance, modulus and conductivity over a wide temperature range (300–775 K) along with frequency (1 Hz - 1 MHz). XPS spectra at room temperature revealed the gradual reduction of valence states i.e., Fe3+ to Fe2+ and Ti4+ to Ti3+ resulting in the formation of oxygen vacancies in LFNBT system. A decrease in dielectric constant as well dielectric loss has been observed at room temperature i.e., from 898 to 541 and 0.75–0.25 respectively at 1 KHz frequency with the incorporation of LaFeO3 in the NBT. A phase transition from ferroelectric to para-electric phase is obtained at 583 K and 623 K for LFNBT0 and LFNBT5 respectively. The negative temperature coefficient of resistance (NTCR) behaviour is obtained from the analysis of impedance data. The Cole-Cole plots perceives the grain and grain boundary effect contribution of the materials with the non-Debye type of relaxation which is also confirmed by electric modulus data and aids in understanding of the transport phenomenon. The fitted conductivity data indicated that the conduction in the NBT system is governed by correlated barrier hopping (CBH). XPS analysis and activation energy values obtained from imaginary part of electrical impedance, modulus, and ac conductivity confirmed that the relaxation and conduction processes in LFNBT0 and LFNBT5 ceramics are attribute to the presence of oxygen vacancies.

Effect of frequencies on the change of electrical impedance in sand dunes of Ouargla region

In this paper, we put the accent on the measurement of real and imaginary parts of electrical impedance and effective loss tangent respectively z′, z″ and tgδ in sand dunes of Ouargla region at a range of frequency intervals between 4,6849×10−2 Hz and 1,8593×10+6 Hz with AC voltage of 1.000 V using the impedance spectroscopy. The experimental results revealed that the real and imaginary parts of electrical impedance and effective loss tangent have strong frequency dependence. In the frequencies range (4,6849×10−2 – 4,9385×10−1) Hz z′ < 0 and z″ change between (4,8118×10+2 × 5,0422×10+1) Ω, in the frequencies range (5,4877×10+1 – 2,3426×10+4) Hz z′change between 146,04 Ω and 4,8193 Ω and z″<0. In high frequencies range (1,2599×10+5 – 1,8593× 10+6) Hz z′ change between 4,5359 Ω and 5,0567 Ω. The effective loss tangent values increase until they reach a peak, in frequencies range between 4,6849×10−2 Hz and 2,5197×10−1 Hz, but then the remaining frequency the values decrease until they become constant. The nature of impedance electric variation indicated a possibility to knowledge the polarization of sand dunes of Ouargla region and acquaintance the frequencies when the material is passive devices or active devices. It is also possible to know the quality of equivalent electrical circuit, whether it is induction or capacitance.

Mycelial Extracts as Sensitive Element for Acoustoelectronic Gas Sensor

The main problem in development of the acoustoelectronic gas sensors is the search of the elements which are sensitive to the presence of different gases. In this paper we suggest to use for this purpose the piezoelectric quartz resonators with the mycelium films of mushroom Lentinula edodes strain F-249, which was cultivated in synthetic medium. The extract of mycelium was deposited on the surface of the resonator. The measurements of the frequency dependencies of the real and imaginary parts of electrical impedance of the resonator allowed finding the density, elastic constants and viscosity of the films under study. The influence of various gases (ammonia, formaldehyde, ethylacetate) and volatile liquids (acetone, acetic acid, chloroform) on physical properties of the extracts of mushroom Lentinula edodes mycelium has been investigated. It has been found that it is possible to use the mycelium films of mushroom Lentinula edodes prepared by different ways as sensitive film to ammonia, formaldehyde and ethyl acetate.

Frequency and voltage dependent electrical and dielectric properties of SiGe thin films for solar cells application deposited on p-type silicon

This work presents an experimental study of the electrical and dielectric properties of \( {\text{Si}}_{1 - y} {\text{Ge}}_{y} \) thin films for solar cells application. In order to through light in the electrical conductivity and dielectric properties of the heterojunction, we have carried out the complex impedance spectroscopy technique in the frequency range 10 kHz–1 MHZ at room temperature. The values of the dielectric constant, the real and the imaginary parts of electrical impedance and AC electrical conductivity were found considerably sensitive to frequency. We also studied the photovoltaic parameters of Au/n(SiGe)/p(c-Si) heterojunction solar cell with (y = 0.2). The experimental results show an open-circuit voltage about 0.82 V, a short-circuit current density about 2.1 (mA/cm2) and an efficiency of the cell about 1.3%. The results indicate that the Au/n(SiGe)/p(c-Si) heterojunction structure might be promising for the solar cell applications.

Immunodetection of bacteriophages by a piezoelectric resonator with lateral electric field

It has been demonstrated that electroacoustic analysis with polyclonal antibodies can be used for bacteriophage detection. The frequency dependences of the real and imaginary parts of electrical impedance of a resonator with a viral suspension with antibodies were shown to be essentially different from the dependences of a resonator with control viral suspension without antibodies. It was shown that ΦAl-Sp59b bacteriophages were detected with the use of antibodies in the presence of foreign virus particles. The ΦAl-Sp59b bacteriophage content in the analyzed suspension was ~1010–106 phages/mL; the time of analysis was no more than 5 min. The optimally informative parameter for obtaining reliable information was the change in the real or imaginary part of electrical impedance at a fixed frequency near the resonance upon the addition of specific antibodies to the analyzed suspension. It was demonstrated that the interaction between bacteriophages and antibodies can be recorded, offering good prospects for the development of a biological sensor for liquid-phase identification and virus detection.

Real-time electrical impedance resonance shift of piezoelectric sensor for detection of damage in honeycomb core sandwich structures

A simple and low cost method for structural health monitoring of honeycomb composite shaped in cantilever beam was reported. A lead zirconate titanate (PZT) sensor was attached to the cantilever beam and vibrated resonantly. The real-time imaginary part of electrical impedance of PZT sensor was measured to correlate with the induced mechanical impedance resonance shift of cantilever beam when a proof mass was moved on top of cantilever beam. When a defect was present, it caused a disrupted change of imaginary part of electrical impedance. Such detection is real-time so that no baseline is required to identify the defect accurately.

Relaxation and Conduction Mechanisms of High Tc Lead-Free Ba (Zr,Ti)O3 Positive Temperature Coefficient of Resistivity Ceramic Using Impedance Spectroscopy

High Tc lead–free Ba (Zr0.52Ti0.48)O3 positive temperature coefficient of resistivity (PTCR) ceramic was produced by the standard solid state reaction technique. X–ray diffraction pattern confirms the formation of the tetragonal perovskite structure of the ferroelectric sample. The conduction and relaxation mechanisms of the piezoelectric ceramic have been studied on the basis of activation energy. The relaxation mechanism is investigated for this sample based on the peaks of the imaginary part of electrical impedance and modulus spectra. The Cole-Cole plots indicate that the grain effect is influenced by the increase of temperature up to 200 °C and disappeared beyond this temperature. The temperature versus electrical resistivity plots show that a phase transition occurs at the Curie temperature, Tc =150 °C. The ceramic exhibits a PTCR jump of almost two orders of magnitude starting at 150 °C and ending at 275 °C with a high temperature coefficient of resistivity of ~25 % per °C. The electrical resistivity measurements also reveal that the sample shows semiconducting behavior beyond 275 °C with the value of negative temperature coefficient of resistivity of ~ 0.6% per °C.

Electrical conduction behavior and hopping rates estimate of cadmium zinc telluride single crystal

CdZnTe (CZT) single crystal was grown by a modified vertical Bridgman method. It was used to study the electrical conduction behavior of CZT crystal by impedance spectroscopy in the temperature range over 303–573K. The imaginary part vs real part of complex impedance plots was considered to be a semicircle indicating only bulk contributions. The value of activation energy derived from the peak of the imaginary part of electrical impedance was found to be 0.08±0.005eV, which was assigned to relate the migration and hopping of ionized Cd vacancies and Te antisites. The discrepancy between activation energy of dc electrical conductivity (0.35±0.03eV) and the activation energy (0.20±0.04eV) of hopping rates was attributed to the high ion hopping rates and low attempt frequencies. The mechanism of electrical conduction was mainly ascribed to a short range migration or hopping of charge carriers including ionized Cd vacancies and Te antisites in the CZT crystal system.

Investigation of specific interactions between microbial cells and polyclonal antibodies using a resonator with lateral electric field

The interaction between polyclonal antibodies and Azospirillum brasilense Sp7 cells was studied using a resonator with lateral electric field. To this end, specific polyclonal rabbit antibodies against the O-antigen epitopes of the strain A. brasilense Sp7 were obtained and the possibility of their application for detection of microbial cells using a piezoelectric resonator with lateral electric field was shown. It was established that frequency dependences of the real and imaginary parts of electrical impedance of such a resonator loaded with the suspension of A. brasilense Sp7 cells and antibodies substantially differed from those of the resonator with the control suspension of cells without antibodies. It was shown that the obtained antibodies interacted with azospirilla cells, and the marker was accumulated all over the cell surface. The limit of possible detection of microbial cells during their interaction with antibodies was found to be 104 cells/mL. Detection of A. brasilense Sp7 cells using antibodies proved to be possible in the presence of foreign bacteria. The presented results demonstrate the possibility of recording the interaction between microbial cells and antibodies and developing a biosensor for quantitative detection of microbial cells.

Electrical transport mechanism in a newly synthesized rare earth double perovskite oxide Sr2CeTaO6

A rare earth double perovskite oxide strontium cerium tantalate, Sr2CeTaO6 (SCT) is synthesized by the solid state reaction technique for the first time. The determination of lattice parameters and the identification of phase are carried out by the Rietveld refinement method (RRM) using the Fullprof program in the space group P21/n (C52h). A structure of SCT is obtained from RRM. The bond angle and bond length are calculated and listed in Table 1 for SCT. A small amount of impurity of CeO2 is found in the refinement with space group Fm3m. The scanning electron micrograph shows the average grain size ∼2μm. The ac electrical property is investigated in the temperature range from 303 to 703K and in the frequency range from 0.1kHz to 1MHz using impedance spectroscopy. The relaxation mechanism of SCT is explained in detail by fitting experimental impedance and electric modulus data with the modified Debye (Cole–Cole) model. The frequency-dependent electrical data are analyzed in the framework of the conductivity and modulus formalisms. The σac data are fitted with Jonscher's universal power law. The dc conductivity (σdc) (calculated from σac) follows an Arrhenius law with the estimated conduction activation energy =0.78eV. The scaling behavior of imaginary part of electrical impedance (Z″) shows that the relaxation describes the same mechanism at various temperatures.

Obtaining phage mini-antibodies and using them for detection of microbial cells with an electroacoustic sensor

Phage mini-antibodies to bacterial cells of strain Azospirillum brasilense Sp245 were obtained, and the possibility of using them for detection of microbial cells with a lateral field excited piezoelectric resonator was studied. It has been found that the frequency dependences of the real and imaginary parts of electrical impedance of such a resonator loaded with a suspension of A. brasilense Sp245 cells with the mini-antibodies differ significantly from the dependences of the resonator with a control cell suspension without mini-anti-bodies. The limit of possible determination of the concentration of microbial cells is found to be 103 cells/mL upon interaction with mini-antibodies. It has been ascertained that detection of A. brasilense Sp245 cells with the aid of mini-antibodies is possible even in the presence of other cultures, for example, E. coli BL-Ril and A. brasilense Sp7. Therefore, it has been shown for the first time that detection of microbial cells with an electroacoustic sensor is feasible.

Biological sensor based on a lateral electric field-excited resonator

This paper describes a biological sensor based on a lateral electric field-excited resonator using an X-cut lithium niobate plate. Its potential was shown through the example of biological interaction between bacterial cells and specific bacteriophages. The detection was based on the analysis of the measured real and imaginary parts of electrical impedance for a resonator loaded by the biological suspension under study. It has been shown that the sensor is sensitive to specific interactions between bacterial cells and specific bacteriophages in a pure state as well as in the presence of extraneous microflora. The degree of electrical impedance variation resulting from the biological interaction depends on the numbers of phage particles and bacteria cells. The sensor may be used not only for the qualitative analysis of bacteria but also for their quantitative detection.

Structural and ac electrical properties of a newly synthesized single phase rare earth double perovskite oxide: Ba2CeNbO6

A single phase rare earth double perovskite oxide Ba2CeNbO6 (BCN) is synthesized by solid-state reaction technique for the first time. The X-ray diffraction pattern of the sample at room temperature shows monoclinic structure, with the lattice parameters, a=5.9763Å, b=5.975Å and c=8.48Å and β=90.04°. Impedance spectroscopy is used to study the ac electrical behavior of this material as a function of frequency (102–106Hz) at various temperatures (30–450°C). A relaxation is observed in the entire temperature range. Conduction mechanism is investigated by fitting the complex impedance data to Cole–Cole equation. Complex impedance plane plots show only one semicircular arc, indicating only the grain contribution of dielectric relaxation. The scaling behavior of imaginary part of electric modulus (M″) and imaginary part of electrical impedance (Z″) suggests that the relaxation describes the same mechanism at various temperatures. The frequency dependence of conductivity is interpreted in terms of the jump relaxation model and is fitted to Jonscher's power law. The values of dc conductivities extracted from the Jonscher power law varies from 2.79×10−7 to 3.5×10−5Sm−1 with the increase in temperature from 100 to 450°C. The activation energies (0.37eV) extracted from M″(ω) and Z″(ω) peaks are found to follow the Arrhenius law.