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Interfacial ionic defects in perovskite solar cells (PSCs) significantly influence the efficiency and long‐term stability. In this study, primarily simulation‐assisted analyses are conducted to explore the capacitive effect of these defects on the performance of PSCs through impedance analysis. Simulated data indicate a decrease in capacitance with increasing frequency, leading to a higher built‐in potential (ΔVbi = 150 mV). Moreover, an increase in capacitance with increasing light intensity is observed. Additionally, reducing the ionic defect concentration at the interfaces (from 1019 to 1016 cm−3) results in more significant band bending and a higher Vbi. Potential solutions to mitigate interfacial ionic defects, including doping at transport layer interfaces are proposed. Doping at both interfaces introduces an energy spike (valence band offset) of 0.21 eV and a cliff (conduction band offset) of 0.16 eV, respectively, for holes and electrons, leading to an improvement in the open circuit voltage (VOC). Finally, experimental results demonstrate a notable enhancement in VOC of 0.04 V with the introduction of Li+ doping at the electron transport layer/perovskite interface. These findings provide essential perceptions for effectively mitigating the effect of interfacial ionic defects on the performance of PSCs and enhance their overall performance. [ABSTRACT FROM AUTHOR]

Structure, dielectric and impedance properties of SrSnO3 ceramics co-doped with In3+ and Nb5+ ions (Sr(In0.5Nb0.5)xSn1-xO3), obtained by the solid-state method and sintering at 1550°C, were investigated. In the range of x = 0-0.1, the substitution of Sn4+ by In3+ and Nb5+ ions at B-site did not affect the crystal structure of these ceramics significantly. A high dielectric permittivity (> 1.0 × 104) and low dielectric loss (< 0.2) were demonstrated at the optimal doping concentration of x = 0.04. The dielectric loss displayed distinct relaxation peaks, which shifted towards lower frequencies as the doping concentration increased. Impedance and electric modulus measurements confirmed the different relaxation processes. Our results provide insight into the role of donor and acceptor co-doping on the properties of SrSnO3 ceramics, which is important for their use in dielectric and energy storage applications.

Solid polymer electrolytes are given great importance as they can provide significant potential in building electrochemical devices including batteries, supercapacitors, and fuel cells. This study prepared and optimized a blend of rosin gum and cellulose acetate to which LiNO3 was added to prepare lithium ion conducting solid polymer electrolyte. A maximum ionic conductivity of 6.21×10−5 Scm−1 was attained. The X-ray diffraction (XRD) patterns of the synthesized polymer electrolytes indicated that the films possess an amorphous structure and indicate the complete dissolution of salt. The analysis of the blend polymer doped with the salt using FTIR spectroscopy provided a comprehensive understanding of the detailed interaction between the salt and the blend system. The thermogravimetry study demonstrated that electrolyte membrane was stable up to 205 °C. The electrochemical stability of the produced electrolyte was investigated using LSV analysis which showed that the electrolyte was stable up to 2.6 V. The calculation of transference numbers verified that ions are the main charge carriers. [ABSTRACT FROM AUTHOR]

Non-linear optical materials have greatly impacted science and technology in recent years. In the present work, crystals of amino acid derivative l-histidinium acetate dihydrate (L-HA) were grown using the gradual evaporation method. The powder-crystal X-ray diffraction (PXRD) technique was applied to examine the phase composition of the crystal sample. The XRD analysis showed that the L-HA was crystallized into the triclinic system. Microstructural parameters were evaluated, including dislocation density and micro-strain induced in the samples. The vibrational modes of the L-HA crystal were found using confocal Raman spectrum analysis. UV–Vis spectral analysis was applied to ascertain the crystal's optical absorbance and transmittance. The bandgap and Urbach edge of L-HA were explored in the UV–Vis spectrum. The second harmonic generation potency of L-HA was examined using Kurtz–Perry analysis, and it was found that L-HA exhibited significant SHG efficiency. The dielectric and impedance characteristics of the L-HA were assessed in the 100 Hz‒5 MHz range at different temperatures. Dielectric measurements show that at frequencies higher than 10 kHz, the dielectric constant and dielectric loss are saturated at minimum levels. The Nyquist graph displays the negative temperature coefficient of resistance in the compound. Vickers microhardness analysis demonstrates the normal indentation size effect and hard nature of the L-HA sample. Thus, the L-HA crystals are suitable for optoelectronic applications due to their excellent optical characteristics, considerable SHG efficiency, and appropriate dielectric, impedance, and microhardness features. [ABSTRACT FROM AUTHOR]

A usual solid-state reaction method was evolved to fabricate BaBi1.6Fe0.4TiO6 ceramic oxide at a higher calcination temperature (1000 °C). The initial crystal structure information reveals that the material has dual-phase bearing tetragonal (P4mm) and monoclinic (P121/c1). The material also possesses a tensile strain (0.915) which has been verified by using the Williamson–Hall (W–H) plot. The compound has different functional groups and vibrational modes like a usual perovskite oxide. The optical property of the compound has been studied by UV–Vis spectroscopy, and it is found 2.67-eV bandgap. The result of the UV–visible study suggests that the material can be used as source material in photovoltaic and photocatalytic applications. Complex impedance and modulus spectroscopic verification revealed a semiconducting property and non-Debye behavior. [ABSTRACT FROM AUTHOR]

Electric cell–substrate impedance sensing has been used to measure transepithelial and transendothelial impedances of cultured cell layers and extract cell parameters such as junctional resistance, cell–substrate separation, and membrane capacitance. Previously, a three-path cell–electrode model comprising two transcellular pathways and one paracellular pathway was developed for the impedance analysis of MDCK cells. By ignoring the resistances of the lateral intercellular spaces, we develop a simplified three-path model for the impedance analysis of epithelial cells and solve the model equations in a closed form. The calculated impedance values obtained from this simplified cell–electrode model at frequencies ranging from 31.25 Hz to 100 kHz agree well with the experimental data obtained from MDCK and OVCA429 cells. We also describe how the change in each model-fitting parameter influences the electrical impedance spectra of MDCK cell layers. By assuming that the junctional resistance is much smaller than the specific impedance through the lateral cell membrane, the simplified three-path model reduces to a two-path model, which can be used for the impedance analysis of endothelial cells and other disk-shaped cells with low junctional resistances. The measured impedance spectra of HUVEC and HaCaT cell monolayers nearly coincide with the impedance data calculated from the two-path model. [ABSTRACT FROM AUTHOR]

Although electrolytes prepared from natural substances have taken up research towards a greener future, practical difficulties in their mechanical and water resistive properties are yet to be addressed by many. In this current paper, a natural gum tragacanth is graft copolymerized with tertiary butyl acrylate utilising glutaraldehyde as the crosslinker and ascorbic acid and potassium persulfate as the initiators. From the TGA analysis, enhanced thermal stability is observed in the crosslinked membrane. The DSC analysis reveals that the crosslinked gum exhibits a glass transition temperature (Tg) of 66 °C and a melting temperature (Tm) of 86 °C. The water uptake of the crosslinked membrane was found to be lower than the pure non-crosslinked membrane. The stress-strain curves of the crosslinked electrolyte showed a tensile strength of 3.58Mpa and a percent elongation of 302%. The effect of the crosslinker glutaraldehyde and the ionic salt lithium nitrate is studied with the help of XRD and FTIR. The electrolyte is characterised to be a good ionic conductive membrane as its conductivity value is found to be 4.72 ×10−4 Scm−1 through EIS measurements. The Arrhenius behaviour of temperature-dependent conductivity was studied and the activation energy values for all the films were calculated.

To evaluate the physical and electrochemical variations introduced by the sintering aid TiO2 in the yttria stabilized zirconia (YSZ), a comparison between 3 wt% TiO2 doped YSZ (3TiYSZ) and undoped YSZ films has been carried out. Herein, the NiO/YSZ composite substrates are prepared for the support with enough porosity (32.58%) and surface roughness (16 nm) those are required for better fuel transfer and mechanical integrity. Thin electrolyte films are deposited over NiO/YSZ and fused quartz substrates by performing multiple coating cycles using the slurry spin coating technique. A comparative study has been carried out by observing structural, topographical, and electrochemical properties of the 3TiYSZ and undoped YSZ thin films at 950 °C and 1150 °C sintering temperatures. During X-ray diffraction (XRD) analysis, all the prominent reflections of cubic zirconia are visible in all the samples where no phase distortions are observed with TiO2 addition. For the 3TiYSZ thin films, the grain size is found to be significantly enhanced as compared to the undoped YSZ. The surface topography from atomic force microscopy (AFM) unveils hill like topography and relatively lower roughness for 3TiYSZ thin electrolyte films. The electrical behavior is analyzed through Nyquist data which confirmed the thermal activation of ionic conductivity, while a significant decrement in ionic resistance is observed for 3TiYSZ thin films. Hence, TiO2 played a significant role in enhancing the physical and electrochemical properties at relatively lower sintering temperatures. [ABSTRACT FROM AUTHOR]

In this paper, a comprehensive analysis of the parameters that affect polymer electrolyte membrane fuel-cell performance is presented. Experiments were conducted on a single fuel cell membrane with an active area of 5 cm2. To study the fuel cell operation, parametric studies of temperature, pressure and relative humidity values were conducted under cyclic voltammetry for impedance analysis. The impact of the behavior of all three parameters on the fuel-cell performance were recorded and analyzed. As the temperature increased from 50 °C to 74 °C, the Pt catalyst surface areas demonstrated lower activation losses as the membrane conductivity increased. It is confirmed that an increase in temperature accompanied higher humidity levels to provide sufficient cell hydration that resulted in a higher performance output. The impedance measurements indicate that low humidity levels resulted in higher cell resistance and mass transport losses. As the back pressure increased, the membrane resistance decreased, which also reduced mass transport losses. The results indicate that the important factors affecting the fuel cell performance are mass transport limitation and membrane resistance. Based on the results of this study, the optimum performance can be achieved by operating at higher pressures and temperatures with humidified reactant gases. [ABSTRACT FROM AUTHOR]

In this investigation, α -Fe2O3 was prepared via co-precipitation and nano-NiO and NdFeO3 were synthesized using the sol–gel method. For NdFe 0. 5 Ni 0. 5 O3 synthesis, Nd2O3, α -Fe2O3, and nano-NiO compounds were mixed via the solid state method. The effect of each component and that of nano-NiO on the NdFe 0. 5 Ni 0. 5 O3 crystal properties was characterized by using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), ultraviolet-visible (UV–Vis), vibrating sample magnetometer (VSM), impedance and bandgap analyses. The orthorhombic perovskite structure was confirmed by the XRD data. With the doping of nano-NiO, the unit cell volume was found to decrease. The UV–Vis spectroscopy showed that the nano-NiO-doped optical bandgap ( E g ) had increased. The VSM analysis demonstrated that by doping nano-NiO to weak ferromagnetic NdFeO3, the resulting NdFe 0. 5 Ni 0. 5 O3 was rendered superparamagnetic. The real and imaginary parts of dielectric permittivity ( ′ and ″) and the loss tangent (tan δ) characteristic of the compounds were measured at AC-signaled frequencies of 100 Hz–10 MHz and a voltage range of 0–20 V DC. The increase in active charge transmission with the doping of nano-NiO reduced the ′ values. In addition, the large differences between the ′ values were thought to be caused by the breakdown voltage ( E b ) effect of the compounds. The ″ and tan δ changes revealed the dipole formation of the compounds at different voltages, their relaxation regions and their polarization mechanism type. The dielectric loss behavior of the compounds demonstrated their good dielectric material properties. This study investigated the effect of method difference and doped material particle size on magnetic and dielectric properties. [ABSTRACT FROM AUTHOR]

Ferromagnetic hysteresis measurements can be used to determine both magnetic and mechanical state variables that correlate with each other. Therefore, hysteresis measurements are suitable for mechanical material characterization. The application of standardized hysteresis measurement methods is complex and can only be used to a limited extent in an industrial environment. In this work, a BH (ferromagnetic hysteresis) curve is to be reconstructed on 22NiMoCr3-7 samples that are in different mechanically deformed states (different histories). The reconstruction of the hysteresis is performed by an impedance analysis of the H-field generating coil. The applied method demonstrates that the ferromagnetic hysteresis can be reconstructed by means of an impedance analysis and is sensitive to different states of plastical deformation. [ABSTRACT FROM AUTHOR]

Planar magnetic components are compact and less susceptible to skin effect due to their thin copper layers. However, the increase in parasitic capacitance has been a challenge in high-frequency operation of planar transformers (PTs). Parasitic capacitances resonate with inductance and may damage switch devices. Thicker printed circuit board (PCB) and reconfigured windings are suggested in this paper to mitigate the parasitic capacitances. A detailed analysis of the parasitic capacitances is performed with a prototype PT. The resonant frequency increased from 1.27 to 1.63 MHz with a 0.4 mm thicker PCB. The reconfigured PT was 1.38 MHz, 0.3 MHz higher than the original PT. [ABSTRACT FROM AUTHOR]

In this investigation, α -Fe2O3 was prepared via co-precipitation and nano-NiO and NdFeO3 were synthesized using the sol–gel method. For NdFe 0. 5 Ni 0. 5 O3 synthesis, Nd2O3, α -Fe2O3, and nano-NiO compounds were mixed via the solid state method. The effect of each component and that of nano-NiO on the NdFe 0. 5 Ni 0. 5 O3 crystal properties was characterized by using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), ultraviolet-visible (UV–Vis), vibrating sample magnetometer (VSM), impedance and bandgap analyses. The orthorhombic perovskite structure was confirmed by the XRD data. With the doping of nano-NiO, the unit cell volume was found to decrease. The UV–Vis spectroscopy showed that the nano-NiO-doped optical bandgap ( E g ) had increased. The VSM analysis demonstrated that by doping nano-NiO to weak ferromagnetic NdFeO3, the resulting NdFe 0. 5 Ni 0. 5 O3 was rendered superparamagnetic. The real and imaginary parts of dielectric permittivity ( ′ and ″) and the loss tangent (tan δ) characteristic of the compounds were measured at AC-signaled frequencies of 100 Hz–10 MHz and a voltage range of 0–20 V DC. The increase in active charge transmission with the doping of nano-NiO reduced the ′ values. In addition, the large differences between the ′ values were thought to be caused by the breakdown voltage ( E b ) effect of the compounds. The ″ and tan δ changes revealed the dipole formation of the compounds at different voltages, their relaxation regions and their polarization mechanism type. The dielectric loss behavior of the compounds demonstrated their good dielectric material properties. This study investigated the effect of method difference and doped material particle size on magnetic and dielectric properties. [ABSTRACT FROM AUTHOR]

Transformer oil, crucial for transformer and power system safety, demands effective monitoring. Aiming to address the problems of expensive and bulky equipment, poor real-time performance, and single parameter detection of traditional measurement methods, this study proposes a quartz tuning fork-based simultaneous measurement system for online monitoring of the density, viscosity, and dielectric constant of transformer oil. Based on the Butterworth–Van Dyke quartz tuning fork equivalent circuit model, a working mechanism of transformer oil density, viscosity, and dielectric constant was analyzed, and a measurement model for oil samples was obtained. A miniaturized simultaneous measurement system was designed based on a dedicated chip for vector current-voltage impedance analysis for data acquisition and a Savitzky–Golay filter for data filtering. A transformer oil test platform was built to verify the simultaneous measurement system. The results showed that the system has good repeatability, and the measurement errors of density, viscosity, and dielectric constant are lower than 2.00%, 5.50%, and 3.20%, respectively. The online and offline results showed that the system meets the requirements of the condition maintenance system for online monitoring accuracy and real-time detection. [ABSTRACT FROM AUTHOR]

AlN ceramics exhibit good physical and chemical properties and are ideal materials for the dielectric layer of electrostatic chucks. However, they cannot generate a strong J−R-type electrostatic adsorption force because of their high resistivity. Therefore, adding other substances is necessary to regulate the electrical properties and enable their application. In this study, AlN ceramics were prepared using hot-pressed sintering with 0.2 wt% CaO as an additive at a sintering temperature range of 1700–1900 °C. The effects of CaO doping on the phase composition, microstructure, electrical properties, and thermal conductivity of the AlN ceramics were systematically investigated. The addition of CaO not only enhanced the sintering process of the AlN ceramics, but also significantly reduced the electrical resistivity and increased the thermal conductivity. The relative density of CaO-doped AlN ceramics reached 98.88 % at 1700 °C, with a thermal conductivity of 81.51 W m−1•K−1. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and AC impedance spectroscopy were used to analyse the impurities and defects in the AlN ceramics. The lattice parameters and fitting grain resistance indicated that the CaO-doped AlN presented a higher lattice oxygen concentration, increasing the concentration of Al vacancies and electrons. Moreover, the level of dissolved oxygen could be controlled by altering the sintering temperature, resulting in AlN ceramics with electrical resistivity ranging from 8.1 × 106 to 1.7 × 1012 Ω cm. Further research was conducted to investigate the effect of the electrical resistivity of AlN ceramics on the J−R-type electrostatic adsorption force, and it was found that AlN ceramics with a specific resistivity of 109 Ω cm exhibited the highest electrostatic adsorption of 351.7 g/cm2. [ABSTRACT FROM AUTHOR]

In the membrane electrode assembly (MEA) of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs), many types of resistance existed, but they have not been distinctly characterized in previous research. In this study, the distribution of relaxation times (DRT) methodology is employed, in conjunction with a home-built electrochemical electrode analysis system (EEAS), to figure out the specific resistance components in the cathode gas diffusion electrode (GDE). The impedance analysis by the DRT method was conducted using the electrochemical impedance spectrum obtained at different temperatures and current densities of the cathode only, isolated from the MEA environment. The four peaks (designated as Peak 0 to 3) were depicted at DRT plots of cathode GDE below 103 Hz. By comparing the DRT plots for different conditions and considering the EEAS structure, the four peaks were explained to be caused by distinct resistances occurring at the electrode and interface. The regions of each peak were distinguished according to their position changes with temperature and current density. Furthermore, by contrasting the DRT plots of the cathode GDE with those of MEA containing the same cathode, an additional peak (referred to as Peak 4) is identified between 103 Hz and 104 Hz, which was attributed to resistance originating from the anode. This study could provide a new approach for future research of new catalysts and electrodes utilizing the resistance analysis of MEA for HT-PEMFC. [Display omitted] • The EEAS was utilized to perform electrochemical analysis of the GDE. • DRT method separates resistances as peaks in the cathode GDE of HT-PEMFCs. • Each peak from the DRT plot is assigned according to the origin of resistance. • Comparative study with MEA differentiates the resistance from electrodes. [ABSTRACT FROM AUTHOR]

This study employs a simple and cost-effective technique to enhance the photoelectrochemical (PEC) water-splitting performance of melamine cyanaurate microrods (M), SnO2 nanostructures (S), and melamine cyanaurate microrods decorated with SnO2 quantum dots (MS) by optimizing NaOH and Na2SO3 electrolytes. Notably, the MS electrode demonstrates a remarkable improvement in PEC efficiency in Na2SO3 solution associated with NaOH solution. Specifically, the induced currents of the MS anode in the Na2SO3 electrolyte are approximately 6.28 mAcm−2 more than those observed in the NaOH electrolyte solution. It is revealed that SO 3 2 − anions effectively consume the holes, leading to improved separation of the generated charge pairs. This effective charge separation mechanism significantly contributes to the enhanced PEC performance observed in Na2SO3 electrolytes. The findings of this study suggest a capable approach for improving the PEC activity of the materials through the careful optimization of the supported electrolytes. [ABSTRACT FROM AUTHOR]

In present study, dye-sensitized solar cells (DSSC) are fabricated using bare TiO2, ZnO and TiO2-ZnO nanocomposite via doctor's blade method with N719 sensitizer and platinum-free carbon deposited counter electrode. The ensued TiO2-ZnO (1:1) composite films of photoanodes are characterized with UV-Vis Spectroscopy to investigate the band gaps of bare TiO2, ZnO and their composite, in the range of 3.21-3.31 eV. SEM studies are performed to analyze the surface morphology wherein the TiO2-ZnO composite photoelectrode, displayed additional prominent porosities than the bare TiO2/ZnO. The photo conversion efficiency of the cells based on TiO2, ZnO and their composite were observed as 1.08%, 0.98%, and 1.49%, respectively, which is higher for composite due to low series resistance, high optical absorption, high recombination resistance and longer lifetime as evaluated by impedance analysis. This strategy of using TiO2-ZnO nanocomposite photoanode could pave the way for performance improvement in a cost-effective manner for DSSCs. [ABSTRACT FROM AUTHOR]

The article is mainly devoted to the analysis of the transient process during the phase change of the intra-impulse modulated signal of the system, which is composed of a pair of piezoelectric ceramic transducers. In the introductory part, this article is focused on the most accurate determination of the parameters of electrical equivalent circuit of piezoelectric ceramic transducers commonly available on the market of electrical components and less economically demanding. Based on the determination of these parameters, a system consisting of the piezoelectric ceramic transducer, transmitter - environment - piezoelectric ceramic transducer, receiver is then assembled and represented by transfer function. This system is subjected to simulation. An intra-impulse modulated signal with phase modulation is connected to the system input. The response to this signal is subsequently analyzed and compared with the real response of a real system. The goal is therefore to verify the suitability of the simulation model and, on the basis of this analysis, to determine the possibility of using specific piezoelectric ceramic transducers for application of intra-impulse modulated signal. As a method of verification, main parameter analysis of a cross-correlation function was selected. Based on this analysis it was found that this method is relevant for this purpose.

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. [ABSTRACT FROM AUTHOR]

In this work, the effect of low air relative humidity on the operation of a polymer electrolyte membrane fuel cell is investigated. An innovative method through performing in situ electrochemical impedance spectroscopy is utilised to quantify the effect of inlet air relative humidity at the cathode side on internal ionic resistances and output voltage of the fuel cell. In addition, algorithms are developed to analyse the electrochemical characteristics of the fuel cell. For the specific fuel cell stack used in this study, the membrane resistance drops by over 39 % and the cathode side charge transfer resistance decreases by 23 % after increasing the humidity from 30 % to 85 %, while the results of static operation also show an increase of ∼2.2 % in the voltage output after increasing the relative humidity from 30 % to 85 %. In dynamic operation, visible drying effects occur at < 50 % relative humidity, whereby the increase of the air side stoichiometry increases the drying effects. Furthermore, other parameters, such as hydrogen humidification, internal stack structure, and operating parameters like stoichiometry, pressure, and temperature affect the overall water balance. Therefore, the optimal humidification range must be determined by considering all these parameters to maximise the fuel cell performance and durability. The results of this study are used to develop a health management system to ensure sufficient humidification by continuously monitoring the fuel cell polarisation data and electrochemical impedance spectroscopy indicators. • PEM Fuel cell inlet air relative humidity regulation using a passive humidifier with fuzzy logic control. • Using EIS characteristics to quantify the effect of air relative humidity on PEMFC performance. • Air RH affects PEMFC significantly depicted by mean cell voltage and internal resistances. • Electrochemical analyses using EIS oriented algorithms to develop a health management system. [ABSTRACT FROM AUTHOR]

Polymer membrane electrolyzers benefit from high‐pressure operation conditions and low gas cross‐over and can either conduct protons (H+) or hydroxide ions (OH−). Both types of electrolyzers have a similar design, but differ in power density and the choice of catalysts. Despite the significant endeavor of their optimization, to date, there is no well‐established impedance model for detailed analysis for either type of these devices. This complicates the in‐situ characterization of electrolyzers, hindering the investigation of degradation mechanisms and electrocatalytic processes as a function of applied current density or time. Nevertheless, a detailed understanding of such individual processes and distinguishing the performance‐limiting factors are the keystones for sophisticated device optimization. In this work, an impedance model based on electrode processes has been developed for an anion exchange membrane electrolyzer utilizing iridium oxide anode and platinum cathode electrocatalysts. This model allows to deconvolute the measured impedances into constituents related to the individual electrode processes and to estimate actual physico‐chemical quantities such as the reaction kinetic parameters and double‐layer capacitances. We discuss the meaning of the fitting parameters and show that this model enables, for the first time, the estimation of the electrochemically active surface area of the anode electrocatalysts under reaction conditions. [ABSTRACT FROM AUTHOR]

In this present work, the transition metal oxides of SnO2 and SnO2/rGO nanocomposite were synthesized through a facile hydrothermal method for supercapacitor electrode material applications. The structural, morphological, and elemental analysis of the synthesised samples were characterised by X-ray diffractometer technique (XRD), Field emission scanning electron microscopy (FESEM), Energy dispersive X-ray analysis (EDX), and High-resolution transmission electron microscopy (HR-TEM). The morphology of SnO2 was an agglomeration of quasi-spherical-shaped particles with a diameter range of 12–19 nm, as observed using the HR-TEM technique. The optical properties were characterised by UV-vis and Raman spectroscopy. The electrochemical performance of SnO2 and SnO2/rGO nanocomposite electrode was studied in a 3 M KOH electrolyte. A specific capacitance of 346 F g− 1 at a current density of 0.95 A g− 1 for the SnO2/rGO nanocomposite electrode was recorded, which was significantly higher than that of the as-synthesised SnO2 electrode (267 F g− 1). The higher capacitance obtained was due to the synergistic effect of excellent conductivity and a high surface area of rGO within the composite electrode. The exceptional electrochemical properties clearly indicate that the SnO2/rGO nanocomposites are the best for highly efficient pseudocapacitor electrodes in future energy storage device applications. [ABSTRACT FROM AUTHOR]

Polycrystalline [(0.5) Bi0.5Na0.5TiO3-(0.5) LaFeO3] multiferroic composite is prepared by using the solid-state reaction method. The crystal structure of both phases is characterized by using the X-ray diffraction method (XRD) and confirms the presence of rhombohedral (i.e., bismuth sodium titanate) and orthorhombic (i.e., lanthanum ferrite) phases in the composite. The microstructure of the composite is analyzed using field emission scanning electron microscopy (FESEM). The crystal structure is further studied with Raman spectroscopy. The present composite exhibits ferroelectric and ferrimagnetic-like properties, revealing its multiferroic behavior. Furthermore, the impedance analysis of the composite shows the negative temperature coefficient of resistance behavior. The present study describes the structural and physical properties of the possible lead-free multiferroic composite. [ABSTRACT FROM AUTHOR]

The synthesised films have been characterised via different techniques. Structural studies were carried out using the XRD technique. TGA/DSC analysis revealed that the micro-porous polymer membrane is thermally stable up to 450 C. The electrical measurement for all samples have been carried out in frequency range 42 Hz–5 MHz and temperature range of 30–110 C by Impedance Spectroscopy. The FTIR study showed many excellent spectral changes. These spectral changes indicate an increase in crystallinity, strong molecular bonds, and some crystal phase transitions. The large values of dielectric constant in the low frequency region of the particular polymer electrolyte specimen containing 15% wt% alkali metal may be due to an enhanced level of charge carrier storage at the electrolyte–electrode interface, resulting in an increase in capacitance. The temperature dependent ac ionic conductivity shows the highest ionic conductivity of 1. 35 × 10–4 Scm −1 was found at 333 K for the concentration of 85 Wt% PVdF-CO-HFP: 15 Wt% KCl: 5 Wt% TiO2 of the polymer electrolytes with an activation energy value of 0. As a result, alkali metal can significantly improve the structural, conductivity and dielectric properties of nanocomposite polymer electrolytes over ordinary polymer electrolytes, providing a new method for preparing composites with high structural and dielectric properties. [ABSTRACT FROM AUTHOR]

Synthesis and characterization of single phasic Dy 1-x Pr x MnO 3 (DPMO) ceramic samples through solid-state reaction (SSR) method are reported in present study. XRD analysis confirmed the structural formation of DPMO and revealed lattice changes induced by Pr substitution that affect JT-distortion and tilting of MnO 6 octahedra. Fine-grained microstructures with a micrometre-sized grain size were observed using FESEM images, which increased with increasing Pr concentration. The variation of activation energy in DPMO was found to be induced by modification in Mn–O bond distances. The dielectric behaviour of DPMO was significantly enhanced, which was explained using the UDR model fitting. Impedance analysis confirmed the existence of non-Debye type relaxation and negligible electronic polarization mechanisms in all DPMO samples. With the increase in temperature, a reduction in the magnitude of Z' was observed, indicating a decrease in the resistance of contributing electroactive components such as grains, grain boundaries, and electrode interfaces. Electric modulus studies revealed the existence of grain and grain boundary relaxation processes throughout the studied frequency and temperature range in DPMO compounds. Overall, the study provides deep insights into the effect of Pr substitution on the structural, electrical, and dielectric properties of DPMO and highlights the potential of DPMO for future electronic and energy device applications. [ABSTRACT FROM AUTHOR]

This study examines different methodologies for representing an asynchronous motor at higher harmonics by utilizing its equivalent circuit. Several approaches were compared based on simulation modeling. An experimental investigation was conducted in a laboratory setting using asynchronous electric motors with power ratings of 1.5 kW and 5.5 kW. The purpose of this investigation was to examine the characteristics of impedance in the presence of high-harmonic conditions. The generation of higher harmonics was achieved through the utilization of a precisely regulated thyristor rectifier in conjunction with a thyristor power controller. The findings indicate that the load on the shaft solely impacts the resistance at the fundamental harmonic, while the resistance at higher harmonics remains unaffected by the operating mode of the asynchronous motor (AM). [ABSTRACT FROM AUTHOR]

CdO, ZnO, and CdZnO thin films were deposited using the nebulizer spray pyrolysis method, and their properties were investigated for gas sensing applications. The deposition process involved the use of analytical reagent-grade chemicals and a nebulizer spray pyrolysis setup. X-ray diffraction analysis revealed the cubic and hexagonal crystal structures of the films, with distinct peak positions corresponding to CdO and ZnO. The addition of CdO influenced the growth kinetics and crystallization behavior of the films, leading to an increase in the average crystallite size of CdZnO films compared to pure ZnO films. Optical analysis showed that CdO, CdZnO, and ZnO films had direct band gaps of 2.3 eV, 3.03 eV, and 3.18 eV, respectively. The gas sensing properties of CdO films were investigated, and the sensing mechanism was elucidated in terms of electron release and capture by chemisorbed oxygen species. Impedance spectroscopy measurements demonstrated the sensitivity of the CdO sensor to different concentrations of ammonia gas. The fabricated CdO sensor exhibited enhanced sensitivity at room temperature compared to higher temperatures. Overall, the CdO, ZnO, and CdZnO thin films show promise for gas sensing applications. [ABSTRACT FROM AUTHOR]

AbstractElectrical characteristics of living cells have been proven to reveal important details about their internal structure, charge distribution and composition changes in the cell membrane, as well as the extracellular context. An impedance flow cytometry is a common approach to determine the electrical properties of a cell, having the advantage of label-free and high throughput. However, the current techniques are complex and costly for the fabrication process. For that reason, we introduce an integrated dual microneedle-microchannel for single-cell detection and electrical properties extraction. The dual microneedles utilized a commercially available tungsten needle coated with parylene. When a single cell flows through the parallel-facing electrode configuration of the dual microneedle, the electrical impedance at multiple frequencies is measured. The impedance measurement demonstrated the differential of normal red blood cells (RBCs) with three different sizes of microbeads at low and high frequencies, 100 kHz and 2 MHz, respectively. An electrical equivalent circuit model (ECM) was used to determine the unique membrane capacitance of individual cells. The proposed technique demonstrated that the specific membrane capacitance of an RBC is 9.42 mF/m−2, with the regression coefficients, [Formula: see text] at 0.9895. As a result, this device may potentially be used in developing countries for low-cost single-cell screening and detection.

Synchronization units are vital for the stable operation of grid-tied converters in generation and transmission. There are two main synchronization units, i.e., phase-locked loop (PLL) and power synchronization controller (PSC), with the corresponding drawbacks in weak and strong grid respectively. Recently, the hybrid synchronization controller (HSC) is proposed in order to make up the deficiencies of PLL and PSC in weak and strong grid respectively. This paper deduces the detailed impedance characteristics of PSC and HSC and compares their cons and pros to show the stability mechanism of HSC. Moreover, two types of HSCs are also presented and compared in this article with slight difference in structure. It is found that the impedance of Type II based HSC has smaller amplitude and better phase margin than PSC around fundamental frequency, while Type I based HSC has larger amplitude and less phase margin than PSC. Type II based HSC can improve the stability and Type I based HSC can worsen the stability compared with PSC. Realtime experiments are carried out to verify this.

In this work, two series of BaTiO3-based ceramics, Ba1-xSrxTiO3 (x = 0, 0.2, 0.4, 0.6, 0.8) and BaTi1-xTaxO3 (x = 0.03, 0.06, 0.075, 0.09, 0.1), were synthesized by using standard solid-state reaction method at 1350 °C, and then sintered at 1400 °C for 10 h in air. Frequency-dependent dielectric and impedance properties were investigated at low temperature range of 100-300K. The changes in dielectric properties of the Ba1-xSrxTiO3 ceramics are believed to originate from the phase transition due to the different A-site Sr2+ doping concentration. The local electron-pinned defect-dipole effect is responsible for the enhancement of dielectric constant observed in the B-site Ta5+ doped BaTi1-xTaxO3 ceramics. The complex impedance analysis was used to discern the temperature and frequency dependence of grains and grain boundaries responses. The results suggest that A- and B-site doped BaTiO3 ceramics can be applied for different dielectric devices at low temperatures.

The structural, dielectric and transport properties of modified Bismuth Sodium Titanate (BNT) are reported. Mn and Sr-modified BNT (Bi0.35Na0.35Sr0.3Ti0.9Mn0.1O3) was synthesized by a solid-state reaction route. Structural analysis based on Rietveld refinement of X-ray diffraction data confirms the single-phase characteristic without change of hexagonal crystal structure with R3C space group of BNT. The dielectric characteristics of the modified BNT are recorded in the frequency range of 20 Hz to 1 MHz at temperatures of 50 °C and 200 °C. Using the frequency-dependent, real and imaginary parts of the dielectric constant, ϵ′(ω)-ϵ″(ω) dipolar and hopping conduction-based carrier polarization properties are discussed. The dipole parameters such as relaxation time, static and high-frequency dielectric constant etc. are estimated by using Cole-Cole relaxation model. [ABSTRACT FROM AUTHOR]

Electrical characteristics of living cells have been proven to reveal important details about their internal structure, charge distribution and composition changes in the cell membrane, as well as the extracellular context. An impedance flow cytometry is a common approach to determine the electrical properties of a cell, having the advantage of label-free and high throughput. However, the current techniques are complex and costly for the fabrication process. For that reason, we introduce an integrated dual microneedle-microchannel for single-cell detection and electrical properties extraction. The dual microneedles utilized a commercially available tungsten needle coated with parylene. When a single cell flows through the parallel-facing electrode configuration of the dual microneedle, the electrical impedance at multiple frequencies is measured. The impedance measurement demonstrated the differential of normal red blood cells (RBCs) with three different sizes of microbeads at low and high frequencies, 100 kHz and 2MHz, respectively. An electrical equivalent circuit model (ECM) was used to determine the unique membrane capacitance of individual cells. The proposed technique demonstrated that the specific membrane capacitance of an RBC is 9.42 mF/m-2, with the regression coefficients, p at 0.9895. As a result, this device may potentially be used in developing countries for low-cost single-cell screening and detection. [ABSTRACT FROM AUTHOR]

The morphology of TiO2 nanoparticles deposited on a QCM sensor is crucial in its mechanical loading. Different heating treatments transform the morphology of TiO2 nanoparticles, affecting the loading and hence shifting the resonant frequency and changing the impedance QCM value. In this research, the deposition of TiO2 nanoparticles was carried out above QCM using the ultrasonic spray pyrolysis (USP) technique with variations in calcination temperature of 200, 230, and 250 °C. The analysis results show that the increase in the agglomeration and particle size causes an increase in the inertial mass of TiO2 nanoparticles. [ABSTRACT FROM AUTHOR]

The ongoing digitalization of processes and products in mechanical engineering is accompanied by an increasing demand for data. In order to provide this data, technical systems are being extended with sensory functions. To supply those sensory functions on rotating elements—such as shafts—with electrical energy, and to be able to transmit signals out of the system, sliding contacts can be used as a cost-effective and established solution. However, if electrical properties of machine elements are utilized for sensing purposes, such as condition monitoring of rolling element bearings by means of impedance measurement, sliding contacts are directly in the measurement path and can thus influence the measured impedance. The aim of this paper is to analyze the impedance of graphite and silver graphite carbon brushes under different rotational speeds, in different positions, and with different carrier frequencies. The material of the carbon brushes as well as the position have significant effects on the impedance behavior. Furthermore, carbon brushes show a significant running-in behavior. The results are discussed, and indications for use in impedance measurements are given. Silver graphite carbon brushes in axial positioning are particularly suitable for impedance measurements of sensory utilizable machine elements. Sufficient running-in time must be considered. [ABSTRACT FROM AUTHOR]

The use of piezoelectric transducers for internal dynamic pressure measurements in ammunition testing provides a significant advantage in the development and performance analysis of weapons and ammunition. Knowledge of the electrical characteristics of the dynamic pressure measurement chain, which includes the piezoelectric transducer and the charge amplifier, is a relevant condition for the design of interior ballistics pressure measurement systems. Thus, this study aims to characterize and model a piezoelectric transducer and its associated charge amplifier. First, the piezoelectric transducer was characterized using impedance analysis and modeled using a least squares curve-fitting tool, according to the Butterworth–Van Dyke model. Next, the charge amplifier was characterized through response analysis based on known inputs and modeled using LTSpice simulation techniques and the least squares curve-fit tool. Consequently, a measurement chain model is presented and simulated for two cases with different impulse signals. The first impulse signal was obtained from an interior ballistics computer simulation, and in the second case, it was considered the negative step signal characteristic of the calibration of piezoelectric transducers by means of dead weight. From the simulations, it was possible to verify the effectiveness of the model, which provided results with a low error in relation to the original pressure curve, and its applicability is demonstrated by the result of the simulation of the pressure variation in the calibration, where the attenuation of the signal can be visualized as the characteristic of the input curve changes. [ABSTRACT FROM AUTHOR]

In this report, the new polycrystalline spinel-type chromite Ni0.7Cd0.3Cr2O4 (NCCO) was successfully synthesized by sol-gel process. This sample is characterized by X-Ray diffraction (XRD), optical analysis by DRS spectroscopy and dielectric measurements. The X-ray diffraction (XRD) analysis reveals that the prepared sample is well crystallized in the Fd3̅m space group. Optical results from the reflectance spectrum shows indirect band gap energy that was also evaluated from the reflectance spectra using the Kubelka-Munk function and Marotti's approach, the Egind is found close to 1.64 eV. The variations of Urbach energy (Eu), the penetration depth (δ), extinction coefficient (K) and refractive index (n) were clearly determined and discussed. The Ac impedance spectroscopy type Agilent model 4294 A was used to examine the dielectric and electrical transport properties over a wide temperature (200 K-400 K) and frequency range (100 Hz to100KHz). The obtained results demonstrate that the electrical conductivity (σ) correlates with the Jonscher power law that indicates a semiconducting behavior and confirm the ′′non-overlapping small polaron tunneling, ′′NSPT′′ model of our sample. The activation energy is estimated to be Ea = 0.529 eV based on the study of continuous conductivity. The behavior of permittivity (ε',ε") and the loss coefficient tgδ was attributed to Wagner's Maxwell theory of interfacial polarization. The imaginary part of the impedance curve (Z′′) shows a dielectric relaxation phenomenon in the present compound. The Nyquist plots show a monotonic decrease in grain resistance (Rg) and grain boundary resistance (Rgb) with increasing temperature. This result confirms that the transport mechanism in the chromite NCCO is governed by the effect of grain boundaries. These analysis prove that our sample may be a good candidate for optoelectronics devices. Highlights: Ni0.7Cd0.3Cr2O4 (NCCO) was successfully synthesized by sol–gel technic. X-ray diffraction (XRD) analysis confirm that our sample is well crystallized in the Fd3̅m group. Reflectance spectrum shows indirect band gap energy that is found close to 1.64 eV. Refraction index of our spinel chromite NCCO is n = 1.7. Electrical conductivity (σ) correlates with the Jonscher power law and confirm the non-overlapping small polaron tunneling, "NSPT" model. [ABSTRACT FROM AUTHOR]

Electric cell–substrate impedance sensing has been used to measure transepithelial and transendothelial impedances of cultured cell layers and extract cell parameters such as junctional resistance, cell–substrate separation, and membrane capacitance. Previously, a three-path cell–electrode model comprising two transcellular pathways and one paracellular pathway was developed for the impedance analysis of MDCK cells. By ignoring the resistances of the lateral intercellular spaces, we develop a simplified three-path model for the impedance analysis of epithelial cells and solve the model equations in a closed form. The calculated impedance values obtained from this simplified cell–electrode model at frequencies ranging from 31.25 Hz to 100 kHz agree well with the experimental data obtained from MDCK and OVCA429 cells. We also describe how the change in each model-fitting parameter influences the electrical impedance spectra of MDCK cell layers. By assuming that the junctional resistance is much smaller than the specific impedance through the lateral cell membrane, the simplified three-path model reduces to a two-path model, which can be used for the impedance analysis of endothelial cells and other disk-shaped cells with low junctional resistances. The measured impedance spectra of HUVEC and HaCaT cell monolayers nearly coincide with the impedance data calculated from the two-path model.

In this paper, a comprehensive analysis of the parameters that affect polymer electrolyte membrane fuel-cell performance is presented. Experiments were conducted on a single fuel cell membrane with an active area of 5 cm2. To study the fuel cell operation, parametric studies of temperature, pressure and relative humidity values were conducted under cyclic voltammetry for impedance analysis. The impact of the behavior of all three parameters on the fuel-cell performance were recorded and analyzed. As the temperature increased from 50 °C to 74 °C, the Pt catalyst surface areas demonstrated lower activation losses as the membrane conductivity increased. It is confirmed that an increase in temperature accompanied higher humidity levels to provide sufficient cell hydration that resulted in a higher performance output. The impedance measurements indicate that low humidity levels resulted in higher cell resistance and mass transport losses. As the back pressure increased, the membrane resistance decreased, which also reduced mass transport losses. The results indicate that the important factors affecting the fuel cell performance are mass transport limitation and membrane resistance. Based on the results of this study, the optimum performance can be achieved by operating at higher pressures and temperatures with humidified reactant gases.

Transformer oil, crucial for transformer and power system safety, demands effective monitoring. Aiming to address the problems of expensive and bulky equipment, poor real-time performance, and single parameter detection of traditional measurement methods, this study proposes a quartz tuning fork-based simultaneous measurement system for online monitoring of the density, viscosity, and dielectric constant of transformer oil. Based on the Butterworth–Van Dyke quartz tuning fork equivalent circuit model, a working mechanism of transformer oil density, viscosity, and dielectric constant was analyzed, and a measurement model for oil samples was obtained. A miniaturized simultaneous measurement system was designed based on a dedicated chip for vector current-voltage impedance analysis for data acquisition and a Savitzky–Golay filter for data filtering. A transformer oil test platform was built to verify the simultaneous measurement system. The results showed that the system has good repeatability, and the measurement errors of density, viscosity, and dielectric constant are lower than 2.00%, 5.50%, and 3.20%, respectively. The online and offline results showed that the system meets the requirements of the condition maintenance system for online monitoring accuracy and real-time detection.

Renewable energy generation is a manifestation of global economic and societal advancement and serves as a fundamental assurance for humanity's pursuit of sustainable development. However, recent years have witnessed several instances of high-frequency resonance events in high-voltage direct current (HVDC) transmission systems based on modular multilevel converters (MMC), which have resulted in converter station tripping and significant repercussions on the alternating current (AC) grid. This paper addresses the mid-to-high frequency resonance issues prevalent in flexible DC transmission systems employing modular multilevel converters (MMC-HVDC). To tackle these concerns, an impedance model for MMC's AC side is established. Utilizing impedance analysis, the essential factors contributing to the negative damping characteristics of MMC are identified as delay and voltage feedforward loops, predominantly causing negative damping in the frequency range exceeding 400 Hz. In response, a suppression strategy is proposed, involving the incorporation of a multi-band stop filter and virtual impedance. This strategy ensures that within the 0–2000 Hz frequency range, only the impedance phase within 230–430 Hz slightly surpasses 90°. Consequently, the phase difference between MMC's positive-sequence impedance and the AC system impedance is reduced from 222° to 174.7°, thus guaranteeing secure grid operation. Lastly, the accuracy and effectiveness of the theoretical analysis and suppression methodology are verified through the development of an electromagnetic transient model in MATLAB/Simulink, considering delay fluctuations of ±10%. [ABSTRACT FROM AUTHOR]