AC Impedance Research Articles (Page 1)

ABSTRACT Solid polymer electrolytes (SPEs) incorporating nano-alumina (Al2O3) have been effectively synthesised through a conventional solvent casting technique, utilising poly(methyl methacrylate) (PMMA) as the matrix polymer with sodium bromide (NaBr) as the salt additive. Several characterisation techniques, including AC impedance spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) have been utilised in this study. Using an AC impedance analyser, the ionic conductivity for all samples was determined. The PMMA/NaBr/Al2O3 (7.5 wt%) system exhibited the highest ionic conductivity, reaching a maximum value of 1.15 × 10−3 S cm−1 at ambient temperature. XRD studies have confirmed a decrease in crystallinity, consequently indicating an increase in amorphicity in the samples. The transference number measurement for the maximum ionic conducting polymer electrolyte sample is recorded as 0.95, highlighting the predominant contribution of ions to the conduction process. A significant alteration in the surface morphology of the sample was ascertained through SEM micrographs. The primary battery characteristics of the fabricated system were evaluated by analysing its open-circuit voltage (OCV) and discharge behaviour under a 1 MΩ load.

Diabetes has become one of a major disease in the world, therefore, we present a low-cost, miniaturization device. In this study, human whole blood was used as sample, and ring-shaped interdigital electrodes were used to detect the proportion of glycated hemoglobin in the whole hemoglobin. In order to determine the proportion of glycated hemoglobin, first, we use the electric field generated by the electrodes to lysis the red blood cells and obtain the intracellular HbA1c. Next, the solution which lysis previously containing glycated hemoglobin, is propelled through micro-channels by a pump. The protein is then immobilized by applying a self-assembled monolayer (SAM). The amount of attached protein directly impacts the electric field passing through and subsequently induces variations in AC impedance. These impedance changes serve as the basis for detecting and quantifying the glycated hemoglobin levels accurately. By summing up the result of impedance changes, different proportions of glycated hemoglobin can be detected. The measurement system instrument was used to calculate the protein impedance deviation to successfully detect 5% to 6% of the glycated hemoglobin, that improved the defects of common other measurement instruments, which are not easy to carry and have high cost. The concentration of HbA1c can be identified only by measuring the impedance, and used human whole blood as a sample directly. So this study has potential for clinical applications.

Investigation of high-temperature damage in one-part engineered geopolymer composites via non-destructive AC impedance spectroscopy

The present study focuses on the evaluation of the corrosion resistance of 18K gold alloy in artificial saliva with and without fennel powder. Dental alloys such as 18K gold are widely used in orthodontic and prosthodontic applications due to their excellent biocompatibility and corrosion resistance. However, their long-term performance can be influenced by dietary and medicinal substances consumed orally. In this study, electrochemical techniques such as potentiodynamic polarization and AC impedance spectroscopy were employed to assess the corrosion behavior of 18K gold alloy. The alloy was immersed in artificial saliva, both with and without the addition of fennel powder, a commonly consumed herbal product known for its antioxidant and antimicrobial properties. The findings suggest that fennel powder influences the corrosion resistance of 18K gold, potentially through adsorption of organic compounds on the alloy surface or interaction with alloying elements. This study provides insight into the impact of herbal substances on the electrochemical stability of dental materials in the oral environment.

The objective of this study is to investigate the corrosion behaviour of 110SS carbon steel in a hydrochloric acid–acetic acid mixed system, with dual aims: optimising acetic acid concentration and identifying an effective corrosion inhibitor. A multifaceted methodology was employed, integrating weight-loss measurements, AC impedance and Polarisation curve analysis, SEM-EDS characterisation, orthogonal experimental design, and controlled-variable approaches. Key findings demonstrate that: (1) acetic acid inhibits corrosion of 110SS steel in hydrochloric acid, though the resultant corrosion rate exceeds acceptable industrial thresholds; (2) oleic acid imidazoline a ternary inhibitor comprising oleic acid imidazoline, cinnamaldehyde, and quaternary ammonium salt C14-GC exhibits synergistic corrosion inhibition in the mixed-acid system. This inhibitor can form a dense and homogeneous adsorbent film on 110SS steel surfaces, effectively suppressing anodic corrosion. Orthogonal experiments predicted that at 363.15 K, the corrosion inhibitor could achieve a maximum corrosion inhibition efficiency of 98.31% for 110SS steel in a 9% HCl + 9% HAc system, with a minimum corrosion rate of 4.96 g/(m 2 ·h). This work provides theoretical foundations for corrosion protection strategies targeting 110SS steel in the hydrochloric acid-acetic acid environments during carbonate matrix acidising.

Nitrate-induced microbial metabolic activation and community composition optimization enhance the anaerobic biodegradation of thiamethoxam.

AC impedance spectroscopy characterization of low-temperature sulfate attack in cement-based materials

NASICON-type Li1+XFeXTi2-X(PO4)3 (x = 0.1, 0.3, 0.4) solid electrolytes for all-solid-state Li-ion batteries were synthesized using a sol–gel method. This study investigated the impact of substituting Fe3+ (0.645 Å), a trivalent cation, for Ti4+ (0.605 Å) on ionic conductivity. Li1+XFeXTi2-X(PO4)3 samples, subjected to various sintering temperatures, were characterized using TG-DTA, XRD with Rietveld refinement, XPS, FE-SEM, and AC impedance to evaluate composition, crystal structure, fracture-surface morphology, densification, and ionic conductivity. XRD analysis confirmed the formation of single-crystalline NASICON-type Li1+XFeXTi2-X(PO4)3 at all sintering temperatures. However, impurities in the secondary phase emerged owing to the high sintering temperature above 1000 °C and increased Fe content. Sintered density increased with the densification of Li1+XFeXTi2-X(PO4)3, as evidenced by FE-SEM observations of sharper edges of larger quasi-cubic grains at elevated sintering temperatures. At 1000 °C, with Fe content exceeding 0.4, grain coarsening resulted in additional grain boundaries and internal cracks, thereby reducing the sintered density. Li1.3Fe0.3Ti1.7(PO4)3 sintered at 900 °C exhibited the highest density among the other conditions and achieved the maximum total ionic conductivity of 1.51 × 10−4 S/cm at room temperature, with the lowest activation energy for Li-ion transport at 0.37 eV. In contrast, Li1.4Fe0.4Ti1.6(PO4)3 sintered at 1000 °C demonstrated reduced ionic conductivity owing to increased complex impedance associated with secondary phases and grain crack formation.

Reported rate constants of charge transfer reactions (CTs) have ranged widely, depending on techniques and timescales. This fact can be attributed to the time-dependent double-layer capacitance (DLC), caused by solvent interactions such as hydrogen bonds. The time variation of the DLC necessarily affects the heterogeneous electrode kinetics. The delay by the solvation, being frequency dispersion, is incorporated into the CT kinetics in this report on the basis of the conventional reaction rate equations. It is different from the absolute rate theory. This report insists on a half value of the transfer coefficient owing to the segregation of the electrostatic energy from the chemical one. The rate equation here is akin to the Butler–Volmer one, except for the power law of the time caused by the delay of the DLC. The dipoles orient successively other dipoles in a group associated with the delay, which resembles that in the DLC. The delay suppresses the observed currents in the form of a negative capacitance. The above behavior was examined with a ferrocenyl derivative by ac impedance methods. The delay from diffusion control was attributed to the negative capacitance rather than the CT, even if the conventional DLC effect was corrected.

The objective of this research is to examine the feasibility of storing pomegranate juice in containers constructed from SS 304 alloy, commonly referred to as Ever Silver, or SS 316 L alloy. The corrosion resistance of both SS 304 and SS 316L alloy was evaluated across different environments, including a water system, a pomegranate juice system, and a pomegranate juice system with added sugar (5000 g), utilizing AC impedance spectroscopy for measurement. Key corrosion parameters, including charge transfer resistance, impedance, phase angle, and double layer capacitance, were calculated. The findings indicate that SS 316 L alloy exhibits superior corrosion resistance compared to SS 304 alloy across all three systems. Consequently, it is recommended that pomegranate juice and pomegranate juice with sugar be stored in containers made of SS 316 L alloy, which is also applicable to the water system.

Solid-state electrolytes (SSEs) offer improved safety and electrochemical performance. However, achieving a combination of mechanical and chemical stability and ionic conductivity remains challenging. This work presents a scalable dual-domain SSE design that has attractive ionic transport values and ability to cycle against lithium while retaining a mechanically convenient format. It comprises an electrospun polyacrylonitrile skeleton infiltrated with a composite slurry containing PEO, LLZO, LiTFSI, LiNO3, and TEGDME. The resulting SSE can be formed as a thin, flexible, stand-alone separator. It exhibits a high ionic conductivity of 1.2 mS cm−1, elastic modulus of 5.5 MPa, 14% porosity, and thermal stability up to 600 °C. A detailed analysis of selective cation transport ( ρ + , 0 = 0.46) and salt diffusivity ( D s = 1.0 × 10−6 cm2 s−1) was performed using both DC polarization and AC impedance to assess interfacial and bulk transport behavior. Long-term Li plating/stripping tests confirm 900 h of stable cycling at 0.025 mA cm−2 with low overpotential. A full cell with NMC-811 and Li electrodes delivered 97% capacity retention and 98% average Coulombic efficiency over 150 cycles. A comparative study across six alternative SSE designs highlights the impact of filler content, salt selection, ceramic type, and processing route on performance.

Introduction: A novel attempt to degrade alizarine yellow R (AYR) by lead dioxide (PbO2)/ neodymium (Nd) coated Ti anode was investigated. Methods: Ti/Zr-SnO2/PbO2-Nd electrode showed high oxygen evolution potential, high current density, and neutral conditions, which favored the degradation of AYR. The PbO2-Nd layer on Ti/Zr-SnO2 was further characterized by scanning electron microscopy, and X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The electrochemical properties of Ti/Zr- SnO2/PbO2-Nd electrode were evaluated by cyclic voltammetry, AC impedance spectroscopy, and accelerated life test. Results: The relatively higher oxygen evolution overpotential (~1.80 V) of the developed electrode can effectively suppress the occurrence of surface side reactions and oxygen evolution. A relatively lower charge transfer resistance (Rct, 18.0 Ω) of Ti/Zr-SnO2/PbO2-Nd electrode could be found. The Ti/Zr-SnO2/PbO2-Nd electrode exhibited an accelerated lifetime of 110 min under a very high current density of 10,000 A/m2. The doping of Nd could produce loosely-stacked sheet-like structures, thus, the number of active sites on the electrode surface increases. Conclusion: Moreover, an outstanding conductivity of Ti/Zr-SnO2/PbO2-Nd electrode was obtained, which favored the electron transfer and catalytic activity of the modified electrode. The Ti/Zr-SnO2/PbO2-Nd electrode exhibited improved electrochemical performances and higher oxygen evolution potential, and the highest oxygen evolution potential is 1.80 V. Under the current density of 30 mA/cm2, the electrocatalytic degradation of 92.3% could be achieved in 180 min. The electrochemical oxidation of AYR at the Ti/Zr-SnO2/PbO2-Nd electrode proved to be feasible and effective, indicating that it might be used for the elimination of AYR from wastewater.

Abstract Steel slag, a solid waste from steelmaking, contains active hydration constituents that can enhance the performance of cementitious materials. This study investigated the effects of varying the steel slag content (0–20% by mass of total binder) on the workability, mechanical properties, electrical resistance, AC impedance spectroscopy, and ultrasonic velocity of cement mortars. Mortars were prepared using a ternary binder system composed of ordinary Portland cement (OPC), fly ash (FA), and steel slag. The water-to-binder ratios (W/B) were set at 0.3, 0.4, and 0.5, and the mortars were cured under standard conditions for 3, 7, and 28 days. Results showed that, at a W/B of 0.3, the incorporation of steel slag increased the fluidity of fresh mortar by 6%~17% and prolonged the setting time by up to 48.84%. At the same W/B, the addition of steel slag increased the 28-day compressive strength and flexural strength by 8.45%~24% and 4.84%~11.3%, respectively. The electrical resistance increased with curing age, following a cubic function with steel slag content. Steel slag incorporation reduced electrochemical corrosion resistance at a W/B of 0.3. Steel slag contents of 10% and 15% exhibited superior early-age ultrasonic velocity values. This study elucidates the multifaceted impacts of steel slag on mortar properties, providing essential insights to optimize its utilization in sustainable cement-based construction materials.

A multi-scale microbial aerosol detection method based on the microfluidic AC impedance sensor

Food packaging serves purposes of food product safety and easy handling and transport by preventing chemical contamination and enhancing shelf life, which provides convenience for consumers. Various types of materials, including plastics, glass, metals, and papers and their composites, have been used for food packaging. However, owing to consumers’ increased health awareness, the significance of transferring harmful materials from packaging materials into foods is of greater concern. In the present study corrosion resistance of Ever Silver vessel in the absence and presence of rasam recipe, a light South Indian traditional soup made with basic spices, ripe tomatoes, tamarind and herbs. AC impedance spectra have been used to measure the corrosion resistance. It is observed that the corrosion resistance of Ever Silver vessel increases in the presence of rasam recipe. This is due to the presence of various molecules present in the ingredients of rasam. So it is concluded that rasam recipe can be stored in Ever Silver vessel and also rasam can be served in Ever Silver vessel during dining.

This work will demonstrate the performance of a battery energy storage system (BESS) designed for long duration energy storage thorough time-shifting photovoltaic (PV) power production in Nordic climate. The BESS has an energy capacity of 300kWh, a power capacity of 100kW, and the cells are of NMC-type in pouch-format. All components are installed in a temperature-controlled and insulated 20 feet container. Charging of the battery is controlled by real-time PV power production from the neighboring ground-mounted 24kWp PV-park. This implies that the battery capacity equals about 12 hours of peak PV power production. Discharging is set to occur some hours in the afternoon to support the grid during high-demand hours.The performance is monitored by analyzing data from both battery, converter, auxiliary components, and local weather station to achieve a proper system evaluation covering both winter and summer conditions and the specifics of time-shifting PV-production in the Nordics. Periodic performance characterizations are conducted by full charging-discharging cycles to determine some of the key performance indicators described by the European Commission regulation for digital product passports. These include discharge capacity, round trip efficiency, and power tolerance at various power rates. Internal resistance should be included as one of the key performance metrics in the upcoming digital product passport. High-time resolution pulse tests are not possible to execute on system-level, so a battery quality analyzer is used to measure internal resistance on module-level using AC impedance spectroscopy at 1 kHz. To supplement the understanding of the performance fade during the demonstration period, battery module tests will be conducted in laboratory settings.Initial results confirm that the control system operates as expected and data is being collected for upcoming data analyses. Due to low solar irradiance levels during mid-winter, the battery is occasionally charged over the night to enable discharging during high-demand hours. The manual and occasional charge sessions could be avoided by updating the charge-discharge schedule. Historical PV production data from the site will be used to create statistically correct schedules related to both time and power-level thresholds. This will enable the PV-BESS power plant to adapt the usage to seasonal variations.

To address the challenges of low ionic conductivity and low Li-ion transference number, polymer solid electrolytes such as polyethylene oxide (PEO) is usually combined with oxides. Numerous publications have reported that positively charged oxygen vacancies on oxide materials can improve the dissociation of Li salt and increase the number of mobile Li-ions by Lewis acid-base interaction. In this research, TiO2 was used as a filler in PEO matrix due to its layered two-dimensional morphology, which provides a greater number of oxygen vacancies. Additionally, its relatively high dielectric constant compared to other oxide materials can help Li salt dissociation in composite electrolytes. To utilize the composite with the highest ionic conductivity, TiO2 was mixed with PEO in various ratios. The Li-ion conductivity of the composite electrolyte was analyzed using a 2-probe AC impedance. Cycling performance with Li-Li cell and Li-LiFePO4 cell is also tested. This study shows the promising strategies for utilizing unique structure of TiO2 in all-solid-state batteries.

Over the last decade, numerous impedance studies of the conductivity of suspensions containing colloidal (dielectric, semiconducting or metallic) particles have often led to the conclusion that the well-known Maxwell theory is insufficient to quantitatively explain the properties of these systems. We review some of the most characteristic results and show how the applicability of the Maxwell’s theory can be restored taking into account the adsorption phenomena occurring during AC impedance measurements in nanoparticle suspensions. The latter can drastically change the capacitance of the metal-electrolyte cell boundaries from the standard value, making it strongly dependent on the nanoparticle concentration. This factor significantly affects conductivity measurements through RC circuit characteristics. We present an analysis of available impedance measurement data of the dependence of conductivity on the nanoparticle concentration in this new paradigm. In order to emphasize the novelty and the acute sensitivity of ac-diagnosis to the presence of adsorption phenomena at the metal-electrolyte interface, direct adsorption determinations at such interfaces by using two modern experimental techniques are also presented. The main result of this work is the restoration of Maxwell’s theory, attributing the observed discrepancies to variations in cell conductance.

The study investigates the effectiveness of an amino benzoic acid as an inhibitor in reducing the corrosion rate of zinc metal exposed to seawater. Using a variety of analytical techniques, including mass loss measurements, electrochemical studies, and AC impedance spectroscopy, the researchers examined the inhibitor’s impact on corrosion. To further assess surface morphology changes, by employed atomic force microscopy (AFM), infrared (IR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray analysis (EDAX). Findings from the mass loss approach reveal that the presence of 250 parts per million (ppm) of the amino benzoic acid compound achieves an inhibition efficiency (IE) of 83.78% in protecting zinc from seawater induced corrosion. Polarization studies suggest that the inhibitor operates predominantly through cathodic inhibition mechanisms, effectively impeding corrosion at the cathode of the electrochemical cell. AC impedance spectra indicate the formation of a protective layer on the zinc surface, which reduces corrosion. This protective film, containing a complex of Zn²z ions and amino benzoic acid, is confirmed through SEM, EDAX, and AFM analyses.

Cashew gum/boehmite bio-nanocomposite films: A promising platform for flexible Nano-dielectric devices.