Results Of Impedance Spectroscopy Measurements Research Articles

Study of silicon-oxide RRAM devices based on complex impedance spectroscopy

This work presents a study of Metal-Oxide-Semiconductor RRAM structures with highly doped Si substrates that exhibit the resistive switching effect. We use DC measurements to show the resistance modulation effect and small-signal measurements to investigate the resistive switching layer behavior. We show that by utilizing the results of impedance spectroscopy measurements, we can build an equivalent electrical circuit that can be used to investigate the properties of RRAM devices. Our model fits very well with the measurement data for investigated frequency and voltage values.

In English

Electrochemical impedance spectroscopy has been used for the characterization of electric double layer capacitors also known as supercapacitors. Specific surface area and pore size distribution for supercapacitor electrode materials and the results of impedance spectroscopy measurements for two types of commercially available nanoporous activated carbons and two graphene-type materials have been studied and compared with the results obtained from cyclic voltammetry and galvanostatic charge-discharge cycling the supercapacitor prototypes in different voltage ranges and at different current densities. It has been found that the results for the characteristics of studied supercapacitor prototypes differ insignificantly if they were obtained by different methods, while all three research methods have shown the advantage of materials with nanoporous activated carbon over materials of the graphene type. Besides, according to the data obtained by measuring impedance at low frequencies the deviations from ideal capacitive behaviour are more significant in case of graphene-type materials. Comparison of the three research methods used in this work shows that the method of impedance spectroscopy makes it possible to obtain the most complete and reliable information on the performance characteristics of the supercapacitor system, since not only the capacitance and resistance values, but their frequency dependence, as well as deviations (in degrees) from the purely capacitive vertical line at Nyquist plots and capacitance dissipation can be determined and taken into consideration.

Effects of a Constant Magnetic Field on the Electrochemical Reactions of Quercetin.

The paper presents a study of the effect of a constant magnetic field (CMF) on the basic processes of quercetin electrochemical reactions. According to the observation made in previous studies, the presence of a double bond in the C‐ring of quercetin enhances the antioxidant properties of that compound, whereas the presence of −OH groups also affects the antioxidant properties. Using cyclic voltammetry it was found that the constant magnetic field improves the efficiency of quercetin electrooxidation, especially of the third stage of the process, i. e. the stage in which the oxidation of the OH groups in the A‐ring is the most difficult. The use of HPLC confirmed the electrochemical measurements and the results of cyclic voltammetry studies. The beneficial effect of the magnetic field on the efficiency of quercetin oxidation was confirmed by the results of impedance spectroscopy measurements.

Origin of large dielectric constant in La modified BiFeO3-PbTiO3 multiferroic

The presence of superlattice reflections and detailed analysis of the powder neutron and x-ray diffraction data reveals that La rich BLF-PT (BFO0.50–LF0.50)0.50–(PT)0.50 has a ferroelectric rhombohedral crystal structure with space group R3c at ambient condition. Impedance spectroscopy, dielectric spectroscopy is subset of impedance spectroscopy and ac conductivity measurements were performed in the temperature range 483 K ≤ T ≤ 573 K to probe the origin of large remnant polarization and frequency dependent broad transitions with large dielectric constant near TcFE. Results of impedance spectroscopy measurements clearly show contributions of both grain and grain boundaries throughout the frequency range (1 kHz ≤ f ≤ 10 MHz). It could be concluded that the grain boundaries are more resistive and capacitive as compared to the grains, resulting in inhomogeneity in the sample and cause broad frequency dependent dielectric transitions. The Maxwell-Wagner model fits very well up to ∼105 Hz. Enhancement in dielectric constant and remnant polarization values are possibly due to space charge polarization caused by piling of charges at the interface of grain and grain boundaries.

Intermediate temperature SOFC single cell test using Nd 1.95NiO 4 + δ as cathode

This work deals with SOFC single cell tests using neodymium nickelate Nd 1.95NiO 4 + δ as cathode material. This MIEC oxide exhibits high values of both surface exchange coefficient ( k) and oxygen diffusion coefficient ( D *), as well as high electronic conductivity, which result in an enhanced electrochemical activity with respect to classical materials. The SOFC cells were fabricated from an anode-supported electrolyte half-cell provided by InDEC B.V. Corporation, with a 36 mm diameter. The Nd 1.95NiO 4 + δ cathode was prepared as a two-stage electrode consisting of a thin interlayer of several hundred nanometers covered by a thicker layer of dozens microns. The Nd 1.95NiO 4 + δ oxide powders were synthesized using different routes in order to reduce the final annealing temperature, and to subsequently obtain submicronic powders. I– V characteristics of the single cells were investigated under hydrogen–air conditions. The power densities versus current densities curves are reported and the results of impedance spectroscopy measurements performed under these operating conditions are discussed.

Characterization of Electronic and Dielectric Properties of Anodic Oxide Films on Bismuth by Electrochemical Impedance Spectroscopy

The results of impedance spectroscopy measurements confirm that different types of anodic films grow on bismuth in slightly alkaline solution and under potentiodynamic and potentiostatic experiment...

Polyaniline label-based conductometric sensor for IgG detection

A new method based on a biochemical binding system is developed for detecting the presence and measuring the concentration of a definite analyte in fluids. The conductometric scheme of detection has been employed for detection of the binding reaction of immunoglobulins. Two identical pairs of gold interdigitated electrodes deposited on the insulating solid support have been used as a detector. An electrically conducting polymer, namely polyaniline, has been proposed as a label for immunosensor development. A set of water-soluble forms of polyaniline with different molecular weights and oxidation levels have been prepared by chemical oxidation of aniline and characterized using gel-permeation chromatography. The acceptability of different kinds of polyaniline, and teh selectivity and sensitivity of sensor response have been studied. The method of antibody detection in competitive electroimmunoassay has been developed. The lowest antigen concentration which may be detected in the competitive mode was found to be about 500 nm/ml. The results of impedance spectroscopy measurements obtained for different state of the electrodes are analyzed in order to clarify the mechanism of the sensor response.