Application of Impedance Spectroscopy and Surface Analysis to Obtain Oxide Film Thickness

Abstract

The corrosion behavior of ASTM A416 steel in alkaline electrolyte was investigated by electrochemical and surface analysis approaches, including X-ray photoelectron spectroscopy (XPS) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). The power-law model was used to extract values for oxide film thickness from constant-phase-element (CPE) parameters obtained as functions of operating conditions. Calibration experiments showed that, despite different silicon content in nominally identical steels, different film thicknesses as observed by HAADF-STEM, and different impedance responses, three samples yielded a common value for ρ δ , an important parameter in the power-law model. Application of Monte Carlo simulations showed that values of both ρ δ and film thickness δ followed log normal distributions. Application of the power-law model allowed extraction of film thicknesses, yielding 2-6 nm for silicon-rich steel and 1-2 nm for silicon-poor steel.

Si Nanowire-Based Schottky Sensors for Selective Sensing of NH3 and HCl via Impedance Spectroscopy

“…All the obtained EIS spectra were fitted using the equivalent electrical circuit method. The employed circuit (Figure c) contains: R Ω contact resistance corresponding to the resistance of the gold interdigital electrodes, R resistance related to the Si NWs and Schottky barriers (referred to as the sensor resistance), C capacitance of the sensor, and CPEconstant phase element associated with the linear low frequency part of the spectra . These parameters evolve with adsorption of the analyte species on the NW sidewalls, so their analysis allows us to quantify the sensor response with the change in the resistive and capacitive characteristics.…”

“…The employed circuit (Figure 2c) contains: R Ω �contact resistance corresponding to the resistance of the gold interdigital electrodes, 61 R�resistance related to the Si NWs and Schottky barriers (referred to as the sensor resistance), C�capacitance of the sensor, and CPE� constant phase element associated with the linear low frequency part of the spectra. 62 These parameters evolve with adsorption of the analyte species on the NW sidewalls, so their analysis allows us to quantify the sensor response with the change in the resistive and capacitive characteristics. The carried out fitting allows one to obtain two parameters in the presence of various vapors: R (can be found as a diameter of an arc in Nyquist plot) and characteristic EIS frequency F (see Figure 2b) corresponding to the transition between the predominant action of the contact processes described by CPE at low frequencies to the major role of the resistance R and capacitance C of the NWs and Schottky barriers at higher frequencies.…”

Silicon Nanowire-Based Room-Temperature Multi-environment Ammonia Detection

“…R is the resistance of the medium between the metal contacts (referred to as the sensor resistance), and C is capacitance of the system. The linear low-frequency spectral part is described with a constant phase element (CPE) . Physical aspects of these parameters are discussed hereafter.…”

“…The linear lowfrequency spectral part is described with a constant phase element (CPE). 55 Physical aspects of these parameters are discussed hereafter. R and C are purely active and reactive, correspondingly, and described with the classical expressions.…”

Polyaniline-Based Infrared Dynamic Patterned Encoder with Multiple Thermal Radiation Characteristics

“…The poor conductivity of the film will reduce the carrier concentration and cannot completely transform from high emission to low emission. Therefore, the IR absorption of PANI 1100 and PANI 1300 is strengthened, the reflection function of the Au substrate is weakened, and the IR emissivity control ability of the film decreases. , …”