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

Abstract

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 experimental conditions. The band model of solids can describe the behavior of these films. Several approximations were necessary to introduce, since “rapidly” grown oxide films (with α = 22 nm V-1) were highly nonstoichiometric and amorphous in structure. Numerical analysis showed that two capacitive contributions were involved in the measured impedance spectra, the oxide film capacitance (C ox ) and space charge capacitance (C SC), which were used to characterize the semiconducting and dielectric properties of the Bi2O3/electrolyte structure. Both donor concentration (N D) and the critical electrode potential have been determined from Mott−Schottky behavior. The dielectric properties of the oxide film were discussed in terms of a parallel plate capacitor and in accordance with the high-field growth law, and several parameters were determined: the oxide layer thickness (d ox), the dielectric constant (ε), the potential at which oxide electroformation starts ( ), the thickness of native oxide (d in), and the anodization coefficient (α). Potentiostatic anodization confirms the rearrangement within the oxide film under the high electric field detected by impedance spectroscopy. The results indicate that the film formed potentiostatically behaves almost like a capacitor (insulator). The high resistance of the Bi−Bi2O3/electrolyte structure was ascribed to a very high interfacial charge-transfer resistance.

Electrochemical Corrosion Behavior of Ta2N Nanoceramic Coating in Simulated Body Fluid

“…The space charge layer thickness ( δ sc ) for an n-type semiconductor can be calculated from the following equation [55]: ${\delta }_{sc}={[\frac{2{\epsilon }_r{\epsilon }_0}{e{N}_d}(E-E_{fb}-\frac{kT}{e})]}^{1/2}$…”

“…The thickness of the space-charge layer ( δ sc ) in a semiconductor is an important parameter that controls the movement of electrons. The space charge layer thickness ( δ sc ) for an n-type semiconductor can be calculated from the following equation [ 55 ]: …”

Dielectric characterization of fiber‐ and nanofiller‐reinforced polymeric materials

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“…Since the 1980s, DS methods have advanced, enabling more precise data analysis. [57][58][59][60][61][62][63][64][65][66][67] Today, DS remains a crucial tool in various research areas, thanks to technological advancements allowing for more extensive frequency range measurements.…”

Formation and reduction of anodic film on polycrystalline Bi electrode in pure methanol solutions

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