Conduction mechanism in oxide films on ferrous alloys studied by impedance spectroscopy in symmetrical and asymmetrical configurations

Iva Betova, Martin Bojinov (Corresponding Author), Petri Kinnunen, Kari Mäkelä, Timo Saario

Research output: Contribution to journalArticleScientificpeer-review

30 Citations (Scopus)

Abstract

The electrical and electrochemical properties of the oxide films formed on Fe–25%Cr–x%Mo (x=0, 5 and 10) alloys by polarisation at −0.8–0.2 V vs. SHE in a 0.1 M Na2B4O7 electrolyte at 200 and 300 °C are characterised by impedance measurements in both asymmetrical (alloy|oxide|electrolyte) and symmetrical (alloy|oxide|metal) configurations. The impedance magnitude at low frequencies in the symmetrical configuration has been found to be ca. more than one order of magnitude smaller than that in the asymmetrical configuration, indicating that the oxide films are mixed conductors with predominant electronic conductivity. The impedance spectra in both configurations comprised two time constants. The high-frequency time constant is ascribed to the electronic properties of the space-charge layer in the oxide, whereas the low-frequency time constant is associated with the solid-state transport of point defects. Kinetic parameters characterising the reactions of defect generation and consumption are estimated by fitting the equations of the Mixed-Conduction Model proposed earlier to the experimental impedance spectra in both configurations.

Original languageEnglish
Pages (from-to)211 - 223
Number of pages13
JournalJournal of Electroanalytical Chemistry
Volume572
Issue number2
DOIs
Publication statusPublished - 2004
MoE publication typeA1 Journal article-refereed

Fingerprint

Iron alloys
Oxides
Electrolytes
Oxide films
Spectroscopy
Point defects
Electrochemical properties
Electric space charge
Kinetic parameters
Electronic properties
Electric properties
Polarization
Defects

Keywords

  • hydrothermal oxide film; electrochemical impedance spectroscopy; mixed conductor; kinetic model

Cite this

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title = "Conduction mechanism in oxide films on ferrous alloys studied by impedance spectroscopy in symmetrical and asymmetrical configurations",
abstract = "The electrical and electrochemical properties of the oxide films formed on Fe–25{\%}Cr–x{\%}Mo (x=0, 5 and 10) alloys by polarisation at −0.8–0.2 V vs. SHE in a 0.1 M Na2B4O7 electrolyte at 200 and 300 °C are characterised by impedance measurements in both asymmetrical (alloy|oxide|electrolyte) and symmetrical (alloy|oxide|metal) configurations. The impedance magnitude at low frequencies in the symmetrical configuration has been found to be ca. more than one order of magnitude smaller than that in the asymmetrical configuration, indicating that the oxide films are mixed conductors with predominant electronic conductivity. The impedance spectra in both configurations comprised two time constants. The high-frequency time constant is ascribed to the electronic properties of the space-charge layer in the oxide, whereas the low-frequency time constant is associated with the solid-state transport of point defects. Kinetic parameters characterising the reactions of defect generation and consumption are estimated by fitting the equations of the Mixed-Conduction Model proposed earlier to the experimental impedance spectra in both configurations.",
keywords = "hydrothermal oxide film; electrochemical impedance spectroscopy; mixed conductor; kinetic model",
author = "Iva Betova and Martin Bojinov and Petri Kinnunen and Kari M{\"a}kel{\"a} and Timo Saario",
year = "2004",
doi = "10.1016/j.jelechem.2003.08.030",
language = "English",
volume = "572",
pages = "211 -- 223",
journal = "Journal of Electroanalytical Chemistry",
issn = "1572-6657",
publisher = "Elsevier",
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Conduction mechanism in oxide films on ferrous alloys studied by impedance spectroscopy in symmetrical and asymmetrical configurations. / Betova, Iva; Bojinov, Martin (Corresponding Author); Kinnunen, Petri; Mäkelä, Kari; Saario, Timo.

In: Journal of Electroanalytical Chemistry, Vol. 572, No. 2, 2004, p. 211 - 223.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Conduction mechanism in oxide films on ferrous alloys studied by impedance spectroscopy in symmetrical and asymmetrical configurations

AU - Betova, Iva

AU - Bojinov, Martin

AU - Kinnunen, Petri

AU - Mäkelä, Kari

AU - Saario, Timo

PY - 2004

Y1 - 2004

N2 - The electrical and electrochemical properties of the oxide films formed on Fe–25%Cr–x%Mo (x=0, 5 and 10) alloys by polarisation at −0.8–0.2 V vs. SHE in a 0.1 M Na2B4O7 electrolyte at 200 and 300 °C are characterised by impedance measurements in both asymmetrical (alloy|oxide|electrolyte) and symmetrical (alloy|oxide|metal) configurations. The impedance magnitude at low frequencies in the symmetrical configuration has been found to be ca. more than one order of magnitude smaller than that in the asymmetrical configuration, indicating that the oxide films are mixed conductors with predominant electronic conductivity. The impedance spectra in both configurations comprised two time constants. The high-frequency time constant is ascribed to the electronic properties of the space-charge layer in the oxide, whereas the low-frequency time constant is associated with the solid-state transport of point defects. Kinetic parameters characterising the reactions of defect generation and consumption are estimated by fitting the equations of the Mixed-Conduction Model proposed earlier to the experimental impedance spectra in both configurations.

AB - The electrical and electrochemical properties of the oxide films formed on Fe–25%Cr–x%Mo (x=0, 5 and 10) alloys by polarisation at −0.8–0.2 V vs. SHE in a 0.1 M Na2B4O7 electrolyte at 200 and 300 °C are characterised by impedance measurements in both asymmetrical (alloy|oxide|electrolyte) and symmetrical (alloy|oxide|metal) configurations. The impedance magnitude at low frequencies in the symmetrical configuration has been found to be ca. more than one order of magnitude smaller than that in the asymmetrical configuration, indicating that the oxide films are mixed conductors with predominant electronic conductivity. The impedance spectra in both configurations comprised two time constants. The high-frequency time constant is ascribed to the electronic properties of the space-charge layer in the oxide, whereas the low-frequency time constant is associated with the solid-state transport of point defects. Kinetic parameters characterising the reactions of defect generation and consumption are estimated by fitting the equations of the Mixed-Conduction Model proposed earlier to the experimental impedance spectra in both configurations.

KW - hydrothermal oxide film; electrochemical impedance spectroscopy; mixed conductor; kinetic model

U2 - 10.1016/j.jelechem.2003.08.030

DO - 10.1016/j.jelechem.2003.08.030

M3 - Article

VL - 572

SP - 211

EP - 223

JO - Journal of Electroanalytical Chemistry

JF - Journal of Electroanalytical Chemistry

SN - 1572-6657

IS - 2

ER -