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
    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",
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    pages = "211--223",
    journal = "Journal of Electroanalytical Chemistry",
    issn = "1572-6657",
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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 -