Electrochemical and impedance characterization of passive films on niobium in alkaline and acidic solutions

Authors

  • Dragica B. Camovska Faculty of Technology and Metallurgy, Ss. Cyril & Methodius University, Skopje,
  • Martin Lj. Arsov Faculty of Technology and Metallurgy, Ss. Cyril & Methodius University, Skopje,
  • Toma P. Grcev Faculty of Technology and Metallurgy, Ss. Cyril & Methodius University, Skopje,

DOI:

https://doi.org/10.20450/mjcce.2007.263

Keywords:

passive films, niobium, cyclic voltammetry, electrochemical impedance spectroscopy

Abstract

In this work electrochemical characterization of the anodic passive films formed on Nb in alkaline (0.1 – 5 M KOH) and acidic solution (H2SO4) was carried out by cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Potentiodynamic measurements yielded a classical electrochemical passivation curve for both alkaline (KOH) and acidic (H2SO4) solution. In addition EIS-measurements were performed at several potentials in order to characterize the Nb/solution, and/or Nb/Nb2O5 / solution interfaces. The impedance behaviour of the passive films on Nb can be adequately described with a simple EEC; Rel in series with a parallel circuit CPE (Q) – Rct(ox). The calculate values of the passive oxide (Nb2O5) films resistivity ranged between 1011–1010 Ω cm with relative dielectric constant ( εf ≈ 14) for KOH-solutions and approx. 2⋅1012 Ω cm for 1 M H2SO4, indicating that the Nb-passive films, generated in acidic solutions, are better corrosion protectors then those formed in alkaline solutions.

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Published

2007-12-15

How to Cite

Camovska, D. B., Arsov, M. L., & Grcev, T. P. (2007). Electrochemical and impedance characterization of passive films on niobium in alkaline and acidic solutions. Macedonian Journal of Chemistry and Chemical Engineering, 26(2), 95–101. https://doi.org/10.20450/mjcce.2007.263

Issue

Vol. 26 No. 2 (2007)

Section

Electrochemistry

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