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

Dragica B. Camovska, Martin Lj. Arsov, Toma P. Grcev


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.


passive films; niobium; cyclic voltammetry; electrochemical impedance spectroscopy

Full Text:



T. Hurlen, H. Bentzen, S. Hornkjol, Passive behavior of niobium, Electrochim.Acta, 32, 1613–1617 (1987).

W. A. Badawy, A. Felske, W. J. Plieth, Electrochemical and photoelectrochemical behavior of passivated Ti and Nb electrodes in nitric acid solutions, Electrochim. Acta, 34, 1711–1715 (1989).

R. M. Torresi, F. C. Nart, Growth of anodic niobium oxide films, Electrochim. Acta, 33, 1015–1018 (1988).

A. Robin, Corrosion behaviour of niobium in sodium hydroxide solutions, J. Appl. Electrochem., 34, 623–629 (2004).

F. Di Quarto, S. Piazza, C. Sunseri, Amorphous semiconductors- electrolyte junction. Impedance study on the a Nb2O5-electrolyte junction, Electrochim. Acta, 35, 99– 107 (1990).

G. E. Cavigliasso, M. J. Esplandiu, V. A. Macagno, Influence of the forming electrolyte on the electrical properties of tantalum and niobium oxyde films: an EIS comparative study, J. Appl. Electrochem., 28, 1213–1219 (1998).

M. Eidel’berg, D. Sandulor, Nature of niobium passivation in hydrofluoric-sulfuric acid baths, Electrokhimiya, 23, 533–535 (1987).

S. R. Biaggio, N. Bocchi, R. C. Rocha-Filho, F. E. Varela, Electrochemical characterization of thin passive films on Nb electrodes in H3PO4 solutions, J. Braz. Chem. Soc., 8, 615–620 (1997).

F. Di Quarto, F. La Mantia, M. Santamaria, Recent advances on physico-chemical characterization of passive films by EIS and differential admittance techniques, Corr. Sci., 49, 186–194 (2007).

F. M. Al-Kharafi, W. A. Badawy, Phosphoric acid passivated niobium and tantalum eis-comparative study, Electrochim. Acta, 40, 2623–2626 (1995).

I. Uehara, T. Sakai, H. Ishikawa, H. Takenaka, Corrosion behavior of tantalum and niobium in hydrochloric acid solutions (II) on passive films on hydrogen absorption, Corrosion, 45, 548–553 (1989).

M. M. Lohrengel, Thin anodic oxide layers on aluminium and other valve metals: high-field regime, Materials Science and Engineering, R11, 6, 243–294 (1993).

B. A. Boukamp, Equivalent circuit, Solode State Ionic, 20, 31–38 (1986).

D. Chamovska, M. Cvetkovska, T. Grchev, Electrosorption of some benzotriazole derivatives on gold from acidic media, steady-state and kinetic study, Bull. Chem. Technol. Macedonia, 18, 187–197 (1999).

I. Mickova, Ph.D. thesis, Sts. Cyril and Methodius University, Skopje, R. Macedonia (2006).

DOI: http://dx.doi.org/10.20450/mjcce.2007.263


  • There are currently no refbacks.

Copyright (c) 2016 Dragica B. Camovska, Martin Lj. Arsov, Toma P. Grcev

Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.