An electrochemical and surface analytical study of the formation of nanoporous oxides on niobium

作者：Tzvetkov Bogdan; Bojinov Martin^*; Girginov Assen; Pebere Nadine

来源：Electrochimica Acta, 2007, 52(27): 7724-7731.

DOI：10.1016/j.electacta.2006.12.034

• niobium
• anodic oxidation
• porous oxides
• local electrochemical impedance spectroscopy
• 2D and 3D distributions

In the present paper, the anodization of Nb in mixed sulphate + fluoride electrolytes resulting in the formation of a nanoporous oxide film has been studied. Chronoamperometry and electrochemical impedance spectroscopy have been employed to characterise in situ the kinetics of the oxidation process. In addition. the evolution of the layer structure and morphology has been followed by ex situ scanning electron microscopy. Particularly, local electrochemical impedance spectroscopy has been used to discern between the mesoscopic 2D and 31) distributions of time constants at the electrode surface. The similarity between local and global impedance spectra during anodic oxidation of Nb demonstrates the presence of an inherent 31) distribution of the high-frequency time constant, which is interpreted as in-depth variation of the steady state conductivity of the passive film. The experimental and calculational results are discussed in relation to the micro- and nanoscopic structure of the formed oxide.

• 出版日期2007-10-10
• 单位北京化工大学