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Communication Dans Un Congrès Année : 2017

The complex-capacitance representation : a convenient way to follow in situ modifications of the thickness of an oxide layer during electrochemical polarization

Résumé

Impedance data can be presented in different formats, depending on which specific behaviour has to be emphasized. The impedance format in Nyquist or Bode diagrams are widely used representations, providing interesting information in the low frequency domain, for reaction kinetics or mass transfer controlled reactions. However when the high frequency domain has to be investigated, the complex capacitance format is a more convenient representation and is especially useful for dielectric systems (called also Cole-Cole graphical representation). Accordingly it provides an easy determination of the capacitance value of the dielectric by extrapolation of the real part of the capacitance at infinite frequency. When the dielectric is an oxide layer, its thickness  can be calculated using following equation:  = 0/C∞ where 0 is the permittivity of vacuum (0 = 8.8542 10-14 F cm-1), and is the dielectric constant of the layer. The complex-capacitance representation was used in the present work to follow the modification of the thickness for an aluminium oxide layer during cathodic dissolution (Figure 1). The abrupt thickness decrease at E <-1.3V only obvious from the Cole-Cole plot could clearly be attributed to chemical dissolution of the oxide layer due to interfacial pH increase Some examples of capacitance determination are also given for iron oxide or titanium oxide. [1] T.T.M Tran, B. Tribollet, E.M.M. Sutter. New insights into the cathodic dissolution of aluminium

Domaines

Chimie
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Dates et versions

hal-03968444 , version 1 (01-02-2023)

Identifiants

  • HAL Id : hal-03968444 , version 1

Citer

Eliane M M Sutter, Mai T.T. Tran, Bernard Tribollet. The complex-capacitance representation : a convenient way to follow in situ modifications of the thickness of an oxide layer during electrochemical polarization. 68th ISE annual Meeting, ISE, Aug 2017, Providence, United States. ⟨hal-03968444⟩
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