Growth of surface oxide films

Figure 7.28 is the EIS of the galena electrode at different potential in the lime medium. The relationship between polarization resistance and potential is presented in Fig. 7.9. The EIS of the galena electrode can be divided into three stages according to the different characters of the surface oxidation film. When the potential is between -70 and 300 mV, capacitive reactance loop radius and polarization resistance increases slowly due to the formation of surface oxidation products, and the growth of surface oxidation film is the controlled step of the...

Growth of surface oxide films takes place only if cations, anions, and electrons can diffuse through the oxide layer. The growth kinetics of very thin films ( 10-50 A) often follow the Mott or Cabrera-Mott mechanisms in which electrons tunnel through the film and associate with oxygen atoms to produce oxide ions at the surface. A large local electric field (10 -10 V/cm) results at the surface which facilitates cation diffusion from the metal-oxide interface to an interstitial site of the oxide. The film thickness Z at time t is given by... 

Figure C2.8.5. Growth of an oxide film on a metal surface, (a) In tire absence of an externally applied potential ...

Figure 8.24 Growth of an oxide film on a metal surface (a) diffusion of metal ions and electrons leads to growth at the outer (oxide/gas) side of the oxide film (b) counter diffusion of electrons and oxide ions leads to growth at the inner (metal/oxide) side of the oxide film...

A further, more detailed, radiochemical investigation of growth of anodic oxide films on tantalum and aluminum has recently been made by Davies et Two types of experiments were performed. First, transport number experiments using Xe markers as described previously, and second, experiments with neutron-activated metals to determine the amount of metal lost to the solution during the anodizing process. In the former, trace amounts of Xe were incorporated into a thin surface layer of anodic oxide. The specimen was then anodized, the depth of the embedded tracers being measured at intervals with a 5-spectrometer. Metal foils identical to those used in the transport number experiments were neutron activated, and then anodized at constant current. The amount of activity in the anodizing solution was then determined by comparison with solutions in which a known quantity of activated material had been dissolved. 

Hadzi-Jordanov, S. Angerstein-Kozlowska, H. Vukovic, M. Conway, B. E. Reversibility and Growth Behavior of Surface Oxide Films at Ruthenium Electrodes. J. Electrochem. Soc. 1978, 125, 1471. 

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