Lead oxide growth

Fig. 6. Potential diagram for passivated metals for steady and unsteady conditions with an overvoltage r/2 3 at the oxide/electrolyte interface leading to increased dissolution and oxide growth of d to d2 where a new stationary state is reached.

Similarly, a flow of anion interstitials from the oxide—oxygen interface to the metal—oxide interface can lead to new oxide growth. We can write... 

Cation vacancy and anion vacancy currents can similarly lead to oxide growth. To generalize, we can state that the total oxide growth rate will be the algebraic sum of all such contributions. Mathematically, this can be written as... 

The oxidation rate of the micro- and nanopowders was found to be faster than that of bulk single-crystal silicon, hich can be rationalized as follows. At the initial stages of the oxide growth oxygen adsorption on micro- and nanoparticles leads to SiO formation. The oxidation is then due to an enhanced oxidant diffusion over the particle surface. During the oxidation of the powders, the amount of the oxidant penetrating into the bulk of a particle is so small that its contribution to the oxidation process in the bulk of the particle is insignificant. In this case, the oxidation of the micro- and nanopowders is... 

In this context of proximal probe induced oxidation it is worthwhile to point out an interesting observation where a high current passing through a metal film leads to its oxidation [67]. This process can be coupled to the SPM-based anodic oxidation to form patterns at the nanometer level. The planar oxidation was carried out with a current density of J 10 A cm. The oxide growth rate was found to vary oc/" where n 4. 

Obviously, the kinetics of the overall process will be influenced by both the partial reductive dissolution and the kinetics of the nucleation/growth of the deposit of Co metal. This process may involve intermediate cobalt species in solution or proceed via solid-to-solid conversion to a metal phase, as described by Hasse and Scholz (2001) for the reduction of lead oxide. The properties of the metallic deposit are remarkably different for each of the studied materials, as denoted by the observed differences in their anodic behavior. The oxidation signal at -e0.40 V can be described in terms of total or partial oxidative dissolution processes ... 

---