Solid-gas equilibriums involving mass and charge transfers

Solid-gas equilibriums involving mass and charge transfers 

Next we demonstrate that some materials, particularly metal oxides, tend to facilitate mass and charge transfers with the surrounding gaseous phase. However, three conditions have to be fulfilled  

The oxygen molecule will be received through the point defects that are characteristic of oxygen, that is to say either interstitial sites or sites with anion vacancies. 

The point defects that are characteristic of metal cations, which are cation vacancies and interstitial cations, make it easier for the oxygen to access its assigned lattice sites. 

We can also assume that the first step is often quick to be completed and is therefore always at eqtrilibrium, at all pressme and temperature values. This causes the creation of a surface potential that we have already expressed for adsorption. 

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