Formation of defects involving surface elements

Note that the formation of such vacancies necessarily leads to an electrical disturbance on the surface. For a Schottky-type compound, we might think that these effects cancel ont just on the surface of the material. It is no longer necessarily the 

We have just seen that the existence of elementary defects allows the ions to move inside the crystal lattice. Their movemerrt can be described as a sequence of elemerrtary hopping steps. There are two distinct types of hopping steps  

In both situatiorts, these moves are activated processes (an energy barrier has to be overcome). In the presence of a cherrtical force (a concentration gradient for instance) and/or an electric force (an electric field for instance), these moves will be oriented in the direction of the effective force. All of these hopping steps are identical and are characterized by the same energy barrier or activation energy valrre. Such a process, which identifies with a scattering process in a solid phase, is therefore athermal (AH=0). 

Note finally that equilibriums can form between different stractural elements of the lattice, and that such equilibriums follow the classical rules of thermodynamics. For further details, refer to KrOger s or Soustelle s work.  

DESPORTES, M. DUCLOT, P. FABRY, J. FOULETIER, A. HAMMOU, M. KLEITZ, 

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