Equilibrium Population of Antisite Defects in a Crystal

Antisite defect equilibria can be treated in the same way as the other point defect equilibria. The creation of a complementary pair of antisite defects consisting of an A atom on a B atom site, AB, and a B atom on an A atom site, BA, can then be written  

The relationship between defect number and free energy of formation can then be derived as in the examples above. 

The creation of antisite defects can occur during crystal growth, when wrong atoms are misplaced on the growing surface. Alternatively, they can be created by internal mechanisms once the crystal is formed, provided that sufficient energy is applied to allow for atom movement. For example, antisite defects can be created via the intermediate formation of a Frenkel defect in the following way  

Exchange of the interstitial A atom with a B atom on its correct site, Bb  

The interstitial B atom can eliminate the vacancy to form a B atom antisite defect  

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