In many cases, the concentrations of defects or charges are quite big enough to use SA, due to a big number of Avogadro's number.
The derivation for the well-known formula of a defect concentration is followed.
If the n_v is expected to be lower than 1, then it would be impossible to use SA...
Hi, I am a grad student in Mech.
I joined this forum to get some ideas on my research projects.
Since I am an engineering guy, I am not familiar with physical concepts.
I hope I can learn a lot or I can help you a lot.