Mohammad Hasani,

Are you growing which type of crystals? This information will provide to answer the question relevantly to the specific crystal structure and its defects generation process.

As you say, there is no perfect crystal structure.

In laboratorial practice the structural defects depend on several factors that are related to the manufacturing process. It includes from the purity of the materials used, to the way in which the desired alloy is heat treated. Therefore, when theoretically modeling a structure with a defect all possible point defects must be considered - within these the most possible is the vacancy defect, then the antisite defect, swap defect, ... Everything,will depend on which alloy will be studied...There are alloys that to obtain them in practice by arc melting, for example, it is necessary to melt a non-stoichiometric amount of materials. Due to this the desired alloy is obtained and precipitations of "impurities" appears.

Well, from a theoretical point of view, it is up to you decide which kind of point defects (and quantity) in the defect structures you are going to study.

Dear Mohammad Hasani this is certainly a very interesting technical question. Although this is not my field of expertise (we are synthetic inorganic chemists) I noticed that there are some potentially useful literature references about this topic available. For example, please have a look at the following interesting article:

Defect Chemistry as a Crystal Structure Design Parameter: Intrinsic Point Defects and Ga Substitution in InMnO3

Article Defect Chemistry as a Crystal Structure Design Parameter: In...

Unfortunately the paper has not yet been posted by the authors as public full text on RG. However, two of the authors have RG profiles. Thus it should be no problem to contact one of them via RG and request the full text. Most authors respond quite rapidly to such full text requests.

Please also check the following very instructive presentation for some basic information about the topic:

Imperfections in Solids

https://nanohub.org/resources/5869/download/ch05_defects1.pdf

I hope this helps. Good luck with your work and best wishes, Frank Edelmann

Dear Dattatray Gadkari, thank you for your help. If you mean the material, then I should say that I am looking into cementitious materials. But if you want to know the crystal type, they are consist of minerals with various crystal types.

Dear Carlos Ariel Samudio Pérez,

Thank you very much for your comprehensive answer and explanations. So it is basically something that happens randomly and there is no specific rules for that. And for my studies I should decide by myself.

Dear Professor Frank T. Edelmann,

Thank you very much for your valuable help. The article and presentation were quite helpful.