Dear Fazal,

To be more precise, I think , it is better to think which property you want to focus on.

Then from the theoretical view point you can come to a conclusion of what type of materials are responsible for changing that property.

Then, mostly, I want to suggest DFT calculation .

FEM simulation will give you a clear picture of what material is changing the desired property .

Best Wishes

N Das

As Prof. Das mentioned, it is so important that what properties you are looking for. However, the Radius, valence electrons, electronegativity of the dopants can be considered as the basic issues.