Module 2.2 - Crystal Structures Flashcards
What is radius ratio?
The radius of the cation to the anion
What is the aim of the radius ratio?
To obtain the lowest amount of energy by maximizing attraction while minimizing repulsion.
If anions are too close to other anions in terms of the radius ratio, what happens to the structure?
They become unstable
If anions are too close to other anions in terms of the radius ratio, what happens to the structure?
They become unstable
How come for ZnS structures, tetrahedral coordination is still maintained even if the radius ratio is >0.414, which is supposedly octahedral?
Zinc Sulfide does this because it has 2 polymorphs, wurtzite (HCP), zinc blended (FCC - interpenetrating)
When usually is the tetrahedral coordination followed even if the radius ratio >0.414?
When atoms favor the sp3 hybridization, for small ∆EN.
How can the crystal structures of
