The Calcium Fluorite ceramic (Ionic) crystal structure
Channel: Scott Ramsay
Date: 2016-10-11

In this video I show the calcium fluorite (or just fluorite) crystal structure using two common, but different, unit cells.  I show that both are actually depicting the same structure.  One structure positions the anions in the cube corner positions and in a simple cubic lattice with cations occupying half of the simple cubic interstitial sites.  The other depicts the cations in an "FCC-type" lattice with anions occupying all of the tetrahedral sites.  I generally prefer the former, but both are correct and it is interesting to observe how different the same structure appears from a different perspective.  Which depiction do you prefer?