fluorite structure

 A type of ionic crystal structure in which the cations have an expanded face-centered cubic arrangement with the anions occupy­ing both types of tetrahedral hole. The cations have a coordination number of 8 and the anions have a coordination number of 4. Examples of compounds with this structure are CaF₂, BaCl₂, and PbO₂.

The antifluorite structure is the op­posite arrangement, with anions in the fcc array with coordination num­ber 8 and cations in the tetrahedral holes with coordination number 4. Examples of the antiflurite structure are K₂0, Li₂0, Na,O, K,S. and Na,S.