crystallography Crystallography is the experimental science of determining the arrangement of atoms in crystalline solids. Crystallography is a fundamental subject in the fields of materials science and solid-state physics (condensed matter physics). The wo ...

, an anti-structure is obtained from a salt structure by exchanging anion and cation positions. For instance,

calcium fluoride Calcium fluoride is the inorganic compound of the elements calcium and fluorine with the formula CaF2. It is a white insoluble solid. It occurs as the mineral fluorite (also called fluorspar), which is often deeply coloured owing to impurities. ...

, CaF₂, crystallizes in a cubic motif called the

fluorite structure In solid state chemistry, the fluorite structure refers to a common motif for compounds with the formula MX2. The X ions occupy the eight tetrahedral interstitial sites whereas M ions occupy the regular sites of a face-centered cubic (FCC) struct ...

. The same crystal structure is found in numerous ionic compounds with formula AB₂, such as ceria (CeO₂),

zirconia Zirconium dioxide (), sometimes known as zirconia (not to be confused with zircon), is a white crystalline oxide of zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the mineral baddeleyite. A dopant stab ...

(cubic ZrO₂),

uranium dioxide Uranium dioxide or uranium(IV) oxide (), also known as urania or uranous oxide, is an oxide of uranium, and is a black, radioactive, crystalline powder that naturally occurs in the mineral uraninite. It is used in nuclear fuel rods in nuclear reac ...

(UO₂). In the corresponding ''anti-structure'', called the antifluorite structure, anions and cations are swapped, such as beryllium carbide (Be₂C) or lithium oxide (Li₂O), potassium sulfate (K₂SO₄). Other anti-structures include: * anti- SnO₂: Ti₂N * anti- PbCl₂: Co₂P * anti- CdCl₂: Co₂N * anti- CdI₂: Cs₂O * anti- NbS₂: Hf₂S * anti- ReO₃: Cu₃N * anti- LaF₃: Cu₃P, Cu₃As

References

{{Reflist Crystallography