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 wor ...

, 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) structure ...

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

ceria Cerium(IV) oxide, also known as ceric oxide, ceric dioxide, ceria, cerium oxide or cerium dioxide, is an oxide of the rare-earth metal cerium. It is a pale yellow-white powder with the chemical formula CeO2. It is an important commercial produ ...

(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 sta ...

(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 rea ...

(UO₂). In the corresponding ''anti-structure'', called the antifluorite structure, anions and cations are swapped, such as

beryllium carbide Beryllium carbide, or Be2C, is a metal carbide. Similar to diamond, it is a very hard compound.Beryllium Carbide Info ...

(Be₂C) or

lithium oxide Lithium oxide ( O) or lithia is an inorganic chemical compound. It is a white solid. Although not specifically important, many materials are assessed on the basis of their Li2O content. For example, the Li2O content of the principal lithium miner ...

(Li₂O),

potassium sulfate Potassium sulfate (US) or potassium sulphate (UK), also called sulphate of potash (SOP), arcanite, or archaically potash of sulfur, is the inorganic compound with formula K2SO4, a white water-soluble solid. It is commonly used in fertilizers, pro ...

(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