Editing Titanium dioxide (section)

==Structure==
[[File:Anatase crystal structure.png|alt=A ball-and-stick chemical model of an anatase crystal|left|thumb|Structure of [[anatase]]. Together with rutile and brookite, one of the three major [[polymorphism (materials science)|polymorph]]s of TiO<sub>2</sub>.]]

In all three of its main dioxides, [[titanium]] exhibits [[Octahedral molecular geometry|octahedral geometry]], being bonded to six oxide anions.  The oxides in turn are bonded to three Ti centers.  The overall crystal structures of [[rutile]] and [[anatase]] are tetragonal in symmetry whereas [[brookite]] is orthorhombic. The oxygen substructures are all slight distortions of [[close packing]]: in rutile, the oxide anions are arranged in distorted hexagonal close-packing, whereas they are close to cubic close-packing in anatase and to "double hexagonal close-packing" for brookite. The [[rutile structure]] is widespread for other metal dioxides and difluorides, e.g. RuO<sub>2</sub> and ZnF<sub>2</sub>.

Molten titanium dioxide has a local structure in which each Ti is coordinated to, on average, about 5 oxygen atoms.<ref name="Ald">{{Cite journal |last1=Alderman |first1=O. L. G. |last2=Skinner |first2=L. B. |last3=Benmore |first3=C. J. |last4=Tamalonis |first4=A. |last5=Weber |first5=J. K. R. |year=2014 |title=Structure of molten titanium dioxide |journal=Physical Review B |language=en |volume=90 |issue=9 |page=094204 |bibcode=2014PhRvB..90i4204A |doi=10.1103/PhysRevB.90.094204 |issn=1098-0121 |doi-access=free}}</ref> This is distinct from the crystalline forms in which Ti coordinates to 6 oxygen atoms.