Editing Iron(II) oxide (section)

==Structure==
[[Iron]](II) oxide adopts the cubic, [[sodium chloride|rock salt]] structure, where iron atoms are octahedrally coordinated by oxygen atoms and the oxygen atoms octahedrally coordinated by iron atoms. The non-stoichiometry occurs because of the ease of oxidation of Fe<sup>II</sup> to Fe<sup>III</sup> effectively replacing a small portion of Fe<sup>II</sup> with two-thirds their number of Fe<sup>III</sup>, which take up tetrahedral positions in the close packed oxide lattice.<ref name="Wells" />

In contrast to the crystalline solid, in the molten state iron atoms are coordinated by predominantly 4 or 5 oxygen atoms.<ref name="ShiFeOx2020">{{cite journal |last1=Shi |first1=Caijuan |last2=Alderman |first2=Oliver |last3=Tamalonis |first3=Anthony |last4=Weber |first4=Richard |last5=You |first5=Jinglin |last6=Benmore |first6=Chris |title=Redox-structure dependence of molten iron oxides |journal=Communications Materials |date=2020 |volume=1 |issue=1 |page=80 |doi=10.1038/s43246-020-00080-4 |bibcode=2020CoMat...1...80S |doi-access=free }}</ref>

Below 200&nbsp;K there is a minor change to the structure which changes the symmetry to rhombohedral and samples become [[antiferromagnetism|antiferromagnetic]].<ref name="Wells" /><ref>{{Cite book |date=2017 |title= Proceedings of the 5th Unconventional Resources Technology Conference|url=http://dx.doi.org/10.15530/urtec-2017-2670073 |location=Tulsa, OK, USA |publisher=American Association of Petroleum Geologists |doi=10.15530/urtec-2017-2670073|isbn= 978-0-9912144-4-0}}</ref>