Acta Crystallogr C Struct Chem. 2014 Aug;70(Pt 8):742-8. doi: 10.1107/S2053229614014338. Epub 2014 Jul 4.The crystal structure of the high-pressure (4-8 GPa) form of zirconium tetrafluoride, γ-ZrF4, is based on the association by corner- and edge-sharing of ZrF8 triangulated dodecahedra, forming a three-dimensional framework. It presents some analogies with high-temperature α-ZrF4 but clearly constitutes a new MX4 structure type. The main MX4 ionic structure types, and especially those deriving from the `anion-excess ReO3-type', are compared and it is shown that the TeF4 structure can also be included in this family.