{{chembox | verifiedrevid = 470637858 | Name = Zirconium(IV) fluoride | ImageFile =Kristallstruktur Uran(IV)-fluorid.png | ImageName = Zirconium(IV) fluoride | IUPACName = Zirconium(IV) fluoride<br/>Zirconium tetrafluoride | OtherNames = |Section1={{Chembox Identifiers | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}} | ChemSpiderID = 74196 | PubChem = 82216 | EINECS = 232-018-1 | UNII = 1XHF39056H | InChI = 1/4FH.Zr/h4*1H;/q;;;;+4/p-4 | InChIKey = OMQSJNWFFJOIMO-XBHQNQODAN | SMILES = F[Zr](F)(F)F | StdInChI_Ref = {{stdinchicite|correct|chemspider}} | StdInChI = 1S/4FH.Zr/h4*1H;/q;;;;+4/p-4 | StdInChIKey_Ref = {{stdinchicite|correct|chemspider}} | StdInChIKey = OMQSJNWFFJOIMO-UHFFFAOYSA-J | CASNo = 7783-64-4 | CASNo_Ref = {{cascite|correct|CAS}} | CASNo2 = 15298-38-1 | CASNo2_Comment = (monohydrate) }} |Section2={{Chembox Properties | Formula = ZrF<sub>4</sub> | MolarMass = 167.21 g/mol | Appearance = white crystalline powder | Density = 4.43 g/cm<sup>3</sup> (20 °C) | Solubility = 1.32 g/100mL (20 °C) <br> 1.388 g/100mL (25 °C) | MeltingPtC = 910 | BoilingPt = }} |Section3={{Chembox Structure | CrystalStruct = Monoclinic, mS60 | SpaceGroup = C12/c1, No. 15 }} |Section7={{Chembox Hazards | ExternalSDS = | GHSPictograms = {{GHS05}} | GHSSignalWord = Danger | HPhrases = {{H-phrases|H314}} | PPhrases = {{P-phrases|P260|P264|P280|P301+P330+P331|P302+P361+P354|P304+P340|P305+P354+P338|P316|P321|P363|P405|P501}} | NFPA-H = | NFPA-R = | NFPA-F = | NFPA-S = | FlashPt = Non-flammable | LD50 = 98 mg/kg (oral, mouse)<br/>98 mg/kg (oral, rat)<ref>{{IDLH|7440677|Zirconium compounds (as Zr)}}</ref> }} |Section8={{Chembox Related | OtherAnions = Zirconium(IV) chloride<br/>Zirconium(IV) bromide<br/>Zirconium(IV) iodide | OtherCations = Titanium(IV) fluoride<br/>Hafnium(IV) fluoride }} }}

'''Zirconium(IV) fluoride''' describes members of a family inorganic compounds with the formula ZrF<sub>4</sub>(H<sub>2</sub>O)<sub>x</sub>. All are colorless, diamagnetic solids. Anhydrous Zirconium(IV) fluoride is a component of ZBLAN fluoride glass.<ref name=Ull>{{cite book |doi=10.1002/14356007.a28_543 |chapter=Zirconium and Zirconium Compounds |title=Ullmann's Encyclopedia of Industrial Chemistry |year=2000 |last1=Nielsen |first1=Ralph |isbn=3527306730 }}</ref>

==Structure== [[Image:ZrF4tetragonal.jpg|thumb|left|Tetragonal ZrF<sub>4</sub>]] Three crystalline phases of ZrF<sub>4</sub> have been reported, the stable β phase (monoclinic, space group I2/c), α (tetragonal, space group P4<sub>2</sub>/m) which is a high-temperature meta-stable form that can be stabilized by quenching. The γ-form (monoclinic, space group P2<sub>1</sub>/c) is a high-pressure phase, forming at pressures between (4-8 GPa).<ref name=":0">{{Cite journal |last=Laval |first=J.-P. |date=2014-08-15 |title=Crystal chemistry of anion-excess ReO3-related phases. III. |url=https://journals.iucr.org/c/issues/2014/08/00/ov3051/ |journal=Acta Crystallographica Section C: Structural Chemistry |language=en |volume=70 |issue=8 |pages=742–748 |doi=10.1107/S2053229614014338 |issn=2053-2296|url-access=subscription }}</ref> α and γ phases are unstable and transform into the β phase at 400<ref>{{cite book |author1=Paul L. Brown |url=https://books.google.com/books?id=DvqwTdVhjMEC&pg=PA144 |title=Chemical thermodynamics of zirconium |author2=Federico J. Mompean |author3=Jane Perrone |author4=Myriam Illemassène |publisher=Gulf Professional Publishing |year=2005 |isbn=0-444-51803-7 |page=144}}</ref> and 723&nbsp;°C<ref name=":0" /> respectively. There also exists an amorphous phase.<ref name=":0" />

Zirconium(IV) fluoride forms several hydrates. The trihydrate has the structure {{chem2|(μ\sF)2[ZrF3(H2O)3]2}}.<ref>{{Greenwood&Earnshaw2nd|page=965}}</ref>

==Preparation and reactions== Zirconium fluoride can be produced by several methods. Zirconium dioxide reacts with hydrogen fluoride and hydrofluoric acid to afford the anhydrous and monohydrates: :{{chem2|ZrO2 + 4 HF -> ZrF4 + 2 H2O}} The reaction of Zr metal reacts at high temperatures with HF as well: :{{chem2|Zr + 4 HF -> ZrF4 + 2 H2}}

Zirconium dioxide reacts at 200&nbsp;°C with solid ammonium bifluoride to give the heptafluorozirconate salt, which can be converted to the tetrafluoride at 500&nbsp;°C: :{{chem2|2ZrO2 + 7 (NH4)HF2 -> 2 (NH4)3ZrF7 + 4 H2O + NH3}} :{{chem2|(NH4)3ZrF7 -> ZrF4 + 3 HF + 3 NH3}}

Addition of hydrofluoric acid to solutions of zirconium nitrate precipitates solid monohydrate. Hydrates of zirconium tetrafluoride can be dehydrated by heating under a stream of hydrogen fluoride.

Zirconium fluoride can be purified by distillation or sublimation.<ref name=Ull/>

Zirconium fluoride forms double salts with other fluorides. The most prominent is potassium hexafluorozirconate, formed by fusion of potassium fluoride and zirconium tetrafluoride:<ref>{{Kirk-Othmer|doi=10.1002/0471238961.2009200113051908.a01|title=Fluorine compounds, inorganic, titanium|first=Dayal&nbsp;T.|last=Meshri|year=2000}}</ref> :{{chem2|ZrF4 + 2 KF -> K2ZrF6}}

==Applications== The major and perhaps only commercial application of zirconium fluoride is as a precursor to ZBLAN glasses.<ref name=Ull/>

Mixture of sodium fluoride, zirconium fluoride, and uranium tetrafluoride (53-41-6&nbsp;mol.%) was used as a coolant in the Aircraft Reactor Experiment. A mixture of lithium fluoride, beryllium fluoride, zirconium fluoride, and uranium-233 tetrafluoride was used in the Molten-Salt Reactor Experiment. (Uranium-233 is used in the thorium fuel cycle reactors.){{citation needed|date=June 2023}}

==References== {{reflist}}

* ORNL/TM-2006/12 Assessment of Candidate Molten Salt Coolants for the Advanced High-Temperature Reactor (AHTR), March 2006 (Accessed 2008/9/18)

{{Zirconium compounds}} {{fluorine compounds}}

Category:Fluorides Category:Zirconium(IV) compounds Category:Metal halides