Zirconium tetrafluoride

Zirconium(IV) fluoride
Names
	IUPAC names Zirconium(IV) fluoride; Zirconium tetrafluoride
Identifiers
CAS Number	7783-64-4 ; 15298-38-1 (monohydrate);
3D model (JSmol)	Interactive image;
ChemSpider	74196 ;
ECHA InfoCard	100.029.107
EC Number	232-018-1;
PubChem CID	82216;
UNII	1XHF39056H;
CompTox Dashboard (EPA)	DTXSID5064831 ;
	InChI InChI=1S/4FH.Zr/h41H;/q;;;;+4/p-4 Key: OMQSJNWFFJOIMO-UHFFFAOYSA-J ; InChI=1/4FH.Zr/h41H;/q;;;;+4/p-4 Key: OMQSJNWFFJOIMO-XBHQNQODAN;
	SMILES F[Zr](F)(F)F;
Properties
Chemical formula	ZrF4
Molar mass	167.21 g/mol
Appearance	white crystalline powder
Density	4.43 g/cm3 (20 °C)
Melting point	910 °C (1,670 °F; 1,180 K)
Solubility in water	1.32 g/100mL (20 °C) ; 1.388 g/100mL (25 °C)
Structure
Crystal structure	Monoclinic, mS60
Space group	C12/c1, No. 15
Hazards
Flash point	Non-flammable
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	98 mg/kg (oral, mouse); 98 mg/kg (oral, rat)
Related compounds
Other anions	Zirconium(IV) chloride; Zirconium(IV) bromide; Zirconium(IV) iodide
Other cations	Titanium(IV) fluoride; Hafnium(IV) fluoride
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Zirconium(IV) fluoride describes members of a family inorganic compounds with the formula (Zr F₄(H₂O)_x. All are colorless, diamagnetic solids. Anhydrous Zirconium(IV) fluoride' is a component of ZBLAN fluoride glass.^[2]

Structure

Three crystalline phases of ZrF₄ have been reported, α (monoclinic), β (tetragonal, Pearson symbol tP40, space group P42/m, No 84) and γ (unknown structure). β and γ phases are unstable and irreversibly transform into the α phase at 400 °C.^[3]

Zirconium(IV) fluoride forms several hydrates. The trihydrate has the structure (μ−F)₂[ZrF₃(H₂₀)₃]₂.^[4]

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:

ZrO₂ + 4 HF → ZrF₄ + 2 H₂O

The reaction of Zr metal reacts at high temperatures with HF as well:

Zr + 4 HF → ZrF₄ + 2 H₂

Zirconium dioxide reacts at 200 °C with solid ammonium bifluoride to give the heptafluorozirconate salt, which can be converted to the tetrafluoride at 500 °C:

2ZrO₂ + 7 (NH₄)HF₂ → 2 (NH₄)₃ZrF₇ + 4 H₂O + NH₃

(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.^[2]

Zirconium fluoride forms double salts with other fluorides. The most prominent is potassium hexafluorozironate, formed by fusion of potassium fluoride and zirconium tetrafluoride:^[5]

ZrF₄ + 2 KF → K₂ZrF₆

Applications

The major and perhaps only commercial application of zirconium fluoride is as a precursor to ZBLAN glasses.^[2]

Mixture of sodium fluoride, zirconium fluoride, and uranium tetrafluoride (53-41-6 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]}

References

^ "Zirconium compounds (as Zr)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b ^c Nielsen, Ralph (2000). "Zirconium and Zirconium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a28_543. ISBN 3527306730.
^ Paul L. Brown; Federico J. Mompean; Jane Perrone; Myriam Illemassène (2005). Chemical thermodynamics of zirconium. Gulf Professional Publishing. p. 144. ISBN 0-444-51803-7.
^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 965. ISBN 978-0-08-037941-8.
^ Meshri, Dayal T. (2000), "Fluorine compounds, inorganic, titanium", Kirk-Othmer Encyclopedia of Chemical Technology, New York: John Wiley, doi:10.1002/0471238961.2009200113051908.a01, ISBN 9780471238966