Zirconium tetrafluoride

Zirconium(IV) fluoride describes members of a family inorganic compounds with the formula ZrF₄(H₂O)_x. All are colorless, diamagnetic solids. Anhydrous Zirconium(IV) fluoride is a component of ZBLAN fluoride glass.^[2]

Zirconium(IV) fluoride

Zirconium(IV) fluoride
Names
IUPAC names Zirconium(IV) fluoride Zirconium tetrafluoride
Identifiers
CAS Number	7783-64-4 Y 15298-38-1 (monohydrate)
3D model (JSmol)	Interactive image
ChemSpider	74196 Y
ECHA InfoCard	100.029.107
EC Number	232-018-1
PubChem CID	82216
UNII	1XHF39056H
CompTox Dashboard (EPA)	DTXSID5064831
InChI InChI=1S/4FH.Zr/h4*1H;/q;;;;+4/p-4 Y Key: OMQSJNWFFJOIMO-UHFFFAOYSA-J Y InChI=1/4FH.Zr/h4*1H;/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)[1]
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). Y verify (what is YN ?) Infobox references

Structure

Tetragonal ZrF₄

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(H₂O)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 hexafluorozirconate, 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]}