Zirconium tetrafluoride
Chemical compound
From Wikipedia, the free encyclopedia
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]
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| Names | |
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| IUPAC names
Zirconium(IV) fluoride Zirconium tetrafluoride | |
| Identifiers | |
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3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.029.107 |
| EC Number |
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PubChem CID |
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| UNII | |
CompTox Dashboard (EPA) |
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| Properties | |
| 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) |
| 1.32 g/100mL (20 °C) 1.388 g/100mL (25 °C) | |
| Structure | |
| Monoclinic, mS60 | |
| C12/c1, No. 15 | |
| Hazards | |
| GHS labelling: | |
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| Danger | |
| H314 | |
| P260, P264, P280, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P321, P363, P405, P501 | |
| 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).
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Structure
Three crystalline phases of ZrF4 have been reported, the stable β phase (monoclinic, space group I2/c), α (tetragonal, space group P42/m) which is a high-temperature meta-stable form that can be stabilized by quenching. The γ-form (monoclinic, space group P21/c) is a high-pressure phase, forming at pressures between (4-8 GPa).[3] α and γ phases are unstable and transform into the β phase at 400[4] and 723 °C[3] respectively. There also exists an amorphous phase.[3]
Zirconium(IV) fluoride forms several hydrates. The trihydrate has the structure (μ−F)2[ZrF3(H2O)3]2.[5]
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:[6]
- 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]