Uranium tetrafluoride

Uranium tetrafluoride
Names
IUPAC names
Uranium(IV) fluoride
Uranium tetrafluoride
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.142
UNII
Properties
UF4
Molar mass 314.02 g/mol
Appearance Green crystalline solid.
Density 6.70 g/cm3, solid.
Melting point 1,036 °C (1,897 °F; 1,309 K)
Boiling point 1,417 °C (2,583 °F; 1,690 K)
Insoluble.
Structure
Monoclinic, mS60
C2/c, No. 15
Hazards
Safety data sheet External MSDS
Very toxic (T+)
Dangerous for the environment (N)
R-phrases (outdated) R26/28, R33, R51/53
S-phrases (outdated) (S1/2), S20/21, S45, S61
Flash point Non-flammable
Related compounds
Other anions
 Uranium(IV) chloride
Uranium(IV) bromide
Uranium(IV) iodide
Uranium dioxide
Other cations
 Thorium(IV) fluoride
Protactinium(IV) fluoride
Neptunium(IV) fluoride
Plutonium(IV) fluoride
Related compounds
 Uranium hexafluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Uranium tetrafluoride (UF4) is a green crystalline solid compound of uranium with an insignificant vapor pressure and very slight solubility in water. Uranium in its tetravalent (uranous) state is very important in different technological processes. In the uranium refining industry it is known as green salt.

UF4 is generally an intermediate in the conversion of uranium hexafluoride (UF6) to either uranium oxides (U3O8 or UO2) or uranium metal. It is formed by the reaction of UF6 with hydrogen gas in a vertical tube-type reactor or by the action of hydrogen fluoride (HF) on uranium dioxide. UF4 is less stable than the uranium oxides and reacts slowly with moisture at ambient temperature, forming UO2 and HF, the latter of which is very corrosive; it is thus a less favorable form for long-term disposal. The bulk density of UF4 varies from about 2.0 g/cm3 to about 4.5 g/cm3 depending on the production process and the properties of the starting uranium compounds.

A molten salt reactor design, a type of nuclear reactor where the working fluid is a molten salt, would use UF4 as the core material. UF4 is generally chosen over other salts because of the usefulness of the elements without isotope separation, better neutron economy and moderating efficiency, lower vapor pressure and better chemical stability.

Like all uranium salts UF4 is toxic and thus harmful by inhalation, ingestion and through skin contact.

References

    • Booth, H. S.; Krasny-Ergen, W.; Heath, R. E. (1946). "Uranium Tetrafluoride". Journal of the American Chemical Society. 68 (10): 1969. doi:10.1021/ja01214a028.
    • Kern, S.; Hayward, J.; Roberts, S.; Richardson, J. W.; Rotella, F. J.; Soderholm, L.; Cort, B.; Tinkle, M.; West, M.; Hoisington, D.; Lander, G. A. (1994). "Temperature Variation of the Structural Parameters in Actinide Tetrafluorides". The Journal of Chemical Physics. 101 (11): 9333–9337. Bibcode:1994JChPh.101.9333K. doi:10.1063/1.467963.
    • "Uranium Tetrafluoride". Appendix A of the PEIS (DOE/EIS-0269). Argonne National Laboratory. Retrieved 22 November 2011.
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