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Uranium tetrafluoride

Uranium tetrafluoride
IUPAC name Uranium(IV) fluoride
Other names Uranium(IV) fluoride
CAS number 10049-14-6
Molecular formula UF4
Molar mass 314.0226 g/mol
Appearance Green crystalline solid.
Density 6.7 g/cm-3, solid.
Melting point


Boiling point

1417°C (Subl.)

Solubility in water Insoluable.
MSDS Safety (MSDS) data for uranium tetrafluoride
EU classification Irritant (I),
Very Toxic (T+)
R-phrases R14, R15/29. R29
S-phrases Not listed.
Flash point Non-flammable.
Related Compounds
Other anions None.
Related compounds Uranium hexafluoride,
uranium oxide.
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and 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, which are 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. Being radioactive it may also cause cancer, probably through exposure to the breakdown product radon gas and its daughters.


    • Booth H. S., Krasny-Ergen W.,Heath R. E. (1946). "Uranium Tetrafluoride". Journal of the American Chemical Society 68: 1969-1970. doi:10.1021/ja01214a028.
    • S. Kern, J. Hayward,S. Roberts, J. W. Richardson, F. J. Rotella, L. Soderholm, B. Cort, M. Tinkle, M. West, D. Hoisington, G. H. Lander (1994). "Temperature variation of the structural parameters in actinide tetrafluorides". Journal of Chemical Physics 101: 9333-9337. doi:10.1063/1.467963.
    This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Uranium_tetrafluoride". A list of authors is available in Wikipedia.
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