 In the nuclear industry, MoF6 occurs as an impurity in uranium hexafluoride since molybdenum is a fission product of uranium.It is also an impurity in tungsten hexafluoride, which is used in the semiconductor industry.MoF6 can be removed by reduction of a WF6-MoF6 mixture with any of a number of elements including molybdenum at moderately elevated temperature.