Synthesis and thermal stability of europium(II) fluoride

The reduction of EuF 3 by elemental silicon, germanium, and boron was studied. The composition of the products is described as EuF 2 + x , where x = 0.09-0.44, depending on the nature of the reducing agent and synthesis conditions. A correlation between the variation of x and the intensity of the absorption peaks typical of Eu(III) in the near-IR spectral range was established. Europium(II) fluoride is stable on heating in air up to 200°C and high-temperature heat treatment induces its oxidation into the Eu(O,F) 2 . 3 5 oxyfluoride whose luminescence spectrum exhibits a clear Eu(II) line at 440 nm. The heat treatment in high vacuum results in partial disproportionation of EuF 2 .