Interaction, composition, and optical properties of the MgF2(MgO)-EuF3 system

The interaction between MgO and EuF3 resulting in the formation of magnesium fluoride and europium(III) oxyfluorides of variable composition are investigated. A substantial difference between the diffuse reflection spectra of the fluoride phase and oxyfluoride phases of europium(III) is found, specifically, an intense band peaked at 260-270 nm appears in the latter. The effect of silicon and high vacuum as reducers on the systems containing the oxide phase is investigated. For these phases, europium(II) compounds are found, which is confirmed by X-ray powder diffraction analysis and diffuse reflection and luminescence spectroscopy. The character of thermogravimetric curves for the MgF2-EuF3-Si and MgO-EuF3-Si systems is fundamentally different, which allows us to propose a new method for estimating the MgO content in MgF2.