Quantitative Studies on the Structure of Zirconium Fluoride Anions in Molten LiF and FLiBe

Abstract

The quantitative distribution of different zirconium fluoride anions in molten LiF and FLiBe mixtures has been investigated by Raman and theoretical calculations. In molten LiF, zirconium fluorides are present in the forms of ZrF 6 2À and ZrF 7 3À . After correction, the Raman scattering cross sections corresponding to the symmetric stretching vibrational bands were obtained. The ZrF 7 3À anion was a dominant species whatever the concentration of ZrF 4 between 5 and 30 mol % in LiF melt, even though the content of which presents a decreasing trend from 92.3 to 73.2 mol % with the increase of ZrF 4 . Similar specification was identified in FLiBe-ZrF 4 , and ZrF 6 2À /ZrF 7 3À anions were found in equilibrium with free F À ions and beryllium fluoride anions. Detailed deconvolution and calculation were performed on the Raman spectrum measured in the FLiBe melt containing 10 mol % ZrF 4 giving a quantitative content of ZrF 7 3À 78.1 mol % and ZrF 6 2À 21.9 mol %.