Heterovalent Oxygen Substitution for Fluoride Ions

Heterovalent oxygen substitution for fluoride ions occms relatively easily because both ions are rather similar. They have the same electronic stmcture, similar weights and sizes and other characteristics. 

Of course there are a few differences between them the charge, electronegativity and donor activity. A small distinction in the anion-cation bond energy leads to the formation of oxyfluorides with a disordered anion sublattice. Nevertheless there is a preferable coordination of F or 0 ions around some cations. 

The results of oxygen insertion depend on several factors such as the structure of nonstoichiometric phases, the oxygen content and the oxygen positions in the structure as well as the types and concentrations of other defects of the crystal lattice. 

Thus the introduction of oxygen into the fluoride structure can be considered as an effective tool for the ionic transfer control and its investigation. 

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