Reactivity of Ammonium and Potassium Hydrogenfluorides Towards FeVO₄

Abstract

Fluorination of FeVO₄ has been carried out by using NH₄HF₂ and KHF₂ in the solid state. NH₄HF₂ reacts with FeVO₄ at room temperature to give a mixture of (NH₄)₃FeFe 1.5H₂O and (NH₄) ₃ VOF₆ 1.5H₂O. KHF₂ does not react at room temperature in its tetragonal modification. However. it reacts at 200°C in its cubic modification to give a mixture of the corresponding fluoro and oxyfluoro complexes. The course of the reaction with FeVO₄ is shown to be identical to that with a mechanical mixture of α-Fe₂O₃ and V₂O₅.