Die Oxidfluoride des Niobs und Tantals

Oxidefluorides of Niobium and Tantalum The reaction of NbF₅ with SiO₂ (silica glass ampules) at 310°C or with SiO₂ (Aerosil) at 180°C always leads to NbO₂F. To the contrary the reaction with laboratory glass (Jenaer Geräteglas) at 130°C leads to NbOF₃. TaF₅ reacts in silica glass ampules at 400°C by formation of TaO₂F, however at 300°C or 260°C by formation of TaOF₃. Silica glass did not react with NbF₅ at 130°C, however Nb₂O₅ and NbF₅ gave at 130°C in silica glass ampoules NbOF₃. Similarly, TaF₅ and Ta₂O₅ or TaO₂F formed at 260°C in nickel ampoules TaOF₃. The chemical and the thermochemical behaviour of oxidefluorides have been investigated. The compounds NbOF₃ and TaOF₃ are isomorphic. Lattice constants are mentioned.