Electrochemical behavior of tantalum(V) oxide in chloride-fluoride melts

Electrochemical behavior of KCl-KF-Ta₂O₅ melts is studied by cyclic voltammetry. It is a Ta(V) oxyfluoride (KTaO₂F₂, K₃TaO₂F₄, or K₃TaOF₆), yielded by the Ta₂O₅-KF interaction in the melt, that presumably participates in the electrochemical process, rather than Ta₂O₅ proper. The Ta(V) oxyfluoride complex is reduced to tantalum metal at 973 K via three irreversible diffusion-controlled stages. The product of the electrokinetic transfer coefficient and the number of electrons participating in the third stage is determined. The Ta(V) reduction becomes one-staged at 1073 K. Tantalum-containing ternary systems with molybdenum, cobalt, or silicon are prepared by electrolyzing Ta₂O₅-containing melts.