ELECTROCHEMICAL STUDIES OF K2WCL6 IN CHLORIDE AND OXYCHLORIDE MELTS

The electrochemical behaviour of W-IV in the form of K2WCl6 in a LiCl- KCl (eutectic melt) has been studied by cyclic voltammetry at 450 degr ees C on glassy carbon electrodes with and without additions of Na2O. W-IV is reduced to tungsten metal via an irreversible four-electron-tr ansfer process. Titration of the system LiCl-KCl-K2WCl6 with Na2O was carried out in order to investigate the influence of oxide ions on the electroreduction of W-IV. At a molar ratio of Na2O/K2WCl6=0.5, the ma jor complex ion in the melt may be W2OC104- and/or WOCl52-, while at a molar ratio of Na2O/K-2 WCl6=2 precipitation of WO2 probably occurs.