Electrochemical Behavior of Titanium Complexes in the KCl-KF Melt with Additions of Alkaline Earth Metal Cations

Abstract

The charge transfer kinetics for the Ti(IV)/Ti(III) redox couple in the KCl-KF(10 wt.%)-K2TiF6 melt was studied. The standard rate constants of charge transfer (k s ) for the redox couple Ti(IV)/Ti(III) in the KCl-KF(10 wt.%)-K2TiF6 melt were calculated. The temperature dependence of the standard rate constants of charge transfer was described by the empirical equation: logk s = (2.01 ± 0.40) – (4178 ± 810)/Т. The activation energy of charge transfer was equal to (80 ± 15) kJ mol–1. Influence of strongly polarizing cations (Mg2+, Ca2+, Sr2+ and Ва2+) on the charge transfer kinetics was studied. It was determined the linear dependence of k s on the ionic potential of alkaline earth metal cations. Values of activation energy of charge transfer for systems with strongly polarizing cations were considerably less than activation energy of the initial system and decrease in case of ionic potential increasing.