Influence of alkaline earth metal cations on the charge transfer kinetics for the redox couple Ti(IV)/Ti(III) in a chloride–fluoride melt

Abstract

The influence of strongly polarizing cations Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺ on the charge transfer kinetics of the redox couple Ti(IV)/Ti(III) is studied. The standard rate constants of charge transfer (k_s) for the Ti(IV)/Ti(III) redox couple in the (NaCl–KCl)_eq–NaF (10 wt %)–K₂TiF₆ melt upon the addition of the strongly polarizing cations into the starting melt are determined. The dependence of the charge transfer rate constants on the ionic potential of the cations is established. The activation energies of the charge transfer process are calculated for the fluoride complexes of the Ti(IV)/Ti(III) redox couple with the outer-sphere cations Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺.