Effect of fluoride ions on coordination structure of titanium in molten NaCl-KCl

The effects of fluoride ions (F-) on the electrochemical behavior and coordination properties of titanium ions (Tin+) were studied in this work, by combining electrochemical and mathematical analysis as well as spectral techniques. The a was taken as a factor to indicate the molar concentration ratio of F- and Tin+. Cyclic voltammetry (CV), square wave voltammetry (SWV), and open circuit potential method (OCP) were used to study the electrochemical behavior of titanium ions under conditions of various a, and in-situ sampler was used to prepare molten salt samples when a equal to 0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, and 8.0. And then, samples were analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results showed that F- in molten salt can reduce the reduction steps of titanium ions and greatly affects the proportion of valence titanium ions which making the high-valence titanium content increased and more stable. Ti2+ cannot be detected in the molten salt when a is higher than 3.0 and finally transferred to titanium ions with higher valence state. Investigation revealed that the mechanism behind those phenomenon is the coordination compounds (TiCljFim-) forming.