Electrochemical Behavior of Ti(III) Ions in a KF–KCl Eutectic Melt

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The electrochemical behavior of Ti(III) ions in a eutectic KF–KCl molten salt was investigated using cyclic voltammetry, square wave voltammetry, and chronoamperometry at 923 K. Ti(III) ions were produced by the addition of 0.50 mol% of K₂TiF₆ and 0.33 mol% of Ti sponge to the melt. The reduction of Ti(III) ions to metallic Ti was observed as a single 3-electron wave around 0.33 V vs. K⁺/K in the square-wave voltammogram. The electrodeposition was conducted at a Mo electrode by galvanostatic electrolysis at −50 mA cm⁻² for 20 min. The deposits were confirmed to be compact and adherent Ti metal films by scanning electron microscopy, energy dispersive X-ray analysis and X-ray diffraction analysis. The oxidation of Ti(III) to Ti(IV) was observed at 1.82 V vs. K⁺/K as a reversible electrochemical process. The diffusion coefficient of Ti(III) ions was determined to be 3.9 × 10⁻⁵ cm² s⁻¹.