Cyclic voltammetry and square wave voltammetry were performed for TiCl 3 at 1023 K, in molten LiCl, LiCl-KCl, NaCl-CsCl and CsCl, respectively. The anodic process from Ti(III) to Ti(IV) is a simple reversible process in all the alkali chloride melts. Ti(III) can be reduced directly to Ti in one step, in CsCl, while Ti(II) will appear before Ti in LiCl, LiCl-KCl and NaCl-CsCl. The electrode potentials of redox couples of titanium species decrease with the decrease of the polarization power of solvent alkali ion.

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Studies were performed to investigate the cathodic behavior of silicon (IV) ion in a BaF 2 -CaF 2 -SiO 2 melt at a temperature of 1573 K. The results obtained show that the silicon (IV) ion was reduced through a single-step from Si 4+ + 4e = Si, which was an irreversible process with diffusion-controlled mass transfer. The diffusion coefficient (D) for the reduction process of silicon (IV) ion in BaF 2 -CaF 2 -SiO 2 melt was 9.76×10 −5 cm 2 s −1 , at 1573 K. Furthermore, galvanostatic electrolysis performed on a molybdenum electrode, which further presents the feasibility of electro-depositing silicon in molten BaF 2 -CaF 2 -SiO 2 system.

The structural properties and mixing thermodynamic of TiC 1 -xN x and TiO 1−x N x (0 ≤ x ≤ 1) solid solutions have been studied by X-ray diffraction method and first-principles calculations. The TiC 1x N x and TiO 1x N x compounds were synthesized via solid-state reaction and the analysis of XRD patterns show the properties of continuous solid solutions over the whole composition range. Thermodynamic analyses and structural stability studies were performed based on the mixing enthalpies and electronic structures. The mixing enthalpies of TiC 1x N x and TiO 1x N x can be fitted using a second-degree polynomial with the increasing of supercell. The first-principles calculations results reveal that the TiO 1x N x shows large number vacancies segregated in TiO-part. The charge redistributed around Ti vacancy constitutes the main contribution to the stabilization rather than the Ti-Ti bond across the O vacancy through analyzing the electron density difference plots and PDOS . These results provide theoretical basis for the development and application of the TiC 1x N x and TiO 1x N x solid solutions.

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