High-Temperature (1700–1800°C) Electrochemical Preparation of Metallic Ti from Rutile: A Pathway of Step-by-Step Electrodeoxidization

The mechanism of producing metallic titanium by electrochemically reducing rutile (TiO2) at high temperatures was studied. First, the oxygen was successfully electroremoved from TiO2 at temperatures 1700, 1750, and 1800°C in molten CaF2 under a stable electrolytic potential of 2.5 V. Second, the electrodeoxidization process was studied with cyclic voltammetry (CV) tests at 1750°C. It was found that the electrochemical reduction for preparing metallic Ti from TiO2 at the high temperatures can be divided into several steps. In other words, the oxygen in TiO2 was electro-removed as a step-by-step pathway (TiO2→Ti4O7→Ti3O5/Ti2O3→TiO→Ti) at different electrolytic potentials. It unraveled the mechanism of electrochemical reduction of TiO2 at the high temperatures, which is helpful for monitoring the reduction procedure.

Embedded Atom Model of Surface Stress and Early Film Growth in Electrodeposition: Ag/Au(111)

ABSTRACTWe develop an embedded-atom-model (EAM) for simulations of metallic film growth under electrodeposition. The surface charge induced by the electric field is handled as an addition to the electron density to be used in the EAM. Parameters relating the shift in electron density to the electrolytic potential are calibrated to measurements of the capacitance and of surface stress versus potential for Au. For Ag the calibration is to capacitance and local density approximation calculations of surface energy. The resulting parameters are physically realistic for the experiments performed. The model is then applied to calculating migration and step edge barriers for Ag electrodeposited on Au (111) as an explanation of the observed Stranski-Krastanov growth.