Electrochemical Formation of Ca-Si in Molten CaCl2-KCl

Electrochemical formation of a Ca-Si film in a molten CaCl2-KCl at 923 K was investigated. Potentiostatic electrolysis of a Si electrode at −0.10 V for 1 h resulted in the formation of a multiphase Ca-Si film having a thickness of about 30 μm. The Ca-Si film was converted into other alloy phases by anodic potentiostatic electrolysis after the cathodic electrodeposition of Ca metal at −0.10 V. The various transformation reactions and the corresponding equilibrium potentials were clarified. At 923 K, the equilibrium potential was found to be 0.18 V (CaSi2). Reflectance measurements in the ultraviolet, visible, and near-infrared region clarified that the CaSi2 film has a direct bandgap of 3.1 eV.