In situ synchrotron X-ray diffraction study of the electrochemical reduction of SiO₂ in molten CaCl₂

Abstract

In situ synchrotron X-ray diffraction was used to investigate the electrochemical reduction of SiO₂ to Si in molten CaCl₂ at 1123 K for the first time. The present technique enabled direct determination of intermediate products at high temperature, without cooling and washing treatments. Based on the diffraction data, the Ca₂SiO₄ phase was detected inside the electrode, but not at the electrode edge. These results were explained by the presence of different concentrations of O²⁻ ions in molten CaCl₂ permeating different regions of the electrode.