Direct Electrolytic Reduction of Solid Silicon Dioxide in Molten LiCl–KCl–CaCl[sub 2] at 773 K

We investigated electrolytic reduction of solid by a contacting electrode method in molten at . The results of cyclic voltammetry indicated that reduction of occurs at potential more negative than (vs , ). Samples were prepared by potentiostatic electrolysis for at 0.25, 0.50, 0.70, and . Energy dispersive X-ray analysis and Raman spectra clarified that the reduction products at 0.50 and are composed of amorphous Si and microcrystalline Si. Scanning electron microscope (SEM) observations revealed that the morphology of the produced Si is spongelike with a particle size smaller than . The mechanism of Si formation was discussed by comparing the SEM observations and the Raman spectra of the Si samples prepared at 773 and . The reduction mechanism of the direct electrolytic reduction of at lower temperature was also discussed.