LAUSR

Semiconductive silicon is widely used in solar cells, thyristors, and other important application. However, smelting and refining Si from silicon dioxide (SiO2) still require a large amount of energy, particularly for the reduction of SiO2 and removal of impurities. In this work, we designed an approach to prepare very fine Si powder from crystalline and/or amorphous SiO2 through the magnesiothermic reduction of SiO2 in molten salts. Moreover, the mechanism of reduction below 1273K was elucidated. The composition of molten salts and the reaction temperature were varied, and their effect on the Si yield was investigated. The yield was lower in the molten NaCl-MgCl2 molten salt solvent than in LiCl-MgCl2, likely because of the Mg2Si by-product formation. The higher yield in LiCl-MgCl2 resulted from the better solubility of Mg in this molten salt and the suppression of Mg2Si formation. © The Electrochemical Society of Japan, All rights reserved.