Abstract
We produced a pure Si substance directly from a SiO2-Mg system using the solar furnace in the air. After the reagent of SiO2-Mg system was melting for 2–3 minutes under the solar furnace, Si grains (~1–3 mm) surrounded by forsterite (Mg2SiO4) were produced as the reaction product. From the phase diagram of MgO-SiO2 system, it is considered that the reaction, 2 SiO2 + 2 Mg → Si + Mg2SiO4, occurred. In this reaction, the existence of Mg2SiO4 melt might have protected Si reduced from SiO2 against O2 in the air, and might have made Si grain grow larger in the melt. In the reduction of SiO2 by Mg, we could have obtained Si grains visible to the naked eye within a few minutes under the solar furnace. Being a simple and short experiment this experiment is suitable for science students.
