Simultaneous preparation of high-purity silicides, eutectic Si/MSi2 (M: Nb, Ta, Mo, or W) alloys, and silicon through the separation of Si-M solvents using electromagnetic directional crystallization

Refractory silicides, eutectic Si/MSi2 (M: Nb, Ta, Mo, or W) alloys, and high-purity silicon are materials that have been used in many high-tech industries. Today, they are prepared using different technologies, i.e., each of them is prepared using an independent technology. This study proposes a new method to simultaneously prepare three high-purity materials (refractory silicides, eutectic Si/MSi2 alloys, and silicon) using electromagnetic directional crystallization. The Si-M (Si-Nb, Si-Ta, Si-Mo, or Si-W) solvents are separated using electromagnetic directional crystallization, and then the MSi2 (NbSi2, TaSi2, MoSi2, or WSi2) and eutectic Si/MSi2 (Si/NbSi2, Si/TaSi2, Si/ MoSi2, or Si/WSi2) alloys are precipitated in sequence because the crystallization temperature of MSi2 is higher than that of the eutectic Si/MSi2 alloys. Additionally, owing to the segregation behavior of impurities between the solid and liquid phases, impurities in the Si-M solvents can be eliminated efficiently to prepare high-purity MSi2 and eutectic Si/MSi2 alloys. In addition, as the eutectic Si/MSi2 alloys consist of Si and MSi2 phases, high-purity Si powders (>99.98%) can be obtained by separating the Si and MSi2 phases using acid leaching. The results indicate the feasibility of the new approach in preparing refractory silicides, eutectic Si/MSi2 alloys, and high-purity Si.