Effect of solidification conditions on the silicon growth and refining using Si–Sn melt

Abstract

Effect of solidification conditions on the silicon growth and refining using si-Sn melt, Journal of Crystal Growth, http://dx.doi.org/10.1016/j. jcrysgro. 2015.08.001 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Institute of Industrial Science, The University of Tokyo, Tokyo, Japan. AbstractThe solidification refining of Si using a Si-Sn solvent was investigated under various cooling conditions: (1) slow cooling, (2) slow cooling with electromagnetic stirring, and (3) directional solidification with the aim of developing a novel low-cost route for solar-grade Si production. The separation efficiency of refined Si achieved by combining slow cooling and electromagnetic stirring was much higher than that achieved using directional solidification; in addition, the purification efficiency of the refined Si in both methods was similar. The separation mechanism of refined Si from a Si-Sn melt is also discussed. Purification testing of the refined Si revealed that more than 96% of the metallic impurities, approximately 60% B, and over 70% P were removed.

Effect of Mg alloying and cooling rate on the microstructure of silicon

“…Therefore, considering this issue, additional elements were introduced into the Si melt to further enhance the impurity segregation behavior. The solvent refining technique involves adding substantial quantities of alloying elements such as Al (Yoshikawa and Morita, 2003;Yoshikawa and Morita, 2012;Lei et al, 2018), Sn (Ma et al, 2015;Ren et al, 2019), and Cu (Huang et al, 2018) to form a solvent alloy. The solvent not only decreases the alloy melting point and operation temperature but also improves the segregation of various impurities due to the interaction with the introduced solvent element.…”

An approach to prepare high-purity TiSi2 for clean utilization of Ti-bearing blast furnace slag

“…The purified Si crystals were separated from the Al-Si solvent using electromagnetic directional crystallization. Ma et al 27 prepared SOG-Si by Si-Sn solvent refining, and most metallic impurities (Fe, Al, Ca, and Ti) and non-metal impurities (B and P) were removed. Purified Si crystals were also easily agglomerated and separated from Sn-Si solvent using electromagnetic force.…”

New Insights into Silicon Purification by Alloying–Leaching Refining: A Comparative Study of Mg–Si, Ca–Si, and Ca–Mg–Si Systems

“…Even though it has been theoretically and experimentally confirmed that P tends to segregate along Si grain boundaries, its segregation coefficient ( k p = 0.35) is still relatively high compared to metallic impurities, which is usually less than 10 –3 . To further improve the extraction efficiency of P and other impurities, considerable attention has been paid to redistribute impurities by adding alloying elements as impurity getters such as calcium (Ca), − magnesium (Mg), − titanium (Ti), aluminum (Al), − copper (Cu), − tin (Sn), , iron (Fe), − and nickel (Ni) . The widely known solvent refining usually involves alloying by Al, Sn, Cu, and Fe with a large amount of metal addition (around or more than 50 wt %).…”