201. Removal of Boron from Silicon-Tin Solvent by Slag Treatment
- Author
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Kazuki Morita, Xiaodong Ma, and Takeshi Yoshikawa
- Subjects
Activity coefficient ,Materials science ,Alloy ,Metallurgy ,Inorganic chemistry ,Metals and Alloys ,Slag ,chemistry.chemical_element ,Partial pressure ,engineering.material ,Condensed Matter Physics ,Solvent ,Partition coefficient ,chemistry ,Mechanics of Materials ,visual_art ,Materials Chemistry ,engineering ,visual_art.visual_art_medium ,Chemical equilibrium ,Boron - Abstract
To eliminate B effectively from Si for its use in a solar cell, a novel process involving the slag refining of molten Si with Sn addition was investigated. The partition ratio of B between CaO-SiO2-24 mol pct CaF2 slag and Si-Sn alloy at 1673 K (1400 °C) was determined by the chemical equilibrium technique. It was found that the partition ratio of B was remarkably increased with the increase in Sn content of alloy, which attributes to the increase in activity coefficient of B as well as the oxygen partial pressure. The partition function was accounted as much as 200 when the alloy composition was Si-82.4 mol pct Sn, which was much higher than the reported values in the range of 1 to 3. The required amounts of slag used for B removal from Si-30, 50, and 70 mol pct Sn melts were only 15.6 pct, 6.5 pct, and 1.2 pct of that used for the removal of B directly from MG-Si without Sn addition in a single slag treatment. more...
- Published
- 2013
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