Abstract
The electrochemical reduction behavior of stratified SiO2 granules in molten CaCl2 at 1123 K (850 °C) was investigated to develop a new process for producing solar-grade silicon. The cross sections of the electrolyzed electrode prepared from a graphite crucible filled with SiO2 granules were observed and analyzed. The visual and SEM observations indicate that the overall reduction proceeds via two different routes. In one route, the reduction proceeds along the granule surfaces from the SiO2 near the conductor to the distant SiO2. In the other route, the reduction proceeds from the granule surface to the core of each granule. The reduction along the granule surfaces is faster than that from the surface to the core. Fine SiO2 granules are expected to be favorable for a high reduction rate.
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European Photovoltaic Industry Association: Global Market Outlook for Photovoltaics 2013–2017, European Photovoltaic Industry Association, Brussels, May 2013.
Arumu Publishing Co.: Rare Metal News, Arumu Publishing Co., Tokyo, June 16, 2013.
H. Oda: Kogyo Zairyo, 2007, vol. 55, pp. 30-34.
Arumu Publishing Co.: Industrial Rare Metal 2012, vol. 128, Arumu Publishing Co., Tokyo, 2012.
K. Yasuda and T. H. Okabe: JOM, 2010, vol. 62, pp. 94-101.
K. Yasuda, K. Saegusa, and T. H. Okabe: Metall. Mater. Trans. B, 2011, vol. 42B, pp. 37-49.
T. Yoshikawa and K. Morita: JOM, 2012, vol. 64, pp. 946-51.
J. Sanchez, J. Barona, E. Conejero, M. Canle, X. Rel, P. Garcia, and M. Martinez: U.S. Patent, US008168123B2, 2012.
B. G. Gribov and K. V. Zinov’ev: Inorg. Mater. 2003, vol. 39, pp. 653-62.
D. Elwell and R. S. Feigelson: Sol. Energy Mater., 1982, vol. 6, pp. 123-45.
D. Elwell and G. M. Rao: J. Appl. Electrochem., 1988, vol. 18, pp. 15-22.
J. Olson and K. Carleton: J. Electrochem. Soc., 1981, vol. 128, pp. 2698-99.
J. Cai, X. Luo, G. M. Haarberg, O. E. Kongstein, and S. Wang: J. Electrochem. Soc., 2012, vol. 159, pp. D155-58.
T. Nohira, K. Yasuda, and Y. Ito: Nat. Mater., 2003, vol. 2, pp. 397-401.
K. Yasuda, T. Nohira, K. Amezawa, Y. H. Ogata, and Y. Ito: J. Electrochem. Soc., 2005, vol. 152, pp. D69-D74.
K. Yasuda, T. Nohira, Y. H. Ogata, and Y. Ito: Electrochim. Acta, 2005, vol. 51, pp. 561-65.
K. Yasuda, T. Nohira, and Y. Ito: J. Phys. Chem. Solids, 2005, vol. 66, pp. 443-47.
K. Yasuda, T. Nohira, Y. H. Ogata, and Y. Ito: J. Electrochem. Soc., 2005, vol. 152, pp. D208-12.
K. Yasuda, T. Nohira, R. Hagiwara, and Y. H. Ogata: J. Electrochem. Soc., 2007, vol. 154, pp. E95-E101.
K. Yasuda, T. Nohira, R. Hagiwara, and Y. H. Ogata: Electrochim. Acta, 2007, vol. 53, pp. 106-10.
K. Yasuda, T. Nohira, K. Takahashi, R. Hagiwara, and Y. H. Ogata: J. Electrochem. Soc., 2005, vol. 152, pp. D232-37.
W. Xiao, X. Wang, H. Yin, H. Zhu, X. Mao, and D. Wang: RSC Adv., 2012, vol. 2, pp. 7588-93.
X. Jin, P. Gao, D. Wang, X. Hu, and G. Z. Chen: Angew. Chem., 2004, vol. 116, pp. 751-54.
P. C. Pistorius and D. J. Fray: J. S. Afr. Inst. Min. Metall., 2006, vol. 106, pp. 31-41.
W. Xiao, X. Jin, Y. Deng, D. Wang, X. Hu, and G. Z. Chen: ChemPhysChem., 2006, vol. 7, pp. 1750-58.
W. Xiao, X. Jin, Y. Deng, D. Wang, X. Hu, and G. Z. Chen: J. Electroanal. Chem., 2010, vol. 639, pp. 130-40.
S. K. Cho, F. F. Fan, and A. J. Bard: Electrochim. Acta, 2012, vol. 65, pp. 57-63.
Y. Jiang, J. Xu, X. Guan, U.B. Pal, and S.N. Basu: MRS Proc., 2012, vol. 1493, pp 231-35.
T. Oishi, M. Watanabe, K. Koyama, M. Tanaka, and K. Saegusa: J. Electrochem. Soc., 2011, vol. 158, pp. E93-E99.
K. Yasuda, T. Nohira, K. Kobayashi, N. Kani, T. Tsuda, and R. Hagiwara: Energy Technol., 2013, vol. 1, pp. 245-52.
T. Toba, K. Yasuda, T. Nohira, X. Yang, R. Hagiwara, K. Ichitsubo, K. Masuda, and T. Homma: Electrochemistry, 2013, vol. 81, pp. 559-65.
T. Kagami and A. Hayashi: Product and Application of High-purity Silica, CMC Publications, Tokyo, 1991.
Y. Okada and Y. Tokumaru: J. Appl. Phys.,1984, vol. 56, pp. 314-20.
G. L. Pearson and J. Bardeen: Phy. Rev., 1949, vol. 75, pp. 865-83.
Acknowledgments
This study was partly supported by JST-CREST and Grants-in-Aid for Scientific Research A from the Japan Society for the Promotion of Science (JSPS). The authors thank Taiheiyo Cement Corporation for providing high-purity SiO2 granules.
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Manuscript submitted December 13, 2013.
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Yang, X., Yasuda, K., Nohira, T. et al. Reaction Behavior of Stratified SiO2 Granules during Electrochemical Reduction in Molten CaCl2 . Metall Mater Trans B 45, 1337–1344 (2014). https://doi.org/10.1007/s11663-014-0056-5
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DOI: https://doi.org/10.1007/s11663-014-0056-5