Electrochemically driven three-phase interlines into insulator compounds: electroreduction of solid SiO2 in molten CaCl2.
Electrochemically driven three-phase interlines into insulator compounds: electroreduction of solid SiO2 in molten CaCl2.
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DOI：
10.1002/cphc.200600149
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发表时间：
2006-08
期刊：
影响因子：
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通讯作者：
Wei Xiao;Xianbo Jin;Yuan Deng;Dihua Wang;Xiaohong Hu;G. Chen
中科院分区：
文献类型：
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作者：
Wei Xiao;Xianbo Jin;Yuan Deng;Dihua Wang;Xiaohong Hu;G. Chen
研究了1173K下，固体SiO_2(石英)在CaCl2熔体中电化学还原为Si的过程，实验结果与一种新的与动态导体-绝缘体-电解液三相界面电化学模型相一致。结果表明，在一定的电势下，圆柱形石英球的还原主要由O(2-)离子的扩散和还原生成的多孔硅层中的欧姆极化决定。还原速率随着过电位的增加而增加，在过电位达到最大值后，还原过程被延缓，这很可能是由于CaO在反应区域中的析出(阴极钝化)。报道了恒电位条件下石英电还原的还原速度、电流效率和能耗的数据。这些理论和实验结果为深入讨论生产硅的电还原方法的优化奠定了基础。
The electrochemical reduction of solid SiO2 (quartz) to Si is studied in molten CaCl2 at 1173 K. Experimental observations are compared and agree well with a novel penetration model in relation with electrochemistry at the dynamic conductor|insulator|electrolyte three-phase interlines. The findings show that the reduction of a cylindrical quartz pellet at certain potentials is mainly determined by the diffusion of the O(2-) ions and also the ohmic polarisation in the reduction-generated porous silicon layer. The reduction rate increases with the overpotential to a maximum after which the process is retarded, most likely due to precipitation of CaO in the reaction region (cathodic passivation). Data are reported on the reduction rate, current efficiency and energy consumption during the electroreduction of quartz under potentiostatic conditions. These theoretical and experimental findings form the basis for an in-depth discussion on the optimisation of the electroreduction method for the production of silicon.