Physical Chemistry on Low Temperature Solidification Refining of Solar Grade Silicon Using Solvent

通过Cu-Si和Sn-Si合金的定向凝固，研究了优化冷却条件产生块状Si晶体的效果。通过控制两种溶剂的温度梯度和冷却速度可以获得大块硅，并且发现凝固速度受硅在溶剂中的扩散控制。精炼效果不如澄清后的铝硅溶剂和我们之前研究的效果显著。通过对Sn-Si-B体系的热力学测量，澄清了熔体中B的不稳定性，验证了CaO-CaF2-SiO2渣对B的去除效果较好。

By unidirectional solidification of Cu-Si and Sn-Si alloys, optimized cooling condition for producing a bulk Si crystal as well as the refining effect was investigated. Bulk Si was obtained by controlling the temperature gradient and cooling rate for both solvents and the solidification rates were found to be controlled by the diffusion of Si in the solvents. Refining effects were no so significant as that of Al-Si solvent which was clarified and our former research. From the thermodynamic measurement of Sn-Si-B system, instability of B in the melts was clarified and more effective removal of B using CaO-CaF2-SiO2 slag was verified.