中文摘要：

杂质元素硼的去除是当前冶金法制备太阳能级硅技术中最重要的环节之一．本文研究了氧气精炼去除冶金级硅中杂质元素的热力学行为，通过氧化物标准生成吉布斯自由能，明确了Fe、Al、Ca、Cu、V、Ti、C、B、P等杂质氧化去除的难易程度，通过BO、B2O2、B2O3、BO2、B2O等气态硼氧化物热力学的研究，获得了平衡时硅中硼质量分数与硼气态氧化物平衡分压的关系．结果显示：BO的挥发性最大，1750℃时，将冶金级硅中的杂质硼从5×10^-6降低至0．1×10^-6，体系内BO的平衡分压将从2．5Pa降低至0．05Pa，由此可知：氧气精炼时冶金级硅中的杂质硼主要以BO的形式挥发，且提高精炼温度更有利于硼的去除．

英文摘要：

Boron removal is one of the most important steps for metallurgical method in preparing solar grade silicon. The thermodynamic behavior of impurities in metallurgical grade silicon was studied using 02 gas blowing. The order of difficulties for impurities removal was confirmed through the standard Gibbs free energy of formation. The relationships between the boron content in silicon and the equilibrium partial pressure of gaseous boron species were obtained through the thermodynamic calculation. Results show that it is the most for the volatility of BO and the equilibrium partial pressure for BO is reduced from 2.5 Pa to0.05 Pa at 1 750℃ when the boron content in silicon decreases from5 ×10^-6 to0. 1 ×10^-6 It was presumed that the gaseous species BO is the main form for boron volatility from metallurgical grade silicon melt and it is helpful for boron removal with higher refining temperature using 02 blowing.