多组元硅液中典型杂质组元的热力学性质研究

The thermodynamic properities of typical impurities Fe, Al, Ca, B, P in the multicomponent melted silicon will be studied in this project. The activity interaction coefficients among the typical impurity components in the melted silicon will be determined in experiment by the equilibrium solubility method based on the Si-i binary and Si-i-j ternary systems. The activities, activity coefficients and interaction coefficients of impurity components in the Si-i and Si-i-j systems will be also estimated based on the molecular interaction volume model (MIVM). Then, the relationship between activity coefficient and interaction coefficient will be obtained. The effect of the third component j to the second component i in the melted silicon on the solubility and the activity will be discussed. The thermodynamic properities such as standard dissolved functions, partial molar dissolved functions, excessive functions and mixed functions of components in the melted silicon will be calculated and gained. The interaction characteristics of components in silicon will be studied and the relationships among interaction forces, interaction coefficients and solubilities of impurity components are discussed and obtained. The purpose of this project is to obtain the basic thermodynamic parameters for the multicomponent melted silicon and to supply the theoretical basis to the applied and fundamental study of silicon refining process.

本项目拟进行多组元硅液中Fe、Al、Ca、B、P等典型杂质组元热力学性质的研究。以Si-i二元系和Si-i-j三元系为基础，通过溶解度平衡法测定硅液中典型杂质组元间的活度相互作用系数，并获得组元活度系数与相互作用系数的关系式，研究第3组元j对第2组元i在硅液中溶解度和活度的影响规律。基于分子相互作用体积模型(MIVM)，计算Si-i和Si-i-j体系中典型杂质组元的活度、活度系数与相互作用系数。计算硅液中杂质组元的标准溶解函数、偏摩尔溶解函数、偏摩尔过剩函数及体系混合函数等热力学性质。研究硅液中组元间的相互作用特性，探讨杂质组元溶解对组元间作用力和相互作用系数的影响规律，建立多组元硅液中杂质组元与其热力学性质间的关联特性。旨在获得硅液最基本的热力学参数，为硅精炼过程中的应用基础研究提供热力学依据。

本研究通过采用分子相互作用体积（MIVM）模型、溶解平衡实验对二元和多元硅基熔体中各组元的活度、活度系数、自身活度作用系数、第三组元对第二组元活度相互作用系数、溶解函数、分离系数以及饱和溶解度等热力学性质进行了测定和计算。通过MIVM模型计算分别获得了Si-Fe、Si-Al、Si-P和Si-B二元硅基熔体中杂质组元的活度、活度系数和自身交互作用系数的热力学数据；Si-Fe-B、Si-Al-B和Si-Fe-Al三元硅基熔体中杂质组元的活度以及Fe对B和Al对B的相互作用系数热力学数据；Si-Fe-P、Si-Ca-B和Si-Al-P体系中杂质组元活度、活度相互作用系数以及偏摩尔过量吉布斯自由能和溶解吉布斯自由能等热力学数据；真空精炼过程硅中Zn、Sb、Mg、Mn、Cu、Sn杂质元素的活度系数与蒸发系数、挥发速率、气液相平衡，铝硅合金中铝的分离系数和气液相平衡图，得到了这些数据随温度和元素含量变化的关系。本研究通过共存理论模型计算获得了Si-Fe-P体系和Si-Fe-Ca体系中杂质组元活度相互作用系数和各组元等活度图。另外，本研究还通过溶解平衡实验，测定了Si-Fe-Al、Si-B-Fe、Si-B-Al、Si-P-Fe以及Si-Ca-Al各个体系中组元间的活度相互作用系数，并得到了各溶液中杂质组元分布状态，与计算结果相互验证。这些热力学数据将为工业硅精炼提纯过程的进一步工艺改进和效率提高提供重要的理论基础，具有重要的理论依据。