Model Calculation Of Thermodynamic Properties Of Al And Ca Components In Silicon Melt

At present, an expensive semiconductor grade silicon (SEG-Si) is used for solar cell to convert solar energy into electricity. However, the amount of SEG-Si for so lar cell supply is limited and we have to develop an innovative process for silicon production with low energy consumption in order to spread the solar cell system widely. Using relatively inexpensive metallurgical grade silicon (MG-Si) as a startin g material for solar grade silicon (SOG-Si) is believed to be a promising way to produce inexpensive solar cell. But the promotion of efficiency in Al, Ca removal is one of the crucial matter in the metallurgical Si refining process. For optimizatio n or design of the impurity removal from Si, knowledge of the thermodynamic pr operty of Al, Ca in molten Si will be necessary to perform deeply analyses of ref ining techniques.In this paper, the molecular interaction volume model (MIVM) was used for a calculation of the thermodynamic properties of impurity components in dilute Si-based binary melts. The activities and activity coefficients of Si, Al, Ca, Pb are predicted by MIVM in Si-Al, Si-Ca, Al-Ca and Al-Pb binary alloys in a range o f temperature. Meanwhile, the activties and activity coefficients of Si, Ca, Pb are calculated by the Kuo-chih Chou’s method using phase diagrams. The calculated values are presented graphically and evaluated with the reported experiment data i n the literatures, which shows that the prediction effect of the Tao’s model is of stability and reliability. Furthermore, the method of MIVM is able to expand to a multicomponent Si-based melts.Otherwise, the MIVM was also used for a calculation of the properties of i mpurity components in Si-Ca-Pb and Si-Al-Pb ternary alloys and Si-Al-Ca-Pb quat ernary alloy. The calculation of self-interaction parameters of Al and Ca and inter action parameter between Al and Ca in dilute silicon melts at 1723K were obtai ned by the use of MIVM, the iso-activity curves of Si, Al and Ca at 1723K w ere obtained. Meanwhile, The vapor-liquid phase equilibrium of Si-Al, Si-Ca and Si-Al-Ca are predicted base on MIVM, it is meaningful for conducting the silicon vacuum refinning.