Experimental Determination Of The Activity Interaction Coefficients Of Fe, Al, B, Ca And Ti Components In Silicon Melt

The thermodynamic properties of alloys are the theoretical basis for production applications and are one of the factors that contribute to the differences in the microstructure and properties of materials.They have important theoretical and practical values.Therefore,it is necessary to carry out experimental thermodynamic measurements of the alloy to provide reliable thermodynamic data and provide reliable data support for the raw materials of the solar cell front end.As raw material polysilicon in the photovoltaic industry,the market demand is also growing.At this stage,semiconductor-grade polysilicon has high manufacturing costs for photovoltaic solar cells.Due to these drawbacks,the current metallurgical process has low cost,short cycle,and low investment.The advantages of less environmental pollution are considered to be the most popular method for obtaining solar grade polysilicon.The key challenge of this process is the removal of impurities B,Fe,Ca,Al,and Ti in the metallurgical grade silicon.Therefore,the experimental determination of the thermodynamic properties of the impurity components B,Fe,Ca,Al,Ti in the silicon is obtained and related The thermodynamic data provide reliable thermodynamic data support for the metallurgical purification process.In this paper,the activity co-efficients of B,Fe,Ca,Al and Ti impurity components in silicon melt were determined by the same activity method and the same concentration method.The Si-Fe-Al was measured at 1663 K and 1673 K.The experimental measurements were performed using the same activity method at 1693 K,1723 K,and 1753 K.The measured values(?FeAl)were-4.502,-2.627,-0,689,0.0310,-0.3602,respectively.In the temperature range of 1663-1753K,the expression of the interaction coefficient of temperature and activity was obtained as.The SEM-EDS,EPMA,and XRD were used to characterize and verify the reliability of the determination results,and crystallographic data of related phases were obtained.At 1723 K,the activity of the ternary Si-B-Fe and Si-B-Al was measured by the same concentration method.The temperature was kept at the specific temperature for 5,7,9 and 11 h.The samples were quenched at high temperature and the samples were processed and characterized by ICP,SEM-EDS,EPMA and XRD.The verification demonstrated that the reliability of the activity interaction coefficient of each component was measured by this method,and the measured values(?BFe,?BAl)were 2.7076,9.8287,respectively.The quaternary Si-Fe-Ca-Al and Si-Fe-Ti-Al were measured by the same concentration method;the samples were incubated at a specific temperature for 5,7,9 and 11 h;and the sample was quenched at high temperature.Processing,ICP,SEM-EDS,EPMA,XRD and other detection methods to characterize.The verification shows that the reliability of the activity interaction coefficient of each component is measured by this method.In the Si-Fe-Ca-Al system,and the measurement result of the activity interaction coefficient(?FeAl,?FeCa)are-6.7,-4.6,respectively.Measurement results of the activity interaction coefficient(?FeAl,?FeTi)were 51.046 and 2.827 in the Si-Fe-Ti-Al system,respectively.It lays the foundation for studying the thermodynamic properties of multi-component silicon-based melts...