Ab initio molecular dynamics simulation is introduced as an important method to study the microstructure of disordered systems. From the microscopic perspective that cannot be measured by experiments such as electronic structure properties and interatomic interaction, the reaction mechanism of industrial silicon slagging refining (CaO-SiO2) and oxygen blowing refining process is studied, providing a new idea for optimizing the purification process, thus promoting the wide application and further development of photovoltaic technology. It is studied that the Si supercell doped with O has a very strong interaction with Ca and Al, and they form Ca-O bond and Al-O bond respectively. The B-O interaction also has a strong interaction with the increase of temperature, but the interaction between Fe-O and P-O is weak. It is also found that the interaction between impurity atoms and oxygen atoms is stronger at 1823K than at 1723K. The results before and after dynamic simulation show that although the direct removal of P by Si subcellular doping with O is very poor, the P-P bond is generated in the later period, indicating that P will be removed in the form of P2 during the refining process. The diffusion coefficients of impurity atoms can be obtained according to the root mean square shift. The results show that the diffusion coefficients of metal impurities Fe, Al, Ca are greater than those of non-metallic impurities B and P, and the diffusion coefficients of impurity atoms at 1823K are generally greater than those at 1723K. At the same time, the mechanism of removing B and P from industrial silicon slagging (CaO-SiO2) was investigated. It was found that B and P could interact with CaO-SiO2 and generate corresponding acid radical ions BO33- and PO43-. The diffusion coefficients of BO33- and PO43- in Cao-SiO2 slag system at 1823K were calculated.

Ab initio molecular dynamics simulation of oxygen blowing and slagging refining processes in industrial silicon

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