Elemental Interactions and Local Structures in Liquid Sb-As and Sb-Al-As Alloys: Insights from Ab Initio Molecular Dynamics and Experimental Studies on As Aggregation and Diffusion Behaviors

The local structure, element interactions, and electronic structure properties in Sb-As and Sb-Al-As melts were studied using ab initio molecular dynamics (AIMD) simulations. Sb-0.1wt%Al alloy was prepared using vacuum melting, and both pure Sb and Sb-0.1wt%Al alloys were subjected to zone refining experiments to investigate the effect of Al addition on the removal efficiency of impurity As. The results show that in the Sb-Al-As ternary melt, the interaction between Al and As atoms is stronger than the interactions between other solvent atoms. The introduction of Al disrupts the Sb-As and As-As bonds, promoting the formation of Al-As bonds, which alters the state of As atoms in the melt and subsequently affects their diffusion properties. The study elucidates the kinetic process of Al-As bond formation in the melt. The bond-angle distribution function and the coordination polyhedron sequence indicate that with the addition of Al atoms, the geometric configuration around As atoms in the Sb melt and the types and numbers of clusters undergo significant changes. A strong hybridization occurs between the 4p orbitals of As atoms and the 3p orbitals of Al atoms. Moreover, the noticeable charge accumulation between Al and As atoms suggests a strong interaction between them. The addition of aluminum increased the removal rate of arsenic impurities in antimony from 67.27% to 83.24%, significantly enhancing the efficiency of arsenic removal.