Molecular Dynamics Analysis of the Structural Behavior of Aluminum Ion in the Slag of CaO–SiO2–Al2O3–Li2O System

In the study of CaO–SiO 2 –Al 2 O 3 –Li 2 O system slag, molecular dynamics simulations are performed to analyze the behavior of Al 3+ at different alkalinities. The results show that the AlO bond length increases with increasing alkalinity and is unstable compared to the SiO bond. The [AlO 4 ] 5− tetrahedra are less stable than the [SiO 4 ] 4− tetrahedra. The higher the alkalinity, the shorter the AlO bonds and the longer the CaO bonds, thus destroying the aluminum‐oxygen ionophore. Increasing alkalinity converts complex structures into simpler ones, such as AlOAl, bringing the OAlO bond angles closer to the ideal tetrahedron. Reduced slag polymerization increases the distance between neighboring [AlO 4 ] 5− tetrahedra, thereby increasing the AlOAl bond angles. The [SiO 4 ] 4− tetrahedra prefer to bond with the [AlO 4 ] 5− tetrahedra. The change in SiOAl is less than that of SiOSi. The dissociation of CaO provides the O 2− , which allows the depolymerization of SiOSi to form nonbridging oxygen SiO, whereas the depolymerization of SiOAl occurs when alkalinity is sufficient to form the SiO and AlO bonds. The [AlO 4 ] 5− tetrahedra are more likely to bond with [AlO 4 ] 5− tetrahedra than [AlO 4 ] 5− tetrahedra.