Local Structure and Transport Characteristics of TiO2-FeO-Al2O3 System with Various FeO Contents Based on Molecular Dynamics Simulations

Local structure of the TiO₂-FeO-Al₂O₃ system was investigated by molecular dynamics simulations to disclose the essential reason for variation of its transport characteristics in this work. [TiO₆] octahedron and [AlO₄] tetrahedron form the skeleton of network structure in the system. There are two different connection ways for both [TiO₆] octahedra and [AlO₄] tetrahedra: corner-sharing and edge-sharing. There is a conversion between corner-sharing polyhedron and edge-sharing polyhedron with the various FeO contents. The conversion between non-bridging oxygen and tri-coordinated oxygen directly determines the complexity degree of structure and even transport characteristics of the system. The sequence of diffusion abilities of different ions is displayed as follows: Fe²⁺ > Al³⁺ > O²⁻ > Ti⁴⁺. The viscosity of the system increases from 0.045 to 0.067 Pa s, as the FeO content decreases from 36 to 4 pct. The model between viscosity and local structural parameter of the system is constructed. The removal of FeO can increase the polymerization degree and the viscosity of the system. The findings will help to establish the theoretical foundation for the green and efficient preparation of high-grade titania slag.