Effect of Ce 2 O 3 on microscopic structure of CaF 2 -CaO-Al 2 O 3 slag with molecular dynamics simulation

Abstract

Molecular dynamics simulations were used to investigate the structural evolution of Ce₂O₃-CaF₂-CaO-Al₂O₃ slag with Ce₂O₃ content ranging from 0 wt% to 16 wt% at 1873 K. The results show that increasing Ce₂O₃ content leads to a shift in the role of F⁻ from network former to modifier, as Ce³⁺ ions replace F⁻ with O²⁻ in [AlO₃F]⁴⁻ units. Slag polymerisation increases up to 12 wt% Ce₂O₃, as evidenced by an increase in bridging oxygen from 30·8% to 39·2% and a rise in complex Q³+Q⁴ units from 18·1% to 43·4%. However, at 16 wt%, excess O²⁻ ions disrupt the network, leading to depolymerisation. Consequently, the viscosity was calculated from diffusion coefficients derived from mean square displacement analysis. It exhibits a non-monotonic trend, increasing with Ce₂O₃ content up to 12 wt% and decreasing at 16 wt%. This study highlights the effect of Ce₂O₃ on slag structure and diffusion, providing insights for optimising Electroslag Remelting slag design. The simulation framework can be extended to other rare earth-modified slags and combined with experiments to further validate the polymerisation-depolymerisation mechanism.