Coordination evolution and stability of Al3+in Al2O3-rich melts: Modulated by alkaline oxide type (M=Ca, Mg, Fe) and MO/Al2O3 ratio

HH Zhou and J Guo and S Zhang and Y Hou and XW Lv, JOURNAL OF NON- CRYSTALLINE SOLIDS, 669, 123808 (2025).

DOI: 10.1016/j.jnoncrysol.2025.123808

As an amphoteric oxide, the structural behavior of Al2O3 in aluminosilicate melts is complex. Current understanding of the coordination structure of Al3+ in different alkaline oxide environments remains limited. This study employed molecular dynamics simulations to investigate the coordination structure and stability of Al3+ in MO- SiO2-Al2O3 melts with different alkaline oxide types (CaO, MgO, FeO) and concentrations (MO/ Al2O3=0.25-3). The results indicate that different alkaline oxides exhibit varying capabilities in achieving charge compensation balance for Al3+: CaO/Al2O3=0.5 for Ca2+ and FeO/Al2O3=1.0 for Fe2+, whereas Mg2+ cannot achieve charge balance even at MgO/Al2O3 ratio exceeding 3.0. Kinetic lifetime analysis reveals that only tetrahedrally coordinated SiO4 and AlO4 exhibits significant structural persistence. Oxygen linkage analysis shows that Si-O-Si structures possess the highest persistence, substantially exceeding Si- O-Al and Al-O-Al structures. These results fundamentally elucidate the structural behavior of Al3+ in different alkaline environments and their implications for regulating the properties of high-Al2O3 aluminosilicate melts.

Return to Publications page