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FeO and Fe2O3 represent similar but different effects on the structure and properties of aluminosilicate system. Molecular dynamics was conducted to clarify the influences of FeO and Fe2O3 on the structure and properties of SiO2-CaO-Al2O3-FeO (Fe2O3) systems. The bond length and coordination number (CNs) of Si-O bond are almost not affected by FeO (Fe2O3), but FeO and Fe2O3 have opposite effects on the CNs of Al-O bond. The more the Fe3+ ion is, the closer the CN is to 4. The ability of Fe3+ ions to reduce bridging oxygen (BO) is greater than that of Fe2+ ions, while non-bridging oxygen (NBO) and free oxygen (FO) show an opposite trend. In the same way, the influence of Fe atomic numbers of different valence on BO, NBO and FO is similar to that of FeO (Fe2O3) on BO, NBO and FO. The total diffusion coefficient and viscosity of the system increase with the addition of iron oxide. [ABSTRACT FROM AUTHOR]

Polymerization degree theory and traditional charge compensation theory are the most fundamental principles to understand the structure and properties of oxide melts. It can well explain the behavior characteristics of acidic oxides and basic oxides in a melt. However, the amphoteric behavior of oxides cannot be explained well by these two theories. Herein, the octahedral connection mode and the behavior of the amphoteric transition of TiO 2 are analyzed by molecular dynamics simulation, and then, a calculation model which can quantitatively calculate the amphoteric transition of the oxide is established by analyzing a large number of data. On the basis of the model, a novel theory of supply and demand is put forward, which can explain the amphoteric transition behavior of oxides very well. To a great extent, the supply and demand theory makes up for the deficiency of the atomic structure theory of oxide melts and provides mechanism explanation and model prediction for the oxide amphoteric transformation behavior., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)