Composition-structure-property relationships in SiO2-Al2O3-Fe2O3- MgO glasses derived from coal gangue: A molecular dynamics study

LH Ren and WQ Li and YX Niu and ZF Yang and Y Dong and J Shen and YY Meng, COMPUTATIONAL MATERIALS SCIENCE, 260, 114254 (2025).

DOI: 10.1016/j.commatsci.2025.114254

This study investigates the approach of producing high-performance glasses from coal gangue, using MgO as a modifying agent, and performs molecular dynamics simulations on the SiO2-Al2O3-Fe2O3-MgO system to elucidate the relationships among composition, structure, and properties. The results show that Si-O and Al-O local structures are relatively stable, with their coordination numbers approaching four and leveling off at a clear plateau. By contrast, Fe3+, owing to its diverse coordination environments, displays no comparable stabilization. Analysis of oxygen species suggests that increasing the Si/Al ratio is associated with a higher fraction of bridging oxygen (BO) and non- bridging oxygen (NBO), In contrast the fraction of tribridging oxygen (TBO) tends to decrease, which appears alongside a general reduction in network connectivity. Conversely, increasing the Fe2O3 content decreases the fractions of Si-O-Si and Si-O-Al bonds, increases Fe3+-associated bridging bonds, raises TBO, and either decreases or maintains network connectivity. Mg2+ primarily provides charge compensation for AlO4- units, thereby mitigating depolymerization. Regarding mechanical properties, increasing Fe2O3 reduces the elastic modulus, while higher Si/Al ratios are associated with a slight decreasing trend. Overall, maintaining Fe2O3 at low to moderate levels (similar to 2-3.5 wt%) and the Si/Al ratio within a moderate range (similar to 2-2.5) is favorable for optimizing network connectivity and glass formability at a given MgO content. This study provides molecular-level evidence to guide the optimization of coal gangue glass compositions.

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