Unraveling the nano-structure of a glassy CaO-FeO-SiO2 slag by molecular dynamics simulations

C Siakati and R Macchieraldo and B Kirchner and F Tielens and A Peys and D Seveno and Y Pontikes, JOURNAL OF NON-CRYSTALLINE SOLIDS, 528, 119771 (2020).

DOI: 10.1016/j.jnoncrysol.2019.119771

Non-ferrous metallurgy slags are gaining significant interest as a resource in the production of alternative low-energy cementitious materials. Their atomistic structures, however, are still not fully understood due to their glassy nature. In the work presented herein, a comprehensive description of the nano-structure of a CaO-FeO-SiO2 slag was obtained by using molecular dynamic simulations in conjunction with previously obtained experimental data from X-ray and neutron pair distribution function studies. Iron was predominately 4- and 5-fold coordinated with oxygen, forming polyhedra in tetrahedral and pyramidal/triangular bipyramidal configuration. The FeOx polyhedra were corner-shared to the silica tetrahedra, while the higher coordinated fractions (x = 5 or 6) seemed to prefer to be next to each other, sharing edges. Ca was mostly surrounded by 6 or 7 oxygens in polyhedra that are predominantly edge-sharing with other units. The obtained results fit the experimental data well and as such provide an accurate and realistic picture of the iron-rich slag structure.

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