Molecular structure of CaO–FeOx–SiO2 glassy slags and resultant inorganic polymer binders |
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Authors: | Arne Peys Claire E White Daniel Olds Hubert Rahier Bart Blanpain Yiannis Pontikes |
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Affiliation: | 1. KU Leuven Department of Materials Engineering, Leuven, Belgium;2. Department of Civil and Environmental Engineering, Andlinger Center for Energy and the Environment, Princeton University, Princeton, New Jersey;3. Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee;4. Department of Materials and Chemistry, Vrije Universiteit Brussel, Brussels, Belgium |
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Abstract: | The molecular structures of CaO–FeOx–SiO2 slags and their inorganic polymer counterparts were determined using neutron and X‐ray scattering with subsequent pair distribution function (PDF) analysis. The slags were synthesized with approximate molar compositions: 0.17CaO–0.83FeO–SiO2 and 0.33CaO–0.67FeO–SiO2 (referred to as low‐Ca and high‐Ca, respectively). The PDF data on the slags reasserted the predominantly glassy nature of this iron‐rich industrial byproduct. The dominant metal‐metal correlation was Fe–Si (3.20‐3.25 Å), with smaller contributions from Fe–Ca (3.45‐3.50 Å) and Fe–Fe (2.95‐3.00 Å). After inorganic polymer synthesis, a rise in the amount of Fe3+ was observed via the shift of the Fe–O bond length to shorter distances. This shortening of the Fe–O distance in the binder is also evidenced by the apparent rise of the Fe–Fe correlation at 2.95‐3.00 Å, although this feature may also suggest a potential aggregation of FeOx clusters. In general, the atomic arrangements of the reaction product was shown to be very similar to the precursor structure and the dominance of the Fe–Si correlation suggests the participation of Fe in the silicate network. The binder was shown to be glassy, as no distinct atom‐atom correlations were observed beyond 8 Å. |
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Keywords: | alkali‐activated materials inorganic polymers iron silicate pair distribution function analysis silicate glass |
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