Total understanding of the local structures of an amorphous slag: Perspective from multi-nuclear (29Si, 27Al, 17O, 25Mg, and 43Ca) solid-state NMR

Detailed Structure Elucidation of the Blast Furnace Slag by Molecular Dynamics Simulation

“…The interesting finding is that SiO 4 tetrahedra tend to stay in more depolymerized units than AlO 4 . Such a tendency is also supported by our 29 Si and 27 Al NMR study, 29) another 17 O NMR study for CaO-Al 2 O 3 -SiO 2 glasses, 32) and MD simulations. 33) These consistencies between the present simulation and NMR results as well as X-ray diffraction strongly suggest the validity of the applied potential parameters, because the solid state NMR spectroscopy is the most effective method to elucidate the local environments on each atomic species constituting the glassy material.…”

“…28,29) The interconnections between the tetrahedral and nontetrahedral cations, i.e., Mg-Si, Mg-Al, Ca-Si, and Ca-Al pairs show a doublet-like peak at 2.5-4.5 Å, suggesting their edge-sharing (2.8-3.1 Å) and corner-sharing (3.3-3.6 Å) fashions of the polyhedra, respectively (Figures 1(h), 1(i), 1(l), and 1(m)). Mg-(Si,Al) show a tendency to corner-sharing compared with Ca-(Si,Al), and in turn, (Mg,Ca)-Si show a tendency to corner-sharing compared .…”

Recent Advances in Solid-State 25Mg NMR Spectroscopy

“…9,18 The condition n 1 (n q is satisfied for most usual probes, since the RF strength n 1 is typically well below n q value for a low-g nucleus such as 25 Mg. In the cases where more RF power is required, as it is typically the case of MQMAS and related experiments, the use of probes especially designed to attain high RF power levels and appropriate tuning at the low 25 Mg NMR frequency has been reported. 37,[42][43][44] Typical commercial probes used for MAS experiments are equipped with rotors having diameters in the range 2.5-7mm, which allows spinning speeds up to 45kHz. This value is sufficient in many cases for attaining the maximum possible narrowing of the second-order quadrupolar broadened CT in 25 Mg NMR spectra recorded at strong magnetic Δf d 0 Figure 3 Definition of the parameters d 0 (shift of the most intense peak) and Df (total breadth), in the 25 fields.…”

“…Besides the use of large volume samples, there are also other ''brute force'' approaches frequently used since the earlier reports of solid-state 25 Mg NMR, including isotopic enrichment and the use of magnetic fields as strong as possible. 6,37,39,42,43,[45][46][47][48][49][50][51][52] There is no doubt that the increase in the number of reports involving solid-state 25 Mg NMR has been driven by the wider availability of high-field magnets (e.g. !14.1T).…”

“…42 Amorphous slags-which are by-products of iron-and steel-making processes-constitute another example of Mg-containing glassy materials studied using 25 fields. 37,43 In a first work, two slag samples containing 25 Mg at natural abundance were investigated at 16.4T in comparison to model compounds, showing the presence of Mg species other than MgO and Mg (OH) 2 . 37 More recently, a multinuclear study combining 17 O, 25 Mg, 27 Al, 29 Si and 43 Ca NMR in a synthetic model slag enriched in 17 O, 25 Mg and 43 Ca was carried out.…”