Structural Understanding of MnO–SiO2–Al2O3–Ce2O3 Slag via Raman, 27Al NMR and X-ray Photoelectron Spectroscopies

• Published in: Metals and materials international Vol. 26; no. 12; pp. 1872 - 1880
• Main Authors: Kim, Tae Sung, Jeong, Se Ji, Park, Joo Hyun
• Format: Journal Article
• Language: English
• Published: Seoul The Korean Institute of Metals and Materials 01.12.2020; 대한금속·재료학회
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Engineering Thermodynamics; Heat and Mass Transfer; Machines; Magnetic Materials; Magnetism; Manufacturing; Materials Science; Metallic Materials; Processes; Solid Mechanics; 재료공학; Ce; slag or inclusion; Tetrahedron; MnO–SiO; Octahedron; Al NMR spectroscopy; Al; Raman spectroscopy; X-ray photoelectron spectroscopy; O
• ISSN: 1598-9623; 2005-4149
• DOI: 10.1007/s12540-019-00474-1

In order to understand sulfur solubility in the MnO–SiO 2 –Al 2 O 3 –Ce 2 O 3 slag or inclusion system (mol MnO/mol SiO 2  = M/S = 2.2 or 0.9, Al 2 O 3  = 14.2[± 1.8] mol%, Ce 2 O 3  = 0–5.6 mol%), the effect of Ce 3+ ions on the structure of the Mn–aluminosilicate system with different M/S molar ratios has been studied by micro-Raman spectroscopy, solid-state nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Because constant oxygen partial pressure was maintained at p (O 2 ) = 2.8 × 10 −7 atm, oxidation state of Mn and Ce would be in Mn 2+ and Ce 3+ in the MnO–SiO 2 –Al 2 O 3 –Ce 2 O 3 system, which were also confirmed by XPS analysis. Although it was difficult to measure the 27 Al solid-state NMR spectra of the quenched MnO–SiO 2 –Al 2 O 3 system due to the paramagnetic effect, 27 Al NMR spectra did show structural changes in aluminate when cerium was added to the Mn–aluminosilicate melts. Addition of Ce 2 O 3 in the high M/S(= 2.2) system caused both an explosive enhancement in the intensity of Raman bands at 600 cm −1 and a peak shift in 27 Al NMR spectra, indicating the transition from the [AlO 4 ] – :0.5Mn 2+ tetrahedron to a [AlO 6 ] 3– :Ce 3+ octahedron complex due to a strong attraction between aluminate and the cerium ion. XPS spectra show that the transition of the aluminate structure upon introduction of Ce 3+ ions consumes free oxygen in Mn–aluminosilicate melts in high M/S(= 2.2) system. However, the same structural changes were not observed when Ce 2 O 3 was added to lower M/S(= 0.9) system, because Ce 3+ ions primarily interact with the pre-existing [AlO 6 ]-octahedron in low M/S system. Graphic Abstract