Electronic and local atomistic structure of MgSiO3 glass under pressure: a study of X-ray Raman scattering at the silicon and magnesium L-edges

• Published in: Physics and chemistry of minerals Vol. 45; no. 2; pp. 211 - 218
• Main Authors: Fukui, Hiroshi, Hiraoka, Nozomu
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2018; Springer Nature B.V
• Subjects: Coordination numbers; Crystallography and Scattering Methods; Earth and Environmental Science; Earth Sciences; Electronic structure; Enstatite; Geochemistry; Glass; Magnesium silicates; Mathematical analysis; Melts; Mineral Resources; Mineralogy; Original Paper; Oxygen; Raman spectra; Silicon; MgSiO; glass; Electronic structure; Short-range structure; X-ray Raman scattering; High pressure
• ISSN: 0342-1791; 1432-2021
• DOI: 10.1007/s00269-017-0909-y

We applied X-ray Raman scattering technique to MgSiO 3 glass, a precursor to magnesium silicate melts, with respect to magnesium and silicon under high-pressure conditions as well as some polycrystalline phases of MgSiO 3 at ambient conditions. We also performed ab initio calculations to interpret the X-ray Raman spectra. Experimentally obtained silicon L -edge spectra indicate that the local environment around silicon started changing at pressure above 10 GPa, where the electronic structure of oxygen is known to change. In contrast, the shape of the magnesium L -edge spectrum changed below 10 GPa. This indicates that the magnesium sites in MgSiO 3 glass first distort and that the local structure around magnesium shows a wide variation under pressure. The framework structure consisting of silicon and oxygen changed above 10 GPa, where the coordination number of silicon was more than four. Our results imply that 6-oxygen-coordinated silicon was formed above 20 GPa.