The mechanism of solution of aluminum oxide in MgSiO3 perovskite

We report Al-27 and Si-29 Nuclear Magnetic Resonance (NMR) spectra, collected at magnetic fields of 14.1 and 18.8 Tesla on samples as small as 1 mg, for Al-bearing MgSiO3 perovskite synthesized at 26-28 GPa. For Al, we find a 1:1 ratio of two types of sites: a symmetrical, octahedral site and a low symmetry, distorted site that is most likely to be Al in modifications of normally eight-coordinated Mg sites. A charge coupled substitution of 2 Al for one Si and one Mg cation is strongly supported as the predominant mechanism in this pressure range.