High-resolution 17O MAS NMR spectroscopy of forsterite (alpha-Mg2SiO4) wadsleyite (beta-Mg2SiO4), and ringwoodite (gamma-Mg2SiO4)

Ashbrook, S.E., Berry, A.J., Hibberson, W.O., Steuernagel, S. and Wimperis, S. (2005) High-resolution 17O MAS NMR spectroscopy of forsterite (alpha-Mg2SiO4) wadsleyite (beta-Mg2SiO4), and ringwoodite (gamma-Mg2SiO4). American Mineralogist, 90(11-12), pp. 1861-1870. (doi: 10.2138/am.2005.1915)

Abstract

The high sensitivity of the satellite-transition (ST) MAS NMR technique was exploited to obtain high-resolution 17O MAS NMR spectra of the three polymorphs of Mg2SiO4: forsterite ({alpha}-Mg2SiO4), wadsleyite (ß-Mg2SiO4), and ringwoodite ({gamma}-Mg2SiO4). High NMR sensitivity was important in this application because 17O-enriched, Fe-free materials are required for 17O NMR and high-pressure syntheses of the dense ß and {gamma} polymorphs result in a only a few milligrams of these solids. In all, eight distinct O species were identified and assigned: three in forsterite, four in wadsleyite, and one in ringwoodite, in agreement with the number of O sites in their crystal structures. The isotropic chemical shifts extracted are in excellent agreement with a previously published correlation with Si-O bond length. However, unexpectedly large quadrupolar coupling constants were found for the non-bridging O species in the dense polymorphs wadsleyite and ringwoodite.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Wimperis, Professor Stephen
• Authors: Ashbrook, S.E., Berry, A.J., Hibberson, W.O., Steuernagel, S., and Wimperis, S.
• Subjects: Q Science > QD Chemistry
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: American Mineralogist
• ISSN: 0003-004X
• ISSN (Online): 1945-3027