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

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

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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:	Article
Additional Information:	Bruker BioSpin GmbH ; cml
Uncontrolled Keywords:	2005 AREP 2005 P IA49
Subjects:	03 - Mineral Sciences
Divisions:	03 - Mineral Sciences
Journal or Publication Title:	American Mineralogist
Volume:	90
Page Range:	pp. 1861-1870
Identification Number:	10.2138/am.2005.1915
Depositing User:	Sarah Humbert
Date Deposited:	06 Sep 2011 13:38
Last Modified:	23 Jul 2013 09:58
URI:	http://eprints.esc.cam.ac.uk/id/eprint/1571

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