^{17}{O} and ^{29}{Si} {NMR} parameters of \mathrm{MgSiO_3} phases from high-resolution solid-state {NMR} spectroscopy and first-principles calculations.

  • Ashbrook S
  • Berry A
  • Frost D
 et al. 
  • 20

    Readers

    Mendeley users who have this article in their library.
  • N/A

    Citations

    Citations of this article.

Abstract

The 29Si and 17O NMR parameters of six polymorphs of MgSiO3 were determined
through a combination of high-resolution solid-state NMR and first-principles
gauge including projector augmented wave (GIPAW) formalism calculations
using periodic boundary conditions. MgSiO3 is an important component
of the Earth's mantle that undergoes structural changes as a function
of pressure and temperature. For the lower pressure polymorphs (ortho-,
clino-, and protoenstatite), all oxygen species in the 17O high-resolution
triple-quantum magic angle spinning (MAS) NMR spectra were resolved
and assigned. These assignments differ from those tentatively suggested
in previous work on the basis of empirical experimental correlations.
The higher pressure polymorphs of MgSiO3 (majorite, akimotoite, and
perovskite) are stabilized at pressures corresponding to the Earth's
transition zone and lower mantle, with perovskite being the major
constituent at depths >660 km. We present the first 17O NMR data
for these materials and confirm previous 29Si work in the literature.
The use of high-resolution multiple-quantum MAS (MQMAS) and satellite-transition
MAS (STMAS) experiments allows us to resolve distinct oxygen species,
and full assignments are suggested. The six polymorphs exhibit a
wide variety of structure types, providing an ideal opportunity to
consider the variation of NMR parameters (both shielding and quadrupolar)
with local structure, including changes in coordination number, local
geometry (bond distances and angles), and bonding. For example, we
find that, although there is a general correlation of increasing
17O chemical shift with increasing Si-O bond length, the shift observed
also depends upon the exact coordination environment.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Authors

  • Sharon E Ashbrook

  • Andrew J Berry

  • Daniel J Frost

  • Alan Gregorovic

  • Chris J Pickard

  • Jennifer E Readman

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free