Aluminum substitution in MgSiO3 perovskite: Investigation of multiple mechanisms by 27Al NMR

Jonathan F. Stebbins, Hiroshi Kojitani, Masaki Akaogi, Alexandra Navrotsky

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

In the Earth's mantle, the mechanism(s) of solid solution of Al in MgSiO3 perovskite strongly impacts its thermodynamic and transport properties. We present 27Al NMR data for perovskite samples of nominal composition Mg(Si0.9Al0.1 O2.95, to test a mechanism by which Al3+ substitutes at the octahedral Si4+ sites, leaving a corresponding number of O-site vacancies. We find evidence for this process in a significantly greater peak area for Al at B (Si) sites vs. A (Mg) sites in the structure, and the possible identification of a small concentration of five-coordinated Al adjacent to such vacancies. However, substitution of Al3+ at the A sites remains significant. As in perovskite-type technological ceramics, O-atom vacancies may play an important role in enhancing ion mobility and the dissolution of water.

Original languageEnglish (US)
Pages (from-to)1161-1164
Number of pages4
JournalAmerican Mineralogist
Volume88
Issue number7
DOIs
StatePublished - Jul 2003
Externally publishedYes

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

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