• journal_title：American Mineralogist
• Contributor：Jonathan F. Stebbins ; Hiroshi Kojitani ; Masaki Akaogi ; Alexandra Navrotsky
• Publisher：Mineralogical Society of America
• Date：2003-
• Format：text/html
• Language：en
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：88
• issue：7
• firstpage：1161
• section：Letters

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(Si_0.9Al_0.1)O_2.95, 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.