The high-pressure phase of alumina and implications for Earth's D″ layer

Artem R. Oganov, Shigeaki Ono

Research output: Contribution to journalArticlepeer-review

110 Citations (Scopus)

Abstract

Using ab initio simulations and high-pressure experiments in a diamond anvil cell, we show that alumina (AI2O3) adopts the CalrO3-type structure above 130 GPa. This finding substantially changes the picture of high-pressure behavior of alumina; in particular, we find that perovskite structure is never stable for Al2O3 at zero Kelvin. The CalrOa-type phase suggests a reinterpretation of previous shock-wave experiments and has important implications for the use of alumina as a window material in shock-wave experiments. In particular, the conditions of the stability of this phase correspond to those at which shock-wave experiments indicated an increase of the electrical conductivity. If this increase is caused by high ionic mobility in the CalrO3-type phase of AI 2O3, similar effect can be expected in the isostructural postperovskite phase of MgSiO3 (which is the dominant mineral phase in the Earth's D" layer). The effect of the incorporation of Al on the perovskite/postperovskite transition of MgSiO3 is discussed.

Original languageEnglish
Pages (from-to)10828-10831
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume102
Issue number31
DOIs
Publication statusPublished - 2 Aug 2005
Externally publishedYes

Keywords

  • Ab initio
  • AlO
  • CalrO type
  • Density-functional perturbation theory
  • Phase diagram

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