Multi-mbar phase transitions in minerals

Koichiro Umemoto, Renata M. Wentzcovitch

Research output: Chapter in Book/Report/Conference proceedingChapter

7 Scopus citations


Two post-post-perovskite transitions have been identified by first principles calculations: the dissociation of MgSiO3 into CsCl-type MgO and cotunnite-type SiO2 at ∼1 TPa and the transition Of Al2O3 to the U2S3-type phase at -370 GPa. These transition pressures are currently very challenging for static compression experiments. NaMgF3 may be a good low-pressure analog of MgSiO3. We found a close relationship between the multi-Mbar crystal chemistry of planet-forming minerals and that of rare-earth sesquisulfides. Some of them may be used as low-pressure analogs of planet-forming minerals in the multi-Mbar range. In transitionmetal sesquioxides, the Th2S 3-type phase (very similar to U2S3-type) was discovered in Ti2O3, suggesting that some transition-metal sesquioxides could serve as low-pressure analog(s) of Al2O 3. Finally, a new type of dissociation, FeTiO3 perovskite into (Fe1,δTiδ)O and Fe1+ 7 delta;Ti2-delta;O5, has recently been reported (Wu et al. 2009). This finding suggests that solid solutions (probably with transition-metals) among dissociation products (and in parent phases) could complicate the transition mechanisms we have discussed in this chapter.

Original languageEnglish (US)
Title of host publicationTheoretical and Computational Methods in Mineral Physics
Subtitle of host publicationGeophysical Applications
EditorsRenata Wentzcovitch, Larz Stixrude
Number of pages16
StatePublished - 2010

Publication series

NameReviews in Mineralogy and Geochemistry
ISSN (Print)1529-6466


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