Effect of the d electrons on phase transitions in transition-metal sesquioxides

Koichiro Umemoto, Renata M Wentzcovitch

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26 Scopus citations


We present a systematic density-functional study of phase relations in three 4d-transition-metal sesquioxides: Y2O3, Rh2O3, and In2O3. Y2O3 and In2O3 undergo pressure-induced transitions to phases with larger cation coordination number (from 6 to 7) at low pressures. However, this does not occur in Rh2O3 at least up tõ 300 GPa. This cannot be explained by usual arguments based on ionic-radii ratios often used successfully to explain phase relations in simple-metal and rare-earth sesquioxides and sesquisulfides. Inspection of their electronic structures shows that, in Rh2O3, the electronic occupancy of 4d orbitals, 4d6, plays a fundamental role in the extraordinary stability of the Rh2O3(II)-type phase with respect to coordination increase. We point out that d-orbital occupancy is a fundamental factor in explaining phase relations in transition-metal sesquioxides and sesquisulfides.

Original languageEnglish (US)
Pages (from-to)387-395
Number of pages9
JournalPhysics and Chemistry of Minerals
Issue number5
StatePublished - May 2011


  • Electronic structure
  • First-principles calculation
  • Phase transition
  • Sesquioxides
  • d-orbital occupancy


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