Physics and Chemistry of Minerals

, Volume 35, Issue 7, pp 381–386

First-principles simulation of high-pressure polymorphs in MgAl2O4

Original Paper

DOI: 10.1007/s00269-008-0231-9

Cite this article as:
Ono, S., Brodholt, J.P. & Price, G.D. Phys Chem Minerals (2008) 35: 381. doi:10.1007/s00269-008-0231-9

Abstract

We have used density functional theory to investigate the stability of MgAl2O4 polymorphs under pressure. Our results can reasonably explain the transition sequence of MgAl2O4 polymorphs observed in previous experiments. The spinel phase (stable at ambient conditions) dissociates into periclase and corundum at 14 GPa. With increasing pressure, a phase change from the two oxides to a calcium-ferrite phase occurs, and finally transforms to a calcium-titanate phase at 68 GPa. The calcium-titanate phase is stable up to at least 150 GPa, and we did not observe a stability field for a hexagonal phase or periclase + Rh2O3(II)-type Al2O3. The bulk moduli of the phases calculated in this study are in good agreement with those measured in high-pressure experiments. Our results differ from those of a previous study using similar methods. We attribute this inconsistency to an incomplete optimization of a cell shape and ionic positions at high pressures in the previous calculations.

Keywords

MgAl2O4 phasesAb initio calculationsPhase transitionEquation of stateHigh pressure

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Shigeaki Ono
    • 1
    • 2
  • John P. Brodholt
    • 1
  • G. David Price
    • 1
  1. 1.Department of Earth SciencesUniversity College LondonLondonUK
  2. 2.Institute for Research on Earth EvolutionJapan Agency for Marine-Earth Science and TechnologyYokosukaJapan