High pressure structure studies of 6H-SrIrO3 and the octahedral tilting in 3C-SrIrO3 towards a post-perovskite

Camilla H. Kronbo, Morten Bormann Nielsen, Simone M. Kevy, Paraskevas Parisiades, Martin Bremholm*

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

10 Citations (Scopus)

Abstract

The high pressure behaviors of the two perovskite structures (hexagonal 6H-SrIrO 3 and orthorhombic 3C-SrIrO 3) have been studied in diamond anvil cells to 43 and 60 GPa, respectively, using synchrotron powder X-ray diffraction. 6H-SrIrO 3 was first synthesized at ambient pressure and subsequently transformed into 3C-SrIrO 3 in a large volume press at 8.8 GPa and 1000 °C. Both polymorphs were found to retain the initial symmetry up to the highest pressures measured, but in the case of 6H-SrIrO 3, two anomalies were identified: a change in the axial compressibilities at 24 GPa and a change in both the axial and volume compressibilities at 32 GPa. Fitting a 3rd order Birch-Murnaghan equation of state to the obtained P-V data yielded bulk moduli of K 0=151.5(12) GPa (fitted range 0<P<30 GPa) for 6H-SrIrO 3 and K 0=187.1(9) GPa for 3C-SrIrO 3. Analysis of the structural parameters for 6H-SrIrO 3 aided by F-f plots suggests the anomalies are caused by changes in the compression mechanism. Comparison of the two polymorphs reveals that 6H-SrIrO 3 becomes less compressible than 3C-SrIrO 3 above 32 GPa as a result of the mechanistic change, and a crossing of their P-V curves is avoided. For 3C-SrIrO 3, analysis of the octahedral tilt angles shows that these increase monotonically from the ambient value of 7.23(6) to 23.0(2)° at 60 GPa suggesting that a transition to a post-perovskite is approached.

Original languageEnglish
JournalJournal of Solid State Chemistry
Volume238
Pages (from-to)74-82
Number of pages9
ISSN0022-4596
DOIs
Publication statusPublished - Jun 2016

Keywords

  • CAIRO3
  • EQUATIONS
  • FERROMAGNETISM
  • High pressure
  • MGSIO3
  • NAMGF3 PEROVSKITE
  • NEUTRON POWDER DIFFRACTION
  • PHASE-TRANSITION
  • Perovskite
  • Polymorphism
  • Post-perovskite
  • SINGLE-CRYSTAL
  • SRIRO3
  • STATE
  • SrlrO(3)

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