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

TY - JOUR

T1 - High pressure structure studies of 6H-SrIrO3 and the octahedral tilting in 3C-SrIrO3 towards a post-perovskite

AU - Kronbo, Camilla H.

AU - Nielsen, Morten Bormann

AU - Kevy, Simone M.

AU - Parisiades, Paraskevas

AU - Bremholm, Martin

PY - 2016/6

Y1 - 2016/6

N2 - 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 03 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.

AB - 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 03 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.

KW - CAIRO3

KW - EQUATIONS

KW - FERROMAGNETISM

KW - High pressure

KW - MGSIO3

KW - NAMGF3 PEROVSKITE

KW - NEUTRON POWDER DIFFRACTION

KW - PHASE-TRANSITION

KW - Perovskite

KW - Polymorphism

KW - Post-perovskite

KW - SINGLE-CRYSTAL

KW - SRIRO3

KW - STATE

KW - SrlrO(3)

UR - http://www.scopus.com/inward/record.url?scp=84960876448&partnerID=8YFLogxK

U2 - 10.1016/j.jssc.2016.03.012

DO - 10.1016/j.jssc.2016.03.012

M3 - Journal article

SN - 0022-4596

VL - 238

SP - 74

EP - 82

JO - Journal of Solid State Chemistry

JF - Journal of Solid State Chemistry

ER -