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GEOPHYSICAL RESEARCH LETTERS, VOL. 33, L12302, doi:10.1029/2005GL025001, 2006

Crystal morphology and dislocation microstructures of CaIrO3: A TEM study of an analogue of the MgSiO3 post-perovskite phase

Nobuyoshi Miyajima

Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan


Kenya Ohgushi

Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan


Masaki Ichihara

Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan


Takehiko Yagi

Institute for Solid State Physics, University of Tokyo, Kashiwa, Japan


Abstract

Polycrystalline CaIrO3 phase, synthesized in a cubic-anvil type high pressure apparatus at 4 GPa and 1473 K, has been investigated using transmission electron microscopy (TEM). Individual crystallites have a platy crystal habit elongated parallel to the crystallographic a-axis, which is the direction of the edge-shared octahedral chain. The dislocations with Burgers vectors b = [100] and 〈u0w〉 nucleated in the CaIrO3 phase during the synthesis experiments. The potential slip plane could be (010), the most likely having with the (010)-layered structure of IrO6 octahedrons. The crystal morphology and dislocation microstructures of CaIrO3 should provide important constraints for the discussion of the deformation behaviour and polarization anisotropy of the post-perovskite phase in the lowermost mantle.

Received 19 October 2005; accepted 2 May 2006; published 22 June 2006.

Index Terms: 3620 Mineralogy and Petrology: Mineral and crystal chemistry (1042); 3625 Mineralogy and Petrology: Petrography, microstructures, and textures; 3630 Mineralogy and Petrology: Experimental mineralogy and petrology; 3902 Mineral Physics: Creep and deformation; 7208 Seismology: Mantle (1212, 1213, 8124).

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Citation: Miyajima, N., K. Ohgushi, M. Ichihara, and T. Yagi (2006), Crystal morphology and dislocation microstructures of CaIrO3: A TEM study of an analogue of the MgSiO3 post-perovskite phase, Geophys. Res. Lett., 33, L12302, doi:10.1029/2005GL025001.