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Persistent URL http://purl.org/net/epubs/work/41883
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Title High-pressure structure and bonding in CaIrO3 : the structure model of MgSiO3 post-perovskite investigated with time-of-flight neutron powder diffraction.
Abstract The structure of CaIrO<sub>3</sub> (C<i>mcm</i>) has been refined at high pressure and at low temperature using time-of-flight neutron powder diffraction data. Evidence supporting deviation from space group C<i>mcm</i> to C<i>mc2<sub>1</sub></i> is inconclusive. As CaIrO<sub>3</sub> (C<i>mcm</i>) unit-cell volume changes, refinements indicate deformation of cation-centered coordination polyhedra, rather than tilting. Structure models demonstrate Ca<sup>2+</sup>-centered polyhedra are an order of magnitude more compressible than Ir<sup>4+</sup>-centered octahedra. Bond valence sums show significant chemical strain (over-bonding) of calcium and oxygen at ambient conditions. Implications for structure change in MgSiO<sub>3</sub> post-perovskite are discussed and a method for predicting the Clapeyron slope between perovskite and post-perovskite phases is proposed based on extrapolation of the volume-ratio between cation-centered polyhedra.
Keywords Physics , Natural environment
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Language English (EN)
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Journal Article Am Miner 92 (2007): 1912-1918. doi:10.2138/am.2007.2585 2007