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Structure and microstructure of the high pressure synthesised misfit layer compound [Sr2O2][CrO2]1.85

Castillo Martínez, Elizabeth and Schönleber, Andreas and Smaalen, Sander van and Arévalo López, Ángel M. and Alario Franco , Miguel Ángel (2008) Structure and microstructure of the high pressure synthesised misfit layer compound [Sr2O2][CrO2]1.85. Journal of Solid State Chemistry, 181 . pp. 1840-1847. ISSN 0022-4596

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Abstract

The strontium chromium oxide [Sr2O2][CrO2]1.85 misfit layer compound has been synthesised at high pressure and high-temperature conditions. Electron diffraction patterns and high-resolution transmission electron microscopy images along [001] show the misfit character of the different layers composing the structure with a supercell along the incommensurate parameter b=7b1=13b2. The modulated
crystal structure has been refined within the superspace formalism against single-crystal X-ray diffraction data, employing the (3+1)-dimensional superspace group Cnmb(0s20)0 0 s. The compound has a composite structure with lattice parameters a1=5.182(1)A˚ , b1=5.411(1)A˚ , c1=18.194(3)A˚ for the first, SrO, subsystem and the same a and c, but with b2=2.925(1)A˚ for the second, CrO2, subsystem. The layer stacking is similar to that of orthorhombic PbS(TiS2)1.18, but with a much stronger
intersubsytem bonding in the case of the oxide. The intersubsystem lattice mismatch is mainly handled by displacement modulations of the Sr atoms, correlated with modulations of the valence, the coordination and the anisotropic displacement parameters.


Item Type:Article
Uncontrolled Keywords:misfit layer compounds, crystallography, high pressure
Subjects:Sciences > Chemistry > Crystallography
Sciences > Chemistry > Chemistry, Inorganic
ID Code:8827
Deposited On:14 Aug 2009 11:38
Last Modified:03 Sep 2010 08:03

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