A five-dimensional structural investigation of the misfit layer compound [Bi0.87SrO2]2[CoO2]1.82
Acta Crystallographica Section B
Volume 56, Issue 2, pages 173–182, April 2000
How to Cite
Leligny, H., Grebille, D., Pérez, O., Masset, A. C., Hervieu, M. and Raveau, B. (2000), A five-dimensional structural investigation of the misfit layer compound [Bi0.87SrO2]2[CoO2]1.82. Acta Cryst. B, 56: 173–182. doi: 10.1107/S0108768199012586
- Misfit layer compound;
- Structural investigation;
- Commensurate structures.
The structure of the misfit layer compound [BiSrO][CoO], bismuth strontium cobaltite, was determined by single-crystal X-ray diffraction using the five-dimensional superspace-group formalism. This composite crystal, of monoclinic symmetry, is composed of two subsystems exhibiting incommensurate periodicities along b, the binary axis direction. The first composite part [BiSrO] displays an intrinsic modulation of planar monoclinic type characterized by the wavevector . The second composite part [CoO] shows two different centered lattice variants. The structure of the misfit layer crystal can be described as an alternation along c of distorted rock-salt-type slabs, formed from [BiO] and [SrO] layers (first subsystem), and of [CoO] layers (second subsystem) displaying a distorted CdI-type structure. Two main structural results are obtained. First, as a consequence of the intrinsic modulation, disordered zones, characterized by Bi vacancies, are regularly distributed in the [BiO] layers. Second, strong chemical bonds are implied between the strontium atoms of the first subsystem and the oxygen atoms of the second one.