Crystal structure of the parent misfit-layered cobalt oxide [Sr2O2]qCoO2

T. Nagai*, K. Sakai, M. Karppinen, T. Asaka, K. Kimoto, A. Yamazaki, H. Yamauchi, Y. Matsui

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


The crystal structure of our newly discovered Sr-Co-O phase is investigated in detail through high-resolution electron microscopy (HREM) techniques. Electron diffraction (ED) measurement together with energy dispersive X-ray spectroscopy (EDS) analysis show that an ampoule-synthesized sample contains an unknown Sr-Co-O ternary phase with monoclinic symmetry and the cation ratio of Sr/Co=1. From HREM images a layered structure with a regular stacking of a CdI2-type CoO2 sheet and a rock-salt-type Sr2O2 double-layered block is observed, which confirms that the phase is the parent of the more complex "misfit-layered (ML)" cobalt oxides of [MmA2Om+2]qCoO2 with the formula of [Sr2O2]qCoO2, i.e. m = 0. It is revealed that the misfit parameter q is 0.5, i.e. the two sublattices of the CoO2 sheet and the Sr2O2 block coexist to form a commensurate composite structure. We propose a structural model with monoclinic P21/m symmetry, which is supported by simulations of ED patterns and HREM images based on dynamical diffraction theory.

Original languageEnglish
Pages (from-to)1898-1903
Number of pages6
JournalJournal of Solid State Chemistry
Issue number6
Publication statusPublished - 2006 Jun


  • Electron diffraction
  • High resolution electron microscopy
  • Misfit-layered cobalt oxide
  • Strontium cobalt oxide
  • Thermoelectric material
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry


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