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

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

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    Abstract

    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
    Volume179
    Issue number6
    DOIs
    Publication statusPublished - 2006 Jun

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    Keywords

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

    ASJC Scopus subject areas

    • Inorganic Chemistry
    • Physical and Theoretical Chemistry
    • Materials Chemistry

    Cite this

    Nagai, T., Sakai, K., Karppinen, M., Asaka, T., Kimoto, K., Yamazaki, A., Yamauchi, H., & Matsui, Y. (2006). Crystal structure of the parent misfit-layered cobalt oxide [Sr2O2]qCoO2 Journal of Solid State Chemistry, 179(6), 1898-1903. https://doi.org/10.1016/j.jssc.2006.03.016