Modulated structure of misfit layered cobalt oxide [(Ca 0.90Bi0.10)2(Co0.95Bi 0.05)O3]pCoO2

Yuzuru Miyazaki, Yousuke Suzuki, Mitsuko Onoda, Yoshinobu Ishii, Yukio Morii, Tsuyoshi Kajitani

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31 Citations (Scopus)


We have determined the crystal structure of Bi-substituted and Bi-free misfit layered cobalt oxides [Ca2CoO3] 0.62CoO2, by a (3+1)-dimensional superspace group approach. Structural parameters have been refined with a superspace group of C2/m(1p0)s0 using powder neutron diffraction data. Bismuth atoms are found to substitute for both Ca and Co atoms in the rock salt-type [Ca 2CoO3] subsystem. The resulting structural formula is expressed as [(Ca0.90Bi0.10)2(Co 0.95Bi0.05)O3]pCoO2 with a refined b-axis ratio of p = 0.6183. By Bi substitution, the modulation of the Co-O distances in the [Ca2CoO3] subsystem is markedly decreased relative to the Bi-free counterpart, whereas such a modulation in the [CoO2] subsystem is slightly increased. The observed increase in the Seebeck coefficient and electrical resistivity of the Bi-substituted phase can be explained in terms of the decrease in hole concentration in the CoO 2 sheets.

Original languageEnglish
Pages (from-to)6252-6258
Number of pages7
JournalJapanese Journal of Applied Physics
Issue number9 A
Publication statusPublished - 2004 Sept


  • Calcium bismuth cobalt oxide
  • Misfit layer
  • Rietveld analysis
  • Superspace group
  • Thermoelectric compound


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