Incommensurately modulated crystal structure of a0 (O03)-type sodium cobalt oxide NaxCoO2 (x ~ 0.78)

Yuzuru Miyazaki, Naoki Igawa, Kunio Yubuta

研究成果: Review article査読


A single-phase sample of α0 (O03)-type layered sodium cobalt oxide NaxCoO2 (x ~ 0.78) was prepared and its incommensurately modulated crystal structure was analyzed using the (3+1)-dimensional superspace approach to the powder neutron diffraction data. The crystal structure of the cobaltate is accurately described based on the superspace group C2/m(α0γ)00, wherein the positions of Na atoms are most significantly modulated in the monoclinic a direction to form an ordered arrangement. Such a displacive modulation causes a quasi-periodic shift of Na atoms from the centers of the NaO6 polyhedra between undulated CoO2 sheets, changing the form of the NaO6 polyhedron from an octahedral coordination (O) to a trigonal prismatic (P) one, via an intermediate capped trigonal prismatic NaO7 coordination (C). At the positions where the Na atoms are most significantly shifted, the neighboring Na atoms are located at almost touching distances. However, the occupation factor of Na atoms becomes zero at such positions, yielding Na-deficient sites VNa, sandwiched either between C and P, or C and C-type polyhedra.

ジャーナルActa Crystallographica Section B: Structural Science, Crystal Engineering and Materials
出版ステータスPublished - 2021 6月 1

ASJC Scopus subject areas

  • 電子材料、光学材料、および磁性材料
  • 原子分子物理学および光学
  • 金属および合金
  • 材料化学


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