Superspace group approach to the crystal structure of Na 0.5CoO2

Dai Igarashi, Yuzuru Miyazaki, Kunio Yubuta, Tsuyoshi Kajitani

Research output: Contribution to journalArticlepeer-review

10 Citations (Scopus)


The crystal structure of layered cobalt oxide Na0.5CoO 2 has been determined by means of the (3 + 1)-dimensional superspace group approach. Structural parameters have been refined with a superspace group of Ccmm(1p0)000 using powder neutron diffraction data collected below room temperature. The compound can be regarded as a misfit-layered cobalt oxide which consists of [Na] and [CoO2] subsystems, with a refined misfit parameter p = bcoO2/bNa = 0.5011(7) at 296 K. A parallel set of zigzag arrangements, i.e., the positional modulation, of Na ions has been revealed along the b-axis. The temperature-dependent alteration of Co-O distances shows discontinuous characteristics below the phase transition temperature around 80 K, which indicates the charge-separation of Co ions. On the basis of the bond valence sum calculation, a one-dimensional charge-separation pattern of Co ions with charges of +3.5 + δ and +3.5 - δ, perpendicular to the Na zigzag chains, is established.

Original languageEnglish
Pages (from-to)304-310
Number of pages7
JournalJapanese Journal of Applied Physics
Issue number1
Publication statusPublished - Jan 10 2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • General Engineering
  • General Physics and Astronomy


Dive into the research topics of 'Superspace group approach to the crystal structure of Na 0.5CoO2'. Together they form a unique fingerprint.

Cite this