X-ray absorption spectroscopy in NaCo2O4, LaCoO3 and SrCoO3

Tomohira Matsushita, Masaichiro Mizumaki, Naoshi Ikeda, Makoto Nakazawa, Akane Agui, Yuji Saitoh, Takeshi Nakatani, Akitaka Yoshigoe, Shin Nakamura

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)


We have performed Co 2p x-ray absorption spectroscopy (XAS) on a mixed valence hexagonal layered system NaCo2O4, which shows large thermopower and metallic conductivity. We also measured XAS for SrCoO3 and LaCoO3 as examples of typical Co ionic states. The Co ions of the last two materials are octahedrally surrounded by oxygen atoms. A Co atom in NaCo2O4 also has octahedral coordination with oxygen atoms but it is distorted slightly. The Co ions in SrCoO3 and LaCoO3 are in the d5 and d6 configuration respectively. The spectrum of NaCo2O4 resembles that of LaCoO3 rather than that of SrCoO3; the Co ions in NaCo2O4 can be regarded as the d6 configuration. Also, we have tried to calculate the XAS spectra by using the charge-transfer multiplet model (CT-M). Although we could not find out the best-fitting parameters, the results suggested the itinerancy of the Co 3d states.

Original languageEnglish
Pages (from-to)1327-1331
Number of pages5
JournalSurface Review and Letters
Issue number2
Publication statusPublished - Apr 2002
Externally publishedYes

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry


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