Sodium trimer ordering on a NaxCoO2 surface

Woei Wu Pai, S. H. Huang, Ying S. Meng, Y. C. Chao, C. H. Lin, H. L. Liu, F. C. Chou

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


Sodium ion ordering on an in situ cleaved NaxCoO2 (x=0.84) surface has been studied by ultrahigh vacuum scanning tunneling microscopy at room temperature. Three main phases, with p(3×3), (7×7), and (2 3×2 3) hexagonal unit cells and a surface Na concentration of 1/3, 3/7, 1/2, respectively, were identified. One surprising finding is that Na trimers act as the basic building blocks that order in long range. The stability of Na trimers is attributed to the increased Na coordination with oxygen as indicated by ab initio calculations, and possibly at finite temperature by configuration entropy.

Original languageEnglish
Article number206404
JournalPhysical Review Letters
Issue number20
Publication statusPublished - 2008 May 21

ASJC Scopus subject areas

  • General Physics and Astronomy


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