Sodium Trimer Ordering on NaxCoO2 Surface

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

doi:10.1103/PhysRevLett.100.206404

Sodium Trimer Ordering on NaxCoO2 Surface

Materials Science 2009-11-13 v1 Strongly Correlated Electrons

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

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Abstract

Sodium ion ordering on in situ cleaved NaxCoO2 (x=0.84) surface has been studied by ultra high vacuum scanning tunneling microscopy (UHV-STM) at room temperature. Three main phases, with p(3x3), (root 7 x root 7), and (2 root 3 x 2 root 3) hexagonal unit cells and 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.

Keywords

surface science phase transitions

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@article{arxiv.0805.0475,
  title  = {Sodium Trimer Ordering on NaxCoO2 Surface},
  author = {Woei Wu Pai and S. H. Huang and Ying S. Meng and Y. C. Chao and C. H. Lin and H. L. Liu and F. C. Chou},
  journal= {arXiv preprint arXiv:0805.0475},
  year   = {2009}
}

Sodium Trimer Ordering on NaxCoO2 Surface

Abstract

Keywords

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