Oxygen nonstoichiometry and the origin of Na ion ordering in P2-Na[subscript x]CoO[subscript 2]
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Shu-2010-Oxygen nonstoichiome.pdf
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546.22 KB
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Author(s)
Lee, Patrick A.
Shu, G. J.
Lee, W. L.
Huang, F.-T.
Chu, M.-W.
Chou, F. C.
Alternative Title
Oxygen nonstoichiometry and the origin of Na ion ordering in P2-NaxCoO2
Date Issued
August 2010
Journal
Physical Review B
Publisher
American Physical Society
Citation
Shu, G. J. et al. “Oxygen nonstoichiometry and the origin of Na ion ordering in P2-Na_{x}CoO_{2}.” Physical Review B 82.5 (2010): 054106. © 2010 The American Physical Society.
Version
Final published version
Abstract
The impact of oxygen deficiency on physical properties of Na[subscript 2/3]CoO[subscript 2−delta] has been investigated. From the combined thermogravimetric, magnetic susceptibility, and synchrotron x-ray Laue diffraction studies, it is demonstrated that Na[subscript 2/3]CoO[subscript 2] shows no superlattice ordering due to Na ions; however Na[subscript 2/3]CoO[subscript 1.98], which has the same Co valence as that of Na0.71CoO[subscript 2], shows nearly identical magnetic and transport properties and the same simple hexagonal superlattice ordering of [sqrt]12a. It is proposed that the Na ion ordering found in Na[subscript 2/3]CoO[subscript 1.98] is identical to the ideal Na[subscript 0.71]CoO[subscript 2] of large [sqrt]12a×[sqrt]12a×3c superlattice but with additional Na vacancies which are bound to the oxygen defects at room temperature. We conclude that oxygen vacancies play a key role in stabilizing the superlattice structure and must be accounted for in its modeling.
MIT Department
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
https://doi.org/10.1103/PhysRevB.82.054106
