Oxygen nonstoichiometry and the origin of Na ion ordering in P2-Na[subscript x]CoO[subscript 2]
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 su...
| Main Authors: | , , , , , |
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| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
American Physical Society
2011
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| Online Access: | http://hdl.handle.net/1721.1/61331 https://orcid.org/0000-0001-7809-8157 |
| Summary: | 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. |
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