High-resolution neutron diffraction study of possible charge ordering in Na{sub 0.5}CoO{sub 2}
- Centre for Science at Extreme Conditions and School of Chemistry, University of Edinburgh, King's Buildings, Mayfield Road, Edinburgh, EH9 3JZ (United Kingdom)
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544 (United States)
The structure of Na{sub 0.5}CoO{sub 2}, the low-temperature insulator that separates the antiferromagnetic and normal metals in the Na{sub x}CoO{sub 2} phase diagram, is studied by high-resolution powder neutron diffraction at temperatures between 10 and 300 K. Profile analysis confirms that it has an orthorhombic symmetry structure, space group Pnmm, consisting of layers of edge-sharing CoO{sub 6} octahedra in a triangular lattice, with Na ions occupying ordered positions in the interleaving planes. The oxygen content is found to be stoichiometric within 1%, indicating that the Na concentration accurately determines the electronic doping. The Na ordering creates two distinct Co sites, in parallel chains running along one crystallographic direction. The differences in their Co-O bond distances and the derived bond valence sums, reflections of the degree of charge ordering in this phase, are very small.
- OSTI ID:
- 20788043
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 73, Issue 13; Other Information: DOI: 10.1103/PhysRevB.73.134401; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 1098-0121
- Country of Publication:
- United States
- Language:
- English
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