X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering in gamma-Na[subscript x]CoO[subscript 2] (x=0.71 and 0.84)
We have recently demonstrated that x=0.71 and 0.84 are the two most stable single-phase compounds above x=0.5 in gamma-Na[subscript x]CoO[subscript 2] [G. J. Shu et al., Phys. Rev. B 76, 184115 (2007); F. C. Chou et al., Phys. Rev. Lett. 101, 127404 (2008)], and this structural investigation was pe...
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American Physical Society
2010
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Online Access: | http://hdl.handle.net/1721.1/54757 https://orcid.org/0000-0001-7809-8157 |
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author | Chou, F. C. Liu, L.-K. Chen, C. H. Sheu, H. S. Shu, G. J. Chu, M.-W. Huang, F.-T. Lee, Patrick A. |
author2 | Massachusetts Institute of Technology. Department of Physics |
author_facet | Massachusetts Institute of Technology. Department of Physics Chou, F. C. Liu, L.-K. Chen, C. H. Sheu, H. S. Shu, G. J. Chu, M.-W. Huang, F.-T. Lee, Patrick A. |
author_sort | Chou, F. C. |
collection | MIT |
description | We have recently demonstrated that x=0.71 and 0.84 are the two most stable single-phase compounds above x=0.5 in gamma-Na[subscript x]CoO[subscript 2] [G. J. Shu et al., Phys. Rev. B 76, 184115 (2007); F. C. Chou et al., Phys. Rev. Lett. 101, 127404 (2008)], and this structural investigation was performed on the single crystals and pulverized samples elaborately synthesized therein. Using the complementary techniques of x-ray and electron diffractions, we unambiguously established the existence of superlattices in x=0.71 and 0.84, sqrt12a[subscript p]×sqrt12a[subscript p]×3c[subscript p], and sqrt13a[subscript p]×sqrt13a[subscript p]×3c[subscript p] (a[subscript p] and c[subscript p] the hexagonal primitive cell parameters), respectively. The exceptionally large superlattice for x=0.71 arises from the long-range three-dimensional sodium ordering, consisting of the spiral-like sodium-trimer chain screwing along c axis and being decorated with alternating truncated-triangle and honeycomb sodium sublattices in ab plane. The trimers in the neighboring sodium planes show corner-shared-like characteristics along the chain direction. A larger interplane separation of the trimers that was expected to minimize the trimer interlayer Coulomb repulsion was, however, not observed, and all Co ions in the superlattice show similar charge characteristics. In x=0.84, the large superlattice is rather a result of the long-range ordering of sodium monomers both in ab plane and along c axis. The differences in the superlattice structure and the corresponding long-range sodium ordering between x=0.71 and 0.84 may provide the critical information in understanding their distinctly different physical properties from structural aspects. |
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institution | Massachusetts Institute of Technology |
language | en_US |
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spelling | mit-1721.1/547572022-10-01T21:08:23Z X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering in gamma-Na[subscript x]CoO[subscript 2] (x=0.71 and 0.84) X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering in γ-NaxCoO2 (x=0.71 and 0.84) Chou, F. C. Liu, L.-K. Chen, C. H. Sheu, H. S. Shu, G. J. Chu, M.-W. Huang, F.-T. Lee, Patrick A. Massachusetts Institute of Technology. Department of Physics Lee, Patrick A. Lee, Patrick A. We have recently demonstrated that x=0.71 and 0.84 are the two most stable single-phase compounds above x=0.5 in gamma-Na[subscript x]CoO[subscript 2] [G. J. Shu et al., Phys. Rev. B 76, 184115 (2007); F. C. Chou et al., Phys. Rev. Lett. 101, 127404 (2008)], and this structural investigation was performed on the single crystals and pulverized samples elaborately synthesized therein. Using the complementary techniques of x-ray and electron diffractions, we unambiguously established the existence of superlattices in x=0.71 and 0.84, sqrt12a[subscript p]×sqrt12a[subscript p]×3c[subscript p], and sqrt13a[subscript p]×sqrt13a[subscript p]×3c[subscript p] (a[subscript p] and c[subscript p] the hexagonal primitive cell parameters), respectively. The exceptionally large superlattice for x=0.71 arises from the long-range three-dimensional sodium ordering, consisting of the spiral-like sodium-trimer chain screwing along c axis and being decorated with alternating truncated-triangle and honeycomb sodium sublattices in ab plane. The trimers in the neighboring sodium planes show corner-shared-like characteristics along the chain direction. A larger interplane separation of the trimers that was expected to minimize the trimer interlayer Coulomb repulsion was, however, not observed, and all Co ions in the superlattice show similar charge characteristics. In x=0.84, the large superlattice is rather a result of the long-range ordering of sodium monomers both in ab plane and along c axis. The differences in the superlattice structure and the corresponding long-range sodium ordering between x=0.71 and 0.84 may provide the critical information in understanding their distinctly different physical properties from structural aspects. National Science Council of the Republic of China National Taiwan University Excellence Project 2010-05-11T16:12:21Z 2010-05-11T16:12:21Z 2009-01 2008-07 Article http://purl.org/eprint/type/JournalArticle 1098-0121 http://hdl.handle.net/1721.1/54757 Huang, F.-T. et al. “X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering in gamma -Na[subscript x] CoO[subscript 2] ( x=0.71 and 0.84).” Physical Review B 79.1 (2009): 014413. © 2009 American Physical Society. https://orcid.org/0000-0001-7809-8157 en_US http://dx.doi.org/10.1103/PhysRevB.79.014413 Physical Review B Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf American Physical Society APS |
spellingShingle | Chou, F. C. Liu, L.-K. Chen, C. H. Sheu, H. S. Shu, G. J. Chu, M.-W. Huang, F.-T. Lee, Patrick A. X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering in gamma-Na[subscript x]CoO[subscript 2] (x=0.71 and 0.84) |
title | X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering in gamma-Na[subscript x]CoO[subscript 2] (x=0.71 and 0.84) |
title_full | X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering in gamma-Na[subscript x]CoO[subscript 2] (x=0.71 and 0.84) |
title_fullStr | X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering in gamma-Na[subscript x]CoO[subscript 2] (x=0.71 and 0.84) |
title_full_unstemmed | X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering in gamma-Na[subscript x]CoO[subscript 2] (x=0.71 and 0.84) |
title_short | X-ray and electron diffraction studies of superlattices and long-range three-dimensional Na ordering in gamma-Na[subscript x]CoO[subscript 2] (x=0.71 and 0.84) |
title_sort | x ray and electron diffraction studies of superlattices and long range three dimensional na ordering in gamma na subscript x coo subscript 2 x 0 71 and 0 84 |
url | http://hdl.handle.net/1721.1/54757 https://orcid.org/0000-0001-7809-8157 |
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