Monoclinic phase of the misfit-layered cobalt oxide (Ca{sub 0.85}OH){sub 1.16}CoO{sub 2}
- National Institute for Materials Science (NIMS), 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan)
A monoclinic phase of the misfit-layered cobalt oxide (Ca{sub 0.85}OH){sub 1.16}CoO{sub 2} was successfully synthesized and characterized. It was found that this new material is a poly-type phase of the orthorhombic form of (CaOH){sub 1.14}CoO{sub 2}, recently discovered by the present authors. Both the compounds consist of two interpenetrating subsystems: CdI{sub 2}-type CoO{sub 2} layers and rock-salt-type double-atomic-layer CaOH blocks. However, these two phases exhibit a different stacking structure. By powder X-ray and electron diffraction (ED) studies, it was found that the two subsystems of (Ca{sub 0.85}OH){sub 1.16}CoO{sub 2} have c-centered monoclinic Bravais lattices with common a=4.898 A, c=8.810 A and {beta}=95.8{sup o} lattice parameters, and different b parameters: b {sub 1}=2.820 A and b {sub 2}=4.870 A. Chemical analyses revealed that the monoclinic phase has a cobalt valence of +3.1-3.2. Resistivity of the monoclinic phase is approximately 10{sup 1}-10{sup 5} times lower than that of the orthorhombic phase. This suggests that the monoclinic phase is a hole-doped phase of the insulating orthorhombic phase. Furthermore, large positive Seebeck coefficients ({approx}100 {mu}V/K) were observed near room temperature. - Graphical abstract: Crystal structure of two kinds of poly-type phases of the misfit-layered cobalt oxides (Ca{sub 1-} {sub {delta}} OH) {sub x} CoO{sub 2}: (a) projection along the a-axis of the orthorhombic structure; (b) projection along the b-axis of the monoclinic structure; and (c) projection along the [-1 0 0] direction of the clinic structure. In each case, the rectangle is the unit cell.
- OSTI ID:
- 20900938
- Journal Information:
- Journal of Solid State Chemistry, Vol. 179, Issue 12; Other Information: DOI: 10.1016/j.jssc.2006.09.008; PII: S0022-4596(06)00516-0; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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