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Monoclinic phase of the misfit-layered cobalt oxide (Ca0.85OH)1.16CoO2

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Title: Monoclinic phase of the misfit-layered cobalt oxide (Ca0.85OH)1.16CoO2
Authors: Shizuya, Mitsuyuki1, Isobe, Masaaki ISOBE.Masaaki@nims.go.jp, Baba, Yuji1, Nagai, Takuro1, Matsui, Yoshio1, Takayama-Muromachi, Eiji1
Source: Journal of Solid State Chemistry. Dec2006, Vol. 179 Issue 12, p3974-3980. 7p.
Subjects: Transition metals, Electron microscopy, Electron diffraction, Analytical chemistry
Abstract: Abstract: A monoclinic phase of the misfit-layered cobalt oxide (Ca0.85OH)1.16CoO2 was successfully synthesized and characterized. It was found that this new material is a poly-type phase of the orthorhombic form of (CaOH)1.14CoO2, recently discovered by the present authors. Both the compounds consist of two interpenetrating subsystems: CdI2-type CoO2 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 (Ca0.85OH)1.16CoO2 have c-centered monoclinic Bravais lattices with common a=4.898Å, c=8.810Å and β=95.8° lattice parameters, and different b parameters: b 1=2.820Å and b 2=4.870Å. Chemical analyses revealed that the monoclinic phase has a cobalt valence of +3.1–3.2. Resistivity of the monoclinic phase is approximately 101–105 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 (∼100μV/K) were observed near room temperature. [Copyright &y& Elsevier]
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Database: Engineering Source
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Abstract:Abstract: A monoclinic phase of the misfit-layered cobalt oxide (Ca0.85OH)1.16CoO2 was successfully synthesized and characterized. It was found that this new material is a poly-type phase of the orthorhombic form of (CaOH)1.14CoO2, recently discovered by the present authors. Both the compounds consist of two interpenetrating subsystems: CdI2-type CoO2 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 (Ca0.85OH)1.16CoO2 have c-centered monoclinic Bravais lattices with common a=4.898Å, c=8.810Å and β=95.8° lattice parameters, and different b parameters: b 1=2.820Å and b 2=4.870Å. Chemical analyses revealed that the monoclinic phase has a cobalt valence of +3.1–3.2. Resistivity of the monoclinic phase is approximately 101–105 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 (∼100μV/K) were observed near room temperature. [Copyright &y& Elsevier]
ISSN:00224596
DOI:10.1016/j.jssc.2006.09.008