Modulated structure of misfit layered cobalt oxide [(Ca 0.90Bi0.10)2(Co0.95Bi 0.05)O3]pCoO2

Yuzuru Miyazaki; Yousuke Suzuki; Mitsuko Onoda; Yoshinobu Ishii; Yukio Morii; Tsuyoshi Kajitani

doi:10.1143/JJAP.43.6252

Modulated structure of misfit layered cobalt oxide [(Ca _0.90Bi_0.10)₂(Co_0.95Bi _0.05)O₃]_pCoO₂

Yuzuru Miyazaki, Yousuke Suzuki, Mitsuko Onoda, Yoshinobu Ishii, Yukio Morii, Tsuyoshi Kajitani

ENG - Applied Physics

Research output: Contribution to journal › Article › peer-review

31 Citations (Scopus)

Abstract

We have determined the crystal structure of Bi-substituted and Bi-free misfit layered cobalt oxides [Ca₂CoO₃] _0.62CoO₂, by a (3+1)-dimensional superspace group approach. Structural parameters have been refined with a superspace group of C2/m(1p0)s0 using powder neutron diffraction data. Bismuth atoms are found to substitute for both Ca and Co atoms in the rock salt-type [Ca ₂CoO₃] subsystem. The resulting structural formula is expressed as [(Ca_0.90Bi_0.10)₂(Co _0.95Bi_0.05)O₃]_pCoO₂ with a refined b-axis ratio of p = 0.6183. By Bi substitution, the modulation of the Co-O distances in the [Ca₂CoO₃] subsystem is markedly decreased relative to the Bi-free counterpart, whereas such a modulation in the [CoO₂] subsystem is slightly increased. The observed increase in the Seebeck coefficient and electrical resistivity of the Bi-substituted phase can be explained in terms of the decrease in hole concentration in the CoO ₂ sheets.

Original language	English
Pages (from-to)	6252-6258
Number of pages	7
Journal	Japanese Journal of Applied Physics
Volume	43
Issue number	9 A
DOIs	https://doi.org/10.1143/JJAP.43.6252
Publication status	Published - 2004 Sept

Keywords

Calcium bismuth cobalt oxide
Misfit layer
Rietveld analysis
Superspace group
Thermoelectric compound

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10.1143/JJAP.43.6252

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title = "Modulated structure of misfit layered cobalt oxide [(Ca 0.90Bi0.10)2(Co0.95Bi 0.05)O3]pCoO2",

abstract = "We have determined the crystal structure of Bi-substituted and Bi-free misfit layered cobalt oxides [Ca2CoO3] 0.62CoO2, by a (3+1)-dimensional superspace group approach. Structural parameters have been refined with a superspace group of C2/m(1p0)s0 using powder neutron diffraction data. Bismuth atoms are found to substitute for both Ca and Co atoms in the rock salt-type [Ca 2CoO3] subsystem. The resulting structural formula is expressed as [(Ca0.90Bi0.10)2(Co 0.95Bi0.05)O3]pCoO2 with a refined b-axis ratio of p = 0.6183. By Bi substitution, the modulation of the Co-O distances in the [Ca2CoO3] subsystem is markedly decreased relative to the Bi-free counterpart, whereas such a modulation in the [CoO2] subsystem is slightly increased. The observed increase in the Seebeck coefficient and electrical resistivity of the Bi-substituted phase can be explained in terms of the decrease in hole concentration in the CoO 2 sheets.",

keywords = "Calcium bismuth cobalt oxide, Misfit layer, Rietveld analysis, Superspace group, Thermoelectric compound",

author = "Yuzuru Miyazaki and Yousuke Suzuki and Mitsuko Onoda and Yoshinobu Ishii and Yukio Morii and Tsuyoshi Kajitani",

year = "2004",

month = sep,

doi = "10.1143/JJAP.43.6252",

language = "English",

volume = "43",

pages = "6252--6258",

journal = "Japanese Journal of Applied Physics",

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publisher = "Japan Society of Applied Physics",

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TY - JOUR

T1 - Modulated structure of misfit layered cobalt oxide [(Ca 0.90Bi0.10)2(Co0.95Bi 0.05)O3]pCoO2

AU - Miyazaki, Yuzuru

AU - Suzuki, Yousuke

AU - Onoda, Mitsuko

AU - Ishii, Yoshinobu

AU - Morii, Yukio

AU - Kajitani, Tsuyoshi

PY - 2004/9

Y1 - 2004/9

N2 - We have determined the crystal structure of Bi-substituted and Bi-free misfit layered cobalt oxides [Ca2CoO3] 0.62CoO2, by a (3+1)-dimensional superspace group approach. Structural parameters have been refined with a superspace group of C2/m(1p0)s0 using powder neutron diffraction data. Bismuth atoms are found to substitute for both Ca and Co atoms in the rock salt-type [Ca 2CoO3] subsystem. The resulting structural formula is expressed as [(Ca0.90Bi0.10)2(Co 0.95Bi0.05)O3]pCoO2 with a refined b-axis ratio of p = 0.6183. By Bi substitution, the modulation of the Co-O distances in the [Ca2CoO3] subsystem is markedly decreased relative to the Bi-free counterpart, whereas such a modulation in the [CoO2] subsystem is slightly increased. The observed increase in the Seebeck coefficient and electrical resistivity of the Bi-substituted phase can be explained in terms of the decrease in hole concentration in the CoO 2 sheets.

AB - We have determined the crystal structure of Bi-substituted and Bi-free misfit layered cobalt oxides [Ca2CoO3] 0.62CoO2, by a (3+1)-dimensional superspace group approach. Structural parameters have been refined with a superspace group of C2/m(1p0)s0 using powder neutron diffraction data. Bismuth atoms are found to substitute for both Ca and Co atoms in the rock salt-type [Ca 2CoO3] subsystem. The resulting structural formula is expressed as [(Ca0.90Bi0.10)2(Co 0.95Bi0.05)O3]pCoO2 with a refined b-axis ratio of p = 0.6183. By Bi substitution, the modulation of the Co-O distances in the [Ca2CoO3] subsystem is markedly decreased relative to the Bi-free counterpart, whereas such a modulation in the [CoO2] subsystem is slightly increased. The observed increase in the Seebeck coefficient and electrical resistivity of the Bi-substituted phase can be explained in terms of the decrease in hole concentration in the CoO 2 sheets.

KW - Calcium bismuth cobalt oxide

KW - Misfit layer

KW - Rietveld analysis

KW - Superspace group

KW - Thermoelectric compound

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JO - Japanese Journal of Applied Physics

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IS - 9 A

ER -

Modulated structure of misfit layered cobalt oxide [(Ca _0.90Bi_0.10)₂(Co_0.95Bi _0.05)O₃]_pCoO₂

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