Crystal structure and thermoelectric properties of the misfit-layered cobalt oxides

Yuzuru Miyazaki

doi:10.1016/j.ssi.2004.01.046

Crystal structure and thermoelectric properties of the misfit-layered cobalt oxides

Yuzuru Miyazaki

ENG - Applied Physics

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

104 Citations (Scopus)

Abstract

On the basis of the crystal chemistry and electronic structure of γ-Na_xCoO₂, we explored many cobalt-based oxide systems and encountered the compound "Ca₃Co₄O ₉". Through the detailed structure analyses, the cobalt oxide has been revealed to be a misfit-layered compound, which consists of two interpenetrating monoclinic subsystems. The first subsystem [CoO₂] has a CdI₂-type triangular lattice while the second subsystem [Ca₂CoO₃] is built up from an ordered three-layered NaCl-type (RS) block. The structure formula can be expressed as [Ca ₂CoO₃]_pCoO₂, where p stands for the b-axis ratio, b_CoO2/b_RS ∼ 0.62. A typical polycrystalline sample of the compound exhibits reasonable thermoelectric (TE) performance with thermopower S = 130 μV K^-1, resistivity = 15 mΩ cm and thermal conductivity κ = 1 W m^-1 K ^-1 at 300 K. The resulting figure-of-merit Z (S ²/ρκ) = 1.1 × 10^-4 K^-1 is comparable to that of polycrystalline samples of the γ-phase, indicating that the present misfit cobalt oxide is a potential candidate for a thermoelectric material.

Original language	English
Pages (from-to)	463-467
Number of pages	5
Journal	Solid State Ionics
Volume	172
Issue number	1-4 SPEC. ISS.
DOIs	https://doi.org/10.1016/j.ssi.2004.01.046
Publication status	Published - 2004 Aug 31

Keywords

Crystal structure
Misfit-layered compounds
Modulated structure
Superspace group
Thermoelectrics

ASJC Scopus subject areas

Chemistry(all)
Materials Science(all)
Condensed Matter Physics

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10.1016/j.ssi.2004.01.046

Cite this

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title = "Crystal structure and thermoelectric properties of the misfit-layered cobalt oxides",

abstract = "On the basis of the crystal chemistry and electronic structure of γ-NaxCoO2, we explored many cobalt-based oxide systems and encountered the compound {"}Ca3Co4O 9{"}. Through the detailed structure analyses, the cobalt oxide has been revealed to be a misfit-layered compound, which consists of two interpenetrating monoclinic subsystems. The first subsystem [CoO2] has a CdI2-type triangular lattice while the second subsystem [Ca2CoO3] is built up from an ordered three-layered NaCl-type (RS) block. The structure formula can be expressed as [Ca 2CoO3]pCoO2, where p stands for the b-axis ratio, bCoO2/bRS ∼ 0.62. A typical polycrystalline sample of the compound exhibits reasonable thermoelectric (TE) performance with thermopower S = 130 μV K-1, resistivity = 15 mΩ cm and thermal conductivity κ = 1 W m-1 K -1 at 300 K. The resulting figure-of-merit Z (S 2/ρκ) = 1.1 × 10-4 K-1 is comparable to that of polycrystalline samples of the γ-phase, indicating that the present misfit cobalt oxide is a potential candidate for a thermoelectric material.",

keywords = "Crystal structure, Misfit-layered compounds, Modulated structure, Superspace group, Thermoelectrics",

author = "Yuzuru Miyazaki",

note = "Funding Information: The author appreciates M. Onoda, A. Yamamoto, T. Kajitani, Y. Koike, M. Akoshima, K. Kudo, T. Oku, M. Kikuchi, Y. Ishii, Y. Shimojo, T. Miura, Y. Suzuki, Y. Ono and S. Kawano for their help. This work was supported, in part, by the Research Foundation for Materials Science and by CREST, JST.",

year = "2004",

month = aug,

day = "31",

doi = "10.1016/j.ssi.2004.01.046",

language = "English",

volume = "172",

pages = "463--467",

journal = "Solid State Ionics",

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number = "1-4 SPEC. ISS.",

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TY - JOUR

T1 - Crystal structure and thermoelectric properties of the misfit-layered cobalt oxides

AU - Miyazaki, Yuzuru

N1 - Funding Information: The author appreciates M. Onoda, A. Yamamoto, T. Kajitani, Y. Koike, M. Akoshima, K. Kudo, T. Oku, M. Kikuchi, Y. Ishii, Y. Shimojo, T. Miura, Y. Suzuki, Y. Ono and S. Kawano for their help. This work was supported, in part, by the Research Foundation for Materials Science and by CREST, JST.

PY - 2004/8/31

Y1 - 2004/8/31

N2 - On the basis of the crystal chemistry and electronic structure of γ-NaxCoO2, we explored many cobalt-based oxide systems and encountered the compound "Ca3Co4O 9". Through the detailed structure analyses, the cobalt oxide has been revealed to be a misfit-layered compound, which consists of two interpenetrating monoclinic subsystems. The first subsystem [CoO2] has a CdI2-type triangular lattice while the second subsystem [Ca2CoO3] is built up from an ordered three-layered NaCl-type (RS) block. The structure formula can be expressed as [Ca 2CoO3]pCoO2, where p stands for the b-axis ratio, bCoO2/bRS ∼ 0.62. A typical polycrystalline sample of the compound exhibits reasonable thermoelectric (TE) performance with thermopower S = 130 μV K-1, resistivity = 15 mΩ cm and thermal conductivity κ = 1 W m-1 K -1 at 300 K. The resulting figure-of-merit Z (S 2/ρκ) = 1.1 × 10-4 K-1 is comparable to that of polycrystalline samples of the γ-phase, indicating that the present misfit cobalt oxide is a potential candidate for a thermoelectric material.

AB - On the basis of the crystal chemistry and electronic structure of γ-NaxCoO2, we explored many cobalt-based oxide systems and encountered the compound "Ca3Co4O 9". Through the detailed structure analyses, the cobalt oxide has been revealed to be a misfit-layered compound, which consists of two interpenetrating monoclinic subsystems. The first subsystem [CoO2] has a CdI2-type triangular lattice while the second subsystem [Ca2CoO3] is built up from an ordered three-layered NaCl-type (RS) block. The structure formula can be expressed as [Ca 2CoO3]pCoO2, where p stands for the b-axis ratio, bCoO2/bRS ∼ 0.62. A typical polycrystalline sample of the compound exhibits reasonable thermoelectric (TE) performance with thermopower S = 130 μV K-1, resistivity = 15 mΩ cm and thermal conductivity κ = 1 W m-1 K -1 at 300 K. The resulting figure-of-merit Z (S 2/ρκ) = 1.1 × 10-4 K-1 is comparable to that of polycrystalline samples of the γ-phase, indicating that the present misfit cobalt oxide is a potential candidate for a thermoelectric material.

KW - Crystal structure

KW - Misfit-layered compounds

KW - Modulated structure

KW - Superspace group

KW - Thermoelectrics

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SN - 0167-2738

VL - 172

SP - 463

EP - 467

JO - Solid State Ionics

JF - Solid State Ionics

IS - 1-4 SPEC. ISS.

ER -

Crystal structure and thermoelectric properties of the misfit-layered cobalt oxides

Abstract

Keywords

ASJC Scopus subject areas

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