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Effect of High Valence Metal Doping on Thermoelectric Properties of [Ca2CoO3-δ]0.62CoO2

Published online by Cambridge University Press:  01 February 2011

K. Fujie
Affiliation:
Department of Superconductivity, University of Tokyo, Tokyo 113–8656, Japan
S. Horii
Affiliation:
Department of Superconductivity, University of Tokyo, Tokyo 113–8656, Japan
I. Matsubara
Affiliation:
National Institute of Advanced Industrial Science and Technology, Osaka 563–8577, Japan
W. Shin
Affiliation:
National Institute of Advanced Industrial Science and Technology, Osaka 563–8577, Japan
N. Murayama
Affiliation:
National Institute of Advanced Industrial Science and Technology, Osaka 563–8577, Japan
J. Shimoyama
Affiliation:
Department of Superconductivity, University of Tokyo, Tokyo 113–8656, Japan PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332–0012, Japan
K. Kishio
Affiliation:
Department of Superconductivity, University of Tokyo, Tokyo 113–8656, Japan
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Abstract

We report the synthesis and thermoelectric properties of high valence metal-doped [Ca2Co1-xMxO3-δ]0.62CoO2 (M = Re, Mo or Nb) compounds. Approximately 10% M-doping for Co sites in block layer was found to be effective for dramatic suppression of oxygen nonstoichiometries. Seebeck coefficients were systematically enhanced with M-doping levels (x), and however, electrical resistivities also increased with x for conventionally sintered bulk samples. On the other hand, magnetic alignment and/or densification were remarkably effective for reduction of the resistivity. In the case of Mo-doped (x = 0.1) sample, a highly c-axis aligned and densified sample showed 1–3 times larger power factor at 1100K (5.3 μ WK−2cm−1) than the non-doped one. Moreover, these high valence metal doped Ca349 compounds exhibited the oxygen nonstoichiometry suppressed dramatically.

Type
Research Article
Copyright
Copyright © Materials Research Society 2004

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References

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