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Enhancement of thermoelectric figure of merit by incorporation of large single crystals in Ca3Co4O9 bulk materials

Published online by Cambridge University Press:  31 January 2011

Ryoji Funahashi ,
Saori Urata ,
Toyohide Sano  and
Masaaki Kitawaki
Ryoji Funahashi
Affiliation:
National Institute of Advanced Industrial Science and Technology, Midorigaoka, Ikeda, Osaka 563-8577, Japan
Saori Urata
Affiliation:
National Institute of Advanced Industrial Science and Technology, Midorigaoka, Ikeda, Osaka 563-8577, Japan
Toyohide Sano
Affiliation:
Osaka Electro-Communication University, Hatsu-cho, Neyagawa, Osaka 572-8530, Japan
Masaaki Kitawaki
Affiliation:
Osaka Electro-Communication University, Hatsu-cho, Neyagawa, Osaka 572-8530, Japan
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Abstract

Having recently succeeded in synthesizing large single crystals of (Ca2CoO3)CoO2 (Co-349) with superior thermoelectric properties using a modified flux method, we have prepared a composite material of Co-349 powder and single crystals and examined its thermoelectric properties. The electrical conductivity σ of this composite, which contained 20 wt.% single crystals, was higher than that of a sample without the single crystals. While the achievable effect has yet to be fully realized, improved grain alignment and the effect of current bypassing grain boundaries through the large single crystals in the composite are thought to cause the increasing σ, which consequently results in an enhanced thermoelectric figure of merit of about 0.56 at 973 K in air.

Type
Articles
Information
Journal of Materials Research , Volume 18 , Issue 7 , July 2003 , pp. 1646 - 1651
Copyright
Copyright © Materials Research Society 2003

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References

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