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Effects of Ga- and In-doping on the Thermoelectric Properties in Ba-Ge Clathrate Compounds

Published online by Cambridge University Press:  26 February 2011

Norihiko L. Okamoto
Affiliation:
Department of Materials Science and Engineering, Kyoto University Sakyo-ku, Kyoto 606–8501, Japan
Haruyuki Inui
Affiliation:
Department of Materials Science and Engineering, Kyoto University Sakyo-ku, Kyoto 606–8501, Japan
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Abstract

The crystal structures and thermoelectric properties of Ba-Ge type-I clathrate compounds (Ba8GaXGe46-X and Ba8Ga16-YInYGe30) have been investigated as a function of Ga and In contents. Ba8GaXGe46-X alloys have a crystal structure that contains an ordered arrangement of Ge vacancies, forming a superstructure based on the normal type-I structure until X reaches 3, whereas they have the normal type-I structure when X exceeds 3. The dimensionless thermoelectric figure of merit (ZT) increases with the increase in the Ga content, exhibiting the highest value of 0.49 for Ba8Ga16Ge30. The power factor for Ba8Ga10In6Ge30 is 1.5 times that for Ba8Ga16Ge30 so that the In containing alloy exhibits a ZT value as high as 1.03 at 700°C.

Type
Research Article
Copyright
Copyright © Materials Research Society 2005

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References

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