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Thermoelectric Properties of Mg2Si1-x-yGexSby Prepared by Spark Plasma Sintering

Published online by Cambridge University Press:  10 May 2016

Miharu Iida*
Affiliation:
Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan
Tomoyuki Nakamura
Affiliation:
Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan SWCC Showa Cable Systems Co., Ltd., LTD, 4-1-1 Minami-Hashimoto Chuo-Ku Sagamihara, Kanagawa, Japan
Kenjiro Fujimoto
Affiliation:
Department of Pure and Applied Chemistry, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan
Yuki Yamaguchi
Affiliation:
Department of Pure and Applied Chemistry, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan
Ryuji Tamura
Affiliation:
Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan
Tsutomu Iida
Affiliation:
Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan
Keishi Nishio
Affiliation:
Department of Materials Science and Technology, Tokyo University of Science, 6-3-1 Niijyuku, Katsushika-ku, Tokyo 125-8585, Japan
*
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Abstract

The magnesium compound Mg2Si and its solid solutions are expected as n-type thermoelectric (TE) material because they are non-toxic, have a large Clarke number, and are light weight. In this study, we improved TE performance by doping Ge into Sb-doped Mg2Si to cause phonon scattering and increase carrier concentration. A bulk of Sb-doped Si-Ge alloy as the raw material was fabricated using an arc-melting method. A high-purity Mg2Si was synthesized from metal Mg and Sb-doped Si-Ge alloy using spark plasma sintering equipment. For the samples with the same Sb concentration, the electrical conductivity was equivalent. On the other hand, the Seebeck coefficient was dependent on Ge concentration. Due to phonon scattering, thermal conductivity decreased by a small amount of Ge doping and κph dominated for thermal conduction. The minimum thermal conductivity of Mg2Si0.90Ge0.10 was 2.25 W/mK (κph: 2.06 W/mK, κel: 0.19 W/mK). The dimensionless figure of merit (ZT) for the Mg2Si0.945Ge0.05Sb0.005 sample was higher than that of the others due to reducing thermal conductivity and increasing carrier concentration. The maximum ZT was 0.47 at 713 K.

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Articles
Copyright
Copyright © Materials Research Society 2016 

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References

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