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Single crystallization of Ba8AlxSi46−x clathrate for improvement of thermoelectric properties

Published online by Cambridge University Press:  27 July 2011

Naoki Mugita ,
Yusuke Nakakohara ,
Ryo Teranishi  and
Shinji Munetoh
Naoki Mugita*
Affiliation:
Department of Materials Science and Engineering, Kyushu University, Fukuoka 819-0395, Japan
Yusuke Nakakohara
Affiliation:
Department of Materials Science and Engineering, Kyushu University, Fukuoka 819-0395, Japan
Ryo Teranishi
Affiliation:
Department of Materials Science and Engineering, Kyushu University, Fukuoka 819-0395, Japan
Shinji Munetoh
Affiliation:
Department of Materials Science and Engineering, Kyushu University, Fukuoka 819-0395, Japan
*
a)Address all correspondence to this author. e-mail: mugita@zaiko14.zaiko.kyushu-u.ac.jp
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Abstract

We have synthesized single- and polycrystal Ba8AlxSi46−x clathrates to compare their thermoelectric properties. Single-crystal sample was prepared by Czochralski method in an argon atmosphere. Polycrystal sample was prepared by arc melting and annealed at 850 °C for 100 h in an argon atmosphere. The Seebeck coefficients of single- and polycrystal Ba8Al12Si34 at 500 °C were 44.5 and 53.0 μV/K, respectively. The Seebeck coefficients of both samples were almost the same because the Seebeck coefficients depend on carrier concentration, which is related to aluminum content. The electrical resistivity of the single-crystal sample with 0.49 mΩcm was lower than that of the polycrystal sample with 0.95 mΩcm because of the reduction of electron scattering. Therefore, the power factor of the single-crystal sample with 4.0 × 10−4 V2/K2Ωm was higher than that of the polycrystal sample with 3.0 × 10−4 V2/K2Ωm at 500 °C. It is suggested that single crystallization is efficient for improvement of the thermoelectric property in the Ba8AlxSi46−x clathrate.

Keywords

ThermoelectricCrystal growth
Type
Articles
Information
Journal of Materials Research , Volume 26 , Issue 15: Focus Issue: Advances in Thermoelectric Materials , 14 August 2011 , pp. 1857 - 1860
Copyright
Copyright © Materials Research Society 2011

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References

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