日本金属学会誌

J. Japan Inst. Met. Mater, Vol. 79, No. 11 (2015),
pp. 581-585

Improvement of Thermoelectric Performance and P-N Control for Metal-Doped β-Rhombohedral Boron

Yoshiki Takagiwa1, Norihide Kuroda2, Erika Imai2, Ikuzo Kanazawa2, Hiroshi Hyodo3, Kohei Soga4 and Kaoru Kimura1

1Department of Advanced Materials Science, Graduate School of Frontier Sciences, The University of Tokyo, Kashiwa 277-8561
2Department of Physics, Tokyo Gakugei University, Tokyo 184-0015
3Institute for Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577
4Department of Materials Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, Tokyo 125-8585

Abstract:

The effects of Cu-doping into β-rhombohedral boron on the thermoelectric properties have been investigated. The electrical conductivity increases with increasing Cu concentration up to 5 at%, while a positive Seebeck coefficient monotonically decreases because of an increase in the carrier concentration. Consequently, the power factor enhances by four times from 22 µW m-1 K-2 to 90 µW m-1 K-2 at 973 K. In addition, Cu-doping contributes to lower the thermal conductivity from 4.3 W m-1 K-1 to 2.3 W m-1 K-1 at 973 K due to an increase in phonon scattering events. The dimensionless figure of merit, ZT, enhances from 0.006 to 0.038 at 973 K for Cu4B105 as p-type. The observed ZT is higher than that of conventional thermoelectric boride B4C.

[doi:10.2320/jinstmet.JA201507]


(Received 2015/5/1)

Keywords:

boron, borides, thermoelectric properties, chemical doping


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