Materials Transactions Online

Materials Transactions, Vol.49 No.04 (2008) pp.889-891
© 2008 The Japan Institute of Metals

Equal Channel Angular Extrued Bi0.5Sb1.5Te3 Thermoelectric Compound

CheolHo Lim1, KyungTaek Kim2, YongHwan Kim2, ChangHun Lee1 and ChiHwan Lee1

1Dept. of Metallurgical Engineering, College of Engineering, Inha University, 253 Yonghyun-Dong, Nam-Gu, Incheon, 402-751, Korea
2New Functional Materials Team, Korea Institute of Industrial Technology, 7-47 Songdo-Dong, Yeonsu-Gu, Incheon, 406-840, Korea

The effects of equal channel angular extrusion (ECAE) process parameters on microstructure and thermoelectric properties of the p-type Bi0.5Sb1.5Te3 compound have been investigated. ECAE was carried out under various temperatures (653 K, 693 K, 733 K) and ram speeds (0.5 mm/s, 1 mm/s, 2 mm/s). Fraction of recrystallized grains and grain size was found to be increase with lower ram speed and higher deformation temperature. As a result, Seebeck coefficient increased, and electrical resistivity and thermal conductivity decreased. The decrease in thermal conductivity was attributed to the decrease of lattice thermal conductivity (κph) which is independent of electrical properties. Maximum figure-of-merit (2.87× 10-3 K-1) was achieved in as-ECAE'ed specimen at 733 K and at ram speed of 0.5 mm/s. This value was found to be 6% higher than that of as-sintered specimen.

(Received 2007/11/27; Accepted 2008/2/13; Published 2008/3/19)

Keywords: thermoelectric, Bi2Te3, equal channel angular extrusion

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