FABRICATION AND THERMOELECTRIC PROPERTIES OF n-TYPE SbI 3 -DOPED Bi 2 Te 2.85 Se 0.15 COMPOUNDS BY HOT EXTRUSION J. Seo 1 , K. Park 2 , and C. Lee 1 *† 1 Department of Metallurgical Engineering, Inha University, Inchon 402–751, Republic of Korea 2 Department of Materials Engineering, Chung-ju National University, Chungbuk 380 –702, Republic of Korea (Refereed) Received June 9, 1997; Accepted October 10, 1997 ABSTRACT The n-type 0.1 wt% SbI 3 -doped Bi 2 Te 2.85 Se 0.15 compounds were fabricated by hot extrusion in the temperature range 300 –510°C under an extrusion ratio of 20:1. The extruded compounds were highly dense. The grains were small, equiaxed (1.0 m), and contained many dislocations due to the dynamic recrystallization during the extrusion. The grains were also preferentially oriented through the extrusion. The bending strength and the figure of merit of the compounds, hot-extruded at 440°C, were 97 MPa and 2.62  10 -3 /K, respectively. © 1998 Elsevier Science Ltd KEYWORDS: A. intermetallic compounds, C. electron microscopy, D. elec- trical properties, D. microstructure, D. thermal conductivity INTRODUCTION Bismuth telluride (Bi 2 Te 3 ) based compounds have been used as thermoelectric cooling and heating materials, because they have the high figure of merit at room temperature. The compounds have a rhombohedral structure (a = 0.438 nm and c = 3.049 nm) and belong to space group R3  m [1]. This crystal structure is composed of atomic layers in the order of *To whom correspondence should be addressed. †Jointly appointed at the Center for Advanced Aerospace Materials, Pohang University of Science and Technology, Pohang 790 –784, Republic of Korea. Materials Research Bulletin, Vol. 33, No. 4, pp. 553–559, 1998 Copyright © 1998 Elsevier Science Ltd Printed in the USA. All rights reserved 0025-5408/98 $19.00 + .00 PII S0025-5408(97)00250-X 553