THERMOELECTRIC AND MECHANICAL-PROPERTIES OF BI-TE MATERIALS PREPARED BY HOT PRESS METHOD

The purpose of this work is to present thermoelectric and mechanical p roperties of Bi-Te polycrystalline materials. Semiconducting ceramics of p- and n-type bismuth telluride were prepared by a hot press method . High purity row materials of Bi, Sb, Te and Se were used for the all oy preparation and the sample with a dimension of 144 mm in diameter a nd 35 mm in hight was obtained. The tensile and compressive strengths of n-type were 20.6 and 118 MPa, respectively, being independent of ho t press directions. A thermomechanical analysis (TMA) was used to dete rmine the thermal expansion coefficient of 1.59 x 10(-5) K-1 for n-typ e and 1.69 x 10(-5) K-1 for p-type. The thermal expansion coefficient was dependent on the hot press direction. The thermoelectric modules w ere fabricated to determine their figure of merit of 2.3 x 10(-3) K-1 at 20 degrees C. From the present observations, the polycrystalline bi smuth telluride was found to have the same thermoelectric properties a s zone-melting ones.