Microstructure, mechanical properties and thermoelectric properties of p-type Te-doped Bi_(0.5)Sb_(1.5)Te_3 compounds fabricated by hot extrusion

摘要

Bismuth telluride (Bi2Te3) compounds have been used as thermoelectric cooling and heating materials, since they have a high figure of merit at room temperature and can be fabricated easily and cheaply. The compounds have a rhombohedral structure (a = 0.438 nm and c = 3.049 nm) and belong to the space group R3m [1]. The electrical and mechanical properties along the two equivalent directions parallel to the (1 1 1) cleavage planes are better than those along the c axis, which is perpendicular to these planes [2,3]. Since the compounds have cleavage features, they are difficult materials for the mass production of small thermo-electric modules. In this work, to avoid the cleavage features, we attempted to refine the grains and to improve the mechanical properties by means of hot extrusion.