Application of Spark Plasma Sintering for Manufacturing of Thermoelectric Materials

V-VI thermoelectric compounds like Bi2Te3-based alloys are well known for room temperature applications like Peltier coolers or thermogenerators. Their anisotropic physical properties and mechanical weakness are a problem for the manufacturing. To overcome the mechanical problem Spark Plasma Sintering (SPS) was used. 2 inch Wafers of polycrystalline bismuth telluride based n-type and p-type thermoelectric materials were successfully fabricated through SPS-technique, starting from commercially available zonemelted ingots. This paper will report on the milling technique and the influence of the SPS process on the microstructure, the thermoelectric and mechanical properties of the polycrystalline materials. A preferentially oriented microstructure was formed keeping the high quality of the the starting material. Through the polycrystalline structure, the bending strength of the sintered material was increased about three times compared with coarse crystalline ingots.