Melt Spinning Preparation of Bismuth Telluride and Partially Alloying with IV-VI Compounds for Thermoelectric Application

The melt spinning technique (MST) combined with post annealing processes is evaluated for the development of thermoelectric nanocomposites. The evaluated ones are based on two components almost immiscible in solid state but with crystallographic correlation. One is taken from the V-VI-components system and the other one from the IV-VI-components system. This concept was applied to p-(Bi 0,2 Sb 0,8 ) 2 Te 3 and to p-[(Bi 0,2 Sb 0,8 ) 2 Te 3 ] 1-x PbTe x composites. MST samples of all types were characterised for some structural and thermoelectric properties. All V-VI materials are clearly textured after MST and show no deterioration concerning the thermoelectric properties even after subsequent annealing processes. Structural analysis of p-[(Bi 0,2 Sb 0,8 ) 2 Te 3 ] 1-x PbTe x composites gave significant hints for oriented precipitates of a IV-VI-rich phase incorporated into the V-VI-rich matrix. The thermoelectric figure of merit of the evaluated composites could be enhanced by suitable annealing procedures of both the quenched bulk materials and the melt spin material.