Influence of composition and texture on the thermoelectric and mechanical properties of extruded (Bi1-xSbx)2(Te1-ySey)3 alloys

This paper presents the results obtained after five years of process development to produce bismuth telluride based thermoelectric alloys by powder consolidation approach. The synthesis of the alloys is obtained by mechanical alloying from pure elemental powders. Billets are then produced by cold pressing followed by hot extrusion in order to have a fully dense polycrystalline product with a crystal texture characterized by the c-axis aligned perpendicularly to the extrusion direction. Semiconductors of type-n and type-p were produced by carefully controlling the chemical composition of the alloys and the concentration of doping agents. The evolution of the thermoelectric properties is given as a function of the constituents contents of the alloy to determine an optimal composition that leads to maximum value of the figure of merit. The effect of texture is measured not only on the thermoelectric properties but also on the mechanical behaviour of the material.