Thermoelectric Properties of Texture-Controlled (GeTe) x(AgSbTe2)100-x (x=75, 80, 85, and 90) Alloys Fabricated by Gas-Atomization and Hot-Extrusion Processes

In this study, p-type (GeTe) (x) (AgSbTe2)(100-x) : TAGS-x (where x = 75, 80, 85, and 90) thermoelectric materials were fabricated by a combination of gas atomization and a hot-extrusion process, and the effects of chemical composition on microstructure, thermoelectric, and mechanical properties were investigated. The extruded samples exhibited higher relative densities (> 99%), and a significant orientation degree parallel to the extrusion direction with fine and homogeneous microstructure was observed. The hardness of extruded samples was around 200-260 kgf/mm(2), which indicates that they have much better mechanical properties than most other TE materials. The power factor of the extruded samples showed excellent values; the maximum power factor achieved was 3.81 x 10(-3) W/mK(2) for TAGS-90 at 723 K due to an effective combination of the Seebeck coefficient and electrical conductivity.