Improvement in thermoelectric properties of an n-type bismuth telluride (Bi 2Se 0.3Te 2.7) due to texture development and grain refinement during hot deformation

Abstract

Hot deformation of an n-type bismuth telluride (nBT of composition Bi 2Se 0.3Te 2.7) results in a texture characteristic of the deformation mode. Extruded nBT has a fiber texture with ⟨112̄0⟩ directions aligned with the extrusion direction. Rolling of previously textured (extruded) and untextured (sintered powder compact) material results in a rolling texture with the basal plane parallel to the rolling plane, and the ⟨112̄0⟩ directions randomly oriented on the rolling plane. Results indicate an improvement in thermoelectric figure of merit at 300 K from 0.79 in the as-received extruded material to 0.93 in the rolled material.