Bi 2Te 3-related thermoelectric samples with aligned-texture prepared by plastic deformation

Abstract

Plastic deformation study of Bi 2Te 3-related materials was performed. The ingots were grown by the Bridgman method using source materials with nominal compositions of Bi 0.5Sb 1.5Te 3, Bi 2Sb 2.85Se 0.15 and Bi 1.8Sb 0.2Te 2.85Se 0.15. Disks were cut from the ingots, and were then deformed by either cold-pressing or by hot-pressing under pulse current heating. The crystal structures of the deformed samples were identified by X-ray diffraction. All diffraction peaks were assigned to the Bi 2Te 3 structure, and the diffraction patterns indicate that the surfaces and bottoms of the samples were highly oriented in the hexagonal (00-l) plane. Hall effect measurements show the carrier concentration of the samples to be at an order of magnitude of 10 25 m -3 at room temperature. The power factor for the samples after hot-press deformation exceeded that for the original ingots. The results suggest that hot-press deformation enhances the thermoelectric properties of Bi 2Te 3-related materials. © 2005 The Japan Institute of Metals.