Structure and thermoelectric properties of nanocomposite bismuth telluride prepared by melt spinning or by partially alloying with IV-VI compounds

Bismuth telluride samples are compared with respect to the evolution of their thermoelectric material parameters like thermal and electrical conductivity. The Seebeck coefficient is discussed in dependence on the melt spinning fabrication technique. The melt spinner used is only able to produce small thin ribbon shaped specimens, some as thin as 10 mu m. This limits melt spinning to mainly production of research specimens for alloys with high critical cooling rate, which are difficult to fabricate with other techniques. Additional parameters are alloying or doping of the base material by comparing the properties as prepared to different annealing conditions. The intrinsic p- and n-doped material was alloyed with up to 0.5% lead telluride by rapidly cooling the bulk material to improve the thermoelectric properties analysed from RT up to about 600 K. A Seebeck coefficient of well above 200 mu V/K could be obtained for p- and n-type materials. (C) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.