Preparation of high performance Bi2Sr2Co1.8Ox thermoelectric materials from nanosized precursors

Abstract

ABSTRACTBi2Sr2Co1.8Ox thermoelectric (TE) materials were prepared by three different synthesis methods producing nanosized precursors: coprecipitation (with ammonium carbonate or oxalic acid) and attrition milling, which were compared with those obtained by the classical solid state method. Microstructure has shown that precursors produced by coprecipitation and attrition milling methods produced nanometric precursors much smaller than the typical sizes produced by the solid state route. The TE properties are in agreement with the microstructural features, leading to lower resistivity in all the samples, compared with the solid state ones, while Seebeck coefficient is practically unchanged in all cases. As a consequence, maximum power factor values of around four times higher than those obtained in the classical solid state method have been determined. Moreover, the highest power factor value at 650°C is higher than the best results obtained in as-grown textured materials produced by the laser floating zone technique.