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A5: Nanoscale and low dimensional effects
We made an attempt to increase the ductility and conductivity of a well-known thermoelectric oxide Ca3Co4O9 (Co349) by doping it with nano-sized silver particles. The studied material system was Co349, Co349 with 1 wt-% Ag, as well as Co349 with 5 wt-% Ag. The nominal particle size of Ag was 10 nm. The effect of processing had the most striking effect on thermal conductivity of Ag-doped samples, while electrical conductivity remained at the same level as with the undoped reference material. The decrease in thermal conductivity is related to enhanced porosity, i.e. decrease in density. The measurement data include SEM/EDS, surface area of the samples (BET) and density. Electrical resistivity, Seebeck coefficient and thermal conductivity were measured as a function of temperature. We also measured power generation properties of the rectangular specimen under large temperature difference conditions.