Influence of synthesis method and processing on the thermoelectric properties of CoSb3 skutterudites

In the present work, single phase CoSb3 skutterudite nanomaterials were prepared via a ball milling method, and their thermoelectric characteristics were compared with the samples synthesized by the solvo-hydrothermal method. Thermoelectric transport properties were recorded in the temperature regime of 300-830 K. Both samples exhibit p-type conduction behavior with a positive sign of Seebeck coefficient. CoSb3 ball mill sample exhibit higher resistivity of 127 x 10(-5)Omega.m at 300 K as compared to CoSb3 solvo-hydrothermal sample with 4.85 x 10(-5)Omega.m. However, CoSb3 ball mill sample show enhanced Seebeck coefficient of 183 mu V/K at 473 K where CoSb3 solvo-hydrothermal sample depict 98 mu V/K at 650 K. Furthermore, the total thermal conductivity of sintered CoSb3 ball mill and CoSb3 solvo-hydrothermal samples was found to be 3.02 Wm(-1)K(-1) and 3.23 W m(-1)K(-1) at room temperature and reaches a significantly lower value of 2.47 W m(-1)K(-1) and 2.46 W m(-1)K(-1) at 580 and 670 K, respectively. The dimensionless figure of merit ZT values of CoSb3 ball mill and CoSb3 solvo-hydrothermal obtained are 0.053 and 0.060 at 650 and 700 K, respectively. A systematic tuning of processing parameters by ball milling method can lead to better thermoelectric efficiency.