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 ×  \({10}^{-5}\) ${10}^{-5}$ Ω.m at 300 K as compared to CoSb₃ solvo-hydrothermal sample with 4.85 ×  \({10}^{-5}\) ${10}^{-5}$ Ω.m. However, CoSb₃ ball mill sample show enhanced Seebeck coefficient of 183µ V/K at 473 K where CoSb₃ solvo-hydrothermal sample depict 98 µ 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⁻¹K⁻¹ and 3.23 W m⁻¹K⁻¹ at room temperature and reaches a significantly lower value of 2.47 W m⁻¹K⁻¹ and 2.46 W m⁻¹K⁻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.