Effect of triple fillers in thermoelectric performance of p-type skutterudites

Up-to-date, the thermoelectric performance of p-type skutterudites lags that of the corresponding n-type materials. In this work, we report improved thermoelectric performance of p-type skutterudites by triple filling the voids. The samples were synthesized by hot pressing nano-powder made by ball milling the annealed ingots of CaxCe0.35Nd0.35Fe4−yCoySb12 with varying concentration of x and y. By tuning the fillers concentration and Fe/Co ratio, we achieved a lower thermal conductivity (∼2.0 W m−1 K−1 at room temperature and ∼2.6 W m−1 K−1 at 535 °C) and a higher power factor (∼35 μW cm−1 K−2 at 475 °C), leading to a peak ZT of about 1.1 at 475 °C. The observed lower thermal conductivity can be attributed to a broad range of phonon scattering due to multiple fillers and the enhanced mobility due to the light element Ca leading to a high power factor.