Thermoelectric performance of Ni compensated cerium and neodymium double filled p-type skutterudites.

We have synthesized Ni compensated Ce and Nd double filled p-type skutterudites CexNdxFe3.7Ni0.3Sb12 with x = 0.35, 0.40, 0.45, and 0.5 by a melting-quenching-annealing method. The samples were made by directly hot pressing the hand ground powder at 650 °C for 5 minutes at a pressure of about 80 MPa. Since Ni has two more electrons than Fe, a lower power factor and a stronger bipolar effect in thermal conductivity are expected at higher temperature. In the experiments, we have demonstrated that by suitably tuning the Fe-Ni ratio and filler concentration, we can achieve both a higher power factor (∼35 µW cm(-1) K(-2) at 535 °C) and a lower thermal conductivity (∼2.1 W m(-1) K(-1) at room temperature and ∼2.7 W m(-1) K(-1) at 535 °C) in Ce0.4Nd0.4Fe3.7Ni0.3Sb12. A peak thermoelectric figure-of-merit of ∼1.1 at 475 °C is achieved in Ce0.4Nd0.4Fe3.7Ni0.3Sb12.