Thermoelectric properties of Ni-doped CeFe₄Sb₁₂ skutterudites Available to Purchase

We have prepared Ni-doped p-type skutterudites Ce_yFe_4−xNi_xSb₁₂ and systematically studied their thermoelectric properties. The lattice parameters of these skutterudites are found to be sensitive to both the Ni content and Ce-filling fraction. With increasing Ni content, the electrical conductivity decreases and the Seebeck coefficient increases, consistent with the expected decrease in hole concentration due to the extra electrons introduced by Ni. All Ni-doped samples possess similar band gap values. We also find that the Ni-doped Ce_yFe_4−xNi_xSb₁₂ system has electrical transport properties similar to those of Co-doped Ce_yFe_4−xCo_xSb₁₂ system at a similar nominal hole concentration based on a simple charge counting. We do, however, find a pronounced bi-polar phenomenon in thermal conductivity that rapidly increases for Ni-doped samples when temperature is above 600 K. Importantly, Ni-doped samples have higher dimensionless thermoelectric figures of merit values than CeFe₄Sb₁₂ over the entire temperature range measured. Therefore, Ni doping is useful for improving the energy conversion efficiency in applications.