Enhancement of thermoelectric performance with pressure in Ce0.8Fe3CoSb12.1

•High pressure properties of Ce0.8Fe3CoSb12.1 have been measured.•Estimates of acoustic and electronic contributions to thermal conductivity have been computed.•Based on thermal conductivity, another scattering process is required for low pressures.•Thermoelectric performance is improved up to approximately 6 GPa.•Anomalous trends are coincident with ‘universal’ EOS models. All can be associated with Ce valence.

Transport properties (resistivity, thermal conductivity, and Seebeck coefficient) and sound velocities have been determined for the skutterudite Ce0.8Fe3CoSb12.1 with pressure up to 14 GPa. From these measurements, high pressure anomalous features were found in all transport properties. By correlating these with results from previous x-ray work, it has been determined that there is likely an electronic topological transition in this material induced by pressure. This is possibly due to the known pressure variation of valence in the void-filling Ce atom and has been found to induce an improved figure of merit at higher pressures, which shows a nearly two-fold increase with applied pressure. At higher pressures, it was determined that this anomalous behavior is suppressed and is possibly induced by insertion of Sb from the cage into the remaining central voids of the structure, similar to that seen in the CoSb3 parent compound.