Thermal Conductivity Reduction in CoSb 3 –CeO 2 Nanocomposites

CoSb3 + x% CeO2 nanocomposites (x = 1, 3, 5) were synthesized by ball-milling and spark plasma sintering. Scanning electron microscopy showed that some CeO2 nano-inclusions sit at the boundaries of CoSb3 grains. These inclusions also reduce the sizes of the CoSb3 grains and crystallites by inhibiting their growth during sintering. Hall-effect measurements show that the CeO2 inclusions modify the charge-carrier concentration in CoSb3. The variations of the electrical resistivity for the 1% and 3% CeO2 samples can at least partially be attributed to these modifications of the carrier concentration. Nonetheless, the resistivity increase in the 5% CeO2 sample can unambiguously be ascribed to the presence of the CeO2 inclusions. Thermal conductivity is systematically reduced (by more than 15% at 300 K) upon CeO2 addition. Phonon diffusion by the increased number of CoSb3 grain boundaries is one of the mechanisms involved in this reduction.