Thermoelectric properties of composites made of Ni0.05Mo3Sb5.4Te1.6 and fullerene

About 18 g of Ni0.05Mo3Sb5.4Te1.6 were prepared by heating the elements in the stoichiometric ratio at 1000 K. The product was divided into four parts, and then C60 was added to three of these four parts at 1, 2, and 3 mass%, respectively. Each part was hot-pressed at 150 MPa and 923 K. The sample with 1% C60 was characterized via a Rietveld refinement and TEM analyses. Measurements of the three thermoelectric key properties revealed that the Seebeck coefficient barely depends on the carbon amount added, while both the electrical and the thermal conductivity decrease with increasing amount of carbon. Depending on the amount of C60 used and on the temperature, the thermoelectric performance was either enhanced or decreased, depending on whether the electrical conductivity decreased less or more than the thermal conductivity. At the highest temperature measured, all carbon-containing samples performed better than the unmodified bulk sample, namely up to 14%. These improvements are within the error margin, however.