Influence of multi-walled carbon nanotubes on the thermoelectric properties of La-filled CoSb3 skutterudite composites

Abstract

Ideal thermoelectric materials are featured with high electrical and low thermal conduction. Oxide nanoparticles are usually added to these materials to increase their thermoelectric properties. The conductive particles are seldom employed since they have a complex effect on thermoelectric properties. Here we select the multi-walled carbon nanotubes (MWCNTs) as additives to synthesize a composite of La-filled CoSb3 skutterudite via a solvothermal method. The electrical conductivities and Seebeck coefficients of the obtained composites are tested by using a four-probe technique. The thermal conductivities are measured by a thermal diffusivity system using Pyroceram as a reference sample. The thermoelectric properties of the La-filled CoSb3/MWCNTs composites are investigated in the temperature range of 300–800 K. The influence of the MWCNTs on the electrical conductivity, the Seebeck coefficient and the thermal conductivity of the La-filled CoSb3/MWCNTs composites are discussed. The maximum figure of merit of the composites at 780 K is improved by 37%.