Tuning electrical and thermal connectivity in multiwalled carbon nanotube buckypaper.

We find that the electrical and thermal connectivity in multiwalled carbon nanotube buckypaper can be tuned using a spark plasma sintering (SPS) technique. Elevated SPS temperatures promote the formation of inter-tube connections and consequently impact the electrical resistivity, thermoelectric power and thermal conductivity of the buckypaper. In particular, the electrical resistivity as a function of SPS temperature exhibits a percolation-type behavior while the low temperature lattice thermal conductivity shows a crossover behavior in the sample dimensionality. The results are discussed in terms of the quasi-one-dimensional metallic nature of multiwalled carbon nanotubes, the packing density and the electron-phonon coupling.