Significant improvement of thermoelectric performance in nanostructured bismuth networks

We present here the first experimental evidence of a significant enhancement in the thermoelectric properties of networks containing bismuth nanotubes and nanowires fabricated via aqueous chemical routes. The as-prepared samples revealed two dominant morphologies: double wall nanotubes with 4-6 nm diameter and nanowires of 15-30 nm diameters. Transport measurements in the range 15-300 K were performed on cold pressed pellets which contained these bismuth nanostructures. We find that the cold pressed networks of nanostructured bismuth exhibit a non-metallic behavior, the corresponding room temperature resistivities vary from similar to 0.54 to 5.8 m Omega-cm, depending on the detailed nanomorphology. The measured thermal conductivity for the networks of bismuth nanotubes and nanowires is almost 5 times lower compared to bismuth powder at room temperature. The observed improvement in the thermoelectric performance has been attributed to the reduced lattice thermal conductivity of nanostructured bismuth networks via interface scattering. (C) 2012 Elsevier Ltd. All rights reserved.