Improved zT in Nb 5 Ge 3 -GeTe thermoelectric nanocomposite.

Robust electronic transport properties is a crucial in designing high performance thermoelectrics. A key similarity between superconductor and thermoelectric lies in their generally high electrical conductivity, even at above its superconducting temperature. In this work, we design a nanocomposite between Nb 5 Ge 3 and GeTe-based thermoelectric to improve its thermoelectric figure of merit zT . Phase and microstructural characterization shows distinct Nb 5 Ge 3 precipitates embed in Ge 0.9 Sb 0.1 Te matrix. In addition, experimental electronic and thermal transport analysis, together with density functional theory calculation were employed to show the synergistic effect of doping Sb and Nb 5 Ge 3 nanocomposite approach. 10% Sb doping was found to optimize the electronic properties of the GeTe-based matrix. Further addition of 2 wt% Nb 5 Ge 3 nanocomposite to the matrix enhances the phonon scattering, which consequently lowers the lattice thermal conductivity, which results in zT of up to 2.0 at 723 K. Such superconductor nanocomposite approach shown in this work can be employed to enhance the properties of other thermoelectric materials.