Improved zT in Nb5Ge3-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 Nb5Ge3 and GeTe-based thermoelectric to improve its thermoelectric figure of merit zT. Phase and microstructural characterization shows distinct Nb5Ge3 precipitates embed in Ge0.9Sb0.1Te 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 Nb5Ge3 nanocomposite approach. 10% Sb doping was found to optimize the electronic properties of the GeTe-based matrix. Further addition of 2 wt% Nb5Ge3 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.

Automated summary

In this study, a nanocomposite of Nb5Ge3 and GeTe-based thermoelectric material was designed to improve zT by optimizing electronic properties and enhancing phonon scattering. The addition of 10% Sb doping and 2 wt% Nb5Ge3 nanocomposite showed synergistic effects in lowering lattice thermal conductivity and achieving zT of up to 2.0 at 723 K, demonstrating the potential for enhancing the properties of other thermoelectric materials.