Enhanced Thermoelectric Performance of GeTe-Based Composites Incorporated with Fe Nanoparticles.

Incorporated nanoscale phases in thermoelectric (TE) materials can optimize the electronic and thermal transport properties to obtain high-performance TE materials. The rapid spark plasma sintering (SPS) technique is adopted to synthesize GeBiTe composites incorporated with soft magnetic Fe nanoparticles (nano-Fe) and their thermoelectric performance is researched in this study. With the phase transition of the GeBiTe matrix from the low-temperature rhombohedral phase to the high-temperature cubic one, the interface contact between GeBiTe and nano-Fe is transformed from Schottky contact to Ohmic one, which improves its electronic transport performance at high temperatures. At the same time, the additional Fe nanoprecipitation phonon scattering can reduce the lattice thermal conductivity to ∼0.66 W m K. These mechanisms result in a high value of 1.65 and a relatively highquality factor of 1.05 at 785 K for GeBiTe/2 mol % Fe. This work suggests that the thermoelectric performance of composite materials can be enhanced by introducing a variable interface band structure.