Multiscale Phonon Scattering for Ultra‐Low Thermal Conductivity in Co‐Doped ZrCoBi Half‐Heusler

Abstract

AbstractZrCoBi‐based half‐Heuslers have great potential in thermoelectric power generation due to their high performance in both n‐ and p‐type constituents. In this work, Te and Ni is adopted as an n‐type co‐dopant to increase the carrier concentration and lower the lattice thermal conductivity of ZrCoBi. By further alloying with Sb at the Bi site, a large number of scattering centers of different scales are introduced, significantly reducing the lattice thermal conductivity to ≈1.2 W m−1 K−1 at 300 K and ≈0.96 W m−1 K−1 at 973 K in ZrCo0.94Ni0.06Bi0.775Te0.075Sb0.15. Consequently, the state‐of‐the‐art figure‐of‐merit zT ≈1.2 is achieved, and the average zT reached ≈0.66, which is higher than all of the reported n‐type ZrCoSb‐based and ZrCoBi‐based half‐Heusler alloys. This work provides an effective pathway for optimizing n‐type ZrCoBi alloys, laying the foundation for their further development and application in thermoelectric power generation.