: The present invention discloses a new thermoelectric material families, ZrCoBi-based half-Heuslers. The present invention also discloses a new method for half-Heusler materials preparation. Due to the small sound velocity, ZrCoBi-based half-Heuslers demonstrate a lower lattice thermal conductivity. The good power factor is obtained based on the unique band structure. Therefore, ZrCoBi-based half-Heuslers have a higher zT value from 300 K to 973 K. For a typical example, the peak zT of ~1.4 at 973 K with average zT of ~0.8 is achieved in p-type ZrCoBi0.65Sb0.15Sn0.20. A novel ball-milling synthesis method for half-heuslers nano-powder and the hot-pressing method for preparation of the bulk half-heusler materials from this nano-powder are disclosed in present invention. High quality half-heuslers nano-powder can be prepared by ball milling the stoichiometric elements in specific order. Bulk half-heuslers materials with fine grain size and uniform elemental distribution can easily be fabricated by hot pressing nano-powder under specific temperature and pressure.