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New high-throughput search strategies based on statistical identification of promising chemical subspaces show potential for accelerating half-Heusler thermoelectric materials discovery. 

Compositional diversity and intriguing structural features have made Zintl phases excellent candidates as thermoelectric materials. Zintl phase with 21-4-18 composition has shown high thermoelectric performance in the mid- to high-temperature ranges. The complex crystal structure and favorable transport properties of these compounds indicate the potential for high thermoelectric efficiency. Arsenic-based Eu21Zn4As18, belonging to the Ca21Mn4Sb18 structure type, exhibits a semiconductor-like p-type transport behavior and has a calculated band gap of 0.49 eV. The compound is paramagnetic at high temperatures, with an antiferromagnetic transition occurring at T-N = similar to 10 K. The moment obtained from the Curie-Weiss data fit aligns with Eu2+ ions. At the same time, the field-dependent measurement at 2 K indicates complex magnetic ordering with a saturation moment consistent with Eu2+ ions. Pristine Eu21Zn4As18 exhibits an ultralow lattice thermal conductivity of 0.40 W m(-1) K-1 at 873 K. Electronic transport properties measurement shows evidence of bipolar conduction across much of the measured temperature range (450-780 K). However, the Seebeck coefficient remains extremely high (>440 mu V K-1) across this range, indicating the potential for high zT if an appropriate dopant is found. This work represents the first report on the temperature-dependent thermal conductivity, Seebeck coefficient, and thermoelectric efficiency of the arsenic-containing Zintl phase with 21-4-18 composition, showcasing its promise for further optimization of the thermoelectric performance. 

Bi1−xSbx alloys are classic thermoelectric materials for near-cryogenic applications. Despite more than half a century of study, unraveling the underlying transport physics within this space has been nontrivial due to the complex electronic structure, disorder, and small bandgap within these alloys. Furthermore, as Peltier coolers, Bi1−xSbx alloys operate in a bipolar regime; as such, understanding the impact of minority carriers is critical for further improvements in device performance. This study unites first principles calculations with low-temperature experimental measurements to create a generalized model for transport within semiconducting Bi-Sb alloys. Our exploration reveals the interplay between the complex, degenerate valence band structure with the extremely light conduction bands. By building a hybrid computational/experimental model, an understanding of both the electron and hole relaxation times emerges both as a function of temperature and energy. Special quasi-random supercell calculations reveal that, despite significant atomic disorder, the electronic band structures within the alloy remains largely unaffected and electron–phonon scattering dominates. For charge carriers near the band edges, the relaxation times are thus extremely long, consistent with cyclotronic behavior appearing at low magnetic fields (≪ 1 T). Modeling thermoelectric performance suggests that the valence band edge deformation potential is significantly weaker and highlights the potential for p-type compositions to meet or exceed the current n-type alloys.