Finding Unprecedentedly Low-Thermal-Conductivity Half-Heusler Semiconductors via High-Throughput Materials Modeling

The lattice thermal conductivity (kappa(omega)) is a key property for many potential applications of compounds. Discovery of materials with very low or high kappa(omega) remains an experimental challenge due to high costs and time-consuming synthesis procedures. High-throughput computational prescreening is a valuable approach for significantly reducing the set of candidate compounds. In this article, we introduce efficient methods for reliably estimating the bulk kappa(omega) for a large number of compounds. The algorithms are based on a combination of machine-learning algorithms, physical insights, and automatic ab initio calculations. We scanned approximately 79,000 half-Heusler entries in the AFLOWLIB.org database. Among the 450 mechanically stable ordered semiconductors identified, we find that kappa(omega) spans more than 2 orders of magnitude-a much larger range than that previously thought. kappa(omega) is lowest for compounds whose elements in equivalent positions have large atomic radii. We then perform a thorough screening of thermodynamical stability that allows us to reduce the list to 75 systems. We then provide a quantitative estimate of kappa(omega) for this selected range of systems. Three semiconductors having kappa(omega) < 5 Wm(-1) K-1 are proposed for further experimental study.