Discovery of ZrCoBi based half Heuslers with high thermoelectric conversion efficiency

Thermoelectric materials are capable of converting waste heat into electricity. The dimensionless figure-of-merit (ZT), as the critical measure for the material's thermoelectric performance, plays a decisive role in the energy conversion efficiency. Half-Heusler materials, as one of the most promising candidates for thermoelectric power generation, have relatively low ZTs compared to other material systems. Here we report the discovery of p-type ZrCoBibased half-Heuslers with a record-high ZT of similar to 1.42 at 973 K and a high thermoelectric conversion efficiency of similar to 9% at the temperature difference of similar to 500 K. Such an outstanding thermoelectric performance originates from its unique band structure offering a high band degeneracy (N-v) of 10 in conjunction with a low thermal conductivity benefiting from the low mean sound velocity (v(m) similar to 2800ms(-1)). Our work demonstrates that ZrCoBi-based half-Heuslers are promising candidates for high-temperature thermoelectric power generation.