Abstract
Discovery of thermoelectric materials has long been realized by the Edisonian trial and error approach. However, recent progress in theoretical calculations, including the ability to predict structures of unknown phases along with their thermodynamic stability and functional properties, has enabled the so-called inverse design approach. Compared to the traditional materials discovery, the inverse design approach has the potential to substantially reduce the experimental efforts needed to identify promising compounds with target functionalities. By adopting this approach, here we have discovered several unreported half-Heusler compounds. Among them, the p-type TaFeSb-based half-Heusler demonstrates a record high ZT of ~1.52 at 973 K. Additionally, an ultrahigh average ZT of ~0.93 between 300 and 973 K is achieved. Such an extraordinary thermoelectric performance is further verified by the heat-to-electricity conversion efficiency measurement and a high efficiency of ~11.4% is obtained. Our work demonstrates that the TaFeSb-based half-Heuslers are highly promising for thermoelectric power generation.
Highlights
Discovery of thermoelectric materials has long been realized by the Edisonian trial and error approach
We have discovered 6 undocumented compounds and 5 of them are stable with the half-Heusler crystal structure
Heusler phases were first conducted. In this family (27 compounds in total), 8 compounds have been documented to be stable while no experimental reports can be found for the remaining 19
Summary
Discovery of thermoelectric materials has long been realized by the Edisonian trial and error approach. Compared to the traditional materials discovery, the inverse design approach has the potential to substantially reduce the experimental efforts needed to identify promising compounds with target functionalities. By adopting this approach, here we have discovered several unreported half-Heusler compounds. A consequence of the low reliability is that the predicted compounds (especially ones that have not yet been experimentally made) with promising thermoelectric performance may be experimentally identified as metastable or unstable This is a particular challenge for thermoelectrics because a main approach for resolving the opposite dependencies of the transport properties, e.g., S and σ, is through unusual electronic structures, but unusual electronic properties are often found in calculations for unstable compounds, e.g., due to unfavorable bonding. The inverse design approach[20], which targets at the specific functionalities and involves with calculations of structure as well as thermodynamic stability and followed by the experimental realization, is capable of significantly expediting the material discovery
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