By Josh Perry, Editor
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Researchers at the University of Houston (Texas) used theoretical calculation to discover a new set of half-Heusler thermoelectric compounds, including one with a record high figure of merit, which is used to measure how efficiently thermoelectric materials convert heat to electricity.

New thermoelectric materials could enhance waste heat conversion for clean power applications. (Wikimedia Commons)

In fact, the material maintained its high figure of merit at all temperatures, according to a report from the university, and researchers see it having potential in waste heat conversion and clean power. The record-breaking material was composed of tantalum, iron and antimony.

The researchers measured the conversion efficiency of one compound at 11.4 percent – meaning the material produced 11.4 watts of electricity for every 100 watts of heat it took in,” the report explained. “Theoretical calculations suggest the efficiency could reach 14 percent.” This would be higher than the 10 percent of thermoelectric devices.

Simulations demonstrated six different compounds and the researchers were able to synthesize one.

“Relying on theoretical calculations to predict compounds expected to have high thermoelectric performance allowed the researchers to hone in on the most promising compounds,” the report said. “But actually creating materials composed of tantalum, iron and antimony…proved complex, partly because the components have such disparate physical properties.”

The materials are cost-effective, and the results of testing matched the simulation data, which researchers insist proves the viability of computational methods for determining material properties.

The research was recently published in Nature Communications. The abstract read:

“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.”