Half-Heusler compounds exhibit significant potential in thermoelectric applications for power generation up to 1000 K, notwithstanding the substantial challenges posed by the cost of constituent elements and the imperative to augment the average thermoelectric figure-of-merit (
zTave) for more practical applications. Overcoming these obstacles demands the advancement of high-performance
p-type TaFeSb thermoelectric materials with diminished Ta content. This investigation systematically explores the quaternary-phase space encompassing Ta, Nb, V, and Ti to ascertain an optimal composition, namely Ta
0.42Nb
0.3V
0.15Ti
0.13FeSb. This composition is characterized by a remarkable reduction in Ta concentration coupled with an enhancement in
zT, peaking at 1.23 at 973 K. Moreover, the integration of a high-mobility secondary phase, InSb, fosters enhancements in both the Seebeck coefficient and electrical conductivity, resulting in a 23% augmentation in the average power factor, while concurrently suppressing lattice thermal conductivity. The optimized composite, Ta
0.42Nb
0.3V
0.15Ti
0.13FeSb-(InSb)
0.015, achieves a peak
zT value of 1.43 at 973 K and a
zTave of 1 from 300 K to 973 K, thereby setting a precedent among
p-type half-Heusler materials. Additionally, a single-leg device demonstrates a peak efficiency of approximately 8% under a temperature difference of 823 K vs. 303 K. These findings underscore the substantial potential of the proposed material design and fabrication methodologies in fostering efficient and sustainable thermoelectric applications.
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