Discovery of ZrCoBi based half Heuslers with high thermoelectric conversion efficiency

Abstract

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 ZrCoBi-based half-Heuslers with a record-high ZT of ∼1.42 at 973 K and a high thermoelectric conversion efficiency of ∼9% at the temperature difference of ∼500 K. Such an outstanding thermoelectric performance originates from its unique band structure offering a high band degeneracy (Nv) of 10 in conjunction with a low thermal conductivity benefiting from the low mean sound velocity (vm ∼2800 m s−1). Our work demonstrates that ZrCoBi-based half-Heuslers are promising candidates for high-temperature thermoelectric power generation.

Zintl-phase Eu 2 ZnSb 2 : A promising thermoelectric material with ultralow thermal conductivity

“…5A, Inset). The room-temperature total thermal conductivity of Eu 2 ZnSb 2 is as low as ∼0.4 W m −1 •K −1 , which is lower than most of the highperformance TE materials (42,43). With increasing Zn deficiency, the total thermal conductivity increases due to the carrier contribution, but remains lower than 0.6 W m −1 •K −1 over the whole measured temperature range.…”

Phase Boundary Mapping in ZrNiSn Half-Heusler for Enhanced Thermoelectric Performance

“…Good TE materials should not only have high ZTs, but also be environmentally friendly, cost-effective, stable, and strong, which arouses the interest on the promising half-Heusler alloys. Many strategies have been proven useful in enhancing the TE performance in this material system, including carrier concentration manipulating and energy band tailoring for improved power factor, and isoelectronic alloying, nano-structure constructing, and phase separation for lowered lattice thermal conductivity [3][4][5][6][7][8][9][10][11][12][13]. High ZTs > 1:5 have been achieved in different kinds of half-Heusler alloys, such as a high ZT~1:52 at 973 K for Ta 0.74 V 0.1 Ti 0.16 FeSb and a high ZT~1:6 at 1200 K for (Nb 1−x Ta x ) 0.8 Ti 0.2 FeSb (x = 0:36 or 0.4) [14,15].…”

Recent Advances in Thermoelectric Performance of Half-Heusler Compounds

“…More recently, a three-stage cascade TEG with a conversion efficiency of 20% was reported [19]. TEGs based on the high zT > 1 HH compounds discussed would have ideal conversion efficiency η near 13% [12,17]. The power-conversion efficiency and power density for an n-p couple and unileg devices built from HH compounds are summarized in Table 2.…”