Enhanced thermoelectric properties of n-type NbCoSn half-Heusler by improving phase purity

Abstract

Here we report the thermoelectric properties of NbCoSn-based n-type half-Heuslers (HHs) that were obtained through arc melting, ball milling, and hot pressing process. With 10% Sb substitution at the Sn site, we obtained enhanced n-type properties with a maximum power factor reaching ∼35 μW cm−1 K−2 and figure of merit (ZT) value ∼0.6 in NbCoSn0.9Sb0.1. The ZT is doubled compared to the previous report. In addition, the specific power cost ($ W−1) is decreased by ∼68% comparing to HfNiSn-based n-type HH because of the elimination of Hf.

Realizing p-type NbCoSn half-Heusler compounds with enhanced thermoelectric performance via Sc substitution

“…To further understand the conduction mechanism, the Hall coefficient at room temperature was measured and the calculated charge carriers concentration and mobility are presented in Figure 5 (a,b). The electron concentration n H for NbCoSn is 17 × 10 19 cm −3, which is on the same order of magnitude as compared to the value reported by He et al (~24 × 10 19 cm −3 ) [37]. Moreover, the n H decreases remarkably with the Sc content reaching 0.04.…”

“…Unsubstituted NbCoSn is an intrinsically n-type semiconductor. In 2006 Ono et al [36] investigated the Sb and Ti substituted n-type NbCoSn and the highest ZT of 0.3 was achieved for the Nb 0.99 Ti 0.01 CoSn 0.9 Sb 0.1 at 850 K. A decade later, He et al [37] synthesized n-type NbCoSn 1-x Sb x samples by arc melting combined with ball milling and hotpressing processes, and the highest ZT reached~0.6 at 1000 K for NbCoSn 0.9 Sb 0.1 . Generally, a TE device needs not only high ZT in n-type and p-type materials, but the n-type and p-type materials should have similar compositions and thus comparable mechanical properties and thermal expansion coefficient.…”

Accelerated Screening of Thermoelectric Materials by First‐Principles Computations of Electron–Phonon Scattering

“…Energy Mater. [2] We note that the experimentally determined values of ZT and x for these compounds [1,2,[39][40][41]43] (filled symbols in Figure 4a,b) somewhat differ from the predicted ones. a-f) The electrical conductivity σ, the Seebeck coefficient S, and the Lorenz number L for p-type HfCoSb and n-type HfNiSn as a function of carrier concentrations p and n calculated within the CRT approximation (long-dashed curves), the EPA approximation (solid curves), and the EPW method (short-dashed curves).…”

“…[40,41] As mentioned above, electronic transport coefficients depend strongly on the electronic chemical potential, and hence the carrier concentration x. [1,2,[39][40][41]43] performance as well as material-level cost and record thermal cycling reliability. Energy Mater.…”

“…The goal of this work is to describe in detail the method that enabled recent computation-driven discovery of new materials, [1,2] demonstrating the power of first-principles design and laying the foundation for future discovery efforts. The goal of this work is to describe in detail the method that enabled recent computation-driven discovery of new materials, [1,2] demonstrating the power of first-principles design and laying the foundation for future discovery efforts.…”