Improved thermoelectric performance of (Zr_0.3Hf_0.7)NiSn half-Heusler compounds by Ta substitution

Abstract

Articles you may be interested inThe thermoelectric performance of Ta substituted (ZrHf)NiSn-based half-Heusler compounds is studied. Here, Ta is used on the Hf site for controlling the charge carrier concentration in contrast to the widely used Sb substitution on the Sn site. The influence of the Ta content on the thermoelectric and transport properties of (Zr 0.3 Hf 0.7-x Ta x )NiSn (x ¼ 0, 0.01, 0.05) is investigated by means of Seebeck coefficient, electrical resistivity, thermal conductivity, and Hall coefficient measurements. The results are analyzed in context of the single parabolic band model. Ta substitution increases the charge carrier concentration and suppresses the influence of impurity band, which is present in the pristine (Zr 0.3 Hf 0.7 )NiSn. Moreover, Ta substitution decouples and simultaneously increases the density-of-states effective mass (m*) and the charge carrier mobility (l), leading to a larger weighted mobility lÁ(m*) 3/2 . The lattice thermal conductivity is slightly suppressed due to increased point defect scattering. As a result, a Figure

Hf/Sb co-doping induced a high thermoelectric performance of ZrNiSn: First-principles calculation

“…The calculated E g of ZrNiSn is about 0.52 eV which is similar to that with PBE-GGA (0.51 eV), and it is also good agreement with previously calculated value (~0.50 eV) 29,30 . The band gap can be estimated using experimental data from the temperature reliance on σ by 31 :where σ 0 is a pre-exponential factor. Muta et al .…”

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

“…Due to the excellent electrical and mechanical properties, high-temperature stability, and possibility to use non-critical elements, half-Heusler (HH) compounds have become attractive candidates for thermoelectric application [27][28][29][30][31]. This compound has a general formula XYZ (X, Y = transition metals, Z = main group elements), crystallizing in cubic C1 b structure, F 43m space group [32,33].…”

Half‐Heusler materials as model systems for phase‐separated thermoelectrics

“…In particular, the n‐type system (Ti/Zr/Hf)NiSn has been investigated in this regard , leading to several patent applications . It was shown that band engineering by Ta substitution of (ZrHf)NiSn not only reduces effectively the thermal conductivity, but also improves the stability as well as the charge carrier mobility and effective mass (). In contrast, state‐of‐the‐art p‐type half‐Heusler materials rely on a nanostructuring approach involving ball milling followed by a rapid consolidation method which is a very time and energy consuming synthesis route .…”