Power factor enhancement in a composite based on the half-Heusler antimonide TmNiSb

Abstract

Electrical transport studies of half-Heusler (HH)-based composites (TmNiSb)1−x(TmNiSn)x were carried out in a wide temperature range aimed at searching for possible enhancement in the thermoelectric power factor (PF) over that observed in the parent compound TmNiSb. The best thermoelectric performance was found in the sample with x = 0.25, which showed PF = 1.3 × 10−3 W/mK at 1000 K, i.e., about 70% larger than PF of TmNiSb at the same temperature. The PF improvement was obtained due to the formation in the composite system of a microstructure in which semiconducting-like particles of TmNiSb were covered with a metallic layer of TmNiSn. The largest Seebeck coefficient S = 137 μV/K was observed for HH alloy TmNiSb at 560 K. In turn, TmNiSn showed a metallic behavior with small negative thermoelectric power (S = –2.6 μV/K).

Thermal and Electronic Transport Properties of the Half-Heusler Phase ScNiSb

“…The temperature dependence of the power factor (PF = S 2 / ρ ) calculated from the measured data of ScNiSb is presented in Figure 3c. On increasing temperature, PF starts growing above about 50 K and reaches a maximum of 0.90(4) × 10 −3 W m K 2 at 810 K. This value is similar to those determined for other RE-based HH phases [3,5,38,39,40,41,42] and other thermoelectric materials [49].…”

“…Motivated by the literature data, we decided to investigate high-temperature thermoelectric properties of ScNiSb, which seemed to be not explored before, and low-temperature thermoelectric properties in order to not only compare our results with those already published, but also to search for other physical properties, e.g., superconductivity. This research is a part of our comprehensive studies on thermoelectricity in RE-based HH phases [38,39,40,41,42].…”

Anomalous Hall effect and negative longitudinal magnetoresistance in half-Heusler topological semimetal candidates TbPtBi and HoPtBi

“…3 We focus our investigations mainly on the rare-earth (RE) based half-Heusler phases whose physical properties are very diverse, including antiferromagnetism, superconductivity, heavy-fermion behavior, good thermoelectric performance, and non-trivial topological properties. [4][5][6][7][8][9][10][11][12][13][14] Particular attention is paid to platinum-bearing half-Heusler materials, which were found to exhibit the distinctive features of topological semimetals. 6,[15][16][17] Besides, some of these compounds were reported to superconduct at low temperatures despite very low carrier concentrations.…”

Half-Heusler phase TmNiSb under pressure: intrinsic phase separation, thermoelectric performance and structural transition

“…Further ab-initio study seems necessary to clarify the driving force of this intriguing type of phase separation. PS was not observed for TmNiSb samples prepared at ambient pressures 48 , 60 , neither it was reported for Sc Tm NiSb solid solutions prepared by HPHT method 59 . In the latter case, reason for overlooking this feature was high magnification in EDS mapping (scale bar 1 m), allowing only observation of elemental distribution in single grain and possibly the neighboring impurity.…”

“…The study is complemented by thermoelectric characterization, which shows that pressure-driven phase separation might be useful for optimization of the performance. This work is part of larger project aimed at investigation of structural, thermoelectric and magnetic properties of rare-earth bearing HH compounds 60 – 67 .…”