On electrical transport and thermoelectric performance in Half-Heusler phase ScNiSb

Half-Heusler (HH) phases are among the most extensively studied thermoelectric materials. Bipolar thermal conductivity analysis performed for their sub-group based on rare-earth (R) metals, RNiSb, indicated high mobility ratio in favor of electrons. The result motivated studies of ScNiSb1-xTex series in which n-type-doped samples shown higher mobility and significantly improved thermoelectric performance [K. Ciesielski et al., Phys. Rev. Appl. 15, 044047 (2021)]. Recently, Kajikawa attempted alternative interpretation of transport properties in ScNiSb, where multi-parameter fit led to mobility ratio in favor of holes [Y. Kajikawa, Int. J. Mod. Phys. B 2250071 (2022)]. In this work we discuss the details of electrical properties and thermoelectric performance of ScNiSb in the context of structural disorder and the most recent experimental literature on a related chemical system. The paper considers also relevant assumptions regarding band degeneracy and scattering mechanisms for effective mass modeling in ScNiSb. Last, technical difficulties of the model proposed by Kajikawa are addressed. We believe that the provided insight will be useful for understating electrical transport in HH compounds, which can contribute to further improvement of their thermoelectric performance.

Automated summary

Researchers analyzed the bipolar thermal conductivity of Half-Heusler phases based on rare-earth metals and found a high mobility ratio favoring electrons. They then studied the doped samples of ScNiSb1-xTex and observed higher mobility and improved thermoelectric performance.