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

TL;DR

This paper investigates the electrical transport and thermoelectric properties of ScNiSb, addressing conflicting interpretations and emphasizing the role of structural disorder, band degeneracy, and scattering mechanisms to improve thermoelectric performance.

Contribution

It provides a detailed analysis of electrical properties and thermoelectric performance of ScNiSb, clarifying transport mechanisms and addressing previous model limitations.

Findings

High mobility ratio favoring electrons confirmed experimentally

Structural disorder significantly influences transport properties

Insights into band degeneracy and scattering mechanisms for better modeling

Abstract

Half-Heusler phases are among the most extensively studied thermoelectic materials. Bipolar thermal conductivity analysis performed for their sub-group based on rare-earth (R) metals, RNiSb, indicated on high mobility ratio in favor of electrons. The suggestion found its experimental verification and led to significant improvement of thermoelectric properties in $n$-type doped series ScNiSb$_{1-x}$Te$_x$. Recently, an alternative interpretation of transport properties in ScNiSb was proposed, where multi-parameter fit lead to mobility ratio in favor of holes. In this work we discuss the details of electrical properties and thermoelectric performance of ScNiSb in context of structural disorder. The article considers also relevant assumptions regarding band degeneracy and scattering mechanisms for effective mass modeling in ScNiSb. Lastly, technical difficulties of the model proposed by the others are addressed. We believe, that the provided insight will be useful for understating electrical transport in half-Heusler compounds, which can contribute to further improvement of their thermoelectric performance.