Double Half-Heuslers

By Shashwat Anand, Max Wood, Yi Xia, Chris Wolverton, G. J. Snyder. Joule, 2019

153 citations recorded by the source corpus.

Summary Since their discovery around a century ago, multi-functional half-Heusler semiconductors have been studied extensively as three-component systems (nominal formula XYZ) with valence balanced compositions. From the very same set of elements and stability rules, we explore a much larger phase space of possible quaternary double (X′X″Y2Z2, X2Y′Y″Z2, and X2Y2Z′Z″), triple (X2′X″Y3Z3), and quadruple (X3′X″Y4Z4) half-Heusler compounds. Using reliable, first-principles thermodynamics on a selection (365) of previously unexplored compositions, we predict more quaternary compounds (131) than those predicted or reported extensively for the ternary systems (84). In comparison to state-of-the-art ternary half-Heusler thermoelectrics, for which performance is limited by their intrinsically high thermal conductivity (κ), κ in double half-Heuslers is dominated by smaller group velocity phonons and limited by disorder scattering. The double half-Heusler Ti2FeNiSb2 was synthesized and confirmed to have a significantly lower κ than TiCoSb, thereby providing a better starting point for thermoelectric efficiency optimization.

Subfields: Electronic, Optical and Magnetic Materials, Materials Chemistry

View Paper: https://www.semanticscholar.org/paper/f0254b66b6663b1ed73c69976c9dca8051e74ae1