Electronic and local crystal structures of the ZrNiSn Half-Heusler thermoelectric material

We investigated the electronic and local crystal structures of the sintered half-Heusler ZrNiSn alloy by synchrotron radiation photoemission spectroscopy (SR-PES), synchrotron radiation X-ray powder diffraction (SR-XRD) measurements, and electronic band structure calculations to clarify mechanisms leading to improvements in the thermoelectric properties of materials. In contrast to the predicted semiconductor-like electronic structure, the SR-PES results show a pseudo-gap at the Fermi level, and the SR-XRD analysis reveals an interstitial Ni disorder in the half-Heusler structure. An improvement in the thermoelectric properties can be achieved by material design based on the pseudo-gap electronic structure of half-Heusler ZrNiSn-based alloys.