Microwave synthesis, microstructure, and thermoelectric properties of Zr substituted ZrxTi1−xNiSn half-Heusler bulks

The half-Heusler thermoelectric bulks ZrxTi1−xNiSn (x = 0.1, 0.2, 0.3, 0.4) were rapidly prepared by microwave heating. The phase composition and microstructure were characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM). The electrical and thermal properties were measured by Seebeck coefficient/resistance analysis system (S/RAs) and laser flash thermal analyzer (LFT). The point defects came from Zr-substitution and the in-situ nanostructure attributed to microwave sintering were found to lead to special microstructure and excellent thermal performance. The grain size of Zr0.3Ti0.7NiSn is ∼10 μm. The in-situ nanoscale pores and inclusions are about 300-500 nm. The highest ZT 0.60 for Zr0.3Ti0.7NiSn was achieved at 673 K.