Effect of Nb Doping on Thermoelectric Properties of TiNiSn Half-Heusler Alloy Prepared by Microwave Method

The inherent high thermal conductivity of TiNiSn half-Heusler (HH) alloy, as well as the long preparation cycle time and high cost of conventional preparation methods limited its commercial application. Herein, Ti1 - xNbxNiSn half-Heusler alloys with low lattice thermal conductivity were successfully prepared by microwave synthesis combined with rapid hot-pressing sintering, which significantly shortened the preparation cycle and ensured high density of TiNiSn half-Heusler alloys. The effects of Nb substitution at Ti sites on the composition distribution, thermal and electrical transport properties of Ti1 - xNbxNiSn half-Heusler samples were studied. The maximum ZT value of Ti0.9Nb0.1NiSn sample was 0.39 at 725 K due to the increase of power factor (PF) and the decrease of lattice thermal conductivity caused by the enhanced phonon scattering, which was about 204% higher than that of undoped TiNiSn.