Abstract
A effect of Sb doping (x=0~0.5) on the thermoelectric properties of annealed Ti0.5Zr0.5NiSn1-xSbx multi-element alloys is studied based on Ti0.5Zr0.5NiSn quaternary alloy with half-Heusler structure. The result shows both the absolute value of Seebeck coefficient and electrical resistivity decrease as the quantity of Sb doping increases at room temperature. The change of resistivity is marked for the alloy with slight Sb doping. The maximum power factor(S2/λ) is 2.83×10-3W/m-K2 for the annealed Ti0.5Zr0.5NiSn1-xSbx (x=0.005) alloy. It is three times larger than that of Ti0.5Zr0.5NiSn which is 0.72×10-3W/m-K2. The maximum ZT value is about 0.16 for the Ti0.5Zr0.5NiSn1-xSbx (x=0.005) alloy at room temperature which is four times larger than that of Ti0.5Zr0.5NiSn. Therefore, the lightly Sb doping would dramatically improve the thermoelectric properties of the Ti0.5Zr0.5NiSn alloy system. Besides, the results of thermoelectric properties measurement at high temperature reveal that the absolute value of Seebeck coefficient increases as the temperature rises. The resistivity of Sb doped alloys increases with rising temperature, indicating that the Sb doping would promote the metallic transport properties. Consequently, a slight Sb doping (below 5at% substitution of Sn atoms)would enhance the thermoelectric properties of Ti0.5Zr0.5NiSn1-xSbx alloy system.