High-Temperature Thermoelectric Properties Of Half-Heusler Phases Er1-Xhoxnisb

Polycrystalline samples of Er1-xHoxNiSb (x = 0, 0.2, 0.3, 0.5, 0.7, 0.8, 1) were characterized by means of x-ray powder diffraction (XRD), scanning electron microscopy (SEM), and optical metallography. The results proved the formation of half-Heusler alloys in the entire composition range. Their electrical transport properties (resistivity, thermoelectric power) were studied in the temperature interval 350-1000 K. The measured electrical resistivity spanned between 5 and 25 mu Omega m. The maximum thermopower of 50-65 mu V/K was observed at temperatures 500-650 K. Replacing Ho for Er resulted in a non-monotonous variation of the thermoelectric power factor (PF = S-2/p). The largest PF of 4.6 mu WcmK(-2) was found at 660 K for Er0.5Ho0.5NiSb. This value is distinctly larger than PF determined for the terminal phases ErNiSb and HoNiSb.