Synthesis of FeVSb1−xSex Half-Heusler Alloys via Mechanical Alloying and Evaluation of Transport and Thermoelectric Properties

Abstract

Se-doped half-Heusler compositions, FeVSb1−xSex (0.03 ≤ x ≤ 0.15), were fabricated by mechanical alloying followed by vacuum hot pressing. The goal of this synthesis was to explore the effect of Se doping on the thermoelectric and transport properties of FeVSb system. A near single half-Heusler phase was found to form; however, a second phase of FeSb2 couldn’t be avoided in this process. N-type conduction was confirmed and Se acted as a donor for the FeVSb system. Lattice thermal conductivity also considerably decreased after Se doping. The absolute value of Seebeck coefficient is increased to a maximum of 126 μVK−1 at 956 K for x = 0.12, which may help to increase the figure of merit (ZT) of the FeVSb system. The figure of merit is improved by Se doping, and the improvement is possibly owing to the combined effect of fine grain structure, increased effective mass and phonon scattering at the grain boundaries. A maximum ZT of 0.27 was achieved for FeVSb0.88Se0.12 at 847 K.