Synthesis and thermoelectric properties of high-entropy half-Heusler MFe1−xCoxSb (M = equimolar Ti, Zr, Hf, V, Nb, Ta)

•High-entropy half-Heusler compounds were synthesized by mechanical alloying combined with spark plasma sintering•Low thermal conductivity of 1.8–1.5 Wm−1K−1 (300–923 K) is achieved in high-entropy half-Heusler•Tuning thermoelectric properties by adjusting Fe/Co ratio; maximum zT values of 0.3 (n-type) and 0.25 (p-type) are achieved