Thermoelectric performance of NiyMo3Sb7-xTex (y≤0.1, 1.5≤x≤1.7)

Mo3Sb7-xTex is a high temperature thermoelectric material, reported to reach figure of merit (ZT)=0.8 at 1023 K. Various p-type samples of NiyMo3Sb7-xTex were prepared with y <= 0.1 and 1.5 <= x <= 1.7 via high temperature reactions at 993 K. Adding transition metal atoms into the empty cube formed by Sb atoms significantly alters the band structure and thus the thermoelectric properties. Electronic band structure calculations indicate that adding Ni slightly increases the charge carrier concentration, while higher Te content causes a decrease. Thermoelectric properties were determined on pellets densified via hot pressing at 993 K. Seebeck as well as electrical and thermal conductivity measurements were performed up to 1023 K. The highest ZT value thus far was obtained from a sample of nominal composition Ni0.06Mo3Sb5.4Te1.6, which amounts to 0.93 at 1023 K.