Effects of Nb doping on thermoelectric properties of Zn4Sb3 at high temperatures

The thermoelectric properties of Nb-doped Zn4Sb3 compounds, (Zn1-xNbx)(4)Sb-3 (x = 0, 0.005, and 0.01), were investigated at temperatures ranging from 300 to 685 K. The results showed that by substituting Zn with Nb, the thermal conductivities of all the Nb-doped compounds were lower than that of the pristine beta-Zn4Sb3. Among the compounds studied, the lightly substituted (Zn0.995Nb0.005)(4)Sb-3 compound exhibited the best thermoelectric performance due to the improvement in both its electrical resistivity and thermal conductivity. Its figure of merit, ZT, was greater than the undoped Zn4Sb3 compound for the temperature range investigated. In particular, the ZT of (Zn0.995Nb0.005)(4)Sb-3 reached a value of 1.1 at 680 K, which was 69% greater than that of the undoped Zn4Sb3 obtained in this study.