Effects of Nb doping on thermoelectric properties of Zn₄Sb₃at high temperatures

The thermoelectric properties of Nb-doped Zn₄Sb₃compounds, (Zn_1–xNb_x)₄Sb₃(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 β-Zn₄Sb₃. Among the compounds studied, the lightly substituted (Zn_0.995Nb_0.005)₄Sb₃compound 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 Zn₄Sb₃compound for the temperature range investigated. In particular, the ZT of (Zn_0.995Nb_0.005)₄Sb₃reached a value of 1.1 at 680 K, which was 69% greater than that of the undoped Zn₄Sb₃obtained in this study.