Thermoelectric properties of Cu-added Zn–Sb based alloys with multi-phase equilibrium

The polycrystalline samples of Cu-added Zn–Sb based alloys with multi-phase equilibrium were prepared by spark plasma sintering and their microstructures and thermoelectric properties were evaluated. After Cu addition into Zn–Sb based alloys we observed a major phase ZnSb, β-Zn4Sb3, the second phase Cu2Sb and remnant Zn. The ZnSb phase plays an important role in increasing Seebeck coefficient (α) and decreasing electrical conductivity (σ), and Cu2Sb is of significance to the improvement of the thermoelectric performance. The thermal conductivities (κ) increase with Cu content, and are almost independent of temperature below 574 K. If in comparison with the highest ZT value (ZT = 0.48, at 654 K) of Zn4Sb3 prepared in the present work, we obtain the value of 0.7 for the alloy with a certain Cu concentration at the corresponding temperature.