NiO added Zn1−xNixO (0 ≤ x ≤ 0.05) for thermoelectric power generation

The Ni-added Zn1−xNixO (0.01 ≤ x ≤ 0.05) crystallized in ZnOss with a wurtzite structure, along with a small amount of NiOss with a cubic structure. The addition of NiO to ZnO showed a significant effect on the microstructure along with the development of the cubic NiOss, yielding a smaller grain size. The sign of the Seebeck coefficient for all samples was negative over the entire temperature range (600-800 °C), i.e., n-type conduction. The addition of NiO to ZnO led to a dramatic increase in both the electrical conductivity and the absolute value of the Seebeck coefficient, providing a significantly improved thermoelectric power factor. Zn0.97Ni0.03O showed an outstanding power factor (1.76 × 10−3 W m−1 K−2) at 800 °C due to a high conductivity (69.7 Ω−1 cm−1) and a large absolute value of the Seebeck coefficient (503 μV K−1). The power factor was over 29 times higher than that of NiO-free ZnO (0.62 × 10−4 W m−1 K−2).