Preparation of Ni-doped ZnO ceramics for thermoelectric applications

Zn1-xNixO dense ceramics were prepared from Zn1-xNixO nanoparticles with x varying from 0 to 0.06. These nanoparticles were synthesized by liquid route. In the sintered samples, the solubility limit of Ni in the Zn1-xNixO wurtzite structure was found to be 0.03. The increase of x until 0.03 led to a significant raise in both electrical conductivity (sigma) and absolute value of Seebeck coefficient (vertical bar S vertical bar). Ni-richer samples (x > 0.03) contained in addition a small amount of Ni rich secondary phase (ZnyNizO) with a cubic structure similar to NiO. The thermoelectric properties of all samples were investigated from room temperature to 1000K. All doped samples showed a n-type semiconducting conductivity. For Ni contents higher than x = 0.03, the increase of the secondary phase content induced a decrease in sigma and vertical bar S vertical bar. The highest power factor (0.6 mW m(-1) K-2) and ZT (0.09) were found for Zn0.97Ni0.03O at 1000 K. (C) 2011 Elsevier Ltd. All rights reserved.