The effect of Ni doping on the thermoelectric transport properties of CdO ceramics

• The thermoelectric performance of CdO ceramics was greatly enhanced by Ni doping.
• Doping Ni can synergistically optimize the power factor and thermal conductivity of CdO ceramics.
• A high ZT of 0.43 was achieved in the Cd0.99Ni0.01O sample at about 1000 K.

Cd1-xNixO ceramics were synthesized by the conventional solid state reaction method and the effect of Ni doping on the thermoelectric performance of CdO was investigated. The introduction of Ni led to dramatic changes in the electrical transport behaviors of CdO ceramics and thus an improvement in power factor, which were suggested to be related to the widening of the band gap as well as the formation of an impurity level in the band gap of CdO after the substitution of Ni2+ for Cd2+. Doping of Ni also had a significant influence on the microstructure of CdO along with the development of NiO second phase when the Ni concentration exceeded 1%, which effectively suppressed the heat transfer by enhanced phonon scattering. Benefiting from the improved power factor and the reduced thermal conductivity, a high ZT of 0.43 was achieved in the Cd0.99Ni0.01O sample at about 1000 K.