Investigation of the thermoelectric properties of reduced Nb-doped TiO2-δ ceramics

A series of Nb-doped TiO2-δ (Ti1-xNbxO2-δ) ceramics was fabricated using a conventional solid state reaction method with subsequent annealing in a reducing atmosphere. X-ray diffraction revealed that there are different phases in the ceramics with different Nb doping levels, x. The thermoelectric properties of the Ti1-xNbxO2-δ samples were measured in the temperature range from 100 K to 380 K, and the resistivities and Seebeck coefficients for these samples were found to show semiconductor behavior. It has been shown that the transport behavior of these samples is consistent with the small polaron conduction mechanism for the temperature range from room temperature to 380 K. The largest ZT value observed, 0.023, was obtained for the x = 0.01 sample at the highest test temperature, 380 K.