Effect of cooling on electrical conductivity of TiO2

The present work reports the effect of cooling on the electrical conductivity of undoped and Nb-doped TiO2 in the temperature range 1273-300 K in the gas phase of controlled oxygen activity. It is shown that the character of the electrical conductivity changes during cooling depends critically on the processing conditions at elevated temperatures before cooling and the related defect disorder. It is shown that processing in reductive conditions results in the imposition of electronic charge compensation leading, in consequence, to higher values of electrical conductivity at room temperature for both undoped TiO2 and Nb-doped TiO2. It is shown that the "dynamic" activation energy of the electrical conductivity during cooling differs from that determined in equilibrium.