Electrical properties and defect chemistry of indium-doped TiO2 : electrical conductivity

This work reports the electrical conductivity of indium-doped TiO 2 at elevated temperatures (1023 K - 1273 K) and in the gas phase of controlled oxygen activity in the range 10-16 Pa < p(O 2)< 105 Pa. The effect of indium on charge transport in TiO2 is considered in terms of the electrical conductivity components related to electrons, electron holes and ions. It is shown that addition of 0.4 at% of indium to TiO2 results in a shift of the n-p transition point toward lower values of oxygen activity by the factor of about 10. The obtained experimental data in oxidizing conditions are consistent with the mechanism of indium incorporation into the titanium sublattice leading to the formation of acceptor energy levels. However, the determined effect of indium on the ionic conductivity component indicates that indium is incorporated into interstitial sites resulting in the formation of donors. The reported data may be used for processing TiO2 with controlled properties that are desired for specific applications.