The influence of kinetic processes on the electrical conductivity of donor-doped BaTiO3 ceramics

Barium titanate doped with donors is a good n-type semiconductor, the conductivity of which, however, is considerably influenced by intrinsic defects always present in these materials. Therefore not only the equilibrium behaviour of these defects but also the defect formation and the defect diffusion play an important role with respect to investigations concerning the semiconducting properties. It is shown that in many cases a heterogeneous distribution of frozen defects is formed at room temperature which leads to a corresponding inhomogeneity of the conductivity. A kinetic model is developed based on these considerations that gives a satisfactory explanation of the experimentally well known characteristic of conductivity vs. doping concentration.