Ferroelectric-semiconductive properties of BaTiO3-based PTCR ceramics

The interrelated semiconductor and ferroelectric properties of n-doped BaTiO3 ceramics were considered for describing their electrical properties in a large range of temperatures. A double barrier Schottky model (Heywang-Jonker) combined with the Landau-Devonshire model were used in order to explain the ferroelectric-semi conductor properties of n-doped BaTiO3 ceramics with PTCR characteristics. The resistivity-temperature R(T) dependencies were simulated for various model parameters, in the whole range of temperatures, including the fierro-para phase transition. A limited range of the donor concentration and of the surface state density for the semiconductive behaviour at room temperature was obtained from the model, similar as in experiments. The results obtained for different model parameters were discussed in connection with the composition and processing parameters of BaTiO3-based PTCR materials.