Conduction mechanism of barium titanate ceramics

Barium titanate ceramics are semiconductor devices presenting a highly non-linear resistivity vs. temperature characteristics (PTCR effect). Although it has been previously determined that this phenomenon can be described by a simple double depletion layer formed at the grain interfaces, details of some effects in these materials are not completely explained. In this work, the electrical properties of barium titanate ceramics above the Curie temperature are studied from the resistivity vs. temperature and dielectric constant vs. temperature at the grain boundaries. Experiments can be explained as the result of double Schottky barriers formed at the grain boundaries. These barriers are considered to have an exponential concentration of electrically donor active dopants.