The Electrical Conduction of Metal-to-Reduced BaTiO₃ Single Crystal Contacts

Abstract

To study the PTC anomaly in semiconductive barium titanate ceramic specimens, some experiments are made with BaTiO_3−x single crystals and a model to explain the results together with the PTC anomaly of ceramic specimens,is proposed.
The barrier height of a metal-to-BaTiO_3−x contact is hardly influenced by the surface states. The resistance through the barrier layer on a c-plate crystal, abruptly increases at the Curie point, while that through the barrier layer on a a-plate crystal decreases. The resistivity vs. temperature relations of some ceramic specimens show a gradual rise-up at the Curie point. It can be explained by the fact that the Curie points are distributed on a wide temperature range owing to the non-uniformity of the grain boundary layers.