Yasumasa Goto

Studies on the mechanism of electric conduction in Fe-doped BaTiO3 single crystals by applying kerr effect

Abstract Long time application of d.c. potentials to Fe-doped BaTiO 3 single crystals causes slow change with time of current and field distribution. The field change has successively been measured in a polarizing microscope, applying electro-optic Kerr effect above the Curie temperature. It has been found that the current is space-charge-limited in the initial stage of the conduction, but the field strength around the anode develops gradually with time and extends toward the cathode. Although the field becomes rather homogeneous ultimately, there remains an almost discontinuous field drop near the cathode. An analysis of the field distribution indicates injection of electrons from the cathode followed by migration of oxygen ions toward the anode, which causes hole injection from the anode. An electron micro-probe X-ray analysis has revealed that iron ions do not migrate perceptibly by the d.c. potential application.