It was noted that asymmetrical polarization of defect dipoles around phase transitions led to hysteretic resistivity behavior and to imprint failure of these ceramics in electric fields. The polarization was determined qualitatively by means of hysteresis loop measurements, together with the detection of current transients as a function of time. A reduction in defect-dipole polarization occurred at high field-strength, due to defect-dipole decomposition and/or O-vacancy migration.

Asymmetric Polarization of Defect Dipoles in Bi4Ti3O12 and Bi2Ti4O11 Ceramics with Na+ and La3+ Modifications. A.Q.Jiang, L.D.Zhang: Physical Review B, 1999, 60[13], 9204-7