A COMPARATIVE-STUDY OF THE AC-FIELD DEPENDENCE OF SOFT AND RELAXOR PLZT FERROELECTRICS

Significant differences in the ac-field dependence of the dielectric c onstant, polarization hysteresis response, and the fatigue behavior ha ve been found between low La-content ''soft'' and high La-content rela xer ferroelectric behaviors in lead zirconate titanate (PZT) ceramics. X-ray diffraction and transmission electron microscopy studies reveal ed a decrease in domain regularity with La concentration in ''soft'' f erroelectrics. This domain breakdown is believed to be responsible for the anomalous ac field effects. An ac field induced relaxer behavior observed in low La content ''soft'' PZT requires an extended concept o f relaxer behavior.