INFLUENCE OF THERMAL AND ELECTRICAL HISTORIES ON DOMAIN-STRUCTURE ANDPOLARIZATION SWITCHING IN POTASSIUM-MODIFIED LEAD-ZIRCONATE-TITANATE CERAMICS

The dependence of domain evolution and polarization switching on therm al and electrical histories has been investigated for K1+-ion-modified lead zirconate titanate (PZT) ceramics by using hot-stage transmissio n electron microscopy and Saywer-Tower polarization methods. In each c ase, the domains were very narrow, on the order of several hundred ang stroms, In the aged condition, the domain structure was dominated by a ''wavy'' morphology. In the as-quenched condition, fine and straight 180 degrees domains were found that extended across entire grains. In the field-cooled condition, fine and straight 70 degrees and 110 degre es domains were found, Corresponding polarization studies revealed dou ble-loop characteristics in the as-quenched and aged conditions. In bo th these cases, the switchable polarization was much less than that of the base PZT composition, In the field-cooled condition, a single pol arization loop was observed. However, the polarization-electric field (P-E) curve was skewed from the origin, and the polarization was not c ompletely switchable on field reversal. These changes in domain stabil ity and P-E properties have then been explained in terms of the depend ence of a spatial distribution of polarizable defect complexes on ther mal and electrical histories.