FERROELECTRIC DOMAINS AND INCOMMENSURATION IN THE INTERMEDIATE PHASE REGION OF LEAD ZIRCONATE

Electron microscopy of lead zirconate (PbZrO3) identified the presence of an intermediate region between the high-temperature cubic state an d the low-temperature antiferroelectric state. Ferroelectric domains w ere found to occur between 200 degrees and 230 degrees C on cooling. C onvergent-beam electron diffraction studies identified rhombohedral sy mmetry for the ferroelectric phase. Selected area electron diffraction patterns determined 1/23{110} superlattice reflections in the ferroel ectric state. The reflections were associated with a softening of an M -type oxygen octahedral rotation mode. In addition, 1/x{110} incommens urate superlattice reflections were detected within a narrow temperatu re range for PbZrO3 between the intermediate ferroelectric and low-tem perature antiferroelectric states.