Studies of the ferroelectric domain configuration and polarization of rhombohedral PZT ceramics

The character of the ferroelectric domains in lead zirconate titanate (PbZr_1-xTi_xO₃ - PZT) ceramics has been studied using transmission electron microscopy (TEM) for compositions right across the rhombohedral phase (x = 0.06 to x = 0.45). The polarization hysteresis has also been determined for the same specimens and it has been demonstrated that the compositions between x = 0.12 and x = 0.40 show double hysteresis loops. It is shown that the occurrence of domain walls which do not correspond exactly to crystallographic planes produces generalized wedge-shaped domains, instead of the typical bands of parallel-sided domains reported in most ferroelectrics. A systematic variation in the arrangement of the domain walls as the composition progresses across the rhombohedral region is reported for the first time. This result is related to the occurrence of double hysteresis loops for these compositions. The role of oxygen octahedral tilts of the low temperature rhombohedral phase in the formation of the domains and in the hysteresis behaviour is discussed.