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

The character of the ferroelectric domains in lead zirconate titanate (PbZr 1-xTixO3-PZT) ceramics has been studied using transmission electron microsc opy (TEM) for compositions right across the rhombohedral phase (x = 0.06 to x = 0.45). The polarization hysteresis has also been determined for the sa me 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 occur rence of domain walls which do not correspond exactly to crystallographic p lanes produces generalized wedge-shaped domains, instead of the typical ban ds of parallel-sided domains reported in most ferroelectrics. A systematic variation in the arrangement of the domain walls as the composition progres ses across the rhombohedral region is reported for the first time. This res ult is related to the occurrence of double hysteresis loops for these compo sitions. The role of oxygen octahedral tilts of the low temperature rhomboh edral phase in the formation of the domains and in the hysteresis behaviour is discussed.