A TEM and neutron diffraction study of the local structure in the rhombohedral phase of lead zirconate titanate

Transmission electron microscopy and neutron diffraction have been used to characterize ceramics and single crystals from the rhombohedral region of the Pb(Zr1-xTix)O-3 (x = 0.06-0.45) phase diagram. Electron diffraction patterns showed the existence of superlattice reflections of the type 1/2{hkl)(p), where h = k = l, and 1/2{hk0}(p), which are not observed by neutron powder diffraction. The analysis of these reflections also revealed satellite spots around the 1/2{hk0}(p), which are associated with periodic antiphase boundaries. The origin of these superlattice reflections is explained by the existence of local regions presenting antiparallel cation displacements, and models for this are suggested and compared with experiment.