Ferroelectric domain patterns and domain boundary imprint in the relaxor ferroelectric Pb(Zn1/3Nb2/3)O3-9%PbTiO3 as observed by using piezoresponse force microscopy

Piezoresponse force microscopy is used to observe the ferroelectric domain structures of a typical relaxor ferroelectric Pb(Zn1/3Nb2/3)O3-9%PbTiO3. Detailed structural phases are identified by analyzing the domain patterns from the viewpoint of symmetry. Sequential phase transitions, starting from a rhombohedral phase at room temperature to a tetragonal phase via an intermediate monoclinic one and then to a cubic phase, are observed as the temperature is raised to 500 K. The system also undergoes the same phase sequence, from rhombohedral to monoclinic to tetragonal, as a function of the applied electric field. The domain boundaries are found to be spatially fixed and unchanged despite the multiple phase transition sequence that the system undergoes as the temperature is raised. Contrastingly, this imprint effect is missing in the field-driven phase transition sequence. The imprint effect is presumably caused by electric charges on the domain boundaries, possibly arising from local charge imbalances in the relaxor ferroelectric.