Ferroelectric domain structure of PbZr_0.35Ti _0.65O₃ single crystals by piezoresponse force microscopy

Ti-rich PbZr_1-xTi_xO₃ (x = 0.65, PZT65) single crystals with the dimensions of 1 × 1 × 0.2 mm³ were grown by the self-flux method. Micron-sized ferroelectric domains were observed and characterized via piezoresponse force microscopy (PFM) and switching spectroscopy PFM. Both out-of-plane and in-plane components of polarization were obtained by detecting vertical and lateral vibrations of the PFM cantilever. The piezoresponse image examination revealed a clear lamellar domain structure due to apparent twinning and the formation of 90° domains. A negative self-polarization was observed in the studied crystals leading to the asymmetry of piezoresponse hysteresis loops and the polarization imprint. The polarization switching mechanism under the external electric field applied via a PFM tip was investigated. The 90° domain wall width was determined from the local PFM measurements and tentatively attributed to the oblique domain walls and chemical disorder. The time-dependent PFM imaging revealed a slow polarization relaxation process with a characteristic time of about 200 min.