fig2
From: Microstructure and piezoelectric properties of AC poled relaxor-PbTiO3 perovskite single crystals

Figure 2. Cycle number dependence of domain structure, dielectric and piezoelectric properties of relaxor-PT SC. Schematic images of domains in NOP (DEP), DCP, UDP, OPP, OVP I and OVP II stages are shown. relaxor-PT; NOP: non-polarization; SC: single crystal; DEP: depolarization; UDP: under-polarization; OPP: optimum polarization; OVP: over-polarization; DCP: direct-current poling.