Major contributor to the large piezoelectric response in (1 -x)Ba(Zr_0.2Ti_0.8)O₃-X(Ba_0.7Ca_0.3)TiO₃ceramics: Domain wall motion

The piezoelectric activity of lead-free Ba(Zr_0.2Ti_0.8)O₃-X(Ba_0.7Ca_0.3)TiO₃ (BZT-vBCT) ceramics has been investigated as a function of composition by using Rayleigh analysis under subsw itching- electric-field in combination with large-electric-field strain measurement. The result shows that the intrinsic piezoelectric response exhibits peak values in the vicinity of composition-induced R (rhombohedral)-MPB (morphotropic phase boundary) and MPB-T (tetragonal) phase transitions, but being much less than total d33value. On the other hand, the extrinsic piezoelectric response, especially the one associated with reversible domain wall motion, has been greatly enhanced in the phase instability regime. Our results indicate that the extrinsic piezoelectric activity is the major contributor to the high piezoelectricity in BZT-vBCT ceramics.