Understanding the strain mechanisms in BiFeO3-BaTiO3 piezoelectric ceramics near the morphotropic phase boundary

Origins of the unipolar strain, strain hysteresis, and remnant strain of Mn-modified BF-BT ceramics near the pseudo-cubic and rhombohedral (PC-R) phase boundary, before and after poling treatments, were investigated by high-energy synchrotron X-ray diffraction. The largest unipolar strain of BF-BT ceramics was found to occur at the composition with a single pseudo-cubic phase, rather than the phase boundary composition, owing to the synergetic contributions from the reversible phase transition of PC-R phase, non-180 degrees domain switching, and lattice distortion. It is interesting to find that the phase boundary composition exhibits an irreversible PC-R phase transition, where its unipolar strain after poling is attributed to the lattice distortion. The lowest strain hysteresis and remnant strain were observed in BF-BT ceramics with rhombohedral phase, due to the fact that the reversible lattice distortion dominates the strain level. These new findings on BF-BT solid solutions are expected to provide new insights on the strain mechanisms of perovskite-structured ferroelectric materials.

Automated summary

The origins of unipolar strain, strain hysteresis, and remnant strain in Mn-modified BF-BT ceramics near the pseudo-cubic and rhombohedral (PC-R) phase boundary were investigated using high-energy synchrotron X-ray diffraction. It was found that the largest unipolar strain occurred at the composition with a single pseudo-cubic phase, due to the synergetic contributions from reversible phase transition, non-180 degrees domain switching, and lattice distortion. The phase boundary composition exhibited irreversible phase transition, with the unipolar strain attributed to lattice distortion. The lowest strain hysteresis and remnant strain were observed in BF-BT ceramics with rhombohedral phase, as reversible lattice distortion dominated the strain level.