Enhanced rhombohedral domain switching and low field driven high electromechanical strain response in BiFeO3-based relaxor ferroelectric ceramics

A low-field driven high electromechanical strain response (large-signal d33* of ∼1100 pm/V at 3.5 kV/mm) was found in a new (0.75-x)BiFeO3-0.25PbTiO3-xPb(Mg1/3Nb2/3)O3 ternary relaxor ferroelectric ceramic. In-situ synchrotron X-ray diffraction measurements suggested that such a large strain be ascribed to a collective effect of electric field induced PNRs’ growth, domain switching and rhombohedral-tetragonal (R–T) phase transition with increasing fields, among which ergodic PNRs’ growth into R ferroelectric microdomains dominated the fastest increase of strains and the formation of the maximum strain hysteresis. Most interestingly, obviously enhanced R domain orientation along the electric field direction was believed to make a unique contribution as a result of its slightly reduced lattice distortion, compared with other Bi-containing relaxor ferroelectrics. An illustration of the domain morphology evolution in an ergodic relaxor was depicted to disclose the formation of strain hysteresis based on the delay in dynamics during electric cycling.