Constructing Relaxor/Ferroelectric Pseudocomposite To Reveal the Domain Role in Electrostrain of Bismuth Ferrite-Barium Titanate Based Ceramics.

Bismuth ferrite-barium titanate (BF-BT) based ceramics have attracted extensive attention due to its excellent energy conversion. Recently it has been found that BF-BT based ceramics with large electrostrain are usually accompanied by a special domain configuration in which weak and strong piezoresponse domain grains coexist. In this work, we purposefully constructed the special domain configuration in the pseudocomposite ceramics of (1 - )0.55BF-0.4BT-0.05BZN/(0.7BF-0.3BT) (relaxor-like phase/ferroelectric phase, RE/FE) by a "two-step" method. Macroproperty characterization suggests that the critical component pseudocomposite ceramic ( = 50%) with the special domain structure can exhibit a maximum electrostrain value ( ∼ 0.28%) at 6 kV/mm, almost 3-fold to that ( ∼ 0.1%) of the two end members and 63% higher than that ( ∼ 0.17%) of the same component ceramic prepared by the "one-step" method. Further mesoscopic structure results show that the "two-phase" composite can induce the formation of grain dependent domain at nanoscale, and just this special domain conformation is conducive to a significant improvement in electrostrain. Therefore, the large strain in BF-BT-based ceramics is mainly caused by the special microstructure rather than component.