Multiple Local Domain Structural Evolutions at Morphotropic Phase Boundary in BiFeO3–Ba0.9Ca0.1TiO3 Ferroelectric Ceramics

Bismuth ferrite–barium titanate (BFO–BT) is a well‐known lead‐free ferroelectric material with a large electric field‐induced strain; however, its piezoelectricity is very low under low electric fields. Herein, by studying Ca‐doped BFO–BT ceramics, multiple structural evolutions are found in the ferroelectric domains at the morphotropic phase boundary (MPB) in BFO–BT‐based ceramics, where a part of the local ferroelectric domains reveals a transition from rhombohedral to tetragonal and to relaxor phases. The superior electrical properties with large electrostrain Sp of 0.38%, large Pr of 38.4 μC cm−2, intermediate d33 of 132 pCN−1, and high TC of 425 °C are obtained at the MPB in these ceramics. Multiple local domain structural evolutions with compound ferroelectric domains and relaxor phases are responsible for the large electrostrain and intermediate piezoelectricity. This can explain the inconsistent piezoelectric response under high and low electric fields at the MPB in the BFO–BT‐based ferroelectric ceramics.