Relaxation degree and defect dipoles‐controlled resistivity and leakage current in BF–BT‐based ceramics

Abstract The low resistivity and high leakage current of bismuth ferrite–barium titanate‐based ceramics greatly limit its development. In this work, the resistivity and leakage current have been regulated by changing the relaxation degree and defect dipoles. With the introduction of Sb, the ceramics endure from weak relaxors with typically ferroelectric behavior to relaxor ferroelectrics and then to relaxors, where nearly 20 times improved resistivity can be obtained in relaxor ferroelectrics with chemical‐homogeneous grain structure and strip‐shaped/submicron‐sized coexisted domains, whereas deteriorated properties appear in relaxors with core–shell structure and tweed‐like ferroelectric domains. The decreased concentration of oxygen vacancies and Ti 3+ is responsible for the improved insulation in relaxor‐ferroelectrics, whereas the emergence of core–shell structure leads to electrical inhomogeneity and the conductive channels result in decreased resistivity. In addition, the leakage current mechanism is transformed from Ohmic conduction to space‐charge‐limited current as the electric field increases, which is induced by different domain switchings in ceramics with varied relaxation degrees.