Effect of co-substitution of Na0.5Bi0.5TiO3 and CaTiO3 on the structure and properties of BiFeO3 ceramics

Ion substitution was the most efficient way for BiFeO3 modification. In this work, polar Na0.5Bi0.5TiO3 and non-polar CaTiO3 were chosen to modify BiFeO3, and the effects of Na0.5Bi0.5TiO3 and CaTiO3 co-substitution on the crystal structure, dielectric, ferroelectric and magnetic properties of BiFeO3 ceramics were investigated. All ceramics exhibited rhombohedral R3c phase with dense microstructure. Two dielectric anomalies were observed, one related to the valence change of Fe ions and the other to the ferroelectric phase transition. The DSC and dielectric analysis confirmed that the Curie temperature T-C linearly increased with increasing Na0.5Bi0.5TiO3 content, while the magnetic transition temperature T-N nearly unchanged. Meanwhile, the leakage current of the ceramic samples with Na+ was three orders of magnitude lower than that of a sample without Na+ ion. Due to the decrease in leakage current density, the breakdown field strength and piezoelectric properties were improved. In addition, the magnetic properties of all co-substituted ceramics were improved to a certain extent, which indicated that the co-doping of A-site and B-site affected the magnetic properties of the present ceramics.