Room-temperature multiferrocity and magnetodielectric properties of ternary BiFeO 3 –Bi 0.5 Na 0.5 TiO 3 –CaTiO 3 ceramics across the rhombohedral–orthorhombic phase boundary

A novel ternary solid solution (1-y)((1-x)BiFeO3–xBi0.5Na0.5TiO3)–yCaTiO3 (0 ≤ x ≤ 0.3, 0.15 ≤ y ≤ 0.25) is designed to present a rhombohedral–orthorhombic morphotropic phase boundary (MPB) with enhanced ferroelectricity, canted ferromagnetism, and room-temperature magnetoelectric responses. The addition of Bi0.5Na0.5TiO3 can generate a distinct MPB region and make BiFeO3–CaTiO3-based ceramics more denser. Therefore, superior ferroelectric properties with the remanent polarization of 37µC/cm2 can be obtained in the x = 0.3, y = 0.15 sample with the presence of rhombohedral–orthorhombic MPB. However, weak ferromagnetism is observed in both the rhombohedral and orthorhombic phases due to a destruction of the spiral spin structure of BiFeO3. The MPB with canted ferromagnetism is constructed. The maximum magnetoelectric interaction constant is found in the MPB compositions with x = 0.2, y = 0.2 which is related with the multiferroic phase boundary.