Effects of Mn doping on multiferroic and magnetocapacitive properties of 0.33Ba_0.70Ca_0.30TiO₃-0.67BiFeO₃ diphasic ceramics

The 0.33Ba_0.70Ca_0.30TiO₃-0.67BiFeO ₃ + x wt% MnO₂ (BCT-67BF:Mn100x, x = 0-0.6) multiferroic ceramics have been prepared. The effects of Mn doping on structures, electric, magnetic as well as magnetocapacitive properties have been intensively investigated. It is found that all the ceramics have diphasic tetragonal-rhombohedral phases, whereas Mn doping improves the densification and significantly decreases the grain size. As x increases, the relaxor degree increases, the ferroelectricity and piezoelectricity weaken monotonically, while the magnetism enhances firstly, reaching the maximum near x = 0.5, and then decreases. Interestingly, the room temperature relative dielectric constant shows an obvious increase with increasing applied magnetic fields (H), the magnetocapacitive coefficient (ε_r(H)-ε_r(0))/ ε_r(0) decreases with increasing Mn content, from 2.96% for x = 0 - 0.86% for x = 0.6.