Effect of transition metal element substitution on magnetoelectric properties of BiFeO3-BaTiO3 ceramics

Highlights: • The coexistence of tetragonal (T) and rhombohedral (R) phases was confirmed in all samples. • The best electrical properties were obtained at BF-BT-003BC sample with P_r = 6.23 μC/cm², d₃₃ = 79.3 pC/N. • The maximum M_r for Mn- and Co substituted ceramics is 0.43 emu/g and 0.39 emu/g, respectively. • The magnetoelectric coefficient α_ME of 0.66 mV/cm Oe was obtained in BF-BT-005BC sample. -- Abstract: BiFeO₃ is the most typical multiferroic materials. However, the poor magnetoelectric coupling effect limits its practical application. In this work, the transition metal elements (Co, Mn) were introduced to suppress the spin cycloid structure of BiFeO₃-based ceramics. The structure, ferroelectric, magnetic and magnetoelectric properties were investigated thoroughly. The XRD and SAED analysis confirmed the coexistence of tetragonal (T) and rhombohedral (R) phases of all samples. The piezoelectric properties were enhanced in Co-substituted samples. In addition, the magnetic properties were enhanced with the addition of Co/Mn ions. According to the analysis of the M-H loops and XRD patterns before and after poling, the electric-field induced magnetic change was observed in all samples, which can be attributed to the phase transition from R-phase to T-phase during poling. The room-temperature linear magnetoelectric coefficient α_ME was analyzed, and the maximum α_ME was obtained at BF-BT-005BC sample, where α_ME = 0.66 mV/cm Oe. The enhanced magnetic and magnetoelectric properties were ascribed to the distortion of the spiral spin structure by transition metal ions.