Structural evolution and enhanced multiferroicity in BiFeO3-based ceramics via rare earth element co-substitution

In this study, multiple rare earth elements were introduced to modify the multiferroic properties of BiFeO₃. The effects of co-substitution on the structural evolution and properties were thoroughly investigated. With increasing substitution content, the ceramics underwent a symmetry transition from R3c to Pna2₁ and finally to Pbnm. Co-substitution significantly enhanced the ferroelectric properties, with the highest remanent polarization of 33.14 μC/cm² observed at x = 0.10. Due to the symmetry evolution, ferromagnetism was released from the cycloidal spin structure, and the hysteresis loop gradually saturated, with the highest remanent magnetization (M_r) of 0.25 emu/g observed at x = 0.16. The concurrent improvement in ferroelectricity and ferromagnetism resulted in substantial magnetoelectric coupling performance, with α_ME = 3.50 mV/(cm·Oe). Moreover, direct current poling significantly induced the reverse transition from R3c to Pna2₁, indicating the potential for electrically controlled magnetism. This study provides a new perspective for modifying the magnetoelectric properties of BiFeO₃.