Effect of Eu substitution on the crystal structure and multiferroic properties of BiFeO3

Single-phase Bi1−xEuxFeO3 (0 ≤ x ≤ 0.3) multiferroic ceramics were prepared to study the effects of Eu substitution on their crystal structure and ferroelectromagnetic behavior. X-ray diffraction studies revealed a sequence of the composition-driven structural phase transitions R3c → Pn21a (occurs at x = 0.2). Magnetic measurements revealed that Eu substitution can effectively induce the appearance of the spontaneous magnetization, which was significantly enhanced upon the composition-driven transition from a rhombohedral to an orthorhombic phase. The leakage current was found to be reduced on increased Eu concentration. The electric hysteresis loops were obtained in the Bi1−xEuxFeO3 ceramics, but the loops were not really saturated. The magnetoelectric coupling in Eu-doped BiFeO3 was estimated by the changes in the dielectric constant with an external magnetic filed.

Research highlightsDespite considerable efforts undertaken in a rapidly developing area of multiferroic research, chemical substitution on crystal structure and physical properties of BiFeO3 is still a matter of intensive research. A-site substitution with rare-earth ions (RE) is known to induce weak ferromagnetism in BiFeO3. However, very few attempts to investigate systematically the crystal structure and multiferroic properties of the Bi1−xRExFeO3 series, have been undertaken in recent years. Eu-doped BiFeO3 has been the subject of several investigations in recent years, but the existing data are very contradictory. In this work, we investigated the influence of the Eu substitution on the crystal structure, and multiferroic properties of BFO ceramic systematically. We found that Eu substitution induces a polar-to-polar R3c → Pn21a structural phase transition. This transition has great effects on the multiferroic properties of BiFeO3. It was found that the phase transition destructs the spin cycloid of BiFeO3, and therefore, releases the locked magnetization and enhances the magnetic properties of BiFeO3. As expected, improved multiferroic properties of the Eu-doped BiFeO3 ceramics were established. In view of the keen interest in advanced multiferroic materials, our results should be of interest to a wide general readership.