Multiferroism and magnetoelectric coupling in single-phase Yb and X (X = Nb, Mn, Mo) co-doped BiFeO3 ceramics

A series of Yb and X co-doped BiFeO₃ (X = Nb, Mn, Mo) and undoped BiFeO₃ polycrystalline ceramics were prepared by sol-gel method. The X-ray diffraction pattern confirmed the rhombohedral perovskite structure for all the ceramics. Reitveld refinement results bring out the impact of doping on the structural distortion. The Transmission Electron Micrograph observation reveals the nanostructure of the doped samples. Well saturated ferromagnetic hysteresis curves were obtained for the doped samples in contrary to undoped BiFeO₃ and this is attributed to the distortion of spin spiral structure. The doped ceramics exhibited improved ferroelectric parameters and very low leakage current density of the order of 10⁻⁹ to 10⁻⁷ A/cm², which is remarkably lower than that of undoped BFO. Remarkable dielectric properties were exhibited for the doped samples. An abrupt noticeable enhancement of magetoelectric coupling for the doped samples in comparison with the undoped BiFeO₃ has been demonstrated in our work.