Influence of Y and Co co-doping in the multiferroic behaviors of BiFeO3 ceramics

Single phase of pure BiFeO3 (BFO) and Bi0.99Y0.01Fe1-xCoxO3 (0.01 <= x <= 0.03) (BYFC) multiferroic ceramics were prepared by using a modified solid state reaction method. The scanning electron microscope (SEM) images revealed that the grain size and morphology were dependent on the nature of dopant. X-ray diffraction peaks were found to belong to the pure BFO structure with R3c space group of symmetry. It was found that the dielectric constant (epsilon') values increased similar to 13.5 times with the addition of Co ions; being similar to 170 and similar to 2300, for pure BFO and x = 0.01, respectively, at the lower frequencies (100 Hz). The dielectric behavior was described by the modified Cole-Cole model. Ferromagnetic (FM) ordering with saturation magnetization, M-s, and coercivity H-c values of similar to 0.75 emu/g and similar to 400 Oe, was found in the BYFC ceramics at x = 0.03 at room temperature. A decrease in the band gap was observed due to the amount of doping in the BYFC ceramics. The origin of the enhanced dielectric and magnetic properties was discussed on the basis of the size effect and the nature of the dopants like Y3+, Co2+ and Co3+ ions in the lattice structure of the doped ceramics.