Dielectric, optical, and multiferroic properties of Co-doped SrBi2Nb1.8Fe0.2O9 ceramics

SrBi2Nb1.8−xCoxFe0.2O9 (SBCFN, x = 0, 0.1, 0.2, 0.3 and 0.4) ceramic samples were fabricated by traditional solid-state reaction. Structure was detected by XRD and SEM, which demonstrated that all samples showed pure orthorhombic Aurivillius structure and the plate-like grains were observed. The morphology gradually disappeared with Co ions doping. Relaxation peak in low-temperature region of Co-doped samples was discussed in dielectric spectra. Besides, the decrease in resistance induced by the motion of first ionized oxygen vacancies was revealed by fitted Arrhenius curves and supported by Correlated Barrier Hopping conduction model. The contribution of leakage current in P–E loops was observed. The optimum magnetic property was obtained when the molar ratio of Fe3+ and Co3+ is 1:1, which is attributed to introduction of double exchange interaction (Fe–O–Co). At the same time, the Eg was narrowed due to hybridization and lattice distortion, which was coincident with the result of resistance.