Enhanced Magnetic Properties of Co-Doped BiFeO(3) Thin Films via Structural Progression

Co(3+) doping in BiFeO(3) is expected to be an effective method for improving its magnetic properties. In this work, pristine BiFeO(3) (BFO) and doped BiFe(1-x)Co(x)O(3) (BFC(x)O, x = 0.01, 0.03, 0.05, 0.07 and 0.10) composite thin films were successfully synthesized by a sol–gel technique. XRD and Raman spectra indicate that the Co(3+) ions are substituted for the Fe(3+) ion sites in the BFO rhombohedral lattice. Raman vibration of oxygen octahedron is obviously weakened due to the lattice distortion induced by the size mismatch between two B-site cations (Fe(3+) and Co(3+) ions), which has an impact on the magnetic properties of BFC(x)O. SEM images reveal a denser agglomeration in Co-doped samples. TEM results indicate that the average size of grains is reduced due to the Co(3+) substitution. XPS measurements illustrate that the replacement of Fe(3+) with Co(3+) effectively suppresses the generation of oxygen defects and increases the concentration of Fe(3+) ions at the B-site of perovskite lattice. Vibrating sample magnetometer (VSM) measurements show that the remanent magnetization (Mr) of BFC(0.07)O (3.6 emu/cm(3)) and the saturation magnetization (Ms) of BFC(0.10)O (48.84 emu/cm(3)) thin film both increase by approximately two times at room temperature, compared with that of the pure BFO counterpart.