Structural and optical properties of Ca doped BiFeO3 thin films prepared by a sol-gel method

Bi1-xCaxFeO3 (BCFO, x = 0.00, 0.05, 0.10, 0.15, 0.20) thin films were prepared by a sol-gel process. The structural and optical properties of the BCFO films were investigated. X-ray diffraction showed that all the films were single perovskite structure, and a phase transition appeared with the increasing of the CO2+ concentration. SEM images showed that the morphologies of the surface became smoother and the grain size reduced with the increasing concentration of Ca2+ ions. Raman spectra showed that the microstructure distortion and phase transition appeared with Ca2+ ion doping. The UV visible absorption spectra showed that the band gaps of Bi1-xCaxFeO3 films with x = 0.00, 0.05, 0.10, 0.15 and 0.20 were about 2.18, 2.19, 2.23, 2.35 and 2.36 eV, respectively.