Theoretical Study On Optical Properties Of Bismuth Ferrite Ceramics

BiFeO3is a kind of multiferroic material, with ferroelectric,ferromagnetic and antiferromagnetic, have good potential applications in sensor, ferroelectric memory and so on. A photovoltaic effect was found in BiFeO3 materials in recent years. So its photoelectric characteristics have become a research hotspot.In this paper, we study the geometric structures, electronic and optical properties on BiFeO3 of the perovskite structure material. The optical absorption effects of the pure BiFeO3 ceramic doped with rare earth elements are discussed.We firstly use the local spin density first principles density functional theory of approximation adding U(LSDA+U) method for pure BiFeO3 band gap is adjusted. The calculation results show, when the U value is equal to 16.5ev, and the band gap value of BFO is 2.418 ev and it is the indirect band gap, which is consistent with the experimental values around 2.5ev. On this basis, we calculated the electrical properties and optical properties. The results showed that when the wavelength of incident light is about 400 nm and the absorption spectrum has the best absorption effect, corresponding to the incident light is purple, and the valence electrons jump from O 2p(up) state to the Fe 3d(down). The fourth chapter is about the study on effect of rare earth element B site doping on the optical absorption. The emphasis of the thesis compared and analyzed several important elements doped by absorption spectra of different. The results found after doping, the absorption spectrum of the range can be increased.This may provide certain theory support for experiment.