Charge transfer and electronic transitions in polycrystalline BiFeO3

We report on the electronic energy-level diagram of polycrystalline BiFeO3 using the elemental, optical, and current-density-electric field (J-E) characteristics. The elemental, electronic composition, and valence-band structure of BiFeO3 ceramics were studied using x-ray photoelectron spectroscopy. The diffuse reflectance spectrum of a mixture of BiFeO3 and BaSO4, used as a standard, was recorded to test the Kubelka-Munk model. From the graph of the Kubelka-Munk function versus wavelength, two charge-transfer bands and two doubly degenerated d-d transitions ((6)A(1g) --> T-4(2g) and (6)A(1g) --> T-4(1g)) were observed in polycrystalline BiFeO3. The J-E curves measured on the BiFeO3 ceramics showed space-charge-limited conduction mechanism.