We report on the electronic energy-level diagram of polycrystalline ${\text{BiFeO}}_3$ using the elemental, optical, and current-density-electric field $\left(J\text{−}E\right)$ characteristics. The elemental, electronic composition, and valence-band structure of ${\text{BiFeO}}_3$ ceramics were studied using x-ray photoelectron spectroscopy. The diffuse reflectance spectrum of a mixture of ${\text{BiFeO}}_3$ and ${\text{BaSO}}_4$, 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 $d\text{−}d$ transitions (${{}^6\text{A}}_{1\text{g}}\to {{}^4\text{T}}_{2\text{g}}$ and ${{}^6\text{A}}_{1\text{g}}\to {{}^4\text{T}}_{1\text{g}}$) were observed in polycrystalline ${\text{BiFeO}}_3$. The $J\text{−}E$ curves measured on the ${\text{BiFeO}}_3$ ceramics showed space-charge-limited conduction mechanism.

• Received 14 March 2010

DOI:https://doi.org/10.1103/PhysRevB.82.012102