Preparation, surface state and band structure studies of SrTi _(1-X)Fe _(x)O _(3-δ) (x = 0-1) perovskite-type nano structure by X-ray and ultraviolet photoelectron spectroscopy

In this report, SrTi _{(1 - x)}Fe _(x)O _{(3 - δ)} photocatalyst powder was synthesized by a high temperature solid state reaction method. The morphology, crystalline structures of obtained samples, was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM), respectively. The electronic properties and local structure of the perovskite STF _x (0 ≤ x ≤ 1) systems have been probed by extended X-ray absorption fine structure (EXAFS) spectroscopy. The effects of iron doping level x (x = 0-1) on the crystal structure and chemical state of the STF _x have been investigated by X-ray photoelectron spectroscopy and the valence band edges for electronic band gaps were obtained for STF _x by ultraviolet photoelectron spectroscopy (UPS). A single cubic perovskite phase of STF _x oxide was successfully obtained at 1200 °C for 24 h by the solid state reaction method. The XPS results showed that the iron present in the STF _x perovskite structure is composed of a mixture of Fe ³⁺ and Fe ⁴⁺ (SrTi _{(1 - x)}[Fe ³⁺, Fe ⁴⁺] _(x)O _{(3 - δ)}). When the content x of iron doping was increased, the amount of Fe ³⁺ and Fe ⁴⁺ increased significantly and the oxygen lattice decreased on the surface of STF _x oxide. The UPS data has confirmed that with more substitution of iron, the position of the valence band decreased.