Band gap measurement of SrFeO3−δ by ultraviolet photoelectron spectroscopy and photovoltage method

• Main Authors: Huang, H., Ghaffari, Mohammad, Tan, Ooi Kiang, Shannon, Mark
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/95267; http://hdl.handle.net/10220/10820
• Institution: Nanyang Technological University

There are very important characteristics of partial substitution of the cations at both A and B sites in ABO3 perovskite structure. In this report, SrFeO(3−δ) (SFO) photocatalyst powder was synthesized by a high temperature solid state reaction method. The morphology and crystalline structure of the obtained samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM). The XRD, TEM and SAED patterns indicated that a single cubic perovskite phase of SrFeO(3−δ) (SFO) oxide has been successfully synthesized. The surface composition of the SrFeO(3−δ) sample was characterized by X-ray photoelectron spectroscopy (XPS). The XPS results showed that the iron existing in the SrFeO(3−δ) perovskite structure is composed of a mixture of Fe3+ and Fe4+. Due to the high absorbance of the SrFeO(3−δ) powder, the Kubelka–Munk model and UV–visible measurement were not applicable. Therefore, in order to study the band positions further, the valence band edges for electronic band gaps were obtained for SrFeO(3−δ) by ultraviolet photoelectron spectroscopy (UPS) while the conduction band position was obtained by photovoltage method.