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      Investigation of local structure effect and X-ray absorption characteristics (EXAFS) of Fe (Ti) K-edge on photocatalyst properties of SrTi (1-x)Fe xO (3-δ)

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      Author
      Ghaffari, M.
      Liu, T.
      Huang H.
      Tan O.K.
      Shannon, M.
      Date
      2012
      Source Title
      Materials Chemistry and Physics
      Print ISSN
      0254-0584
      Volume
      136
      Issue
      2-3
      Pages
      347 - 357
      Language
      English
      Type
      Article
      Item Usage Stats
      152
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      210
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      Abstract
      In this study, the STF x photocatalyst powder was synthesized with a high temperature solid state reaction. The microstructures and surface of samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The electronic properties and local structure of the perovskite STF x (0 ≤ x ≤ 1) systems were probed by extended X-ray absorption fine structure (EXAFS) spectroscopy. The XPS results revealed that with increasing iron doping, the amount of Fe 3+ and Fe 4+ increased significantly. The X-ray absorption data are discussed in detail with respect to the Fe (Ti) K-edge. The substitution of iron by titanium increased the Ti (Fe)-O first shell disorder factors that can be explained by increasing the oxygen vacancies. Oxygen vacancies or defects act as electron traps, which could capture the photo induced electrons and thus could effectively inhibit the recombination of the photo induced electrons and holes. Moreover due to the substitution of Ti with Fe, lattice shrinkage was observed and the largest derivation from the Gaussian distribution in STF x was from those samples with x = 0.6 and x = 0.8. The substitution of iron by titanium increased the iron valence state, hence the formation of the Jahn-Teller Fe 4+ ion. With increasing iron dopant the [Ti(Fe)-O] ave decreased and bond length of [Ti-O] and the consequent [Ti-O-Ti] increased and this phenomenon affected the photocatalyst and photo degradation properties of material and also decreased its efficiency. © 2012 Elsevier B.V. All rights reserved.
      Keywords
      Catalyst
      Oxygen vacancies
      SrTi (1-x)Fe xO (3-δ)
      XAFS
      Electrons and holes
      EXAFS
      Extended X-ray absorption fine structures
      High temperature solid-state reaction
      Iron doping
      Its efficiencies
      Jahn-Teller
      Local structure
      Photo-induced
      Transmission electron microscopy tem
      Valence state
      XAFS
      Oxygen vacancies
      Catalysts
      Permalink
      http://hdl.handle.net/11693/21294
      Published Version (Please cite this version)
      http://dx.doi.org/10.1016/j.matchemphys.2012.06.037
      Collections
      • Department of Electrical and Electronics Engineering 3597
      • Institute of Materials Science and Nanotechnology (UNAM) 1831
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