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Title: Bandgap tuning in SrTi(N,O,F){sub 3} by anionic-lattice variation

Polycrystalline SrTiO{sub 3} and SrTi(O,F){sub 3} powders were synthesized by a solid-state reaction. A partial substitution of oxygen by nitrogen was subsequently carried out using thermal ammonolysis resulting in SrTi(N,O){sub 3} and SrTi(N,O,F){sub 3}. Powder X-ray diffraction (XRD) revealed a cubic perovskite structure with space group Pm-3m for all samples. The thermal ammonolysis slightly increased the lattice parameters, crystallite sizes and strain. As a result from the co-substitution of oxygen with nitrogen and fluorine for SrTi(N,O,F){sub 3}, highly distorted TiO{sub 6} octahedra were detected using X-ray absorption near edge structure (XANES) spectroscopy. The weakening of all active modes of the Raman spectra after thermal ammonolysis also indicated enhanced distortions in the local crystal structure. SrTi(N,O,F){sub 3} has the largest amount of nitrogen as well as fluorine among all four samples as determined by thermogravimetric analysis (TGA), elemental analysis and X-ray photoelectron spectroscopy (XPS). In the UV–vis spectra a distinctive shift of the absorption-edge energy was observed exclusively for the SrTi(N,O,F){sub 3} sample from 390 to 510 nm corresponding to a bandgap narrowing from 3.18 to 2.43 eV. - Graphical abstract: Figure shows the shift of the absorption-edge energy for the SrTi(N,O,F){sub 3} sample from 390 to 510 nm corresponding tomore » a bandgap narrowing from 3.18 to 2.43 eV. Display Omitted - Highlights: • Synthesis of phase-pure SrTi(N,O,F){sub 3} via solid-state reaction. • The incorporated nitrogen contents increase by the presence of fluorine in SrTi(N,O,F){sub 3}. • Co-substitution with nitrogen and fluorine is beneficial for the bandgap narrowing compared to by only nitrogen or fluorine substitution.« less
Authors:
; ; ; ;  [1] ;  [2] ; ;  [3] ;  [1] ;  [1]
  1. Laboratory for Solid State Chemistry and Catalysis, Empa-Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf (Switzerland)
  2. Lehrstuhl für Experimentalphysik 5, EKM, Universität Augsburg, Universitätsstraße 1, 86135 Augsburg (Germany)
  3. Institut für Chemie, Martin-Luther Universität Halle-Wittenberg, Kurt-Mothes-Straße 2, 06120 Halle/Saale (Germany)
Publication Date:
OSTI Identifier:
22278308
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 206; Other Information: Copyright (c) 2013 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION; ABSORPTION SPECTROSCOPY; AMMONOLYSIS; CRYSTAL STRUCTURE; FLUORINE; LATTICE PARAMETERS; PEROVSKITE; POLYCRYSTALS; RAMAN SPECTRA; RAMAN SPECTROSCOPY; SOLIDS; SPACE GROUPS; STRONTIUM; STRONTIUM TITANATES; THERMAL GRAVIMETRIC ANALYSIS; TITANIUM OXIDES; X RADIATION; X-RAY DIFFRACTION; X-RAY PHOTOELECTRON SPECTROSCOPY; X-RAY SPECTROSCOPY