Synthesis and characterization of mixed-valence barium titanates |
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| Authors: | Thomas Höche Paula Olhe Ralf Keding Christian Rüssel Peter A. Van Aken Reinhard Schneider |
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| Affiliation: | 1. Otto-Schott-Institut , Friedrich-Schiller-Universit?t , Fraunhoferstrasse 6, Jena , D-07743 , Germany;2. Institut für Angewandte Geowissenschaften , Technische Universit?t Darmstadt , Schnittspahnstra?e 9, Darmstadt , D-64287 , Germany;3. Lehrstuhl für Kristallographie, Institut für Physik , Humboldt-Universi?t zu Berlin , Invalidenstrasse 110, Berlin , D-10115 , Germany |
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| Abstract: | A single-crystal barium oxotitanate(III, IV) of approximate composition , containing mixed-valence Ti, was grown from a borate flux. The crystal structure was identified as hollandite type by single-crystal X-ray diffractometry. Electron-energy-loss spectroscopy of Ti L 2,3 and O K edges was used to determine chemical shifts related to the presence of mixed-valence Ti in the crystal. Comparison of Ti L 2,3 and O K energy-loss near-edge structure (ELNES) of with those obtained from a K 1.54 Mg 0.77 Ti 7.23 O 16 single crystal with hollandite structure, containing only Ti 4+ , revealed a shift in the Ti L 2,3 edge by 0.4-0.5 eV towards lower energy losses whereas only slight intensity variations without a detectable energy shift of the edge onset occur at the O K ELNES. In addition, valence-specific multiplet structures of the Ti L 23 ELNES are used as valence fingerprints. The observed fine structures of O K and Ti L 2,3 edges can be used to interpret coordination and bonding in related compounds. |
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