Elucidating structural order and disorder phenomena in mullite-type Al{sub 4}B{sub 2}O{sub 9} by automated electron diffraction tomography
- Institute of Inorganic Chemistry and Analytical Chemistry, Jakob-Welder-Weg 11, Johannes Gutenberg-University Mainz, 55128 Mainz (Germany)
- Crystallography, Department of Geosciences, Klagenfurter Str. 2, GEO, University of Bremen, 28359 Bremen (Germany)
- Department of Materials and Geoscience, Technische Universität Darmstadt, Petersenstr. 23, 64287 Darmstadt (Germany)
- Department of Physics, Lehrstuhl für Kristallographie und Strukturphysik, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstr.3, 91058 Erlangen (Germany)
- Institute of Inorganic Chemistry and Crystallography, Leobener Str. NW2, University of Bremen, 28359 Bremen (Germany)
The crystal structure and disorder phenomena of Al{sub 4}B{sub 2}O{sub 9}, an aluminum borate from the mullite-type family, were studied using automated diffraction tomography (ADT), a recently established method for collection and analysis of electron diffraction data. Al{sub 4}B{sub 2}O{sub 9}, prepared by sol-gel approach, crystallizes in the monoclinic space group C2/m. The ab initio structure determination based on three-dimensional electron diffraction data from single ordered crystals reveals that edge-connected AlO{sub 6} octahedra expanding along the b axis constitute the backbone. The ordered structure (A) was confirmed by TEM and HAADF-STEM images. Furthermore, disordered crystals with diffuse scattering along the b axis are observed. Analysis of the modulation pattern implies a mean superstructure (AAB) with a threefold b axis, where B corresponds to an A layer shifted by ½a and ½c. Diffraction patterns simulated for the AAB sequence including additional stacking disorder are in good agreement with experimental electron diffraction patterns. - Graphical abstract: Crystal structure and disorder phenomena of B-rich Al{sub 4}B{sub 2}O{sub 9} studied by automated electron diffraction tomography (ADT) and described by diffraction simulation using DISCUS. - Highlights: • Ab-initio structure solution by electron diffraction from single nanocrystals. • Detected modulation corresponding mainly to three-fold superstructure. • Diffuse diffraction streaks caused by stacking faults in disordered crystals. • Observed streaks explained by simulated electron diffraction patterns.
- OSTI ID:
- 22658267
- Journal Information:
- Journal of Solid State Chemistry, Vol. 249; Other Information: Copyright (c) 2017 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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