Formation, stability and crystal structure of mullite-type Al{sub 6−x}B{sub x}O{sub 9}

Journal Article · Tue Nov 15 04:00:00 EST 2016 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2016.08.018· OSTI ID:22658092

Hooper, T. J.N. ^[1]; Murshed, M. M. ^[2]; Dolotko, O.; Révay, Z.; Senyshyn, A. ^[3]; Schneider, H. ^[4]; Hanna, J. V. ^[1]; Gesing, Th. M. ^[2]; others, and

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1. Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)
2. Institut für Anorganische Chemie und Kristallographie, FB02, Leobener Straße/NW2, Universität Bremen, D-28359 Bremen (Germany)
3. Heinz Maier-Leibnitz Zentrum (MLZ), Technische Universität München, Lichtenbergstr. 1, D-85748 Garching (Germany)
4. Kristallographie, FB05, Klagenfurter Straße/GEO, Universität Bremen, D-28359 Bremen (Germany)

Mullite-type Al{sub 6−x}B{sub x}O{sub 9} compounds were studied by means of powder diffraction and spectroscopic methods. The backbones of this structure are chains of edge-connected AlO{sub 6} octahedra crosslinked by AlO- and BO-polyhedra. Rietveld refinements show that the a and b lattice parameters can be well resolved, thus representing an orthorhombic metric. A continuous decrease of the lattice parameters most pronounced in c-direction indicates a solid solution for Al{sub 6−x}B{sub x}O{sub 9} with 1.09≤x≤2. A preference of boron in 3-fold coordination is confirmed by {sup 11}B MAS NMR spectroscopy and Fourier calculations based on neutron diffraction data collected at 4 K. Distance Least Squares modeling was performed to simulate a local geometry avoiding long B-O distances linking two octahedral chains by planar BO{sub 3} groups yielding split positions for the oxygen atoms and a strong distortion in the octahedral chains. The lattice thermal expansion was calculated using the Grüneisen first-order equation of state Debye-Einstein-Anharmonicity model. - Graphical abstract: Local distortion induced by boron linking the octahedral chains. - Highlights: • Decreasing lattice parameters indicate a solid solution for Al{sub 6−x}B{sub x}O{sub 9} (1.09≤x≤2). • B-atoms induce a local distortion of neighboring AlO{sub 6} octahedra. • A preference of boron in BO{sub 3} coordination is confirmed by {sup 11}B MAS NMR spectroscopy. • An optimized structural model for Al{sub 6−x}B{sub x}O{sub 9} is presented.

• OSTI ID: 22658092
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. 243; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ALUMINIUM COMPOUNDS
BORATES
BORON OXIDES
EQUATIONS OF STATE
EXPERIMENTAL DATA
LATTICE PARAMETERS
LEAST SQUARE FIT
NEUTRON DIFFRACTION
NUCLEAR MAGNETIC RESONANCE
ORTHORHOMBIC LATTICES
SIMULATION
SOLID SOLUTIONS
STRUCTURAL MODELS
THERMAL EXPANSION