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Title: Synthesis and structural characterization of Al{sub 4}SiC{sub 4}-homeotypic aluminum silicon oxycarbide, [Al{sub 4.4}Si{sub 0.6}][O{sub 1.0}C{sub 2.0}]C

A new quaternary layered oxycarbide, [Al{sub 4.39(5)}Si{sub 0.61(5)}]{sub S}IGMA{sub 5}[O{sub 1.00(2)}C{sub 2.00(2)}]{sub S}IGMA{sub 3}C, has been synthesized and characterized by X-ray powder diffraction, transmission electron microscopy and energy dispersive X-ray spectroscopy (EDX). The title compound was found to be hexagonal with space group P6{sub 3}/mmc, Z=2, and unit-cell dimensions a=0.32783(1) nm, c=2.16674(7) nm and V=0.20167(1) nm{sup 3}. The atom ratios Al:Si were determined by EDX, and the initial structural model was derived by the direct methods. The final structural model showed the positional disordering of one of the three types of Al/Si sites. The maximum-entropy methods-based pattern fitting (MPF) method was used to confirm the validity of the split-atom model, in which conventional structure bias caused by assuming intensity partitioning was minimized. The reliability indices calculated from the MPF were R{sub wp}=3.73% (S=1.20), R{sub p}=2.94%, R{sub B}=1.04% and R{sub F}=0.81%. The crystal was an inversion twin. Each twin-related individual was isostructural with Al{sub 4}SiC{sub 4} (space group P6{sub 3}mc, Z=2). - Graphical abstract: A new oxycarbide discovered in the Al-Si-O-C system, Al{sub 4}SiC{sub 4}-homeotypic [Al{sub 4.4}Si{sub 0.6}][O{sub 1.0}C{sub 2.0}]C. The crystal is an inversion twin, and hence the structure is represented by a split-atom model. The three-dimensional electron density distributionsmore » are determined by the maximum-entropy methods-based pattern fitting, being consistent with the disordered structural model.« less
Authors:
;  [1] ;  [2] ;  [1]
  1. Department of Environmental and Materials Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)
  2. Cooperative Research Facility Center, Toyohashi University of Technology, Toyohashi 441-8580 (Japan)
Publication Date:
OSTI Identifier:
21372532
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 183; Journal Issue: 3; Other Information: DOI: 10.1016/j.jssc.2010.01.012; PII: S0022-4596(10)00013-7; Copyright (c) 2010 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ALUMINIUM COMPOUNDS; CALCULATION METHODS; ELECTRON DENSITY; ENTROPY; HCP LATTICES; LATTICE PARAMETERS; OXYCARBIDES; SILICON COMPOUNDS; SPACE GROUPS; STRUCTURAL MODELS; SYNTHESIS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY CARBON COMPOUNDS; COHERENT SCATTERING; CRYSTAL LATTICES; CRYSTAL STRUCTURE; DIFFRACTION; ELECTRON MICROSCOPY; HEXAGONAL LATTICES; MICROSCOPY; OXYGEN COMPOUNDS; PHYSICAL PROPERTIES; SCATTERING; SPECTROSCOPY; SYMMETRY GROUPS; THERMODYNAMIC PROPERTIES