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Title: Disordered crystal structure of 20H-AlON, Al{sub 10}O{sub 3}N{sub 8}

The disordered crystal structure of 20H-AlON (Al{sub 10}O{sub 3}N{sub 8}) was determined by combined use of X-ray powder diffraction and transmission electron microscopy. The title compound is hexagonal with space group P6{sub 3}/mmc (Z=2) and the unit-cell dimensions are a=0.307082(5) nm, c=5.29447(8) nm and V=0.432376(12) nm{sup 3}. The structural model showed the positional disordering of three of the six Al sites in the unit cell. The reliability indices calculated from the Rietveld method were R{sub wp}=6.97%, S (=R{sub wp}/R{sub e})=1.68, R{sub p}=5.45%, R{sub B}=5.13% and R{sub F}=4.56%. We interpreted the disordered structure of 20H-AlON as a statistical average of six different types of ordered structural configurations, which are composed of an octahedral [Al(O, N){sub 6}] layer and tetrahedral [Al(O, N){sub 4}] layers. We demonstrated the high correlations between the hexagonal unit-cell dimensions and the octahedral layer concentrations for AlON and SiAlON polytypoids. - Graphical abstract: Variations of a and c/(n{sub O}+n{sub T}) with n{sub O}/(n{sub O}+n{sub T}). The a and c are the hexagonal unit-cell dimensions of AlON, SiAlON and AlN. The n{sub O} and n{sub T} are, respectively, the numbers of octahedral and tetrahedral layers in the unit cells. The unit-cell dimensions in literature are plotted in black plusmore » for AlON and black cross for SiAlON. The unit-cell dimensions of AlN are a=0.3110 nm and c=0.4980 nm. - Highlights: • Crystal structure of Al10O3N8 is determined by laboratory X-ray powder diffraction. • The atom arrangements are represented by the split-atom model. • Six types of ordered atom arrangements are derived from the disordered structure. • Hexagonal unit-cell dimensions changed systematically for AlON and SiAlON compounds.« less
Authors:
 [1] ;  [2] ;  [3] ;  [1] ;  [3] ;  [1]
  1. Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)
  2. (Japan)
  3. Sialon Unit, National Institute for Materials Science, Tsukuba 305-0044 (Japan)
Publication Date:
OSTI Identifier:
22486800
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 230; Other Information: Copyright (c) 2015 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; ALUMINIUM NITRIDES; ALUMINIUM OXIDES; CERAMICS; CONCENTRATION RATIO; CORRELATIONS; HCP LATTICES; LATTICE PARAMETERS; LAYERS; SILICON NITRIDES; STRUCTURAL MODELS; TRANSMISSION ELECTRON MICROSCOPY; X-RAY DIFFRACTION