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

Journal Article · Thu Oct 15 04:00:00 EDT 2015 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/J.JSSC.2015.06.043· OSTI ID:22486800

Banno, Hiroki ^[1]; Funahashi, Shiro ^[2]; Asaka, Toru ^[1]; Hirosaki, Naoto ^[2]; Fukuda, Koichiro ^[1]

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1. Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)
2. Sialon Unit, National Institute for Materials Science, Tsukuba 305-0044 (Japan)

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 plus 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.

• OSTI ID: 22486800
• Journal Information: Journal of Solid State Chemistry, Journal Name: Journal of Solid State Chemistry Vol. 230; ISSN 0022-4596; ISSN JSSCBI
• Country of Publication: United States
• Language: English

Related Subjects

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