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Structural characterization of Li alpha-sialon ceramics by high-resolution Al-27 and Si-29 NMR spectroscopy

Lookup NU author(s): Emeritus Professor Derek Thompson

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Abstract

High-resolution Si-29 and Al-27 NMR spectra have been obtained from seven crystalline samples of lithium alpha -sialon with different compositions. The Si-29 isotropic chemical shift is found to be constant within the experimental error across the whole substitution range and its value, delta (Si) approximate to -48 ppm, suggests that silicon remains largely in an SiN4 coordination for all compositions. The Al-27 1D MAS NMR spectra exhibit a range of tetrahedral coordinations AlOxN4-x (x=0-4), which vary as the aluminium and oxygen contents increase. The results are consistent with previous studies of sialons, which indicate that silicon prefers to be coordinated by nitrogen whereas aluminium prefers coordination by oxygen. Some NMR parameters are derived from two-dimensional Al-27 MQMAS spectra, including those for the resolved AlO4 peak. However, it is shown that this technique does not allow the different aluminium tetrahedral mixed environments (AlO3N, AlO2N2 and AlON3) to be resolved.

Publication metadata

Author(s): Thompson DP; Kempgens P; Harris RK; Yu ZB

Publication type: Article

Publication status: Published

Journal: Journal of Materials Chemistry

Year: 2001

Volume: 11

Issue: 10

Pages: 2507-2512

Print publication date: 01/01/2001

ISSN (print): 0959-9428

ISSN (electronic): 1364-5501

Publisher: Royal Society of Chemistry

URL: http://dx.doi.org/10.1039/b102168k

DOI: 10.1039/b102168k

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