Distinguishing between Structural Models of β′-Sialons Using a Combined Solid-State NMR, Powder XRD, and Computational Approach

Seymour, V.R. and Smith, M.E. (2019) Distinguishing between Structural Models of β′-Sialons Using a Combined Solid-State NMR, Powder XRD, and Computational Approach. Journal of Physical Chemistry A, 123 (45). pp. 9729-9736. ISSN 1089-5639

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Abstract

β′-Sialons (Si6–zAlzOzN8–z, where 0 ≤ z ≤ ∼4.2) are studied using a combination of 29Si and 27Al solid-state NMR, using magnetic fields of up to 20 T, powder X-ray diffraction, and density functional theory (DFT) calculations of both the structure and NMR parameters. Four different structural models have been proposed in the literature for the replacement of silicon and nitrogen by aluminum and oxygen within a β-Si3N4-structured lattice. Experimental data are presented for the variation with composition (z) of the unit cell parameters from diffraction and the local coordination units present suggested by NMR data. The experimental data are compared to the changes with composition in the DFT calculations of the structure and the NMR parameters according to the four models, allowing the models to be distinguished. It is shown that only one of these, the domain model, is fully consistent with all of the experimental data and is, therefore, a good structural model for β′-sialons. More speculatively, it is suggested that for the domain model, 27Al NMR data might provide a constraint on the thickness of its aluminum-rich layers.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Physical Chemistry A
Additional Information:
This document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of Physical Chemistry A, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://pubs.acs.org/doi/full/10.1021/acs.jpca.9b06729
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/1600/1606
Subjects:
ID Code:
139133
Deposited By:
Deposited On:
16 Dec 2019 16:30
Refereed?:
Yes
Published?:
Published
Last Modified:
29 Mar 2020 06:53