Rights statement: 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
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Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
}
TY - JOUR
T1 - Distinguishing between Structural Models of β′-Sialons Using a Combined Solid-State NMR, Powder XRD, and Computational Approach
AU - Seymour, V.R.
AU - Smith, M.E.
N1 - 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
PY - 2019/11/14
Y1 - 2019/11/14
N2 - 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.
AB - 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.
U2 - 10.1021/acs.jpca.9b06729
DO - 10.1021/acs.jpca.9b06729
M3 - Journal article
VL - 123
SP - 9729
EP - 9736
JO - Journal of Physical Chemistry A
JF - Journal of Physical Chemistry A
SN - 1089-5639
IS - 45
ER -