A High-Resolution NMR Study of the La-Si-Al-O-N System

Dupree, R. and Lewis, M.H. and Smith, M.E. (1989) A High-Resolution NMR Study of the La-Si-Al-O-N System. Journal of the American Chemical Society, 111 (14). pp. 5125-5132. ISSN 0002-7863

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Hieh-resolution 27Al, 29Si, and 139La NMR spectra have been obtained from crystalline phases of the La-Si-Al-O-N system. These results have further defined the 29Si chemical shift ranges in mixed coordination tetrahedra (i.e., SiOxN4-x, 0 ≤ x ≤ 4) and enabled the cation's influence on the chemical shift in such units to be investigated for the first time. The ability to distinguish distinct local environments, despite overlap of the 29Si chemical shift ranges from different units, has allowed structural refinement of certain phases (e.g., La4Si2O7N2). The 27Al NMR spectrum of LaAlO3 shows appreciable intensity from transitions other than the 1/2↔−1/2, emphasing the difficulties of quantitatively interpreting NMR spectra of quadrupole nuclei. For the first time MAS is applied to 139La NMR and is shown to have some limited applicability to the study of ceramics. High-resolution multinuclear NMR is shown to be a powerful monitor of phase development and probe of compositional detail in complex ceramic phase mixtures. © 1989, American Chemical Society. All rights reserved.

Item Type:
Journal Article
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Journal of the American Chemical Society
Uncontrolled Keywords:
?? ceramic materials--spectroscopic analysisnuclear magnetic resonancespectroscopyapatiteceramic mixturessilicon oxynitridelanthanum compoundsbiochemistrycolloid and surface chemistrygeneral chemistrycatalysischemistry(all) ??
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04 Jan 2019 11:45
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16 Jul 2024 10:55