Oxygen/nitrogen ordering in lanthanum new phase (La3Si8N11O4) |
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Authors: | Ahmet Koroglu David C Apperley |
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Institution: | a Department of Physics, Science and Arts Faculty, University of Ondokuz Mayis, Kurupelit, Samsun, 55139, Turkeyb School of Chemical Engineering and Advanced Materials, University of Newcastle, Herschel Building, Newcastle upon Tyne, NE1 7RU, UKc Department of Chemistry, University of Durham, Science Laboratories, South Road, Durham, DH1 3LE, UK |
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Abstract: | High-resolution 17O NMR spectra have been collected for crystalline samples of lanthanum new phase, La3Si8N11O4. In conjunction with previously published 29Si and 15N spectra obtained for this phase, and in the light of the high-quality crystal structure data reported recently, a more detailed interpretation of the NMR spectra is presented than was possible in previous studies. The non-bridging oxygens in the structure are responsible for the single sharp peak seen in the 17O spectrum at 188 ppm; the remaining oxygens, occupying bridging sites shared with nitrogen, show up only weakly on the 17O spectrum as a broad diffuse band centered around zero ppm. The peak at −57.3 ppm on the 29Si spectrum is believed to correspond to an overlap of SiN4] and SiON3] environments, with the −68.2 ppm peak corresponding to an SiO2N2] environment. |
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Keywords: | MAS NMR Sialons Lanthanum new phase |
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