29Si- und 23Na-Festkörper-MAS-NMR-Untersuchungen an Modifikationen des Na2Si2O5 |
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Authors: | D Heidemann C Hübert W Schwieger P Grabner K-H Bergk P Sarv |
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Abstract: | 29Si and 23Na Solid State MAS NMR Investigations of Modifications of the Sodium Phyllosilicate Na2Si2O5 . The results of 29Si- and 23Na-MAS NMR investigations on four modifications of the synthetic Na2Si2O5 demonstrate that the α-, β- and δ-modifications are characterized unequivocally by the parameters of the corresponding NMR spectra. The studies on γ-Na2Si2O5 show that this sample contains a large amount of secondary compounds. For α- und β-Na2Si2O5 the the structural details of the silicate sheets are reflected by the 29Si MAS NMR spectra while from the 23Na MAS NMR spectra conclusions about the coordination number of the sodium atoms can be derived. The 29Si MAS NMR investigations on δ-Na2Si2O5 indicate that the silicate sheet of this modification consist of identical SiO4-tetrahydra the parameter of which differ from those of α- and β-Na2Si2O5. The 23Na MAS NMR studies show that in the interlayer space of δ-Na2Si2O5 two nonidentical sodium atoms exists. The NMR results give rise to the suggestion that one of the sodium is surrounded by five and the other one by six oxygen atoms. |
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Keywords: | Layered sodium silicates Disilicates Solidstate NMR Magic-angle spinning NMR 29Si MAS NMR 23Na MAS NMR Quadrupolar nuclei Line shape simulation |
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