XRD and Si MAS-NMR spectroscopy across the β-Lu2Si2O7-β-Y2Si2O7 solid solution |
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Authors: | Ana I Becerro Alberto Escudero |
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Institution: | Departamento de Química Inorgánica-Instituto de Ciencia de Materiales de Sevilla, Universidad de Sevilla-CSIC. Avda. Américo Vespucio, s/n. 41092 Sevilla, Spain |
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Abstract: | Samples in the system Lu2−xYxSi2O7 (0?x?2) have been synthesized following the sol-gel method and calcined to 1300 °C, a temperature at which the β-polymorph is known to be the stable phase for the end-members Lu2Si2O7 and Y2Si2O7. The XRD patterns of all the compositions studied are compatible with the structure of the β-polymorph. Unit cell parameters are calculated as a function of composition from XRD patterns. They show a linear change with increasing Y content, which indicates a solid solubility of β-Y2Si2O7 in β-Lu2Si2O7 at 1300 °C. 29Si MAS NMR spectra of the different members of the system agree with the XRD results, showing a linear decrease of the 29Si chemical shift with increasing Y content. Finally, a correlation reported in the literature to predict 29Si chemical shifts in silicates is applied here to obtain the theoretical variation in 29Si chemical shift values in the system Lu2Si2O7-Y2Si2O7 and the results compare favorably with the values obtained experimentally. |
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Keywords: | Solid solution Y2Si2O7 Lu2Si2O7 29Si MAS-NMR XRD Group electronegativity Polymorphism Silicates |
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