1. Considerations on the symmetry of pure silica ITQ-7 zeolite (ISV) derived from 29Si MAS NMR and Rietveld analysis.
- Author
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Paillaud, Jean-Louis, Tzanis, Lydie, Marler, Bernd, Rigolet, Séverinne, Patarin, Joël, and Gies, Hermann
- Subjects
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SYMMETRY (Physics) , *SILICA , *ZEOLITES , *CHEMICAL synthesis , *MAGIC angle spinning , *NUCLEAR magnetic resonance spectroscopy , *RIETVELD refinement - Abstract
Pure silica ITQ-7 zeolite of topology ISV synthesized in fluoride media possesses a 3D 12-membered-rings pore system. Originally the structure of ITQ-7 zeolite was solved and refined from a calcined sample in the highest possible space group symmetry P4 2 / mmc . This space group leads to only 5 independent silicon T sites for this structure. However, this high symmetry was not supported by solid state 29 Si MAS NMR spectroscopy. In this short communication, we show from a revised 29 Si solid state MAS NMR and Rietveld analyses, that lowering of the space group symmetry from P4 2 / mmc to P4 2 consolidates structure model and experimental data, in particular, the number of non equivalent crystallographic T sites passing from 5 to 16, is in agreement with 29 Si solid state NMR spectroscopy. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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