17O NMR studies of sodalites

An investigation into the crystallization of low-silica X zeolite

“…The elemental composition obtained from the Raman spectrum and the 29 Si MAS spectrum agrees with each other very well, both suggesting that the as-synthesized LSX zeolite has the Si/Al ratio of around 1. 23 Na MAS NMR spectroscopy has proven to be a powerful tool to determine cation distribution in hydrated and dehydrated zeolites [59]. Located at different crystallographic sites, Na ?…”

“…ions exhibit NMR signals with different chemical shifts. Thus, 23 Na MAS spectra were acquired to investigate the evolution of the local chemical environments of Na ? ions as a function of crystallization time (Fig.…”

“…The NMR experiments were carried out on a Varian/ Chemagnetics Infinityplus 400 WB spectrometer equipped with three rf channels operating at the field strength of 9.4 T. The Larmor frequencies of 1 H, 23 Na, 27 Al, and 29 Si were 399.5, 105.7, 104.1, and 79.4 MHz, respectively. The chemical shifts of 23 Na, 27 Al, and 29 Si were referenced to 1 M NaCl (0 ppm), 1 M Al(NO 3 ) 3 (0 ppm), and tetrakis(trimethylsilyl)-silane (SiMe 3 , -9.9 ppm with respect to liquid tetramethylsilane) [40].…”

“…Here, we report our recent work on the investigations of the crystallization of LSX zeolite. Relations between the structures of the intermediates and the local environments of 27 Al, 29 Si, 23 Na, and 39 K nuclei were probed by solid-state NMR spectroscopy in combination with other characterization techniques such as powder XRD and Raman spectroscopy. A typical procedure for hydrothermal synthesis of LSX zeolite gel samples was the following: 13.0 g potassium hydroxide, 8.7 g sodium hydroxide, and 34.4 g water were combined and subjected to vigorous stirring for 10 min.…”

Microscopic origins of macroscopic properties of silicate melts and glasses at ambient and high pressure: Implications for melt generation and dynamics

“…From the relatively well-established relationship between structurally relevant NMR parameters (isotropic chemical shift, ␦ iso , and quadrupolar coupling constant, C q ) and topology (Tossell and Lazzeretti, 1988;Grandinetti et al, 1995;Stebbins, 1998;Vermillion et al, 1998;Xue and Kanzaki, 1998;Grandinetti, 2000, 2003;Loeser et al, 2003), the distribution of these NMR parameters yields information about the distribution of bond angle and length. Na-O distance distributions in sodium silicate glasses were obtained from 23 Na 3QMAS NMR (Angeli et al, 2000).…”