Structural Characterization of Glass from the Inversion of ²³Na and ²⁷Al 3Q-MAS NMR Spectra

Abstract

A spectrum-inversion approach to extract information from MQ-MAS NMR spectra in glasses is presented. This allows the reconstruction of the underlying two-dimensional distribution of the isotropic chemical shift correlated to the quadrupolar interaction. The dependency upon the quadrupolar interaction and the RF field strength of coherence transfers involved in the MQ-MAS experiment are taken into account in the present approach. The performance of the inversion procedure is examined. Thereafter, we attempt to correlate the distributions of each interaction to structural local information. Two complex glasses (a borosilicate and a basaltic-like glass) have been studied using 17Al and 23Na 3Q-MAS NMR. These two nuclei allowed us to investigate their local environment. The interpretation of the different site distributions is discussed in terms of topological disorder, i.e., the distribution of specific geometrical parameters such as bond distances and angles. Using the semiempirical relationships previously established with crystalline silicate compounds, the distributions of the Na−O distance and the Al−O−Si bond angle have been determined from the extracted distributions of the isotropic chemical shift. The limits of the interpretation of quadrupolar interaction distributions are also discussed.

MAS-NMR studies of glasses and glass-ceramics based on a clinopyroxene–fluorapatite system

“…8) Na MAS-NMR for pure Jd has been reported previously at 11 ppm [44][45][46][47] , which when corrected for field effects (14.1T) the peak comes at 0 ppm. This is clearly seen, at 0 ppm, the site for DJ1.…”

27Al NMR Studies of Aluminosilicate Glasses

“…The Czjzek model was recently extended to separate the contributions from the local coordination environments and longer range effects to the effective C Qη -value [120]. Moreover, de Lacaillerie et al [107] demonstrated that the Czjzek distribution produces an average η % 0:61, which is close to that of η % 0.50 [121][122][123] sometimes invoked as a fixed value together with a distribution of C Q in amorphous materials.…”

Procedures for Labeling the High-Resolution Axis of Two-Dimensional MQ-MAS NMR Spectra of Half-Integer Quadrupole Spins

“…Otherwise, we have to use conventions whose apparent carrier frequencies are always positive. This is the reason for which conventions C z [38,59,96,98,[106][107][108] and C k(1) [17,29,68,72,77,87,91,93,97,98,[109][110][111] are the most applied.…”