Dipolar Solid State NMR Approaches Towards Medium-Range Structure in Oxide Glasses

Abstract

Modern solid state nuclear magnetic resonance presents new powerful opportunities for the elucidation of medium range order in glasses in the sub-nanometer region. In contrast to standard chemical shift spectroscopy, the strategy presented here is based on the precise measurement and quantitative analysis of internuclear magnetic dipole-dipole interactions, which can be related to distance information in a straightforward manner. The review discusses the most commonly employed experimental techniques, producing dipolar coupling information in both homo- and heteronuclear spin systems. The approach is particularly powerful in combination with magic-angle sample spinning, producing site-resolved dipolar coupling information. We present new applications to oxide-based network glasses, permitting network connectivities and spatial cation distributions to be elucidated.

Structural Similarity on Multiple Length Scales and Its Relation to Devitrification Mechanism: A Solid-State NMR Study of Alkali Diborate Glasses and Crystals

“…Figure 2 shows the single pulse 11 B MAS spectra of the investigated samples. All the spectra reveal two distinct spectral components: a sharp line at around 1 ppm assigned to tetrahedral [BO 4 14 Careful inspection shows that (1) the chemical shift of the B4 site shifted to downfield by 1.2 ppm during the L2B crystallization, showing the small structural changes of this high symmetry site, while that of N2B system shifts only marginally upon devitrification and (2) the N 4 values of glasses for both systems are slightly different from those of corresponding crystalline phases, which may be due to the rearrangement of borate groups in the nucleation process.…”

“…3 However, relatively little information is available to test this hypothesis because of the lack of longrange periodicity in glass and the absence of analysis methods that can be used to determine the intermediate-range order (3-10 Å). 4 Numerous glass studies have focused on studying short-range order (1.5-3 Å) in glass, i.e., the first-neighbor coordination environments 5 and tetrahedral connectivity. 6 The problem is that typically the features of the local environment of glass are essentially the same as those of analogous crystalline phases, regardless of the nucleation mechanism.…”

27Al NMR Studies of Aluminosilicate Glasses

“…The utilization of distance/geometry-dependent homo/heteronuclear spin-spin interactions involving 27 Al is a promising avenue, but the engineering and application of such MAS NMR techniques are still in their infancy; e.g., see Refs. [24,91,93,175,289] for recent reviews.…”

Local Li Cation Coordination and Dynamics in Novel Solid Electrolytes

“…With REDOR, the structural motifs are evaluated via the determination of internuclear distances between two nuclei I and S, measuring the heteronuclear dipolar coupling between these two nuclei, which scales with the inverse cubic power of the distance. For further details of these advanced NMR techniques the reader is referred to recent excellent reviews of the field [84,88,89].…”