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Local order in silicate glasses has been observed by many experimental techniques to be similar to that in crystalline materials. Details of the intermediate-range order are more elusive, but essential for understanding the lack of long-range symmetry in glasses and the effect of composition on glass structure. Two-dimensional 17O dynamic-angle-spinning nuclear magnetic resonance experiments reveal intermediate-range order in the distribution of inter-tetrahedral (Si-O-Si) bond angles and a high degree of order in the disposition of oxygen atoms around the network-modifying cations.

An enhanced Rotor Assisted Population Transfer (RAPT) experiment is presented and used as a simple and fast technique to measure the magnitude of the nuclear quadrupolar coupling constant of half-integer quadrupolar nuclei. The enhanced RAPT sequence consists of a train of Gaussian pulses with alternating off-resonant frequencies of +/-nuoff. Simulated and experimental results demonstrating the method are given in the case of 87Rb (spin 3/2) and 27Al (spin 5/2) nuclei. The RAPT sequence is also used to selectively suppress resonances based on their quadrupolar coupling constant.

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The two-dimensional 17 O dynamic-angle spinning solid-state nuclear magnetic resonance spectrum of silica glass produced from the melt was measured. From this spectrum a three-dimensional histogram correlating 17 O chemical shift, quadrupolar coupling constant, and quadrupolar coupling asymmetry parameter for the bridging oxygen was obtained. Using existing correlations between NMR parameters and local structure, the distribution in quadrupolar coupling parameters was mapped into two-dimensional histograms correlating the Si-O-Si angle with Si-O distance, the Si-O-Si angle with Si-Si distance, and the Si-O distance with Si-Si distance. While the peak values for the Si-O-Si angle, the Si-O distance, and Si-Si distance distributions, at 147°, 1.59 Å, and 3.05 Å, respectively, are consistent within the precision of the NMR measurement with previous diffraction studies, the distribution widths are narrower than previous diffraction studies. The two-dimensional histogram reveals an unexpected strong positive correlation between the Si-O-Si angle and Si-O distance in the glass, running opposite to the trend generally found in crystalline silica polymorphs.