Local Structure of Alkaline-Earth Boroaluminate Crystals and Glasses: II, 11B and 27Al MAS NMR Spectroscopy of Alkaline-Earth Boroaluminate Glasses |
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Authors: | Bruce C. Bunker R. James Kirkpatrick Richard K. Brow Gary L. Turner Carolyn Nelson |
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Affiliation: | Sandia National Laboratories, Albuquerque, New Mexico 87185;Department of Geology, University of Illinois, Urbana, Illinois 61801;Spectral Data Services, Champaign, Illinois 61820 |
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Abstract: | 11B and 27Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectra of alkaline-earth boroaluminate glasses show that the structure of these glasses are far more complicated than previously thought. The relative concentrations of 3- and 4-coordinated boron vary as found by previous investigators using continuous-wave NMR methods, but the 27Al NMR spectra indicate the presence of Al in 4-, 5-, and 6-fold coordination, in contrast to previous assignments. Analysis of the data based on local charge balance considerations provides a qualitative model that correctly predicts compositional variations of the NMR peak intensities and 27Al chemical shifts for a wide range of boroaluminate glass compositions. |
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Keywords: | aluminoborate glass nuclear magnetic resonance structure models |
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