Atomic structure of beryllium boroaluminate glasses: A multi-nuclear NMR spectroscopic study

The short-range structure and network speciation have been studied in a series of beryllium boroaluminate glasses using 11B, 27Al and 9Be NMR spectroscopy. All glasses are characterized by a coexistence of BeO4, BO3, BO4, AlO4, AlO5 and AlO6 species. The concentrations of BO3, AlO5 and AlO6 species in these glasses are significantly higher and the geometry of the B–O and Al–O coordination polyhedra are unusually disordered compared to those in other alkali and alkaline-earth boroaluminate glasses reported previously in the literature. These results indicate that Be atoms may not play the typical role of a network-modifying cation in these glasses. This structural scenario is consistent with the highest field strength and electronegativity of Be among all alkali and alkaline-earth metals.