A 11B and 7Li MAS-NMR study of sol-gel lithium triborate glass subjected to thermal densification

The effects of thermal densification on a sol-gel lithium triborate glass have been studied by 11B and 7Li NMR both static and at the magic angle (MAS). 11B spectra show that the boron average coordination is similar in sol-gel and melt-quenched samples and it does not change upon annealing. 7Li T1 is shorter (~8.5 s) in sol-gel glass as prepared than in its melt-quenched counterpart (~13 s) due to dipolar-dipolar LiH interaction. 7Li longitudinal relaxation behavior captures a part of a complex devitrification process which is driven by the loss of both residual solvent and moisture.