Network oxygen sites in calcium aluminoborosilicate glasses: Results from 17O{27Al} and 17O{11B} double resonance NMR

• 17O{11B} TRAPDOR NMR selects oxygen sites with and w/o B neighbors in glasses.
• 17O{27Al} TRAPDOR NMR selects oxygen sites with and w/o Al neighbors in glasses.
• Combining 17O{27Al} and 17O{11B} TRAPDOR selects O sites with Si only neighbors.
• In Ca Al-B-Silicates bridging oxygens with Al, B and Si neighbors are quantifiable.
• Non-bridging oxygens connected to Al or to B are detected in multicomponent glasses.

11B, 17O, and 27Al NMR has widely been used to quantify numerous aspects of oxide glass structure, but many issues remain to be resolved, including basic issues of assignment of overlapping 17O resonances. Double resonance NMR, involving cation spin pairs such as 27Al and 11B, has provided further details of network connectivities in some multicomponent glasses; very recent work on 27Al-17O has allowed unique identification of non-bridging oxygen (NBO) on aluminum cations in lanthanum aluminoborosilicate glasses [1]. Here we have explored 17O{27Al} and 17O{11B} TRAnsfer of Population in DOuble-Resonance (TRAPDOR) NMR experiments in several calcium aluminosilicate and aluminoborosilicate glasses. We have demonstrated clear distinction among resonances for 17O associated with boron and/or aluminum, including quantification of NBO associated with boron, aluminum and silicon in these multicomponent glasses. Additionally, spectral components for bridging oxygens and non-bridging oxygens with aluminum, boron, and silicon can also be at least in part separated, allowing for comparison to proportions expected if cations were connected via random mixing.