The ring structure of boron trioxide glass

A new experiment, sensitive to the dihedral angle distribution of neighbori ng structural units, was applied to boron trioxide glass. The experiment co nsisted of correlating the NMR frequencies of neighboring baron nuclei. The frequencies are identical if the boron oxide polyhedra containing the two borons are co-planar, as found in ring systems, but differ for non-co-plana r geometries. Through the rate of growth of signal intensity arising from t he non-co-planar case. as compared to that obtained in a boron trioxide cry stal of known structure, the fraction of boron contained in rings in the gl ass was determined to be 0.70 +/- 0.08. (C) 2000 Elsevier Science B.V. All rights reserved.