A neutron diffraction investigation of the structure of vitreous boron trioxide

An extended review is given of previous structural work on vitreous B 2O 3 which comes to the conclusion that the best structural model comprises a mixed random network of boroxol groups and independent BO 3 triangles. The neutron scattering length for 11B is slightly greater than that for oxygen so that neutrons should be more sensitive than X-rays to the presence of boroxol groups. Results are presented from a neutron diffraction investigation of vitreous 11B 2O 3, using the Harwell linac pulsed neutron source, in which data have been obtained to high scattering vector values ( Q max =40 A ̊ −1 ) yielding good real space resolution. It is concluded that these data are consistent with a mixed boroxol group - independent BO 3 triangle network having 60% of the boron atoms in boroxol rings.